CLEC4A

COVID-19 came with plenty of mysteries, some of which have been resolved, and many that haven't. One mystery since the beginning of the pandemic was why children seemed much less susceptible to the virus than adults. For that and more research news, continue reading. Why Kids May Have More Protection Against COVID-19 Generally, children are less at risk of COVID-19 infection than adults - not immune, but less likely to be infected and less likely to have severe disease. But why? Researchers at the University of Queensland, Australia, suggest that children's nasal lining, or the nasal epithelium, inhibits infection and replication, particularly of the original Wuhan wild-type strain of SARS-CoV-2 and the Delta variant. However, the Omicron variant and its subvariants do not seem to have the same issue. They published their research in PLOS Biology. "We have provided the first experimental evidence that the pediatric nasal epithelium may play an important role in reducing the susceptibility of children to SARS-CoV-2," the authors wrote. "The data strongly suggest that the nasal epithelium of children is distinct and that it may afford children some level of protection from ancestral SARS-CoV-2." They found that the wild-type virus replicated less efficiently and was linked to an increased antiviral response in the nasal epithelial cells of children. The effect was also seen with the Delta variant, but not with the Omicron. They also found that Omicron replicated better in pediatric nasal epithelial cells than the wildtype or Delta, although they caution that this was a small study and may reflect how the virus is evolving. New Molecules Discovered for Treating Age-Related Diseases Researchers at the Hebrew University of Jerusalem have identified a group of molecules that help cells repair damaged components. Impaired mitophagy is associated with various aging-associated diseases, such as Alzheimer's and Parkinson's, as well as sarcopenia. Augmenting mitophagy, where defective mitochondria are removed and replaced by new ones, is an emerging strategy for treating the elderly. The researchers designed and tested a family of compounds related to spermidine, a known mitophagy-promoting agent. A prototype, 1,8-diaminooctane (VL-004), was better than spermidine in its ability to induce mitophagy and protect against oxidative stress. The research was published in the journal Autophagy. The researchers founded a biotech company, Vitalunga, that is working to develop the drug. Unique Subset of Immune Cells Protects Against Stroke A study from the University of Pittsburg found a subset of white blood cells, a novel subset of CD8+ regulatory-like T cells (CD8+TRLs), that appear to confer fast-acting and lasting protection against ischemic stroke in mice. These cells were attracted to the site of ischemic injury by a unique "homing" signal produced by the damaged brain cells. The CD8+TRLs reached the brain 24 hours after the stroke, then released molecules that provide direct neuroprotective effects and knock down inflammation and secondary brain damage. In the mice studies, the animals who received a transfusion of purified CD8+TRLs did better and recovered faster than the untreated mice over five weeks. The CD8+TRLs appear to act as early responders to alert and recruit defenses after a stroke. Gene Therapy Shows Promise in ALS Researchers at the University of California San Diego School of Medicine report that gene therapy in animal models of ALS measurably delayed disease onset. Although most ALS cases are of unknown cause, the mouse and rat models were of an inherited form of ALS. The therapy involved an AAV-vector carrying synapsin-Caveolin-1 cDNA into the spinal cords of the mice. The SynCav1 protected and preserved spinal cord motor neurons and added to the mice's longevity. They speculate that SynCav1 might serve as novel gene therapy for ALS and other forms of CNS disease. Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease marked by progressive loss of motor neurons in the brain and spinal cord. It is fatal, and there are no cures. New Therapeutic Target for Colorectal Tumors Researchers at the Tokyo University of Science identified a potential new therapeutic target for colorectal tumors. Inflammatory bowel disease (IBD), which includes Crohn's disease and ulcerative colitis, can often lead to colorectal tumors. Innate immune receptors, such as C-type lectin receptors (CLRs), are responsible for the development of IBD. But they also play a key role in regulating gut microbiota and defending against pathogens. One of those CLRs is a dendritic cell immunoreceptor (DCIR), responsible for maintaining the homeostasis of the immune and skeletal systems. Working with mice, the researchers found that mice without DCIR had less colitis severity and AOM-DSS-induced colorectal tumor growth. They found that using an antibody called anti-NA2 against asialo-biantennary-N-glycans (NA2), which binds to DCIR, decreased colitis symptoms and prevented colorectal tumor growth. Two Common Viruses Associated with Alzheimer's Disease A study out of Tufts University and the University of Oxford strengthened the association between specific viral infections and Alzheimer's disease. Two common viruses can lie dormant in brain cells — herpes simplex virus (HSV) and varicella-zoster virus (VZV); the latter is associated with shingles and chickenpox. Researchers leveraged 3D human tissue culture models to mimic the brain and demonstrated that VZV may activate HSV to lay the groundwork for the early stages of Alzheimer's disease. HSV-1, the primary variant of HSV, when activated, leads to the accumulation of tau and amyloid-beta proteins, which are implicated in Alzheimer's disease. They published their research in the Journal of Alzheimer's Disease. "Our results suggest one pathway to Alzheimer's disease, caused by a VZV infection which creates inflammatory triggers that awaken HSV in the brain," Dana Cairns, Ph.D., GBS12, a research associate in the Biomedical Engineering Department at Tufts, said. "While we demonstrated a link between VZV and HSV-1 activation, it's possible that other inflammatory events in the brain could also awaken HSV-1 and lead to Alzheimer's Disease."

Colorectal tumors are a common adverse effect of chronic inflammation of the intestine. In a new study, researchers demonstrate that mice models with dendritic cell immunoreceptor (DCIR) protein deficiency are resistant to colonic tumors induced by dextran sodium sulfate and azoxymethane. Further, they identify an antibody that reduces colitis severity and colonic tumor growth, highlighting the potential of DCIR as a therapeutic target. Inflammatory bowel disease (IBD) is an umbrella term for two diseases, Crohn's disease and ulcerative colitis, that are characterized by the prolonged inflammation of the gastrointestinal tract. This condition often leads to the development of colorectal tumors. Understanding the pathogenesis of IBD is, therefore, crucial to mitigate the incidence of colonic tumors. It turns out that innate immune receptors, particularly those expressed in the gut, such as C-type lectin receptors (CLRs), are responsible for the development of IBD. However, CLRs also play a vital role in the regulation of gut microbiota and defense against pathogens. As a result, a balance needs to be struck to maintain intestinal homeostasis. Dendritic cell immunoreceptor (DCIR) is one such CLR that is responsible for maintaining homeostasis of the immune and skeletal systems. Previous studies have suggested that DCIR negatively regulates both innate and acquired immune responses. Blocking DCIR could, therefore, potentially boost immunity against colon tumor. However, its role in intestinal immunity has remained unclear. Against this backdrop, a research group led by Professor Yoichiro Iwakura of Tokyo University of Science (TUS) in Japan has now shed light on this issue. In their study, to be published online on 02 August 2022 in the international journal Cell Reports, the group studied the development of colitis and colon tumor in mice models deficient in DCIR. To this end, the group fed the mice with drinking water containing dextran sodium sulfate (DSS), a synthetic sulfated polysaccharide, and azoxymethane (AOM), a neurotoxic chemical, to induce colon tumors similar to that observed in humans with IBD. To their surprise, they found that the mice lacking DCIR showed reduced colitis severity and AOM-DSS-induced colorectal tumor growth. Moreover, compared to the wild-type mice (control), the DCIR-deficient mice showed lower body weight loss as well as reduced proinflammatory cell infiltration in the colon. What do these observations imply? Prof. Iwakura explains, "Our findings point to the fact that intestinal carcinogenesis and inflammation are facilitated by DCIR signalling, which points to the possibility that blocking DCIR might prevent ulcerative colitis and colon cancer." Corroborating this possibility, the study further revealed that the use of an antibody called "anti-NA2" against asialo-biantennary-N-glycans (NA2), a ligand (binding molecule) to DCIR, reduced DSS colitis symptoms and prevented colorectal tumor growth. The researchers are excited by these findings. Speaking about the practical applications of their study, Prof. Iwakura says, "Our results suggest that therapeutics targeting DCIR and its ligands could be used to effectively treat autoimmune diseases, IBD, and cancer, which have been traditionally difficult to treat." Sure enough, this study could open doors to novel therapeutic strategies for treating colorectal tumors, improving not only the lives of patients with IBD but also our understanding of the pathogenesis of human diseases.