Biology subjects

Kandasamy, M.

Publications and source records attributed to Kandasamy, M..

9 recordsLinked to original sources

bioRxiv2024

Glycogen synthase kinase-3 is essential for Treg development and function

Tregs are critical regulators of the immune response, but the cellular signalling pathways that control their development and homeostasis remain to be determined. We found that glycogen synthase kinase-3 (GSK3), a kinase which integrates signals from AKT and mTOR, was essential for Treg development, restraining fatal autoimmunity. Loss of Gsk3 led to metabolic rewiring in Tregs, with disordered nucleotide metabolism and activation of OxPhos. Acute deletion of Gsk3 did not affect Treg frequency or numbers, but induced an effector gene expression program, and led to the formation of populations with pro-inflammatory signatures. The loss of Gsk3 in Tregs profoundly enhanced anti-tumoral immune responses and suppressed tumour growth.

immunology↗

bioRxiv2024

The proneurogenic and microglial modulatory properties of botulinum toxin in the hippocampus of aging experimental mice

This study explored the neurogenic and microglial modulatory properties of botulinum toxin in the hippocampus of aging experimental mice. Therapeutic botulinum toxin (BoNT) treatment is widely practiced to reduce the excessive discharge of acetylcholine (ACh) in the management of aging and neurological deficits. While the production of new neurons in the adult brain contributes to cognitive functions, age-related diseases with excessive release of ACh and progressive neuroinflammation have been characterized by impaired hippocampal neurogenesis and memory loss. Therefore, we investigated the effect of BoNT on the regulation of hippocampal neurogenesis, focusing on doublecortin (DCX)-positive immature neurons in the hippocampus of aging experimental mice. We also assessed ionized calcium-binding adapter molecule 1 (Iba1)-positive microglia and the expression of cyclooxygenase (COX)-2, a key inflammatory response element, using reverse transcription polymerase chain reaction (RT-PCR). Results revealed a prominent increase in DCX-positive cells in the BoNT-treated animals compared to the control group. Additionally, the reduced number of microglia accompanied by decreased mRNA expression of COX-2 was evident in the BoNT-treated animals. These dual effects suggest that BoNT could be a promising therapeutic agent for mitigating age-related neuroregenerative decline and neuroinflammation responsible for cognitive impairments.

neuroscience↗

bioRxiv2023

Short-term intermittent hypoxia therapy promotes gliogenesis in a rat model of middle cerebral artery occlusion (MCAO) stroke

AimAfter focal cerebral ischemia, intermittent hypoxia therapy (IHT) could be used as a non-invasive method to stabilize and stimulate neurogenesis in the innate stem cell niche in the brain, and disrupt the glial scar around the infarct to increase neuroblast migration in the striatal infarct area. MethodsWe induced focal cerebral ischemia in Wistar albino rats using the MCAo model. A week later, animals were subjected to intermittent hypoxia (12%O2, 4hr/day) for a period of 14 days. Post-treatment analysis of functional recovery and cellular regeneration was done using immunofluorescence analysis of multiple neuronal cell markers including Doublecortin (DCX), Nestin, and Vimentin among others. ResultsObservations of GFAP-positive cells revealed that IH treatment facilitates gliogenesis in the infarct striatal region of a rat model of MCAo stroke. The percentage of DCX and GFAP double-positive cells was increased in the IH-treated group. Also, there was a significant difference in the morphology of vimentin-positive cells and microglia cells between the stroke groups. ConclusionThese outcomes suggest that exposure of MCAo stroke-affected rats to intermittent hypoxia results in an increase in migrated neuroblasts resulting in a subsequent altered glial scar integrity in the infarct region, thus suggesting an alternative non-invasive method against the common stem cell transplant techniques, to increase endogenous neuroblasts in the infarct area after stroke.

neuroscience↗

bioRxiv2023

Design and Evaluation of an Affordable Hypoxic Chamber with Comprehensive Environmental Control for Research Applications

PurposeIn-vivo Hypoxia chamber is sought after for research on sleep apnea, among others. Recently hypoxia chambers are utilized to create intermittent hypoxia, thereby utilizing it as a treatment strategy. The commonly used Invivo hypoxic chambers only monitor oxygen levels and fail to read up on vital factors like CO2 buildup, and humidity among others. In addition, these devices are expensive and make them unaffordable for many labs. MethodsHere we report a lab-designed and assembled Arduino microcontroller-based hypoxic chamber with automatic maintenance of O2 level, CO2 level, and Humidity. The entire 650$ setup is inclusive of an Arduino module with sensors for oxygen, CO2, humidity, pressure, and temperature. A detailed software program was also written to help efficiently carry out the parameters set out for use. ResultsThe equipment is capable of automatically regulating the inner environment based on the set parameters. The combined cluster of regulators, efficiently controlled the oxygen levels, CO2 levels, and humidity levels within the experimental parameters. ConclusionThis equipment thus acts as one of the easily reproducible simple assembly units with the integration of complex parameters, thus monitoring and controlling the inner environment with high precision.

bioengineering↗

bioRxiv2022

Avian and Human Influenza Viruses Exhibit Distinct Glycoconjugate Receptor Specificities in Human Lung Cells

IAV utilize sialic acid (Sia) containing cell surface glycoconjugates for host cell infection, and IAV strains from different host species show preferences for structurally distinct Sia at the termini of glycoconjugates. Various types of cell surface glycoconjugates (N-glycans, O-glycans, glycolipids) display significant diversity in both structure and carbohydrate composition. To define the types of glycoconjugates that facilitate IAV infection, we utilized the CRISPR/Cas9 technique to truncate different types of glycoconjugates, either individually or in combination, by targeting glycosyltransferases essential to glycan biosynthesis in a human lung epithelial cell line. Our studies show that both human and avian IAV strains do not display strict preferences for a specific type of glycoconjugate. Interestingly, truncation of all three types of glycoconjugates significantly decreased the replication of human IAV strains, yet did not impact the replication of avian IAV strains. Taken together, our studies demonstrate that avian IAV strains utilize a broader repertoire of glycoconjugates for host cell infection as compared to human IAV strains. Author SummaryIt is well known that influenza A viruses (IAV) initiate host cell infection by binding to sialic acid, a sugar molecule present at the ends of various sugar chains called glycoconjugates. These glycoconjugates can vary in chain length, structure, and composition. However, it remains unknown if IAV strains preferentially bind to sialic acid on specific glycoconjugates for host cell infection. Here, we utilized CRISPR gene editing to abolish sialic acid on different glycoconjugate types in human lung cells, and evaluated human versus avian IAV infections. Our studies show that both human and avian IAV strains can infect human lung cells by utilizing any of the three major sialic acid-containing glycoconjugate types, specifically N-glycans, O-glycans, and glycolipids. Interestingly, simultaneous elimination of sialic acid on all three glycoconjugate types in human lung cells dramatically decreased human IAV infection, yet had little effect on avian IAV infection. Our studies indicate that avian IAV strains can utilize a wide variety of glycoconjugates for infection, whereas human IAV strains display restrictions in glycoconjugate type usage. These novel studies show distinct differences in host glycoconjugate preferences between human and avian IAV strains.

microbiology↗

bioRxiv2021

Altered neurogenic pathways in experimental rat models of ischemic cerebral stroke: A transcriptome based meta-analysis

1)ObjectivesPromoting neurogenesis mediated recovery is one of the most sought after strategies in recovery after cerebral stroke. In this paper we elucidate how neurogenesis related genes are altered in the early stroke environment, to hint at potential pathways for therapeutic recovery. Materials and MethodsAround 97 microarray datasets derived from stroke affected rat brains were collected from NCBI-GEO. Datasets were normalized and subjected to meta-analysis in Network Analyst to identify differentially expressed genes. Gene enrichment analyses were carried out using GSEA, and WebGestalt, and results were visualized using Cytoscape Enrichment mapping. ResultsNearly 939 differentially expressing genes were identified in the cerebral stroke group. Among them 30 neurogenesis related genes were identified through enrichment mapping analysis, and 35 genes through Protein- Protein Interaction analysis. Highest upregulated neurogenesis genes were found to be TSPO, GFAP, VIM, and TGFB1. Highest Downregulated neurogenesis genes were found to be THY1, NR1D1, CDK5, STX1B, and NOG. ConclusionsThrough this study, we have identified that during the acute time frame after stroke, majority of the neurogenesis genes related to neural proliferation and neural differentiation are downregulated, while the majority of the genes related to neuronal migration were upregulated. Single or combined therapeutic approach against the identified dysregulated genes could greatly aid neural restoration and functional recovery during the postischemic stage.

neuroscience↗

bioRxiv2021

Single injection of very mild dose BOTOX in the vastus lateralis improves testicular spermatogenesis and sperm motility in ageing experimental mice

Acetylcholine (ACh), a key neurochemical messenger that plays key roles in neuroplasticity and muscle contraction. While ACh is important for the physiological function of the testis, abnormal levels of ACh cause testicular atrophy and male infertility. BOTOX is a therapeutic form of the botulinum neurotoxin that blocks the excessive release of ACh at the neuromuscular junction. Previously, repeated intracremasteric injections and slight overdose of BOTOX have been reported to induce adverse effects in the testicular parameter of experimental rodents. However, a mild dose of BOTOX is highly beneficial against skin ageing, neurological deficits, overactive urinary bladder problems, testicular pain and erectile dysfunctions. Considering the facts, the possible therapeutic benefit of BOTOX on the testis might be achieved via its minimal dose and indirect mode of action rather than repeated high quantity in the local supply. Therefore, we revisited the effect of BOTOX but with a trace amount injected into the vastus lateralis of the thigh muscle, and analyzed histological parameters of testis and quality of semen in ageing experimental mice. Experimental animals injected with 1 U/kg bodyweight of BOTOX showed enhanced spermatogenesis in associations with increased activities of key antioxidants in the testis, leading to increased total sperm count and motility. This study signifies that a mild intramuscular dose of BOTOX can be considered as a potential treatment strategy to manage and prevent male infertility.

pharmacology and toxicology↗

bioRxiv2021

Recombinant single-cycle influenza virus as a new tool to augment antitumour immunity with immune checkpoint inhibitors

Virus-based tumour vaccines offer many advantages compared to other antigen delivering systems. They generate concerted innate and adaptive immune response, and robust CD8+T cell responses. We engineered a non-replicating pseudotyped influenza virus (S-FLU) to deliver the well-known cancer testis antigen, NY-ESO-1 (S-NY-ESO-1 FLU). Intranasal or intramuscular immunization of NY-ESO-1 S-FLU virus in mice elicited a strong NY-ESO-1 specific CD8+T cell response in lungs and spleen that resulted in the regression of NY-ESO-1 expressing lung tumour and subcutaneous tumour respectively. Combined administration with anti PD-1 antibody, NY-ESO-1 S-FLU virus augmented the tumour protection by reducing the tumour metastasis. We propose that the antigen delivery through S-FLU is highly efficient in inducing antigen specific CD8+T cell response and protection against tumour development in combination with PD-1 blockade.

immunology↗

bioRxiv2020

Suppression of Cytotoxic T Cell Functions and Decreased Levels of Tissue Resident Memory T cell During H5N1 infection

Seasonal influenza virus infections cause mild illness in healthy adults, as timely viral clearance is mediated by the functions of cytotoxic T cells. However, avian H5N1 influenza virus infections can result in prolonged and fatal illness across all age groups, which has been attributed to the overt and uncontrolled activation of host immune responses. Here we investigate how excessive innate immune responses to H5N1 impair subsequent adaptive T cell responses in the lungs. Using recombinant H1N1 and H5N1 strains sharing 6 internal genes, we demonstrate that H5N1 (2:6) infection in mice causes higher stimulation and increased migration of lung dendritic cells to the draining lymph nodes, resulting in higher numbers of virus specific T cells in the lungs. Despite robust T cell responses in the lungs, H5N1 (2:6) infected mice showed inefficient and delayed viral clearance as compared to H1N1 infected mice. In addition, we observed higher levels of inhibitory signals including increased PD1 and IL-10 expression by cytotoxic T cells in H5N1 (2:6) infected mice, suggesting that delayed viral clearance of H5N1 (2:6) was due to suppression of T cell functions in vivo. Importantly, H5N1 (2:6) infected mice displayed decreased numbers of tissue resident memory T cells as compared to H1N1 infected mice; however, despite decreased number of tissue resident memory T cells, H5N1 (2:6) were protected against a heterologous challenge from H3N2 virus (X31). Taken together, our study provides mechanistic insight for the prolonged viral replication and protracted illness observed in H5N1 infected patients. ImportanceInfluenza viruses cause upper respiratory tract infections in humans. In healthy adults, seasonal influenza virus infections result in mild disease. Occasionally, influenza viruses endemic in domestic birds can cause severe and fatal disease even in healthy individuals. In avian influenza virus infected patients, the host immune system is activated in an uncontrolled manner and is unable to control infection in a timely fashion. In this study, we investigated why the immune system fails to effectively control a modified form of avian influenza virus. Our studies show that T cell functions important for clearing virally infected cells are impaired by higher negative regulatory signals during modified avian influenza virus infection. In addition, memory T cell numbers were decreased in modified avian influenza virus infected mice. Our studies provide a possible mechanism for the severe and prolonged disease associated with avian influenza virus infections in humans.

microbiology↗