Biology subjects

Nitin, N.

Publications and source records attributed to Nitin, N..

7 recordsLinked to original sources

bioRxiv2026

Discovering a new biocatalytic potential of milk fat globules: in situ conversion of exogenous docosahexaenoic acid to its oxylipins

Milk fat globules (MFG) are complex structures that emulsify the fat in milk and exhibit various biological activities. Using docosahexaenoic acid (DHA) as a model polyunsaturated fatty acid, we demonstrate for the first time that a MFG-enriched fraction (isolated from commercial raw and unhomogenized bovine milk) catalyzes the oxidation of exogenous polyunsaturated fatty acid to its oxylipins. Static incubation of the MFG-enriched fraction (at 20% w/v in phosphate buffer and 5% v/v ethanol) with 150 {micro}M of DHA for 1 h resulted in the production of [~]13 pmol/mg cream of DHA-derived oxylipins in free and esterified (i.e., bound) forms. High enrichment in free DHA-oxylipins was observed, wherein incubation with DHA resulted in >80% of all free oxylipins being derived from DHA, in contrast to control samples in which only <8% of all free oxylipins were DHA derivatives. The most abundant products generated were 17-hydroxydocosahexaenoic acid and 19(20)-epoxydocosapentaenoic acid. Oxylipin generation was dependent on the structural integrity of MFG, with mechanical disruption (vortexing) impairing oxylipin synthesis more severely than thermal treatment. These findings suggest that MFGs harbor multiple metabolically active enzymes, including cytochrome P450, lipoxygenases, acyl-CoA synthetases, and acyltransferases, that act cooperatively to synthesize and esterify DHA-derived oxylipins. In summary, this study highlights the dual potential of MFGs to serve both as a food-grade biocatalyst for the synthesis of DHA-derived oxylipins and as carriers for these bioactive lipids. Future studies should evaluate the bioavailability and physiological relevance of these metabolites when consumed in the diet.

biochemistry↗

bioRxiv2026

Disulfiram Protects Against Diet-Induced Obesity by Reprogramming Systemic Lipid Partitioning Independent of GSDMD

Obesity remains a major global health challenge with limited durable pharmacotherapies. Disulfiram (DSF), an FDA-approved drug reported to inhibit gasdermin D (GSDMD), has been proposed to improve metabolic outcomes through suppression of inflammasome signaling. Here, we demonstrate that GSDMD is dispensable for high-fat diet-induced obesity and insulin resistance, as neither genetic deletion nor antisense-mediated inhibition of GSDMD confers metabolic protection. In contrast, DSF robustly protects against obesity and IR through a GSDMD-independent mechanism. These effects are not attributable to reduced caloric intake but instead reflect a coordinated reprogramming of systemic lipid handling. Under steady-state conditions, DSF suppresses basal lipid oxidation while promoting fecal fatty acid excretion. In striking contrast, during acute lipid challenge, DSF enhances tissue lipid utilization and accelerates systemic clearance. Together, these findings overturn the prevailing inflammasome-centric model and establish context-dependent regulation of lipid partitioning--rather than inflammasome inhibition--as the primary mechanism underlying DSFs anti-obesity effects

pharmacology and toxicology↗

bioRxiv2025

β2 adrenergic receptors orchestrate neutrophil demargination and recruitment to the ischemic heart following myocardial infarction.

Neutrophils play a crucial role in instigating inflammation as well as its resolution post-myocardial infarction (MI). Although granulopoiesis in the bone marrow (BM) is the major source of cardiac neutrophils post-MI, infiltration of neutrophils to the heart occurs much quicker than peak granulopoiesis. These observations suggest that sources other than granulopoiesis may supply neutrophils to the heart during the early hours post-MI. Using a combination of flow cytometry, BM ablation of hematopoietic stem cells, confocal microscopy and multiple proteomics analysis, we found that the first wave of neutrophils recruited to the ischemic heart is exclusively sourced from vasculature and not from granulopoiesis in the BM/ spleen. The MI-evoked neutrophilia during the early hours bore all hallmarks of demargination induced by classical demarginating agents such as dexamethasone/ norepinephrine (NE). Various pharmacological and genetic strategies aimed at suppressing NE synthesis or disruption of {beta}-AR signaling reduced both neutrophil demargination as well as recruitment to the heart. Interestingly, however, despite a marked reduction in cardiac neutrophil burden only short-term inhibition of {beta}-ARs improved cardiac remodeling and function. Our findings support a pharmacological strategy to contain the initial onslaught of neutrophils on the ischemic heart using {beta}2-AR blockers to regulate the otherwise runaway inflammatory response.

immunology↗

bioRxiv2025

Cigarette smoke aggravates atherosclerosis by promoting the infiltration of inflammasome-primed neutrophils and disrupting macrophage function in lesions

BackgroundCigarette smoking (CS) is a major risk factor for cardiovascular disease (CVD) through chronic inflammation. While its pulmonary effects are well established, the mechanisms linking lung inflammation to vascular injury remain unclear. Because neutrophils are early responders to CS-induced inflammation, we hypothesized that they drive systemic myelopoiesis and vascular inflammation via alarmin release. MethodsWild-type (WT) mice were exposed to inhaled CS or orally administered cigarette smoke extract (CSE). Immune cell composition in lung, bronchoalveolar lavage fluid (BALF), blood, spleen, and bone marrow (BM) was assessed by flow cytometry. Hematopoietic stem and progenitor cell (HSPC) proliferation, reactive oxygen species (ROS) production, and S100A8/A9 release were quantified. Atherosclerosis progression was evaluated in Ldlr-/- mice fed a Western diet and treated with CSE. To define the role of neutrophil-derived S100A8/A9, bone marrow transplantation was performed using S100a9-/- or WT donors. ResultsCS exposure increased circulating monocytes and neutrophils through enhanced BM myelopoiesis and elevated ROS-dependent S100A8/A9 release. Oral CSE reproduced these effects, indicating direct activation of neutrophils independent of pulmonary inflammation or lipid changes. In Ldlr-/- mice, CSE accelerated atherosclerosis by promoting infiltration of inflammasome-primed neutrophils, increased IL-1{beta} release, and impaired macrophage efferocytosis. Hematopoietic S100a9 deletion normalized myelopoiesis and reduced vascular inflammation and plaque burden. ConclusionsIngested CS components directly activate neutrophils to release S100A8/A9, triggering myelopoiesis and vascular inflammation. These findings reveal that tobaccos cardiovascular toxicity extends beyond inhalation, implicating oral exposure as a driver of systemic inflammation and atherogenesis. Novelty and SignificanceO_ST_ABSWhat Is Known?C_ST_ABSO_LICigarette smoking (CS) is a major risk factor for atherosclerosis, driving systemic inflammation and innate immune activation. C_LIO_LINeutrophils and monocytes contribute to plaque progression, but the upstream mechanisms by which CS exacerbates their pathogenic roles remain incompletely understood. C_LIO_LIS100A8/A9 levels correlate with neutrophilia and cardiovascular risk in smokers, but their functional role in lesion biology is not fully defined. C_LI What New Information Does This Article Contribute?O_LIIdentifies S100A8/A9 as a key mediator linking CS exposure to enhanced medullary myelopoiesis, neutrophilia, and increased lesional infiltration of inflammasome-primed myeloid cells. C_LIO_LIDemonstrates that neutrophil-derived IL-1{beta} impairs macrophage efferocytosis by downregulating phagocytosis receptors, thereby promoting plaque vulnerability. C_LIO_LIReveals that CS drives atherosclerosis even in the absence of lipid perturbations or overt pulmonary injury, highlighting a novel oral exposure-vascular axis of disease propagation. C_LI

immunology↗

bioRxiv2025

The complete {lambda}-carrageenan depolymerization cascade from a marine Pseudoalteromonad revealed by structural analysis of the enzymes.

Carrageenans are a complex group of polysaccharides derived from the cell walls of red macroalgae. They are an abundant, yet recalcitrant nutrient source for most marine heterotrophic bacteria. Some member species of the Pseudoalteromonas genus are effective at metabolizing carrageenan. However, the enzymatic pathway for {lambda}-carrageenan, one of the most sulfated naturally occurring polysaccharides, remains unknown. Using detailed structural analysis by X-ray crystallography we reveal the sophisticated and cyclic enzymatic cascade deployed by Pseudoalteromonas distincta (strain U2A) to utilize {lambda}-carrageenan. The cascade incorporates ten glycoside hydrolases and five sulfatases that are specific for {lambda}-carrageenan and cooperate to completely deconstruct this polysaccharide, thus yielding galactose monosaccharides for subsequent energy production. The detailed molecular understanding of {lambda}-carrageenan depolymerisation provided includes structural evidence for a lesser described sulfatase catalytic mechanism and elucidation of a distinct catabolic cascade that is unique from previously described carrageenan metabolic pathways. This insight also holds potential for the application of enzymatic logic in the generation of high value products from abundant natural biopolymers, such as carrageenans.

biochemistry↗

bioRxiv2023

Decellularized Banana Leaves: Eco-Friendly Scaffolds for Cell-Based Seafood

Cellular agriculture, as an emerging food production system, holds potential to address sustainability, food security, and agricultural resilience. Within the cell-based meat supply chain, one of the key steps is scaffolding. In this study, we assessed decellularized banana leaves, various coating materials, and different cell seeding strategies to determine their effects on cell viability, cell growth, cell alignment, and the response of the materials to thermal processing. The efficiency of decellularization was verified through DNA quantification, which decreased from 445 ng/mg in fresh banana leaves to non-detectable levels in the decellularized samples. This was further confirmed by FTIR and PCA modeling. Cell viability exceeded 98% on uncoated, soy-coated, and gelatin-coated samples of the decellularized banana leaves. Alignment of cells on gelatin-coated samples was the highest among the samples, with a dominant orientation of 65.8{degrees}, compared to soy-coated and uncoated samples with dominant orientations of 9.2{degrees} and -6.3{degrees}, respectively. In terms of quality attributes, the kinetics of shrinkage indicated that coating with soy and the presence of cells increased the activation energy due to the higher energy required for protein denaturation. Moreover, the kinetics of area changes in plain scaffolds without cells followed a first-order pattern, while with seeded cells a second-order pattern was followed. In summary, decellularized banana leaves present a sustainable and suitable biomaterial to support cells towards future needs related to meat production.

synthetic biology↗

bioRxiv2022

Evaluating the potential of marine invertebrate and insect protein hydrolysates to reduce fetal bovine serum in cell culture media for cultivated fish production

The use of fetal bovine serum (FBS) and the price of the cell culture media are the key constraints for developing serum-free cost-effective media. This study aims to replace or reduce the typical 10% serum application in fish cell culture media by applying protein hydrolysates from insects and marine invertebrate species for the growth of Zebrafish embryonic stem cells (ESC) as the model organism. Protein hydrolysates were produced from Black soldier fly (BSF), cricket, oyster, mussel, and lugworm with high protein content, suitable functional properties, adequate amino acids composition, and the degree of hydrolysis from 18.24 to 33.52%. Protein hydrolysates at low concentrations from 0.001 to 0.1 mg/mL in combination with 1 and 2.5% serum significantly increased cell growth compared to the control groups (5 and 10% serum) (P < 0.05). All protein hydrolysates with concentrations of 1 and 10 mg/mL were found to be toxic to cells and significantly reduced cell growth and performance (P < 0.05). However, except for cricket, all hydrolysates were able to restore or significantly increase cell growth and viability with 50% less serum at a concentration of 0.001, 0.01, and 0.1 mg/mL. Although cell growth was enhanced at lower concentrations of protein hydrolysates, cell morphology was altered due to the lack of serum. Lactate dehydrogenase (LDH) activity results indicated that BSF and lugworm hydrolysates did not alter the cell membrane. In addition, light and fluorescence imaging revealed that cell morphological features were comparable to the 10% serum control group. Overall, lugworm and BSF hydrolysates reduced serum by up to 90% while preserving excellent cell health.

systems biology↗