Serum levels of interleukin-33, soluble ST2 and IgE in patients with asthma: a case-control study.

INTRODUCTION: Interleukins play a very important role in the pathophysiology of asthma. Interleukin-33 (IL-33) is a partially explored cytokine in asthma. It binds with a specific receptor called suppression of tumorigenicity 2 (ST2). The study aims to evaluate the serum levels of IL-33, sST2 and IgE in asthmatic patients and healthy controls and its further association with the forced expiratory volume in one second (FEV 1%) and absolute eosinophil count. MATERIALS AND METHODS: We enrolled 100 asthmatic patients and 57 healthy subjects for the study. We measured serum levels of IgE, IL-33, and sST2. Based on serum IgE levels, patients were divided into allergic and non-allergic groups. Statistical analysis was done by using Graph pad prism software 8. RESULTS: We found significantly elevated levels of IL-33 and IgE in asthmatic patients as compared to healthy subjects. However, sST2 levels were significantly lower in asthmatic patients than in healthy subjects. FEV1% values were decreased in uncontrolled asthmatic patients. In addition, serum levels of IL-33 were significantly correlated with the IgE. Furthermore, we found a significant correlation between IL-33 and AEC in allergic asthmatic patients. CONCLUSION: In this study, we reported elevated IL-33 and IgE levels and decreased sST2 levels in asthmatic patients compared to healthy controls. IL-33 and sST2 may act as inflammatory biomarkers for allergic diseases such as asthma.

Evaluation of interleukin-33 & sST2 levels in type-2 diabetic mellitus patients with or without metabolic syndrome.

Background & objectives: Diabetes mellitus (DM) is characterized by increase in blood glucose levels due to defective insulin secretion or insulin sensitivity. Interleukins (ILs) are known to play an important role in the pathogenesis of DM. The aim of this study was to investigate the serum concentration of IL-33 and its receptor soluble ST2 (sST2) in patients with diabetes and draw a correlation between their serum levels and different standard glycaemic indices of patients affected with type-2 diabetes with or without metabolic syndrome. Methods: Thirty type-2 diabetic individuals and 30 healthy controls were recruited for this study. Serum and plasma were separated by centrifugation of blood for quantitative measurement of IL-33, sST2 and other biochemical parameters. Results: It was observed that serum IL-33 levels were significantly less and sST2 levels were significantly high in type-2 diabetic individuals as compared to healthy controls. A significant correlation between the serum IL-33 concentration and fasting plasma glucose (FPG) and postprandial plasma glucose (PPG) levels were also found. Additionally, data also elucidated that serum levels of high-density lipoprotein, low-density lipoprotein or triglyceride in type-2 diabetics did not influence the serum levels of IL-33 and sST2, thereby excluding these factors as the major drivers of changes in serum IL-33 and sST2 concentration. Interpretation & conclusions: This study demonstrated alteration in serum levels of IL-33 and sST2 in type-2 diabetic individuals. Further mechanistic studies, focusing on the progression of type-2 diabetes could elucidate the involvement of IL-33 in the cellular acquisition of insulin resistance as observed in type-2 diabetics.

Stem cells research prospects towards precision medicine.

The human body possesses an endogenous regeneration system based on stem cells, which may be found in practically every tissue type. They are classified as embryonic stem cells (ESCs) or nonembryonic stem cells (NESCs). Despite its enormous promise, the use of ESCs is presently limited because of ethical and scientific issues. Stem cells have the potential to improve healthcare by using and boosting the body's inherent regenerative capabilities. Although the stem cells offer an enormous promise for tissue regeneration and repair, much more about their biology, administration, and safety must be studied before they may be employed therapeutically. Stem cells and their derivatives will have enormous medical promise in the future. Current animal and laboratory investigations are looking into the viability of bringing stem cell therapy into clinical practice for regeneration in muscular dystrophy, intervertebral disc degeneration, cerebral infarctions, and transplantation medicine. This article delves into the many aspects at play, as well as current situation and possible issues with stem cell treatment in patient care and management (Fig. 1, Ref. 86). Keywords: stem cells, tissue engineering, regenerative medicine, stem cell application.

Tumor-derived exosomes in the regulation of macrophage polarization.

BACKGROUND: This review focuses on exosomes derived from various cancer cells. The review discusses the possibility of differentiating macrophages in alternatively activated anti-inflammatory pro-tumorigenic M2 macrophage phenotypes and classically activated pro-inflammatory, anti-tumorigenic M1 macrophage phenotypes in the tumor microenvironment (TME). The review is divided into two main parts, as follows: (1) role of exosomes in alternatively activating M2-like macrophages-breast cancer-derived exosomes, hepatocellular carcinoma (HCC) cell-derived exosomes, lung cancer-derived exosomes, prostate cancer-derived exosomes, Oral squamous cell carcinoma (OSCC)-derived exosomes, epithelial ovarian cancer (EOC)-derived exosomes, Glioblastoma (GBM) cell-derived exosomes, and colorectal cancer-derived exosomes, (2) role of exosomes in classically activating M1-like macrophages, oral squamous cell carcinoma-derived exosomes, breast cancer-derived exosomes, Pancreatic-cancer derived modified exosomes, and colorectal cancer-derived exosomes, and (3) exosomes and antibody-dependent cellular cytotoxicity (ADCC). This review addresses the following subjects: (1) crosstalk between cancer-derived exosomes and recipient macrophages, (2) the role of cancer-derived exosome payload(s) in modulating macrophage fate of differentiation, and (3) intracellular signaling mechanisms in macrophages regarding the exosome's payload(s) upon its uptake and regulation of the TME. EVIDENCE: Under the electron microscope, nanoscale exosomes appear as specialized membranous vesicles that emerge from the endocytic cellular compartments. Exosomes harbor proteins, growth factors, cytokines, lipids, miRNA, mRNA, and DNAs. Exosomes are released by many cell types, including reticulocytes, dendritic cells, B-lymphocytes, platelets, mast cells, and tumor cells. It is becoming clear that exosomes can impinge upon signal transduction pathways, serve as a mediator of signaling crosstalk, thereby regulating cell-to-cell wireless communications. CONCLUSION: Based on the vesicular cargo, the molecular constituents, the exosomes have the potential to change the fate of macrophage phenotypes, either M1, classically activated macrophages, or M2, alternatively activated macrophages. In this review, we discuss and describe the ability of tumor-derived exosomes in the mechanism of macrophage activation and polarization.

Elevated serum matrix metalloprotease (MMP-2) as a candidate biomarker for stable COPD.

BACKGROUND: The increasing trend of Chronic Obstructive Pulmonary Disease (COPD) in becoming the third leading cause of deaths by 2020 is of great concern, globally as well as in India. Dysregulation of protease/anti-protease balance in COPD has been reported to cause tissue destruction, inflammation and airway remodelling; which are peculiar characteristics of COPD. Therefore, it is imperative to explore various serum proteases involved in COPD pathogenesis, as candidate biomarkers. COPD and Asthma often have overlapping symptoms and therefore involvement of certain proteases in their pathogenesis would render accurate diagnosis of COPD to be difficult. METHODS: Serum samples from controls, COPD and Asthma patients were collected after requisite institutional ethics committee approvals. The preliminary analysis qualitatively and quantitatively analyzed various serum proteases by ELISA and mass spectrometry techniques. In order to identify a distinct biomarker of COPD, serum neutrophil elastase (NE) and matrix metalloprotease-2 (MMP-2) from COPD and Asthma patients were compared; as these proteases tend to have overlapping activities in both the diseases. A quantitative analysis of the reactive oxygen species (ROS) in the serum of controls and COPD patients was also performed. Statistical analysis for estimation of p-values was performed using unpaired t-test with 95% confidence interval. RESULTS: Amongst the significantly elevated proteases in COPD patients vs the controls- neutrophil elastase (NE) [P < 0.0241], caspase-7 [P < 0.0001] and matrix metalloprotease-2 (MMP-2) [P < 0.0001] were observed, along with increased levels of reactive oxygen species (ROS) [P < 0.0001]. The serum dipeptidyl peptidase-IV (DPP-IV) [P < 0.0010) concentration was found to be decreased in COPD patients as compared to controls. Interestingly, a distinct elevation of MMP-2 was observed only in COPD patients, but not in Asthma, as compared to controls. Mass spectrometry analysis further identified significant alterations (fold-change) in various proteases (carboxy peptidase, MMP-2 and human leukocyte elastase), anti-proteases (Preg. zone protein, α-2 macroglobulin, peptidase inhibitor) and signalling mediators (cytokine suppressor- SOCS-3). CONCLUSION: The preliminary study of various serum proteases in stable COPD patients distinctly identified elevated MMP-2 as a candidate biomarker for COPD, subject to its validation in large cohort studies.

Structural insights of resveratrol with its binding partners in the toll-like receptor 4 pathway.

The benefits associated with resveratrol (Resv; 3,4',5-trihydroxy-trans-stilbene) are known for a long time. The therapeutic properties of Resv are observed in diseases like cancer, neurological disorders, atherosclerosis, aging, inflammation, etc. Multiple studies suggest that the beneficial properties of Resv are due to its binding to targets in multiple pathways. The same has been reflected in inflammation, where Resv has been shown to inhibit nuclear factor κ light-chain enhancer of activated B cells in the toll-like receptor 4 (TLR4) pathway. There are multiple cellular targets which bind to Resv, however the mode and the key interactions involved remain elusive for many of them. In the current work, we have investigated the structural insights of Resv with three of its binding partners involved in the inflammatory TLR4 signaling pathway. Through a structure-based modelling and molecular dynamics study, we have unraveled the molecular and atomic interactions involved in the Resv-binary complexes of inhibitor of κB kinase, cyclooxygeanse-2, and tank-binding kinase I, all three of which are key players in TLR4 inflammatory signaling. This study is the latest addition to the investigations of the structural partners of Resv and its molecular interactions.

IL-33 mediated amplification of allergic response in human mast cells.

Context: IL-33 is a pro-inflammatory cytokine that is involved in the development of chronic inflammatory diseases and the initiation of allergic inflammation in response to pathogens and acts an alarmin.Objective: Present study aims to explore the IL-33 mediated effects of histamine induced allergic inflammation in human mast cells.Materials and methods: In this study, cord blood derived CD34+ mast cells and HMC-1 cells were primed with IL-33 followed by the stimulation with histamine. We investigated the functional activation of mast cell by intracellular calcium release using calcium mobilization assay, release of granular content using degranulation assay, profiling of various inflammatory and regulatory cytokines as well as chemokines by Luminex Bioplex assay and its signaling mechanisms involved using western blot analysis.Results: In our study, we found that the IL-33 acts as a mediator in the allergic inflammation induced by the histamine. IL-33 potentiates the release of intracellular calcium and degranulation content in human mast cells. Also, it enhances the production of Th2, Th1 cytokines and chemokines and down-regulates the production of regulatory cytokine. Furthermore, it enhanced the phosphorylation of the signaling molecules such as ERK, Akt, and NFκB in activated mast cells. Therefore, IL-33 acts as a potent activator of mast cells and it can elicit inflammatory response synergistically with histamine.Conclusions: Taken together, IL-33 acts as a potent mediator by inducing the inflammatory response in activated mast cells, hence increasing their responsiveness to antigens and amplifying the allergic response.

Lipid mediator metabolic profiling demonstrates differences in eicosanoid patterns in two phenotypically distinct mast cell populations.

Mast cells are inflammatory cells that play key roles in health and disease. They are distributed in all tissues and appear in two main phenotypes, connective tissue and mucosal mast cells, with differing capacities to release inflammatory mediators. A metabolic profiling approach was used to obtain a more comprehensive understanding of the ability of mast cell phenotypes to produce eicosanoids and other lipid mediators. A total of 90 lipid mediators (oxylipins) were characterized using liquid chromatography-tandem mass spectrometry (LC-MS/MS), representing the cyclooxygenase (COX), lipoxygenase (LO), and cytochrome P450 (CYP) metabolic pathways. In vitro-derived murine mucosal-like mast cells (MLMC) and connective tissue-like mast cells (CTLMC) exhibited distinct mRNA expression patterns of enzymes involved in oxylipin biosynthesis. Oxylipins produced by 5-LO and COX pathways were the predominant species in both phenotypes, with 5-LO products constituting 90 ± 2% of the CTLMCs compared with 58 ± 8% in the MLMCs. Multivariate analyses demonstrated that CTLMCs and MLMCs secrete differing oxylipin profiles at baseline and following calcium ionophore stimulation, evidencing specificity in both a time- and biosynthetic pathway-dependent manner. In addition to the COX-regulated prostaglandin PGD(2) and 5-LO-regulated cysteinyl-leukotrienes (e.g., LTC(4)), several other mediators evidenced phenotype-specificity, which may have biological implications in mast cell-mediated regulation of inflammatory responses.

Impact of COVID-19 on thyroid gland functions with reference to Graves' disease: A systematic review.

Coronavirus disease 2019 (COVID-19) is caused due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Both immediate and long-term adverse effects arise out of this disease's aftermath. It involves various organs, which include endocrine glands, nervous system, musculoskeletal system, and other organs. The long-term outcomes of the SARS-CoV-2 infection are influenced by preexisting comorbidities. Genetic, environmental, and immunological factors contribute to the development of various autoimmune diseases, which include Graves' disease (GD). The growing mystery surrounding this virus is exacerbated by auto-inflammatory diseases, such as pediatric inflammatory multisystemic syndrome (PIMS) or multisystem inflammatory syndrome in children (MIS-C), which raises concerns about the nature of the virus' connection to the autoimmune and auto-inflammatory sequelae. There is a need to understand the underlying mechanisms of developing GD in post-COVID-19 patients. There are limited data regarding the pathogenesis involved in post-COVID-19 GD. Our goal was to understand the various mechanisms involved in post-COVID-19 GD among patients with confirmed COVID-19 infection. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for 2020, a literature search of medical databases (PubMed, Cochrane Central Register of Controlled Trials, and Scopus) from February 2021 to February 2022 was performed by five authors. The keywords used were "Post COVID-19," "Grave's disease," "Cytokine storm," "Autoimmunity," and "Molecular mimicry." This review revealed three underlying mechanisms that resulted in post-COVID GD, which included cytokine storm, molecular mimicry, ACE2 receptor concentration, and cell-mediated immunity. The full spectrum of the effects of COVID-19 needs to be researched.

Molecular and biochemical characterization of nitric oxide synthase isoforms and their intracellular distribution in human peripheral blood mononuclear cells.

Nitric oxide synthase (NOS) expression and catalytic status in human peripheral blood mononuclear cells (PBMCs) is debatable, while its sub-cellular distribution remains unascertained. The present study characterizes NOS transcripts by real time PCR, NOS protein by immunoprecipitation (IP)/Western blot (WB), nitric oxide (NO) generation by DAF-2DA and NOS sub-cellular distribution by immunogold electron microscopy in resting PBMCs, monocytes and lymphocytes obtained from healthy donors. We observed constitutive expression of full length NOS isoforms (nNOS, iNOS and eNOS) in PBMCs: with the highest expression of iNOS in comparison to nNOS and eNOS. Isolated monocytes expressed more eNOS transcript and protein as compared to nNOS and iNOS. Lymphocytes however had more iNOS transcripts and protein than nNOS and eNOS. NOS was catalytically active in PBMCs, monocytes as well as in lymphocytes as evident by NO generation in the presence of substrate and cofactors, which was significantly reduced in the presence of NOS inhibitor. Immunogold electron microscopy and morphometric analysis revealed the distinct pattern of NOS distribution in monocytes and lymphocytes and also exhibited differences in the nuclear-cytoplasmic ratio. nNOS localization was much more in the cytosol than in the nucleus among both monocytes and lymphocytes. Interestingly, iNOS distribution was comparable in both cytosol and nucleus among monocytes, but in lymphocytes iNOS was predominantly localized to the cytosol. The present study exhibits constitutive presence of all the NOS isoforms in PBMCs and reports the distinct pattern of NOS distribution among monocytes and lymphocytes.

Improving Scene Text Recognition for Indian Languages with Transfer Learning and Font Diversity.

Reading Indian scene texts is complex due to the use of regional vocabulary, multiple fonts/scripts, and text size. This work investigates the significant differences in Indian and Latin Scene Text Recognition (STR) systems. Recent STR works rely on synthetic generators that involve diverse fonts to ensure robust reading solutions. We present utilizing additional non-Unicode fonts with generally employed Unicode fonts to cover font diversity in such synthesizers for Indian languages. We also perform experiments on transfer learning among six different Indian languages. Our transfer learning experiments on synthetic images with common backgrounds provide an exciting insight that Indian scripts can benefit from each other than from the extensive English datasets. Our evaluations for the real settings help us achieve significant improvements over previous methods on four Indian languages from standard datasets like IIIT-ILST, MLT-17, and the new dataset (we release) containing 440 scene images with 500 Gujarati and 2535 Tamil words. Further enriching the synthetic dataset with non-Unicode fonts and multiple augmentations helps us achieve a remarkable Word Recognition Rate gain of over 33% on the IIIT-ILST Hindi dataset. We also present the results of lexicon-based transcription approaches for all six languages.

Evaluation of serum interleukin-33 and soluble suppression of tumorigenicity 2 (sST2) receptors in patients with and without periodontal disease.

Context: : Interleukin-33 and its receptor soluble suppression of tumorigenicity 2. (: sST2) play an important role in inflammation and its role in periodontal disease is yet unclear. The role of both IL-33 and sST2 together in periodontal disease as biomarkers has never been studied. Aim: : To assess the levels of IL-33 and sST2 in serum samples of patients with periodontitis and healthy subjects. Methods: : A total of 71 subjects (30 healthy subjects and 41 patients with periodontal disease) were included in the cross-sectional study. Community Periodontal Index (CPI) was used to assess periodontal health by utilizing a mouth mirror and a CPI probe. Venous blood was collected and serum was separated. Serum levels of IL-33 and sST2 were determined by the enzyme-linked immunosorbent assay (ELISA) assay. Statistical Analysis: Graph Pad Prism 5 was used for statistical analysis. Mann Whitney test was applied to compare the two groups. Results: : The level of IL-33 was not found to be elevated among healthy subjects and sST2 was found elevated among patients with periodontal disease. The serum concentration of IL-33 was found at 472 ± 114 pg/ml and 282 ± 77 pg/ml among healthy subjects and patients with periodontal disease respectively. Significantly higher values of sST2 at 28 ± 2 ng/ml were found among periodontal patients as compared to healthy subjects with values of 18 ± 1 ng/ml. No significant differences were noted between mild to moderate and severe periodontitis for IL-33 and sST2 between the two groups. Conclusion: This study shows alteration in serum levels of IL-33 and sST2 in periodontitis patients. IL-33 and sST2 may be potential inflammatory markers of periodontitis. Further studies are required on a large sample size for better understanding. This pilot study is the first to assess the serum levels of both IL-33 and sST2 together among patients with and without periodontal disease.

The expanding roles of neuronal nitric oxide synthase (NOS1).

The nitric oxide synthases (NOS; EC 1.14.13.39) use L-arginine as a substrate to produce nitric oxide (NO) as a by-product in the tissue microenvironment. NOS1 represents the predominant NO-producing enzyme highly enriched in the brain and known to mediate multiple functions, ranging from learning and memory development to maintaining synaptic plasticity and neuronal development, Alzheimer's disease (AD), psychiatric disorders and behavioral deficits. However, accumulating evidence indicate both canonical and non-canonical roles of NOS1-derived NO in several other tissues and chronic diseases. A better understanding of NOS1-derived NO signaling, and identification and characterization of NO-metabolites in non-neuronal tissues could become useful in diagnosis and prognosis of diseases associated with NOS1 expression. Continued investigation on the roles of NOS1, therefore, will synthesize new knowledge and aid in the discovery of small molecules which could be used to titrate the activities of NOS1-derived NO signaling and NO-metabolites. Here, we address the significance of NOS1 and its byproduct NO in modifying pathophysiological events, which could be beneficial in understanding both the disease mechanisms and therapeutics.

Leaf Count Aided Novel Framework for Rice (Oryza sativa L.) Genotypes Discrimination in Phenomics: Leveraging Computer Vision and Deep Learning Applications.

Drought is a detrimental factor to gaining higher yields in rice (Oryza sativa L.), especially amid the rising occurrence of drought across the globe. To combat this situation, it is essential to develop novel drought-resilient varieties. Therefore, screening of drought-adaptive genotypes is required with high precision and high throughput. In contemporary emerging science, high throughput plant phenotyping (HTPP) is a crucial technology that attempts to break the bottleneck of traditional phenotyping. In traditional phenotyping, screening significant genotypes is a tedious task and prone to human error while measuring various plant traits. In contrast, owing to the potential advantage of HTPP over traditional phenotyping, image-based traits, also known as i-traits, were used in our study to discriminate 110 genotypes grown for genome-wide association study experiments under controlled (well-watered), and drought-stress (limited water) conditions, under a phenomics experiment in a controlled environment with RGB images. Our proposed framework non-destructively estimated drought-adaptive plant traits from the images, such as the number of leaves, convex hull, plant-aspect ratio (plant spread), and similarly associated geometrical and morphological traits for analyzing and discriminating genotypes. The results showed that a single trait, the number of leaves, can also be used for discriminating genotypes. This critical drought-adaptive trait was associated with plant size, architecture, and biomass. In this work, the number of leaves and other characteristics were estimated non-destructively from top view images of the rice plant for each genotype. The estimation of the number of leaves for each rice plant was conducted with the deep learning model, YOLO (You Only Look Once). The leaves were counted by detecting corresponding visible leaf tips in the rice plant. The detection accuracy was 86-92% for dense to moderate spread large plants, and 98% for sparse spread small plants. With this framework, the susceptible genotypes (MTU1010, PUSA-1121 and similar genotypes) and drought-resistant genotypes (Heera, Anjali, Dular and similar genotypes) were grouped in the core set with a respective group of drought-susceptible and drought-tolerant genotypes based on the number of leaves, and the leaves' emergence during the peak drought-stress period. Moreover, it was found that the number of leaves was significantly associated with other pertinent morphological, physiological and geometrical traits. Other geometrical traits were measured from the RGB images with the help of computer vision.

The Interplay of Oxidative Stress and ROS Scavenging: Antioxidants as a Therapeutic Potential in Sepsis.

Oxidative stress resulting from the disproportion of oxidants and antioxidants contributes to both physiological and pathological conditions in sepsis. To combat this, the antioxidant defense system comes into the picture, which contributes to limiting the amount of reactive oxygen species (ROS) leading to the reduction of oxidative stress. However, a strong relationship has been found between scavengers of ROS and antioxidants in preclinical in vitro and in vivo models. ROS is widely believed to cause human pathology most specifically in sepsis, where a small increase in ROS levels activates signaling pathways to initiate biological processes. An inclusive understanding of the effects of ROS scavenging in cellular antioxidant signaling is essentially lacking in sepsis. This review compiles the mechanisms of ROS scavenging as well as oxidative damage in sepsis, as well as antioxidants as a potent therapeutic. Direct interaction between ROS and cellular pathways greatly affects sepsis, but such interaction does not provide the explanation behind diverse biological outcomes. Animal models of sepsis and a number of clinical trials with septic patients exploring the efficiency of antioxidants in sepsis are reviewed. In line with this, both enzymatic and non-enzymatic antioxidants were effective, and results from recent studies are promising. The usage of these potent antioxidants in sepsis patients would greatly impact the field of medicine.

Current updates on adaptive immune response by B cell and T cell stimulation and therapeutic strategies for novel coronavirus disease 2019 (COVID-19) treatment.

The prevalence of COVID-19 continues to rise with more than 114,315,846 million confirmed cases and 2,539,427 deaths worldwide by 3 March 2021 and this number kept on increasing day by day. There is no clear therapeutic treatment or vaccine available for COVID-19 till date and by seeing such a high rise in the cases of COVID-19 on daily basis, it would have been necessary to implement precautions and hygienic measures to monitor and reduce human-to-human transmission of SARS-CoV-2 before there is any successful intervention/treatment available. Currently, several studies demonstrated the important improvements in both the innate and adaptive immune systems of COVID-19 patients. In particular, pre-existing research, on immune response to B cell and T cells are highlighting that pre-existing immunity exists in about 90% of the general population because of previous exposure to CoVs and having immunity against these CoVs. Although it is not clear from, the current studies on COVID-19 but it assumed that, it might have implication to COVID-19 severity and could play an important role in treatment or vaccine development against COVID-19. This review summarizes the information from occurrence of SARS-CoV-2 to its pathogenesis, transmission, adaptive immune response with respect to T cell and B cell stimulation and therapeutic interventions/treatment against COVID-19.

Ultrastructural immunogold localization of nitric oxide synthase isoforms in rat and human eosinophils.

The involvement of nitric oxide (NO) as both pro and anti-inflammatory agent in allergic, airway inflammatory, and asthmatic diseases and the active participation of eosinophils in such ailments have been previously suggested. NO modulates eosinophil number, migration and their survival. The microenvironment of NO synthase (NOS) in subcellular organelles determines its rate and efficiency of catalysis, which in turn influences NO generation at distinct intracellular locales. The present study was undertaken to assess the intracellular distribution of NOS isoforms by transmission electron microscopy followed by morphometric analysis in human and rat eosinophils. Rat eosinophils were explored in parallel, and since they are widely used as model systems to mimic human diseases, a comparative study on NOS localization patterns might provide useful information in deciphering NO role in diverse aspects of eosinophil-related inflammatory ailments. The results demonstrated predominance of neuronal NOS (nNOS) in the eosinophilic granules and even distribution of inducible NOS (iNOS) and nNOS in the cytoplasm and nucleus of human eosinophils. In rat eosinophils, however, iNOS was mainly localized in the eosinophilic granules and nucleus, while nNOS was distributed evenly in cytoplasm and nucleus. Distribution of endothelial NOS (eNOS) in eosinophils was scanty. Differences in NOS isoforms and their localization in human and rat cells might have implications in differential mode of catalysis and functional contribution to eosinophil physiology and pathology, warranting detailed investigations. The present study highlights species-specific differences in the relative abundance and distribution pattern of NOS isoforms in rat and human eosinophils, which should be considered cautiously in interpreting the rat data to humans.

Nitric oxide donors release extracellular traps from human neutrophils by augmenting free radical generation.

High availability of NO, oxidative stress and neutrophil extracellular trap (NETs) contents are often noticed at the site of inflammation/infection. Studies from this lab and others have reported NO mediated free radical generation from neutrophils; role of NO in NETs formation however remains undefined so far. The present study was therefore undertaken to explore the effect of NO donors on NET release from human neutrophils (PMNs), using confocal/scanning microscopy, measuring the extracellular DNA content and NET-bound elastase activity. Addition of NO donors (SNAP and SNP) to adhered PMNs led to a time and concentration dependent NETs release, which was blocked by N-acetyl cysteine, suggesting involvement of free radicals in NETs formation. Free radical formation by NO donors was assessed by using DCF-DA, DMPO-nitrone antibody and by p47 phox migration to the neutrophils membrane. NO mediated formation of free radicals and NETs was significantly reduced by the pretreatment of neutrophils with diphenyleneiodonium (DPI), a NADPH-oxidase inhibitor and 4-aminobenzoic acid hydrazide (ABAH), a myeloperoxidase inhibitor, suggesting role of enzymatic free radical generation by NO donors. We thus demonstrate that NO by augmenting free radical formation in human neutrophils mediates NETs release.