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Nath, B.

Publications and source records attributed to Nath, B..

3 recordsLinked to original sources
bioRxiv2026

Platelet-derived CXCL7 induces neutrophil extracellular traps via CXCL7/CXCR2 axis, exacerbating the pathogenesis of diabetic retinopathy

BackgroundProlonged hyperglycemia in diabetes activates platelets and immune cells, forming platelet-immune complexes that damage blood vessels in the retina. However, the role of platelet-neutrophil interactions and neutrophil extracellular traps(NETs) in the development of diabetic retinopathy (DR) was not well studied. In this study, we investigated the mechanisms underlying platelet-mediated NET formation in DR. MethodologyPlatelet activation markers, platelet-neutrophil aggregates (PNA), and NETs markers were assessed by flowcytometry, and the circulatory level of inflammatory markers was measured by Luminex assays in healthy control(HC), type 2 diabetes mellitus(T2DM), non-proliferative DR(NPDR) and proliferative DR(PDR) subjects. In vitro studies investigated platelet-neutrophil interaction in NETs formation using an immunofluorescence assay. Proteomics analysis identified the mechanistic regulators of platelet-induced NETs in DR. Platelet pellet and plasma CXCL7 were quantified using western blot and ELISA, respectively. The role of the CXCL7/CXCR2 axis in inducing NETs formation was examined using CXCL7 recombinant protein, anti-CXCL7 antibody and CXCR2 antagonist (SB225002). ResultsPlatelet activation markers (p-selectin & PF4), PNA, and NETs markers (%NETs, proteinase-3 (PR3), neutrophil elastase (NE)) were significantly increased in the DR group. In vitro studies confirmed that DR-platelets aggregate with healthy neutrophils and form NETs compared to T2DM and HC-platelets. Furthermore, platelet activation and NETs markers were positively correlated with pro-angiogenic (ANGPT2, VEGFA) and inflammatory markers (IL18, ICAM1). In vitro studies reveal that NETs induce inflammation, endothelial dysfunction, disrupt the endothelial monolayer and exacerbate angiogenesis in RF/6A endothelial cell spheroids. Proteomics analysis of platelet-induced NETs in DR revealed dysregulation of proteins involved in platelet activation and NET formation, including CXCL7. Furthermore, increased CXCL-7 levels were observed in platelet pellet and plasma samples from the DR group. Additionally, CXCL7-treated neutrophils formed NETs via the CXCR2 receptor, and inhibition of NETosis was observed in neutrophils exposed to an anti-CXCL-7 antibody and a CXCR2 antagonist. ConclusionOur findings revealed that platelets released CXCL-7 induce NETs formation via the CXCL7/CXCR2 axis and blockade of CXCL7/CXCR2 axis inhibits the NETosis in DR, thereby inhibiting the pathogenesis of DR. Circulating CXCL7 serves as a potential prognostic marker, and the CXCL7/CXCR2 axis may be a therapeutic target for the treatment of DR. What Are the Clinical Implications?Platelets have emerged as immune cells, and platelet-neutrophil interactions are reported to play a significant role in the pathogenesis of various metabolic diseases. The role of platelet-neutrophil interactions and neutrophil extracellular traps (NETs) in the development of diabetic retinopathy (DR) remains poorly understood. Investigating the mechanistic regulators of platelet-mediated NETs in DR is crucial for identifying new therapeutic approaches. Our study observed increased platelet activation, platelet-neutrophil aggregates and NETs among DR subjects. Further, DR-platelet induces NET in healthy neutrophils, and NETs induce inflammation, angiogenesis, and disrupt endothelial barrier function in RF/6A cells in vitro. These findings strengthen the evidence that platelet-neutrophil interactions play a major role in DR pathogenesis. Proteomic analysis identified CXCL7 as a mechanistic regulator of platelet-induced NETs formation in DR. Inhibitors that target the platelet-derived CXCL7/CXCR2 axis for NETosis can be used for the prevention of retinal injury in DR. Overall, our work emphasises the mechanistic understanding of platelet-neutrophil interactions and CXCL7/CXCR2 axis as a therapeutic target for inhibiting the pathogenesis of DR. Graphical abstractScheme for the platelet-derived CXCL7 regulation of NETs in DR. Activated platelets release CXCL7 and platelet aggregates with neutrophils to form NETs via the CXCL7:CXCR2 axis. Blockade of the CXCL7:CXCR2 axis by anti-CXCL7 antibody and CXCR2 inhibitor prevents NETs formation in DR.

immunology↗
bioRxiv2025

PEG400 regulates Falcipain 2 activity through an unprecedented allosteric mechanism

The malarial parasite Plasmodium falciparum cleaves host hemoglobin by cascade of proteolytic enzymes. The cysteine protease, Falcipain-2 (FP2) plays an essential role in the process and important for parasite survival, making it a potential drug target. However, similarities with host cysteine cathepsins hamper selective inhibition, thus necessitates detailed structural and functional characterizations of FP2. The present study uncovers a novel regulatory role of polyethylene glycol 400 (PEG400) on FP2 activity. PEG400 inhibits FP2 activity on small peptide substrate and azo-casein, while enhancing hemoglobin degradation, rendering a dual effect on FP2 catalysis. A mixed-type of inhibition has been observed for PEG400 against small peptide substrate of FP2, consistent with binding of PEG400 to catalytic cleft, confirmed by fluorescence quenching and docking studies. Unlike typical nonspecific PEG-protein interactions, PEG400 adopts a fit within catalytic region of FP2 and partially overlaps with leupeptin binding sites, albeit with lower affinity. Computational analysis further identifies a novel allosteric binding pocket of PEG400, supported by in-silico mutagenesis and molecular dynamics simulation. This pocket exhibits minimal conservation in human cathepsins, suggesting selective potential. In contrast to this inhibitory role, biochemical assay reveals that PEG400 promotes haemoglobin proteolysis. Spectroscopic analyse suggests PEG400 alter hemoglobin structural dynamics to favour proteolysis. ENM based normal mode analysis reveals upon haemoglobin binding, PEG400 restricts FP2 hinge-bending motion, improves FP2-hemoglobin proximity, and simultaneously PEG400 is dislodged from the active site, thereby promoting proteolysis. The combined experimental and computational findings reveal a novel mechanism of FP2 regulation, opening new therapeutic avenues.

biochemistry↗
bioRxiv2024

Aligning with the predecessors and counterarguments: A systematic review of the anatomical correlates for the newly discovered meningeal layer in the existing literature

A recent study reported the existence of a subarachnoid lymphatic-like membrane (SLYM) -an intermediate leptomeningeal layer between the arachnoid and pia mater in mice and human brains - dividing the subarachnoid space (SAS) into two functional compartments. Despite being a macroscopic structure, how it missed detection in previous studies is surprising. We systematically reviewed the published reports in animals and humans to explore whether prior descriptions of this meningeal layer have existed. An electronic search was conducted in PubMed/Medline, EMBASE, Google Scholar, Science Direct, and Web of Science databases using combinations of MeSH terms and keywords with Boolean operators from inception until 31st Dec 2023. We found at least eight studies that provided structural evidence of an intermediate leptomeningeal layer in the brain or spinal cord. However, unequivocal descriptions for this layer all along the central nervous system were scarce. Obscured names were used to describe it, i.e., the epipial layer, intermediate meningeal layer, intermediate lamella, and outer pial layer. Its microscopic/ultrastructural details closely resembled the SLYM. Further, we examined the counterarguments in current literature that are skeptical of this layers existence. Considering the significant physiological/clinical implications, exploring further structural and functional details of the new meningeal layer is a need of the hour.

neuroscience↗