A 'trigger' revs up DNA shuffling to make antibodies
A group of researchers at Johns Hopkins Medicine announce they've learned how an enzyme that reshuffles DNA on one of those rare occasions -- during the birth of new white blood cells -- helps ensure the process doesn't go wrong. The enzyme, RAG, short for recombination activating a gene, only goes to work in developing white blood cells. It makes cuts to highly specific sites on DNA, allowing bits of the genetic material to move around and form new sequences. These sequences serve as the blueprints for novel antibodies that recognize and fend off viruses, bacteria and other biological threats. They also sometimes spark allergies to harmless bystanders, like pollen. When the process goes awry, it can even lead to uncontrolled white blood cell growth, including leukemia.
With the previous findings that RAG is made up of two parts, RAG-1 and RAG-2, and that RAG-1 cuts the DNA, they began with the question that whether RAG-2 was merely anchoring RAG to the site where it could do its work or was actually changing RAG-1's shape to activate it. It turned out that when RAG-2 hooks on to the histone fragment, it changes the shape of the RAG complex, thus activating it. As a matter of fact, many of the similar enzymes are involved in cell growth, including the uncontrolled growth of cancer, the group is now investigating whether other enzymes that bind to the same modified histone site might have a similar control mechanism to help in identifying targets for drug development. Read more »
Scientists Researchers create mosquito resistant to dengue virus
A research paper published Jan. 12 in PLOS Neglected Tropical Diseases, shows it is possible, in the lab, to boost the Aedes aegypti mosquito's natural ability to fight the dengue virus as a first step toward suppressing its ability to spread the disease.
Researchers say that Aedes aegypti mosquitoes mount an immune system response when exposed to the dengue virus, but it appears to be too weak to stop transmission. Knowing this, they were able to manipulate a component of the immune system, the JAK-STAT pathway, that regulates the production of antiviral factors. They did this in a part of the mosquito known as the fat body, its version of the liver. Notably, the JAK-STAT pathway is involved in an antiviral activity in humans as well.
The genetic modification resulted in fewer mosquitoes becoming infected. Most of those that did have very low levels of dengue virus are in their salivary glands, the location from which it gets transmitted to humans. These experiments, however, didn't lower the level of virus in all mosquitoes to zero, something that puzzled the scientists. They say more research is needed to understand whether this level of virus suppression would be enough to halt disease transmission, and they are working on other experiments to see if they can produce antiviral factors in the gut, which could assist in inducing a stronger immune response and possibly confer resistance to the other viruses.
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Scientists produced functional heart pacemaker cells
Sinoatrial node pacemaker cells are the heart's primary pacemaker, controlling the heartbeat throughout life. Defects in the pacemaker can lead to heart rhythm disorders that are commonly treated by implantation of electronic pacemaker devices.
A group of researchers used a developmental-biology approach to establish a specific protocol for generating the pacemaker cells. Based on previous findings in animal models, the researchers tested and mapped out the specific developmental pathway of how human pluripotent stem cells become pacemaker cells. This was achieved by testing different signaling molecules at different times throughout the 21 days to guide the cells towards their goal. Once the team established which signaling pathways are activated at different stages to generate the pacemaker cells, they demonstrated that the new pacemaker cells could initiate and regulate the heartbeat in rats.
The researchers noted that human clinical trials to test such biological pacemakers are from five to ten years away, and that the next step is to launch safety and reliability pre-clinical trials on the pacemaker cells. Meanwhile, researchers can use their new technology to make pacemaker cells from patients suffering from pacemaker dysfunction. They can then use these patient-specific cells to study the "disease in a (petri) dish" and to identify new drugs that will improve their pacemaker function.
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Scientists developed antigen-specific CD8 T cells related assay to test immune response
The immune system orchestrates large- and small-scale attacks on numerous targets, including viruses, bacteria, and cancer, but an also misfire, causing allergy or autoimmune reactions. Compounding the problem, not every immune reaction is equal -- sometimes a necessary reaction is not strong enough or may be too strong.
CaFlux, an immunology test developed by scientists at Thomas Jefferson University, functions by attaching immune cells that can both respond to and display potential immune targets, and then flowing potential antigens across to identify "matches." If the addition of antigen leads to a match between a displayer and responder, the two cells become attached via their receptors. This triggers the opening of calcium channels, which activates green fluorescence in the cells. The green light can be easily detected under a microscope and quantified by image-reading software. Therefore, a stronger match leads to greater calcium influx into the cell and a brighter green color. A weaker match causes less calcium to enter the cell over a longer time period, resulting in a dimmer glow without a strong spike.
The test can help researchers observe both how many T-cells respond in a given sample and how powerfully and rapidly each individual cell responds over time. These three pieces of information can be used to more accurately predict how a person would react to a wide array of immune threats, from viral or bacterial attacks to allergens.
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Scientists developed therapeutic protein to protect nerve cells from Huntington's disease
Because mitochondrial dysfunction is thought to play an important role in the pathogenesis of Huntington's disease, a group of scientists investigated the binding proteins of mutant huntingtin on mitochondria, as recently published in Nature Communications.
These researchers characterized valosin-containing protein (VCP). They showed that VCP was abundant in the mitochondria of mice with mutant huntingtin, as well as in nerve cells donated by Huntington's disease patients. VCP inside the mitochondria only interacted with mutant, but not normal, huntingtin protein. Nerve cells exhibiting VCP-mutant huntingtin interactions dysfunction and self-destruction.
The team identified the regions of VCP and mutant huntingtin that interacted. They cleverly designed a small protein, or peptide, with the same regions to disrupt the VCP-mutant huntingtin protein interaction. In nerve cells exposed to their peptide, VCP and mutant huntingtin bound the peptide rather than each other. Nerve cells exposed to the novel peptide contained healthier mitochondria compared to unexposed cells. In fact, the peptide prevented VCP from relocating to the mitochondria at all and prevented nerve cell death.
According to the authors, the next step will be to determine if the peptide has effects in addition to those at the subcellular level and if the peptide can be used therapeutically to prevent Huntington's disease symptoms.
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First 3-D map of cell-building protein linked to cancer
DCLK1 is a protein that assembles scaffolds within cells called microtubules. These rope-like structures impart shape to cells, enable movement and cell division, and are crucial in enabling the growth and spread of cancer cells. More than one in 10 stomach cancers have defective forms of DCLK1; similar forms have also been found in kidney, rectal, and pancreatic cancers.
Scientists at the Walter and Eliza Hall Institute, Dr. Onisha Patel and Dr. Isabelle Lucet, used the Australian Synchrotron to reveal the three-dimensional structure of a part of DCLK1 known as the 'kinase domain'.
Working with Professor Matthias Ernst and Dr. Michael Buchert at the Olivia Newton-John Cancer Research Institute, the team was able to pinpoint the parts of DCLK1 that can go wrong in cancer cells, thereby providing new information regarding the function of the protein. The research is published in the journal Structure.
The team created a detailed map of the DCLK1 kinase domain using the Australian Synchrotron, providing new information about how the part of the protein functioned, Dr. Patel said. Read more »
Researchers find herpes strain in the nervous system
Human herpesvirus 6A (HHV-6A), HHV-6B, and HHV-7 are classified as roseoloviruses. A group of scientists have recently discovered that pigtailed macaques are naturally infected with viral homologs of HHV-6 and HHV-7, which were provisionally named MneHV6 and MneHV7, respectively. In this study, the scientists confirm that MneHV7 is genetically and biologically similar to its human counterpart, HHV-7. They also determined thecomplete unique MneHV7 genome sequence and provide a comprehensive annotation of all genes. They characterized viral transcription profiles in salivary glands from naturally infected macaques and showed that broad transcriptional activity across most of the viral genome is associated with high viral loads in infected parotid glands and that late viral protein expression is detected in salivary duct cells and peripheral nerve ganglia. This study provides new insights into the natural behavior of an extremely prevalent virus and establishes a basis for subsequent investigations of the mechanisms that cause HHV-7 reactivation and associated disease. Read more »
Fat cells may play a key role in battle against breast cancer
Previously, adipose tissue (body fat) was thought of as an energy reserve. However, fat cells are now believed to be active cells that produce more than 400 adipokines (hormones) that eventually enter the bloodstream and circulate in the body. Interestingly, scientists at New York University found that the hormones produced by fat cells could promote breast cancer growth in obese people, whereas they prevent breast cancer growth in lean people.
Using a rodent model, the researchers analyzed whether the fat cells are a link between obesity and breast cancer and whether interventions targeting obesity counteract any of the life-threatening effects of breast cancer. The research published in Journal of Applied Physiology points out exercise, which has no harmful side effects as many cancer drugs, as a potentially beneficial therapy for some breast cancer patients.
Scientists figure out why period pain hurts so much
Researchers have finally found a lead to explain why period pain and premenstrual symptoms (PMS) can suck so much for some women.
After surveying 2,939 women in the US, a team of researchers from the University of California, Davis, showed that there is a positive correlation between PMS severity and the presence of high-sensitivity C-reactive protein (hs-CRP).
Hs-CRP is a biomarker for inflammation in the body, so the researchers suggest that women with elevated levels of hs-CRP would have more inflammation are likely to experience the worse PMS, excluding headaches.
In the Journal of Women's Health, the researchers reported that "Premenstrual mood symptoms, abdominal cramps/back pain, appetite cravings/weight gain/bloating, and breast pain but not headache appear to be significantly and positively related to elevated hs-CRP levels, a biomarker of inflammation, although with modestly strong associations, even after adjustment for multiple confounding variables."
Study unmasks new infection-fighting T cells
After years of defending our body against influenza and other infectious diseases, the immune system gradually begins to lose its oomph for fighting infections. As a result, viruses, bacteria, and other microbial intruders become the common killers in older adults aged 65 and above. However, new findings from a study led by University of Arizona Health Sciences Department of Immunobiology, show that it may not have to be that way.
Researchers at the University of Arizona examined the blood samples from 92 volunteers, aged between 21 and 97 yrs, and focused specifically on a subset of T cells—white blood cells that fight infection and decrease in number with age—called "naïve T cells" as they have not yet been exposed to any virus or other infectious agents.
These naive T cells can become effector T cells and unlike the naïve cells, which cannot fight the viruses, effector cells are "armed" with anti-viral molecules that can clear the viruses. This breakthrough was achieved when the researchers discovered that on stimulating naïve T cells with pieces of virus, a portion of the cells began making interferon-gamma, a powerful anti-viral molecule.
A human heart cell was chemically reprogrammed from a human skin cell
Adult hearts have a very limited ability to generate new cells, so scientists have searched for a way to replace cells lost after a heart attack, such as transplanting adult heart cells or stem cells into the damaged heart. However, these efforts have been largely ineffective, as most transplanted adult cells do not survive or integrate properly into the heart, and few stem cells can be coaxed into becoming heart cells. An alternative approach pioneered by Deepak Srivastava, MD, director of cardiovascular and stem cell research at Gladstone, used genes to convert scar-forming cells in the heart of animals into new muscle that improved the function of the heart. A chemical reprogramming approach to do the same may offer an easier way to provide the cues that induce heart muscle to regenerate locally.
In the Science study, the researchers used a cocktail of nine chemicals to change human skin cells into beating heart cells. By trial and error, they found the best combination of chemicals to begin the process by changing the cells into a state resembling multi-potent stem cells, which can turn into many different types of cells in a particular organ. A second cocktail of chemicals and growth factors helped transdifferentiate the cells into heart muscle cells.
With this method, more than 97% of the cells began beating, a characteristic of fully developed, healthy heart cells. The cells also responded appropriately to hormones, and molecularly, they resembled heart muscle cells, rather than skin cells. What's more, when the cells were transplanted into a mouse heart early in the process, they developed into healthy-looking heart muscle cells within the organ.
In the second study, published in Cell Stem Cell, the scientists created neural stem cells from mouse skin cells using a similar approach.
The chemical cocktail again consisted of nine molecules, some of which overlapped with those used in the first study. Over ten days, the cocktail changed the identity of the cells, until all of the skin cell genes were turned off and the neural stem cell genes were gradually turned on. When transplanted into mice, the neural stem cells spontaneously developed into the three basic types of brain cells: neurons, oligodendrocytes, and astrocytes. The neural stem cells were also able to self-replicate, making them ideal for treating neurodegenerative diseases or brain injury. Read Science paper and Cell Stem Cell paper for details.
Scientists get first-ever glimpse of 'teenage' HIV-neutralizing antibody
HIV has been hard to beat because the virus mutates rapidly and has a sturdy set of defenses, including a "shield" of glycan molecules on the surface of its envelope glycoproteins. These glycoproteins are the viral machinery used to make initial contact and subsequently infect human host cells.
The antibody in the new study came from a patient in China who was what scientists call an "elite" controller, meaning the patient's immune system had managed to create antibodies with some ability to fight the disease. The patient was among the top 5% of neutralizers assessed in a screening of hundreds of Chinese HIV patients by China CDC scientists.
Genetically, the antibody found in this donor resembled members of the VRC01 class of antibodies, which are "broadly neutralizing antibodies," named for their ability to target a key site of vulnerability on many strains of the virus.
Further studies into the genetics and structure of the antibodies showed that the antibodies were a precursor to mature VRC01 antibodies; in other words, the antibodies represented a middle stage in the evolution of this class of HIV killers.
The scientists also spotted a hurdle they will have to overcome as they engineer their own antibodies. The teenage VRC01 has a slightly longer amino acid chain at one site than the mature version, and this chain clashes with part of the glycoprotein shield (gp120) on HIV and prevents the antibody from effectively neutralizing the virus. Read more »
Scientists successfully grow skin in the lab
Research involving bioengineered tissues has led to important achievements in recent years, with a number of different tissue types being created, but there are still obstacles to overcome. In the area of skin tissue research, epithelial cells have been successfully grown into implantable sheets, but the epithelial cells did not have the proper appendages (oil-secreting and sweat glands) that would allow the epithelial cells to function as normal tissue.
To perform the work, which was published in Science Advances, the researchers obtained cells from mouse gums and used chemicals to transform the cells into stem cell-like iPS cells. In culture, the cells properly developed into embryoid bodies (EBs), a three-dimensional clump of cells that partially resembles the developing embryo in an actual body. The researchers created EBs from iPS cells using Wnt10b signaling, then implanted multiple EBs into immune-deficient mice, where the EBs gradually changed into differentiated tissues, following the pattern of an actual embryo. Once the tissue had differentiated, the scientists transplanted the EBs out of the mice and into the skin tissues of other mice, where the tissues developed normally as integumentary tissue. The tissue between the outer and inner skin that is responsible for much of the function of the skin in terms of hair shaft eruption and fat excretion. The scientists also found that the implanted tissues made normal connections with the surrounding nervous and muscle tissues, allowing the implanting tissues to function normally.
One important key to the development was that treatment with Wnt10b, a signaling molecule, resulted in a larger number of hair follicles, making the bioengineered tissue closer to natural tissue. Read more »
Different kinds of physical activities have been shown to cut the risk for AD in half
A study conducted by investigators at UCLA Medical Center and the University of Pittsburgh was the first to show that virtually any type of aerobic physical activity can improve brain structure and reduce the risk for Alzheimer's disease.
The researchers studied a cohort of patients in the 30-year Cardiovascular Health Study (876 in all) across 4 research sites in the United States. These participants had longitudinal memory follow-up evaluations, which also included standard questionnaires about physical activity habits. The research participants, with an average age of 78 years, also had MRI scans of the brain analyzed by advanced computer algorithms to measure the volumes of brain structures, including those implicated in memory and Alzheimer's disease, such as the hippocampus. The physical activities engaged in by the participants were correlated with brain volumes and spanned a wide variety of interests, from gardening and dancing to riding an exercise cycle at the gym. Weekly caloric output from these activities was summarized.
The results of the analysis showed that increasing physical activity was correlated with larger brain volumes in the frontal, temporal, and parietal lobes, including the hippocampus. Individuals who benefitted from increased physical activity had a 50% reduction in risk of Alzheimer's dementia. Of the approximately 25% of participants who had mild cognitive impairment associated with Alzheimer's disease, increasing physical activity also increased brain volume. Read more »
Daily dose of a secret juice improves endurance and blood pressure
Emerging evidence suggests that dietary inorganic nitrate supplementation has beneficial effects on blood pressure control, vascular health, exercise capacity, and oxygen metabolism. Researchers at Wake Forest Baptist Hospital enrolled 19 patients in a double-blind, randomized safety study to determine if a single dose or a daily dose of the juice given over multiple days was better at improving exercise intolerance. The beetroot juice used is produced by a company in the United Kingdom and is not commercially available in the United States.
The team found that daily dosing of beetroot juice improved aerobic endurance by 24% after 1 week compared to a single dose, which produced no improvement. Aerobic endurance was assessed based on cycling time to exhaustion at a fixed workload lower than the maximum.
Another finding was that consumption of the juice significantly reduced the resting systolic blood pressure in both the single and daily dose groups by 5-10 mmHg.
No adverse events were associated with either intervention. Read more »
DNA repair enzyme discovered as a potential brain cancer drug target
Rapidly dividing cells rely on an enzyme called Dicer to help repair the DNA damage that occurs as cells make mistakes in copying their genetic material over and over for new cells. A group of researchers have built on the discovery of Dicer's role in fixing DNA damage to uncover a new potential strategy to kill rapidly dividing, cancerous cells in the brain.
In the journal Cell Reports, researchers reported that when they removed Dicer from preclinical models of medulloblastoma, a common type of brain cancer in children, high levels of DNA damage in the cancer cells occurred, leading to cell death. The tumor cells were smaller and more sensitive to chemotherapy.
In this study the researchers studied the effect of deleting Dicer in several types of rapidly dividing cells, including preclinical brain cancer models. The researchers deleted Dicer in the normal, rapidly dividing developing brain cells in the cerebellum of animal models, finding spontaneous DNA damage in the brain cells, thus leading to severe degeneration of the cerebellum. The researchers also determined whether or not Dicer had a similar effect on rapidly dividing cells outside of the brain. Upon deleting Dicer from embryonic stem cells, the authors found a similar effect. To test whether or not they could exploit the role of Dicer to kill cancerous cells, they also deleted Dicer in medulloblastoma models, and found that these cells also had high DNA damage levels and degeneration. The tumor load was lower, and the cells were more sensitive to chemotherapy. Read more »
Scientists discover why X chromosome lacks 'housekeeping genes'
Men have one and women have two copies of the X chromosome, but scientists have long puzzled over why the human X chromosome mostly contains genes that are active in a small number of tissues. Now, a team of researchers at the University of Bath studying the evolution of the X chromosome has discovered why the X chromosome contains such an unusual mixture of genes. The researchers analyzed the world's largest compendium of data on gene activity (expression) and looked at how activity on the X chromosome compares with activity on other chromosomes.
The work has implications for new medical treatments, such as gene therapy, as it suggests that replacement genes should not be inserted into the X chromosome because traffic tailbacks may limit the extent to which the gene can be expressed. Read more »
Time of first birth is connected to a woman's midlife health
A group of scientists recently published a report regarding women's health at midlife with a connection to the time of first birth. The study used data from 3,348 women who participated in the National Longitudinal Survey of Youth 1979 (NLSY79) and who were interviewed every 1-2 years between 1979 and 2008. All of the women had their first births between 15 and 35 years of age. They all rated their own health at 40 years of age on a scale from poor-to-excellent. The researchers found that women who had their first child in their early 20s did not report better health at midlife than women who had their first baby as an adolescent. Women who were 25-35 years when they had their first birth also tended to report better health at age 40 years than the two younger groups of women. This finding confirms the public assumption that having the first baby at an advanced age is encouraged. Moreover, this finding also indicated that marriage following a non-marital adolescent or young adult first birth is associated with a modestly worse self-assessment health compared to remaining unmarried. Read more »
Scientists reported that E.coli sustained signaling the IGF-1 and AKT pathways after infection
Infections and inflammation can lead to cachexia and wasting of skeletal muscle and fat tissue by an as yet poorly understood mechanism. A group of scientists observed that gut colonization of mice by a strain of Escherichia coli prevents wasting triggered by infections or physical damage to the intestine. During intestinal infection with the pathogen, Salmonella typhimurium, or lung infection with Burkholderia thailandensis, the presence of E. coli did not alter changes in host metabolism, caloric uptake, or inflammation, but sustained signaling of the insulin-like growth factor 1/phosphatidylinositol 3-kinase/AKT pathway in skeletal muscle, which is required for prevention of muscle wasting. This effect was dependent on engagement of the NLRC4 inflammasome, therefore promoting tolerance to diverse diseases.
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Kidney organoids generated to help human organ modeling
The human kidney contains up to 2 million epithelial nephrons that are responsible for blood filtration. Regenerating the kidney requires the induction of > 20 distinct cell types that are required for excretion, the regulation of pH, and electrolyte and fluid balance. A group of scientists have previously described the simultaneous induction of progenitors for the collecting ducts and nephrons via the directed differentiation of human pluripotent stem cells. Paradoxically, although both are of intermediate mesoderm origin, collecting duct and nephrons have distinct temporospatial origins. Here we identify the developmental mechanism regulating the preferential induction of collecting ducts versus kidney mesenchyme progenitors. Using this knowledge, we further generated kidney organoids that contain nephrons associated with a collecting duct network surrounded by renal interstitium and endothelial cells. Within these organoids, individual nephrons segment into distal and proximal tubules, early loops of Henle, and glomeruli containing podocytes elaborating foot processes and undergoing vascularization. When transcription profiles of kidney organoids were compared to human fetal tissues, the kidney organoids showed the highest congruence with first trimester human kidney. Furthermore, the proximal tubules endocytose dextran and differentially apoptose in response to cisplatin, a nephrotoxicant. Such kidney organoids represent powerful models of the human organ for future applications, including nephrotoxicity screening, disease modelling, and as a source of cells for therapy. Read more »
SERINC5 has been identified as a potent inhibitor of HIV-1 particle infectivity
HIV-1 Nef is a protein that is important for the development of AIDS and has well-characterized effects on host membrane trafficking and receptor downregulation. Through an unidentified mechanism, Nef increases the intrinsic infectivity of HIV-1 virions in a host-cell–dependent manner. We identified host transmembrane proteins SERINC5 and SERINC3 as potent inhibitors of HIV-1 infectivity that is counteracted by Nef; SERINC5 is a more potent inhibitor than SERINC3. SERINC5 localizes to the plasma membrane, where it is efficiently incorporated into budding HIV-1 virions and impairs subsequent virion penetration of susceptible target cells. Nef redirects SERINC5 to a Rab7-positive endosomal compartment and thereby excludes it from HIV-1 particles. The ability to counteract SERINC5 was conserved in Nef encoded by diverse primate immunodeficiency viruses, as well as in structurally unrelated glycosylated Gag from the murine leukemia virus. These examples of functional conservation and convergent evolution emphasize the fundamental importance of SERINC5 as a potent antiretroviral factor. Read more »
Depressing inflammation requires a specific enzyme to inhibit IL-6
Inflammation is a protective response that involves immune cells, blood vessels, and molecular mediators. Indeed, inflammation has been thoroughly studied from different perspectives. Epigenetic modifiers serve a fundamental role in identifying cellular mechanisms and the ten eleven translocation (Tet) methylcytosine dioxygenase family is a key catalyst in DNA modification. A group of researchers recently unveiled a special Tet2 that regulates inflammation via an inhibitory mechanism based on a set of experiments involving mice. Loss of Tet2 was shown to lead to a tendency for endotoxin shock and dextran-sulfate-sodium-induced colitis, indicating a more severe inflammatory phenotype. By recruiting Hdac2, Tet2 tends to repress the transcription of IL-6 via histone deacetylation. Read more »
A phase II trial involving an anti–IL-23 therapy in plaque psoriasis
Plaque psoriasis is generally thought be a genetic disease that is triggered by environmental factors. Many drugs currently being studied target the Th17/IL-23 axis, particularly IL-23p19 inhibitors. Other cytokines such as IL-17 and IL-22 have also been targets that are used as inhibitors because they play an important role in the pathogenesis of psoriasis. A group of doctors tested an anti–IL-23 mAb guselkumab versus adalimumab for the treatment of moderate-to-severe plaque psoriasis in a clinical phase II trial. In the 52-week trial, patients treated with guselkumab were at least 45% better than those treated with adalimumab, while the infection rate was possibility higher with guselkumab. Read more »
Astrocytes undergo metabolic switch from neuro-protective to neurotoxic in aging rat brain
In December 2014, Drs. Jiang and Cadenas from the University of Southern California published a mechanism exploring the switch that astrocytes take in aging brain from a neurotrophic state, to the neurotoxic state. Astrocytes and neurons share a close structural proximity and are involved in inflammatory responses and metabolic coupling in the brain. As the brain ages, the neurons undergo a hypometabolic state in which the glucose transporters are reduced in expression and translocation to the plasma membrane, thereby reducing glucose uptake. Neurons rely on glucose for oxidative metabolism and ATP production. Astrocytes, on the other hand are able to produce ATP from glycolysis, with the endpoint product being lactate, which is extruded from the cells. In aging brain, the neurons take up the lactate produced by astrocytes to help meet their large energy needs. Astrocytes are also involved in age-dependent inflammatory responses. In particular, astrocytes activate a series of NFkB signaling pathways including those responsive to redox (H2O2 produced by NOX) and cytokine stimulation, especially IL-1β and TNFα. Here they tested the hypothesis that the metabolic changes that occur in neurons, along with inflammatory responses that that occur in astrocytes trigger the astrocytes to switch from the neurotrophic state to being neurotoxic in aging brain. Read more »
Blood platelets derived from iPSCs without serum or a feeder cell line
Blood platelet transfusions are critical for patients with a low platelet count due to chemotherapy, radiation treatment and certain blood disorders. However, maintaining a sufficient supply of platelets is challenging. Platelets have a shelf-life of 5 days and must be stored at room temperature thereby increasing the potential risk of bacterial contamination. For these reasons there has been much interest in differentiating platelets in vitro from stem cells for clinical applications. While recent studies have demonstrated success in generating blood platelets from HSCs, ESCs and iPSCs, they have yet to reach clinical applicability due to limited expansion and protocols that require serum and/or mouse feeder cell lines thereby raising the risk of xenogenic contamination.
To address this, a group of scientists devised a three step protocol to differentiate iPSCs into blood platelets without using serum or a feeder cell line. First, scientists differentiated iPSCs into hemogenic endothelial-like cells using a combination of growth factors under hypoxic conditions. Next, the cells were subjected to conditions which generated megakaryocyte progenitor cells (MKPs) positive for cell expression markers CD31, CD34 and CD43. The third and final step was to induce megakaryocyte maturation and subsequent platelet generation.
Testing several different conditions, researchers found that using a serum-free hematopoietic expansion media in the presence of SCF, TPO, IL-6 and IL-9 at a slightly elevated temperature generated the highest purity blood platelets as determined by CD41a/CD42b surface expression (70% compared to 82% of actual blood platelets). The research team went on to investigate the functionality of the iPSC-generated blood platelets by testing their activation in vitro and circulation in vivo. Read more »
MDSCs differentiated from BM for potential autoimmune therapy
What are MDSCs? Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells (monocytes and granulocytes) that accumulate under conditions of chronic inflammation and are immunosuppressive. They inhibit the anti-tumor immune response by producing reactive oxygen species (ROS) and suppressing T cell proliferation and function. They can be generated following tumor growth when myelopoiesis is aberrantly activated, resulting in immature myeloid cells exposed to an inflammatory microenvironment. Accordingly, some studies have demonstrated a relationship between the level of MDSCs and tumor progression. However, due to MDSC's immunosuppressive properties, researchers have investigated their potential to treat certain types of autoimmune disease.
MDSC's as possible autoimmune therapy
In a recent study, researchers sought to investigate the therapeutic potential of MDSCs in the treatment of rheumatoid arthritis (RA). Previously, the scientists had observed a population of cells within the synovial fluid (SF) of proteoglycan -induced arthritis (PGIA) mice that exhibited an MDSC phenotype and inhibited T cell proliferation. However, the level of SF-MDSCs is limited, so the researchers devised a strategy to differentiate bone marrow (BM) into MDSCs and investigate its therapeutic potential. Read more »
Protocol to differentiate MDSCs from BM
Bone marrow was flushed from mouse femur and tibia with sterile PBS, then subjected to blood cell lysis and plated in DMEM containing 10% FBS. Based on flow cytometry data and functional analysis, researchers determined that BM cells cultured in 10% FBS/DMEM containing 10 ng/ml of GM-CSF, G-CSF and IL-6 for three days was optimal to generate functional MDSCs. Once cultured, scientists tested the BM-MDSCs' ability to inhibit antigen-dependent and independent T cell proliferation in vitro, and suppress RA disease progression in an adoptively transferred PGIA mouse model. Read more »
Inflammasomes may help protect against squamous cell carcinoma
Inflammasomes are intracellular multiprotein complexes that form in response to certain types of microbial infection. Recently, there has been much focus on inflammasomes and their role in the regulation of certain cancers. While some studies suggest that inflammasomes promote tumor development due to excessive inflammation, there is also data suggesting inflammasomes may help combat certain types of tumors by enhancing the antitumor activity of certain leukocytes.
Expanding on this, a group of scientists investigated how loss of inflammasome activity affected the progression of squamous cell carcinoma (SCC). Wild type and inflammasome loss of function mice were chemically treated to induce SCC over a period of 20 weeks. The scientists observed that inflammasome loss of function mice had an earlier onset of chemically induced SCC with a significantly higher number of lesions compared to wild type mice. With regard to the tumor microenvironment, inflammasome loss of function mice had a decrease in infiltrating leukocytes following 12 weeks of chemical treatment and reduced levels of IL-1β, IL-18, TNF-α, and IFN-γ after 20 weeks. Read more »
Key protein helps prevent influenza-induced cytokine storm
A recent study indicates that the suppressor of cytokine signaling 4 (SOCS4) protein is a key component in reducing morbidity and preventing overactive cytokine production, known as a cytokine storm, from influenza infection. Scientists generated mice with a loss of function allele in Socs4 and exposed them to two different strains of influenza. When exposed to the more virulent strain, SOCS4 mutant mice had increased morbidity and a significantly higher viral load in their lungs compared to wild type mice. When exposed to the lesser virulent influenza strain, SOCS4 mutant mice demonstrated increased weight loss, higher levels of pro-inflammatory cytokines and chemokines in their lungs (cytokine storm) and reduced T cell activation. Read more »
Modified TLR3 agonist may improve Ebola vaccine
Scientists at the United States Army Medical Research Institute of Infectious Disease (USAMRIID) in Maryland investigated using a modified form of the TLR3/MDA5 agonist, polyinosinic:polycytidylic acid (poly IC), known as poly ICLC as a potential adjuvant in the protein-based Ebola virus-like particle (VLP) vaccine. Previous studies have demonstrated that poly ICLC is effective in eliciting a type I interferon response and can help improve the T cell response against malaria when included as a vaccine adjuvant. Scientists at USAMRIID observed that including poly ICLC in a low dose of the VLP vaccine significantly increased the survival of mice and guinea pigs when challenged with (mouse or guinea pig adapted) Ebola Zaire virus. Further analysis demonstrated an enhanced T cell response in test animals receiving VLP + poly ICLC compared to VLP alone. To evaluate the safety of using poly ICLC as a potential VLP vaccine adjuvant, the scientists investigated the induction profile of several cytokines and chemokines as an indicator of non-specific inflammation. Read more »
Hepatocyte growth factor reduces T cell inflammatory immune response
Experimental autoimmune encephalomyelitis (EAE) is a CNS disease induced in laboratory animals as a model to study multiple sclerosis. Mice (or rats) are immunized with an emulsified myelin antigen thereby generating myelin-specific T cells that permeate through the blood brain barrier and are reactivated by MHC II antigen presenting cells (APCs), such as dendritic cells. This generates autoreactive T-cells that incite an inflammatory response and axon demyelination characteristic of multiple sclerosis (MS).
Dendritic cells (DCs) can also help reduce autoimmune inflammation by promoting T-cell immune tolerance enabling T-cells to distinguish between foreign invaders and host tissue. Studies suggest that generating these tolerogenic DCs could be a valuable strategy in helping to treat certain autoimmune disease including MS. Previously, a group of scientists from the University of Geneva demonstrated that CNS-restricted overexpression of hepatocyte growth factor (HGF) reduced EAE inflammation and inhibited IL-17 production in CD4+ T cells co-cultured with HGF-treated DCs. Expanding on this, the scientists recently investigated the effect of HGF-treated DCs on CD8+ T cells' immune response. Read more »
Expanding CD34+ cells through epigenetic modification
Hematopoietic stem cells (HSC) obtained from cord blood have great potential to treat certain types of leukemia, immune disorders and solid tumors when isolated and reinfused back into patients who initially respond to treatment. However, because the amount of multipotent HSCs (CD34+ cells) is limited, several studies have tried to identify the optimal combination of cytokines and growth reagents to significantly expand CD34+ cells ex-vivo. Recently, scientists from a laboratory at Mount Sinai investigated how various histone deacetylase inhibitors (HDACI) in the presence or absence of serum affected CD34+ cells' ex-vivo expansion. Read more »
Cytokine induced killer cell cytotoxicity augmented by TKI treated dendritic cells
In adoptive immune cell therapy, lymphocytes (NK cells or T cells) are isolated from a cancer patient and treated ex vivo to significantly increase the cytotoxicity and expansion of specific immune cell populations which are reinfused back into the patient. Cytokine induced killer (CIK) cells are generated by collecting a patient's peripheral blood lymphocytes (PBL) which are then cultured ex vivo for 21-28 days with the addition of IFN-gamma, IL-2 and agonistic anti-CD3 monoclonal antibodies. CIK cells are advantageous over other ex vivo immunotherapies such as tumor-infiltrating lymphocytes (TIL) and lymphokine-activated killer (LAK) cells because CIK cells have a higher rate of expansion and lower toxicity to normal cells, while their tumor cytotoxicity is more potent and non-MHC restrictive.
Ex vivo culture of CIK cells results in a heterogeneous population of effector cells with CD3+CD56+ cells having the highest anti-tumor potency and comprising roughly 25% of the cultured population. However, PBLs isolated from cancer patients are often highly enriched with regulatory T cells (Tregs) which can secrete immunosuppressive cytokines inhibiting CIK cells' tumor cytotoxicity. Additionally, IL-2 used to culture CIK cells can increase the level and activation of Tregs over time. To overcome this, scientists have demonstrated that co-culturing CIK cells with dendritic cells (DC) can counteract Tregs' suppressive effect while increasing the level of CD3+CD56+ effector cells. Expanding on this a group of scientists recently investigated whether treating DCs with a tyrosine kinase inhibitor prior to co-culture would increase CIK cells' tumor cytotoxicity. Read more »
HER2-bound trastuzumab activates NK cells for targeted tumor cytotoxicity
Part of trastuzumab's tumor cytotoxicity comes from its ability to initiate an immune response from effector NK cells in a process known as antibody-dependent cellular cytotoxicity (ADCC). The Fc receptor of NK cells binds to the IgG1 Fc region of trastuzumab when it is bound to HER2, resulting in NK cell activation and targeted killing of the trastuzumab-bound tumor cell. Expanding on this, scientists at Stanford University demonstrate that NK cells obtained and purified from healthy donors significantly upregulated their expression of the co-stimulatory surface molecule CD137 (TNFRSF9) following incubation with HER2+ breast cancer cell lines and trastuzumab. Read more »