Gut Microbiome and COVID 19 Role of Probiotics on Gut Lung Axis

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has caused the greatest worldwide pandemic called Coronavirus-2019 (COVID-19) disease. The SARS-CoV-2 virus primarily attacks the respiratory tract, but it also disturbs the gastrointestinal system (GIT). The presence of the angiotensin-converting enzyme-2 (ACE-2) receptor in the intestinal epithelial cells, suggest the transmission of SARS-CoV-2 viruses from lungs to gut through systemic circulation. The virus detected in fecal samples of COVID-19 patients causes several gastrointestinal maladies including vomiting, diarrhea, and pain in abdomen. The gastrointestinal symptoms are associated with alterations in gut microbial composition, an increase in inflammatory cytokines and delayed virus clearance. Several studies demonstrated a decreased abundance of beneficial microbial species and increased opportunistic pathogens in the fecal samples of COVID-19 patients. The gut and lungs, share a bi-directional relationship called the “gut-lung axis” which is modulated by imbalanced gut microbiota. Since the gut microbes are suggested to play a vital role in health and disease by maintaining homeostasis of the immune system, therefore targeting the intestinal dysbiosis with beneficial microbial species, seems plausible to eventually diminish the effects of pulmonary infections and diseases. In this review, we have summarized studies demonstrating the gut-lung axis in association with gut dysbiosis in COVID-19 patients. In addition, the review also highlights the studies showing the potential role of probiotic supplementation in the amelioration of various respiratory infections and diseases. Data demonstrate that the restoration of gut microbial communities by probiotic supplementation can enhance lung capacity to combat respiratory viral infections including SARS-CoV-2

The tyrosine kinase Pyk2 mediates lipopolysaccharide-induced IL-8 expression in human endothelial cells

Secretion of proinflammatory cytokines by LPS activated endothelial cells contributes substantially to the pathogenesis of sepsis. However, the mechanism involved in this process is not well understood. In the present study, we determined the role of a nonreceptor proline-rich tyrosine kinase, Pyk2, in LPS-induced IL-8 (CXCL8) production in endothelial cells. First, we observed a marked activation of Pyk2 in response to LPS. Furthermore, inhibition of Pyk2 activity in these cells by transduction with the catalytically inactive Pyk2 mutant, transfection with Pyk2-specific small interfering RNA, or treatment with Tyrphostin A9 significantly blocked LPS-induced IL-8 production. The supernatants of LPS-stimulated cells exhibiting attenuated Pyk2 activity blocked transendothelial neutrophil migration in comparison to the supernatants of LPS-treated controls, thus confirming the inhibition of functional IL-8 production. Investigations into the molecular mechanism of this pathway revealed that LPS activates Pyk2 leading to IL-8 production through the TLR4. In addition, we identified the p38 MAPK pathway to be a critical step downstream of Pyk2 during LPS-induced IL-8 production. Taken together, these results demonstrate a novel role for Pyk2 in LPS-induced IL-8 production in endothelial cells

Heat Induced Oxidative Stress and Aberrations in Liver Function Leading to Hepatic Injury in Rats

Exposure to heat stress (HS) elicits systemic and cellular response in experimental animals and humans. The current study was undertaken to determine the effect of HS on liver microstructure and function in rats. A heat simulation chamber with ambient temperature (Ta) 45 ± 0.5 °C and relative humidity (RH) 30 ± 5 per cent was used to expose animals to HS. Rats were categorised as moderately heat stressed (MHS, Tc = 40 °C) and severely heat stressed (SHS, Tc = 42 °C) group. We observed that with rise in core temperature (Tc) alanine aminotransferase(ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) levels were increased but glucose level was decreased in both plasma and liver tissue. Significantly elevated levels of reactive oxygen species (ROS) and nitric oxide (NO) were detected in liver of MHS and SHS animals. Additionally, glutathione disulfide and glutathione (GSSG and GSH) ratio was found to be increased with rise in Tc which suggested saturation in antioxidant capacity of tissue. Furthermore, levels of heat shock proteins (HSPs) and caspases were upregulated upon HS. Results of histological examination indicated extensive loss of cells in liver parenchyma leading to disorganisation of lobular structure. Thus, biochemical and histological studies in experimental animals demonstrates that HS may severely altered structural and biochemical functions of liver

Activation of the Connective Tissue Growth Factor (CTGF)-Transforming Growth Factor β 1 (TGF-β 1) Axis in Hepatitis C Virus-Expressing Hepatocytes

Background: The pro-fibrogenic cytokine connective tissue growth factor (CTGF) plays an important role in the development and progression of fibrosis in many organ systems, including liver. However, its role in the pathogenesis of hepatitis C virus (HCV)-induced liver fibrosis remains unclear. Methods: In the present study, we assessed CTGF expression in HCV-infected hepatocytes using replicon cells containing full-length HCV genotype 1 and the infectious HCV clone JFH1 (HCV genotype 2) by real-time PCR, Western blot analysis and confocal microscopy. We evaluated transforming growth factor β1 (TGF-β1) as a key upstream mediator of CTGF production using neutralizing antibodies and shRNAs. We also determined the signaling molecules involved in CTGF production using various immunological techniques. Results: We demonstrated an enhanced expression of CTGF in two independent models of HCV infection. We also demonstrated that HCV induced CTGF expression in a TGF-β1-dependent manner. Further dissection of the molecular mechanisms revealed that CTGF production was mediated through sequential activation of MAPkinase and Smad-dependent pathways. Finally, to determine whether CTGF regulates fibrosis, we showed that shRNA-mediated knock-down of CTGF resulted in reduced expression of fibrotic markers in HCV replicon cells. Conclusion: Our studies demonstrate a central role for CTGF expression in HCV-induced liver fibrosis and highlight the potential value of developing CTGF-based anti-fibrotic therapies to counter HCV-induced liver damage

Crosstalk between Chemokine Receptor CXCR4 and Cannabinoid Receptor CB2 in Modulating Breast Cancer Growth and Invasion

Cannabinoids bind to cannabinoid receptors CB(1) and CB(2) and have been reported to possess anti-tumorigenic activity in various cancers. However, the mechanisms through which cannabinoids modulate tumor growth are not well known. In this study, we report that a synthetic non-psychoactive cannabinoid that specifically binds to cannabinoid receptor CB(2) may modulate breast tumor growth and metastasis by inhibiting signaling of the chemokine receptor CXCR4 and its ligand CXCL12. This signaling pathway has been shown to play an important role in regulating breast cancer progression and metastasis.We observed high expression of both CB(2) and CXCR4 receptors in breast cancer patient tissues by immunohistochemical analysis. We further found that CB(2)-specific agonist JWH-015 inhibits the CXCL12-induced chemotaxis and wound healing of MCF7 overexpressing CXCR4 (MCF7/CXCR4), highly metastatic clone of MDA-MB-231 (SCP2) and NT 2.5 cells (derived from MMTV-neu) by using chemotactic and wound healing assays. Elucidation of the molecular mechanisms using various biochemical techniques and confocal microscopy revealed that JWH-015 treatment inhibited CXCL12-induced P44/P42 ERK activation, cytoskeletal focal adhesion and stress fiber formation, which play a critical role in breast cancer invasion and metastasis. In addition, we have shown that JWH-015 significantly inhibits orthotopic tumor growth in syngenic mice in vivo using NT 2.5 cells. Furthermore, our studies have revealed that JWH-015 significantly inhibits phosphorylation of CXCR4 and its downstream signaling in vivo in orthotopic and spontaneous breast cancer MMTV-PyMT mouse model systems.This study provides novel insights into the crosstalk between CB(2) and CXCR4/CXCL12-signaling pathways in the modulation of breast tumor growth and metastasis. Furthermore, these studies indicate that CB(2) receptors could be used for developing innovative therapeutic strategies against breast cancer

Melanoma Cell Expression of CD200 Inhibits Tumor Formation and Lung Metastasis via Inhibition of Myeloid Cell Functions

CD200 is a cell surface glycoprotein that functions through engaging CD200 receptor on cells of the myeloid lineage and inhibits their functions. Expression of CD200 has been implicated in a variety of human cancer cells including melanoma cells and has been thought to play a protumor role. To investigate the role of cancer cell expression of CD200 in tumor formation and metastasis, we generated CD200-positive and CD200-negative B16 melanoma cells. Subcutaneous injection of CD200-positive B16 melanoma cells inhibited tumor formation and growth in C57BL/6 mice but not in Rag1−/−C57BL/6 mice. However, i.v. injection of CD200-positive B16 melanoma cells dramatically inhibited tumor foci formation in the lungs of both C57BL/6 and Rag1−/−C57BL6 mice. Flow cytometry analysis revealed higher expression of CD200R in Gr1+ myeloid cells in the lung than in peripheral myeloid cells. Depletion of Gr1+ cells or stimulation of CD200R with an agonistic antibody in vivo dramatically inhibited tumor foci formation in the lungs. In addition, treatment with tumor antigen specific CD4 or CD8 T cells or their combination yielded a survival advantage for CD200 positive tumor bearing mice over mice bearing CD200-negative tumors. Taken together, we have revealed a novel role for CD200-CD200R interaction in inhibiting tumor formation and metastasis. Targeting CD200R may represent a novel approach for cancer immunotherapy

S100A7-Downregulation Inhibits Epidermal Growth Factor-Induced Signaling in Breast Cancer Cells and Blocks Osteoclast Formation

S100A7 is a small calcium binding protein, which has been shown to be differentially expressed in psoriatic skin lesions, as well as in squamous cell tumors of the skin, lung and breast. Although its expression has been correlated to HER+ high-grade tumors and to a high risk of progression, the molecular mechanisms of these S100A7-mediated tumorigenic effects are not well known. Here, we showed for the first time that epidermal growth factor (EGF) induces S100A7 expression in both MCF-7 and MDA-MB-468 cell lines. We also observed a decrease in EGF-directed migration in shRNA-downregulated MDA-MB-468 cell lines. Furthermore, our signaling studies revealed that EGF induced simultaneous EGF receptor phosphorylation at Tyr1173 and HER2 phosphorylation at Tyr1248 in S100A7-downregulated cell lines as compared to the vector-transfected controls. In addition, reduced phosphorylation of Src at tyrosine 416 and p-SHP2 at tyrosine 542 was observed in these downregulated cell lines. Further studies revealed that S100A7-downregulated cells had reduced angiogenesis in vivo based on matrigel plug assays. Our results also showed decreased tumor-induced osteoclastic resorption in an intra-tibial bone injection model involving SCID mice. S100A7-downregulated cells had decreased osteoclast number and size as compared to the vector controls, and this decrease was associated with variations in IL-8 expression in in vitro cell cultures. This is a novel report on the role of S100A7 in EGF-induced signaling in breast cancer cells and in osteoclast formation

Factors associated with HIV testing among male injecting drug users: findings from a cross-sectional behavioural and biological survey in Manipur and Nagaland, India

BACKGROUND: Although targeted interventions in India require all high-risk groups, including injecting drug users (IDUs), to test for HIV every 6 months, testing uptake among IDUs remains far from universal. Our study estimates the proportion of IDUs who have taken an HIV test and identifies the factors associated with HIV testing uptake in Nagaland and Manipur, two high HIV prevalence states in India where the epidemic is driven by injecting drug use. METHODS: Data are drawn from the cross-sectional Integrated Behavioural and Biological Assessment (2009) of 1650 male IDUs from two districts each of Manipur and Nagaland. Participants were recruited using respondent-driven sampling (RDS). Descriptive data were analysed using RDSAT 7.1. Multivariate logistic regression analysis was undertaken using STATA 11 to examine the association between HIV testing and socio-demographic, behavioural and programme exposure variables. RESULTS: One third of IDUs reported prior HIV testing, of whom 8 % had tested HIV-positive. Among those without prior testing, 6.2 % tested HIV-positive in the current survey. IDUs aged 25–34 years (adjusted odds ratio (OR) = 1.41; 95 % confidence interval (CI) = 1.03–1.93), married (Adjusted OR = 1.56; 95 % CI = 1.15–2.12), had a paid sexual partner (Adjusted OR = 1.64; 95 % CI = 1.24–2.18), injected drugs for more than 36 months (Adjusted OR = 1.38; 95 % CI = 1.06–1.81), injected frequently (Adjusted OR = 1.49; 95 % CI = 1.12–1.98) and had high-risk perception (Adjusted OR = 1.68; 95 % CI = 1.32–2.14) were more likely than others to test for HIV. Compared to those with no programme exposure, IDUs who received counselling, or counselling and needle/syringe services, were more likely to test for HIV. CONCLUSIONS: HIV testing uptake among IDUs is low in Manipur and Nagaland, and a critical group of HIV-positive IDUs who have never tested for HIV are being missed by current programmes. This study identifies key sub-groups—including early initiators, short duration and less frequent injectors, perceived to be at low risk—for promoting HIV testing. Providing needles/syringes alone is not adequate to increase HIV testing; additionally, interventions must provide counselling services to inform all IDUs about HIV testing benefits, facilitate visits to testing centres and link those testing positive to timely treatment and care