Metformin inhibits IgE- and aryl hydrocarbon receptor-mediated mast cell activation in vitro and in vivo

The Role Played by Autophagy in FcεRI-Dependent Activation of Mast Cells

The significant role of mast cells in the development of allergic and inflammatory diseases is well-established. Among the various mechanisms of mast cell activation, the interaction of antigens/allergens with IgE and the subsequent binding of this complex to the high-affinity IgE receptor FcεRI stand out as the most studied and fundamental pathways. This activation process leads to the rapid exocytosis of granules containing preformed mediators, followed by the production of newly synthesized mediators, including a diverse array of cytokines, chemokines, arachidonic acid metabolites, and more. While conventional approaches to allergy control primarily focus on allergen avoidance and the use of antihistamines (despite their associated side effects), there is increasing interest in exploring novel methods to modulate mast cell activity in modern medicine. Recent evidence suggests a role for autophagy in mast cell activation, offering potential avenues for utilizing low-molecular-weight autophagy regulators in the treatment of allergic diseases. More specifically, mitochondria, which play an important role in the regulation of autophagy as well as mast cell activation, emerge as promising targets for drug development. This review examines the existing literature regarding the involvement of the molecular machinery associated with autophagy in FcεRI-dependent mast cell activation.

Metformin regulates the effects of IR and IGF-1R methylation on mast cell activation and airway reactivity in diabetic rats with asthma through miR-152-3p/DNMT1 axis

BACKGROUND/AIM

Metformin is a drug for treating type 2 diabetes mellitus (T2DM). Recently, metformin has been shown to reduce the risks of asthma-associated outcomes and asthma deterioration, thereby holding promise as a superior medicine for diabetic patients with asthma. However, the mechanism by which metformin reduces diabetic asthma is yet to be clarified. This study aimed at ascertaining the downstream molecules underlying the effect of metformin on the activation of mast cells (MCs) and airway reactivity in a concomitant diabetic and asthmatic rat model.

METHODS

A T2DM model was induced utilizing a high-fat diet and streptozotocin. Then, 10% ovalbumin was utilized to stimulate asthma-like pathology in the T2DM rats. RBL-2H3 cells were induced by anti-dinitrophenyl-specific immunoglobulin E for constructing an in vitro model. Luciferase assay and RNA immunoprecipitation (IP) assay were conducted to identify the interaction between microRNA-152-3p (miR-152-3p) and DNA methyltransferase 1 (DNMT1), while chromatin IP to identify the binding of DNMT1 to insulin receptor (IR) and insulin-like growth factor 1 receptor (IGF-1R) promoters. The effects of metformin on both pathological changes in vivo and biological behaviors of cells were evaluated. Using gain- and loss-of-function approaches, we assessed the role of the two interactions in the metformin-induced effect.

RESULTS

It was suggested that metformin could impede the MC activation and airway resistance in the concomitant diabetic and asthmatic rats. Additionally, metformin downregulated IR and IGF-1R through DNMT1-dependent methylation to repress MC activation and airway resistance. DNMT1 was testified to be a target gene of miR-152-3p. Furthermore, miR-152-3p-induced silencing of DNMT1 was blocked by metformin, hence restraining MC activation and airway resistance.

CONCLUSION

The findings cumulatively demonstrate that metformin downregulates IR/IGF-1R to block MC activation and airway resistance via impairing the binding affinity between miR-152-3p and DNMT1.

The Aryl Hydrocarbon Receptor, Epigenetics and the Aging Process

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor, classically associated with the regulation of xenobiotic metabolism in response to environmental toxins. In recent years, transgenic rodent models have implicated AhR in aging and longevity. Moreover, several AhR ligands, such as resveratrol and quercetin, are compounds proven to extend the lifespan of model organisms. In this paper, we first review AhR biology with a focus on aging and highlight several AhR ligands with potential anti-aging properties. We outline how AhR-driven expression of xenobiotic metabolism genes into old age may be a key mechanism through which moderate induction of AhR elicits positive benefits on longevity and healthspan. Furthermore, via integration of publicly available datasets, we show that liver-specific AhR target genes are enriched among genes subject to epigenetic aging. Changes to epigenetic states can profoundly affect transcription factor binding and are a hallmark of the aging process. We suggest that the interplay between AhR and epigenetic aging should be the subject of future research and outline several key gaps in the current literature. Finally, we recommend that a broad range of non-toxic AhR ligands should be investigated for their potential to promote healthspan and longevity.

Aryl hydrocarbon receptor: The master regulator of immune responses in allergic diseases

The aryl hydrocarbon receptor (AhR) is a widely studied ligand-activated cytosolic transcriptional factor that has been associated with the initiation and progression of various diseases, including autoimmune diseases, cancers, metabolic syndromes, and allergies. Generally, AhR responds and binds to environmental toxins/ligands, dietary ligands, and allergens to regulate toxicological, biological, cellular responses. In a canonical signaling manner, activation of AhR is responsible for the increase in cytochrome P450 enzymes which help individuals to degrade and metabolize these environmental toxins and ligands. However, canonical signaling cannot be applied to all the effects mediated by AhR. Recent findings indicate that activation of AhR signaling also interacts with some non-canonical factors like Kruppel-like-factor-6 (KLF6) or estrogen-receptor-alpha (Erα) to affect the expression of downstream genes. Meanwhile, enormous research has been conducted to evaluate the effect of AhR signaling on innate and adaptive immunity. It has been shown that AhR exerts numerous effects on mast cells, B cells, macrophages, antigen-presenting cells (APCs), Th1/Th2 cell balance, Th17, and regulatory T cells, thus, playing a significant role in allergens-induced diseases. This review discussed how AhR mediates immune responses in allergic diseases. Meanwhile, we believe that understanding the role of AhR in immune responses will enhance our knowledge of AhR-mediated immune regulation in allergic diseases. Also, it will help researchers to understand the role of AhR in regulating immune responses in autoimmune diseases, cancers, metabolic syndromes, and infectious diseases.

Crosstalk between SARS-CoV-2 Infection and Type II Diabetes

Since the outbreak of coronavirus disease (COVID-19) in Wuhan, China, triggered by severe acute respiratory coronavirus 2 (SARS-CoV-2) in late November 2019, spreading to more than 200 countries of the world, the ensuing pandemic to an enormous loss of lives, mainly the older population with comorbidities, like diabetes, cardiovascular disease, chronic obstructive pulmonary disease, obesity, and hypertension. Amongst these immune-debilitating diseases, SARS-CoV-2 infection is the most common in patients with diabetes due to the absence of a normal active immune system to fight the COVID-19. Recovery of patients having a history of diabetes from COVID-19 encounters several complications, and their management becomes cumbersome. For control of coronavirus, antiviral medications, glucose-lowering agents, and steroids have been carefully evaluated. In the present review, we discuss the crosstalk between SARS-CoV-2 infection and patients with a history of diabetes. We mainly emphasize the molecular factors that are involved in diabetic individuals recently infected by SARS-CoV-2 and developed COVID-19 disease. Lastly, we examine the medications available for the long-term management of diabetic patients with SARS-CoV-2 infection.

The Crosstalk between FcεRI and Sphingosine Signaling in Allergic Inflammation

Sphingolipid molecules have recently attracted attention as signaling molecules in allergic inflammation diseases. Sphingosine-1-phosphate (S1P) is synthesized by two isoforms of sphingosine kinases (SPHK 1 and SPHK2) and is known to be involved in various cellular processes. S1P levels reportedly increase in allergic inflammatory diseases, such as asthma and anaphylaxis. FcεRI signaling is necessary for allergic inflammation as it can activate the SPHKs and increase the S1P level; once S1P is secreted, it can bind to the S1P receptors (S1PRs). The role of S1P signaling in various allergic diseases is discussed. Increased levels of S1P are positively associated with asthma and anaphylaxis. S1P can either induce or suppress allergic skin diseases in a context-dependent manner. The crosstalk between FcεRI and S1P/SPHK/S1PRs is discussed. The roles of the microRNAs that regulate the expression of the components of S1P signaling in allergic inflammatory diseases are also discussed. Various reports suggest the role of S1P in FcεRI-mediated mast cell (MC) activation. Thus, S1P/SPHK/S1PRs signaling can be the target for developing anti-allergy drugs.

Metformin and the Risk of Chronic Urticaria in Patients with Type 2 Diabetes

We conducted this study to determine the effect of metformin use on the risk of new-onset chronic urticaria in patients with type 2 diabetes (T2D). In total, 24,987 pairs of metformin users and nonusers were identified with propensity score-matching from Taiwan's National Health Insurance Research Database from 1 January 2000, to 31 December 2017. Multivariable Cox proportional hazards models were used to compare the risks of chronic urticaria development, severe chronic urticaria, and hospitalization for chronic urticaria between metformin users and nonusers. Compared with metformin nonuse, the aHRs (95% CI) for metformin use in chronic urticaria development, severe chronic urticaria, and hospitalization for chronic urticaria were 1.56 (1.39-1.74), 0.40 (0.12-1.30), and 1.45 (0.82-2.56), respectively. The cumulative incidence of chronic urticaria development was significantly higher in metformin users than in nonusers (p < 0.0001). A longer average cumulative duration of metformin use was associated with higher risks of new-onset and hospitalization for chronic urticaria than metformin nonuse. This nationwide cohort study showed that metformin use was associated with a significantly higher risk of chronic urticaria development. A longer average cumulative duration of metformin use was associated with a higher risk of outcomes. More prospective studies are needed to verify our results.

Metformin and the Development of Asthma in Patients with Type 2 Diabetes

We conducted this study to compare the risks of asthma development and exacerbation between metformin users and nonusers. Overall, 57,743 propensity score-matched metformin users and nonusers were identified from Taiwan’s National Health Insurance Research Database between 1 January 2000, and 31 December 2017. We used the Cox proportional hazards model with robust standard error estimates to compare the risks of asthma onset, exacerbation, and hospitalization for asthma in participants with type 2 diabetes (T2D). Compared with metformin nonuse, the aHRs (95% CI) for metformin use in asthma development, exacerbation, and hospitalization for asthma were 1.13 (1.06−1.2), 1.62 (1.35−1.95), and 1.5 (1.22−1.85), respectively. The cumulative incidences of asthma development, exacerbation, and hospitalization for asthma were significantly higher in metformin users than nonusers (p < 0.001). A longer cumulative duration of metformin use for more than 728 days was associated with significantly higher risks of outcomes than metformin nonuse. Our study demonstrated that metformin users showed significantly higher risks of asthma development, exacerbation, and hospitalization for asthma than metformin nonusers. Moreover, metformin use for more than 728 days was associated with higher risks of outcomes. A randomized control study is warranted to verify our results.

Elevated serum IL-13 level is associated with increased Treg cells in tumor microenvironment and disease progression of Diffuse large B-cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is the most common aggressive lymphoid malignancy, with an immunosuppressive microenvironment affecting clinical outcome. Interleukin (IL)-13 overexpression is observed in multiple solid tumors and contributes to tumor progression. This study aims to investigate pretreatment serum IL-13 levels and their relationship with the prognosis of DLBCL patients. One hundred and sixty-six patients with newly diagnosed DLBCL from June 2015 to July 2017 were included. Patients with elevated pretreatment serum IL-13 levels (IL-13≥1.63pg/ml) were classified into the high IL-13 group and they had significantly lower complete remission rate (60% vs. 74%, p=0.0059), higher progression rate (43% vs. 23%, p=0.0051), and poor progression-free survival (2-yr PFS, 63% vs. 78%，p=0.0078) and overall survival (2-yr OS, 75% vs. 92%, p=0.0027), when compared to those in the low IL-13 group (IL-13<1.63pg/ml). Meanwhile, increased Treg cell ratio in peripheral blood (p=0.0147) and elevated serum IL-2 levels (p=0.0272) were observed in the high IL-13 group. Moreover, RNA sequencing data showed that patients in the high IL-13 group had significantly elevated expression of chemokines and chemokine receptors (CCR4, CCL19, CCL21, CXCL2) related to Treg activation and recruitment. Consistent with the chemokine profile, tumor immunophenotyping analysis revealed that higher Treg cells recruitment in the high IL-13 group than the low IL-13 group (p=0.0116). In vitro, when lymphoma cells co-cultured with peripheral blood monocytes of healthy controls, metformin down-regulated both IL-13 level and Treg cell ratio, in consistent with the decreased serum IL-13 levels of patients after 6 months of metformin maintenance therapy in the high IL-13 group. Taken together, pretreatment serum IL-13 level is related to the immunosuppressive microenvironment and poor clinical outcome of DLBCL patients and could be targeted by metformin, thus providing a new therapeutic strategy in treating DLBCL with high serum IL-13 levels. This article is protected by copyright. All rights reserved.

Mechanism exploration of Gouqi-wentang formula against type 2 diabetes mellitus by phytochemistry and network pharmacology-based analysis and biological validation

BACKGROUND

The Gouqi-wentang formula (GQWTF) is a herbal formula used by Academician Xiao-lin Tong for the clinical treatment of T2DM. GQWTF is beneficial to qi, nourishes Yin, clears heat, and promotes fluid production, but the effective components and their mechanism of action remain unclear.

METHODS

The main components of GQWTF were detected by LC-MS, and the multi-target mechanisms of GQWTF in T2DM were elucidated using network pharmacology analysis, including target prediction, protein-protein interaction network construction and analysis, Gene Ontology (GO) terms, Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway annotation, and other network construction. Finally, the efficacy of the GQWTF was verified using biological experiments.

RESULTS

First, the "herb-channel tropism" network suggested that GQWTF focuses more on treating diseases by recuperating the liver, which is considered as an important insulin-sensitive organ. Subsequently, a total of 16 active ingredients in GQWTF were detected and screened, and their biological targets were predicted. Then, "compound-target" network was constructed, where enrichment analysis of GQWTF targets reflected its potential pharmacological activities. After T2DM-related target identification, 39 cross targets of GQWTF and T2DM were obtained, and 30 key targets highly responsible for the beneficial effect of GQWTF on T2DM were identified by PPI analysis. GO analysis of these key targets showed that many biological processes of GQWTF in treating T2DM are key in the occurrence and development of T2DM, including components related to inflammatory/immune response, insulin, and metabolism. KEGG analysis revealed the regulation of multiple signalling pathways, such as insulin resistance, PPAR signalling pathway, FoxO signalling pathway, Fc epsilon RI signalling pathway, and pathways that influence diabetes primarily by regulating metabolism as well as other T2DM directly related pathways. Furthermore, a "formula-compound-pathway-symptom" network was constructed to represent a global view of GQWTF in the treatment of T2DM.

CONCLUSIONS

This study explored the mechanism of action of GQWTF in T2DM by multi-component and multi-target multi pathways, which could provide a theoretical basis for the development and clinical application of GQWTF.

MiR-154-5p-MCP1 Axis Regulates Allergic Inflammation by Mediating Cellular Interactions

In a previous study, we have demonstrated that p62, a selective receptor of autophagy, can regulate allergic inflammation. In the present study, microRNA array analysis showed that miR-154-5p was increased by antigen (DNP-HSA) in a p62-dependent manner in rat basophilic leukemia cells (RBL2H3). NF-kB directly increased the expression of miR-154-5p. miR-154-5p mediated in vivo allergic reactions, including passive cutaneous anaphylaxis and passive systemic anaphylaxis. Cytokine array analysis showed that antigen stimulation increased the expression of MCP1 in RBL2H3 cells in an miR-154-5p-dependent manner. Reactive oxygen species (ROS)-ERK-NF-kB signaling increased the expression of MCP1 in antigen-stimulated RBL2H3 cells. Recombinant MCP1 protein induced molecular features of allergic reactions both in vitro and in vivo. Anaphylaxis-promoted tumorigenic potential has been known to be accompanied by cellular interactions involving mast cells, and macrophages, and cancer cells. Our experiments employing culture medium, co-cultures, and recombinant MCP1 protein showed that miR-154 and MCP1 mediated these cellular interactions. MiR-154-5p and MCP1 were found to be present in exosomes of RBL2H3 cells. Exosomes from PSA-activated BALB/C mouse induced molecular features of passive cutaneous anaphylaxis in an miR-154-5p-dependent manner. Exosomes from antigen-stimulated RBL2H3 cells enhanced both tumorigenic and metastatic potentials of B16F1 melanoma cells in an miR-154-5p-dependent manner. Exosomes regulated both ROS level and ROS mediated cellular interactions during allergic inflammation. Our results indicate that the miR-154-5p-MCP1 axis might serve as a valuable target for the development of anti-allergy therapeutics.

Suppression of Th17 cell differentiation via sphingosine-1-phosphate receptor 2 by cinnamaldehyde can ameliorate ulcerative colitis

Ulcerative colitis (UC) is chronic disease characterized by diffuse inflammation of the mucosa of the colon and rectum. Although the etiology is unknown, dysregulation of the intestinal mucosal immune system is closely related to UC. Cinnamaldehyde (CA) is a major active compound from cinnamon, is known as its anti-inflammatory and antibacterial. However, little research focused on its regulatory function on immune cells in UC. Therefore, we set out to explore the modulating effects of CA on immune cells in UC. We found that CA reduced the progression of colitis through controlling the production of proinflammatory cytokines and inhibiting the proportion of Th17 cells. Furthermore, the liquid chromatography-mass spectrometry (LC-MS) method was employed for analyzing and differentiating metabolites, data showed that sphingolipid pathway has a great influence on the effect of CA on UC. Meanwhile, sphingosine-1-phosphate receptor 2 (S1P2) and Rho-GTP protein levels were downregulated in colonic tissues after CA treatment. Moreover, in vitro assays showed that CA inhibited Th17 cell differentiation and downregulated of S1P2 and Rho-GTP signaling. Notably, we found that treatment with S1P2 antagonist (JTE-013) weakened the inhibitory effect of CA on Th17 cells. Furthermore, S1P2 deficiency (S1P2-/-) blocked the effect of CA on Th17 cell differentiation. In addition, CA can also improve inflammation via lncRNA H19 and MIAT. To sum up, this study provides clear evidence that CA can ameliorate ulcerative colitis through suppressing Th17 cells via S1P2 pathway and regulating lncRNA H19 and MIAT, which further supports S1P2 as a potential drug target for immunity-mediated UC.

Metformin alleviates inflammation in oxazolone induced ulcerative colitis in rats: plausible role of sphingosine kinase 1/sphingosine 1 phosphate signaling pathway

OBJECTIVES

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that is associated with high sphingosine kinase 1(SPHK1) expression in the colon, however its role in pathogenesis of UC is not clearly understood so, the aim of the present study was to clarify the role of SPHK1 and investigate whether the anti-inflammatory effects of metformin in UC is mediated by Sphingosine kinase 1/sphingosine 1 phosphate (S1P) signaling pathway.

MATERIAL AND METHODS

Colitis was induced in adult male wistar rats by intra rectal administration of oxazolone in the fifth and seventh days from initial presensitization. Oxazolone treated rats were divided into untreated oxazolone group, metformin and mesalazine treated groups both in a dose of 100 mg/kg/day orally for 21 days. Along with these groups normal control and saline groups were used .Colitis was assessed by colon length, disease activity index (DAI) and histological examination of colontissue. Plasma samples were used to measure S1P.SPHK1 activity, signal transducer and activator of transcription -3(STAT-3), interleukin-6 (IL-6), nitric oxide (NO), myeloperoxidase activity (MPO), reduced glutathione (GSH) and tissue expression of intracellular cell adhesion molecule -1(ICAM-1) and caspase-3 genes were measured in tissue.

RESULTS

Metformin successfully attenuated oxazolone colitis by increasing colon length, decreasing DAI and improved colon histologic picture. Metformin also induced a significant decrease in Plasma SIP, SPHK1 activity, inflammatory, oxidative stress markers, ICAM-1 and Caspase-3 genes expression compared to oxazolone group.

CONCLUSION

It is revealed that metformin alleviated inflammation and underlying mechanism may result from inhibition of SPHK1/S1P signaling pathway.

Metformin and Covid-19: Focused Review of Mechanisms and Current Literature Suggesting Benefit

Metformin is the first-line medication for type 2 diabetes, but it also has a long history of improved outcomes in infectious diseases, such as influenza, hepatitis C, and in-vitro assays of zika. In the current Covid-19 pandemic, which has rapidly spread throughout the world, 4 observational studies have been published showing reduced mortality among individuals with home metformin use. There are several potential overlapping mechanisms by which metformin may reduce mortality from Covid-19. Metformin's past anti-infectious benefits have been both against the infectious agent directly, as well as by improving the underlying health of the human host. It is unknown if the lower mortality suggested by observational studies in patients infected with Covid-19 who are on home metformin is due to direct activity against the virus itself, improved host substrate, or both.

Metformin and risk of mortality in patients hospitalised with COVID-19: a retrospective cohort analysis

Background

Type 2 diabetes and obesity, as states of chronic inflammation, are risk factors for severe COVID-19. Metformin has cytokine-reducing and sex-specific immunomodulatory effects. Our aim was to identify whether metformin reduced COVID-19-related mortality and whether sex-specific interactions exist.

Methods

In this retrospective cohort analysis, we assessed de-identified claims data from UnitedHealth Group (UHG)'s Clinical Discovery Claims Database. Patient data were eligible for inclusion if they were aged 18 years or older; had type 2 diabetes or obesity (defined based on claims); at least 6 months of continuous enrolment in 2019; and admission to hospital for COVID-19 confirmed by PCR, manual chart review by UHG, or reported from the hospital to UHG. The primary outcome was in-hospital mortality from COVID-19. The independent variable of interest was home metformin use, defined as more than 90 days of claims during the year before admission to hospital. Covariates were comorbidities, medications, demographics, and state. Heterogeneity of effect was assessed by sex. For the Cox proportional hazards, censoring was done on the basis of claims made after admission to hospital up to June 7, 2020, with a best outcome approach. Propensity-matched mixed-effects logistic regression was done, stratified by metformin use.

Findings

6256 of the 15 380 individuals with pharmacy claims data from Jan 1 to June 7, 2020 were eligible for inclusion. 3302 (52·8%) of 6256 were women. Metformin use was not associated with significantly decreased mortality in the overall sample of men and women by either Cox proportional hazards stratified model (hazard ratio [HR] 0·887 [95% CI 0·782-1·008]) or propensity matching (odds ratio [OR] 0·912 [95% CI 0·777-1·071], p=0·15). Metformin was associated with decreased mortality in women by Cox proportional hazards (HR 0·785, 95% CI 0·650-0·951) and propensity matching (OR 0·759, 95% CI 0·601-0·960, p=0·021). There was no significant reduction in mortality among men (HR 0·957, 95% CI 0·82-1·14; p=0·689 by Cox proportional hazards).

Interpretation

Metformin was significantly associated with reduced mortality in women with obesity or type 2 diabetes who were admitted to hospital for COVID-19. Prospective studies are needed to understand mechanism and causality. If findings are reproducible, metformin could be widely distributed for prevention of COVID-19 mortality, because it is safe and inexpensive.

Funding

National Heart, Lung, and Blood Institute; Agency for Healthcare Research and Quality; Patient-Centered Outcomes Research Institute; Minnesota Learning Health System Mentored Training Program, M Health Fairview Institutional Funds; National Center for Advancing Translational Sciences; and National Cancer Institute.

Association of Metformin Use with Asthma Exacerbation in Patients with Concurrent Asthma and Diabetes: A Systematic Review and Meta-Analysis of Observational Studies

Background

Asthma and diabetes are both diseases that affect a wide range of people worldwide. As a common treatment for diabetes, metformin has also been reported to be effective in improving asthma outcomes. We conducted a combined analysis to examine the efficacy of metformin in reducing asthma exacerbation in patients with concurrent asthma and diabetes.

Methods

We searched the PubMed, Embase, and CENTRAL databases for articles published prior to April 2020 to find observational studies of individuals with concurrent asthma and diabetes that compared the risk of asthma exacerbation between metformin users and nonusers. Two researchers separately screened the studies, extracted data, and evaluated the risk of bias. The primary outcome was the adjusted risk of asthma exacerbation. The secondary outcomes were the adjusted risk of asthma-related hospitalization and emergency room visits. Review Manager was used for data analysis and plotting. I² and χ² tests were used to estimate heterogeneity. A random effects or fixed effects model was used depending on the heterogeneity. Odds ratios were calculated for dichotomous variables.

Results

We included two studies with a total of 25252 patients. The pooled effect size showed that metformin was inversely associated with a risk of asthma exacerbation (OR = 0.65, 95% CI 0.28–1.48; χ² = 5.42, P=0.02; I² = 82%), asthma-related emergency department visits (OR = 0.81, 95% CI 0.74–0.89; χ² = 0.36, P=0.55; I² = 0%), and hospitalizations (OR = 0.43, 95% CI 0.14–1.29; χ² = 4.01, P=0.05; I² = 75%).

Conclusion

This meta-analysis suggested that metformin decreased the risk of asthma-related emergency room visits for patients with concurrent asthma and diabetes. Metformin reduced the risk of asthma-related hospitalization and exacerbation but was not statistically significant. More randomized trials involving larger samples should be considered, and the mechanisms of these effects need to be fully elucidated.

Observational Study of Metformin and Risk of Mortality in Patients Hospitalized with Covid-19

Background Type 2 diabetes (T2DM) and obesity are significant risks for mortality in Covid19. Metformin has been hypothesized as a treatment for COVID19. Metformin has sex specific immunomodulatory effects which may elucidate treatment mechanisms in COVID-19. In this study we sought to identify whether metformin reduced mortality from Covid19 and if sex specific interactions exist. Methods De-identified claims data from UnitedHealth were used to identify persons with at least 6 months continuous coverage who were hospitalized with Covid-19. Persons in the metformin group had at least 90 days of metformin claims in the 12 months before hospitalization. Unadjusted and multivariate models were conducted to assess risk of mortality based on metformin as a home medication in individuals with T2DM and obesity, controlling for pre-morbid conditions, medications, demographics, and state. Heterogeneity of effect was assessed by sex. Results 6,256 persons were included; 52.8% female; mean age 75 years. Metformin was associated with decreased mortality in women by logistic regression, OR 0.792 (0.640, 0.979); mixed effects OR 0.780 (0.631, 0.965); Cox proportional-hazards: HR 0.785 (0.650, 0.951); and propensity matching, OR of 0.759 (0.601, 0.960). TNF-alpha inhibitors were associated with decreased mortality in the 38 persons taking them, by propensity matching, OR 0.19 (0.0378, 0.983). Conclusions Metformin was significantly associated with reduced mortality in women with obesity or T2DM in observational analyses of claims data from individuals hospitalized with Covid-19. This sex-specific finding is consistent with metformin reducing TNF-alpha in females over males, and suggests that metformin conveys protection in Covid-19 through TNF-alpha effects. Prospective studies are needed to understand mechanism and causality.

Alterations in viability and CYP1A1 expression in SH SY5Y cell line by pollutants present in Madín Dam, Mexico

Currently one of the problems facing global development is the availability of water. Although water is abundant the planet only a small portion is for human use and consumption. The problem is exacerbated due to different factors, mainly: meteorological phenomena, the presence of contaminants in the water and the increase in the number of inhabitants. Potential effects of pollutants not only can affect freshwater biota but also can be implicated in cancer development and neurodegenerative diseases in humans. The study was conducted in the Madín Dam, a reservoir of economic importance for the geographical area in which it is located, as well as catering to the population of nearby areas, and is a place where recreational activities such as fishing and kayaking are carried out. The aim of this study was to identify the toxic effects that the pollutants present in the water of the Madín Dam can generate on a human cell line (SH SY5Y) evaluating the cell viability and the participation of the Aril Hydrocarbon Receptor (AhR) and Pregnane X receptor (PXR) through of the expression of the CYP1A1 and CYP3A4 (canonical genes). In one of the five sites analyzed, cell viability was up to 50%, in this site a decrease in the normal expression of CYP1A1 was observed (p < 0.05) and the CYP3A4 gene was not expressed in the cells SH SY5Y. These results show that the SH SY5Y cell line is a good biomarker for assessing the human toxicity of environmental pollutants and relating it to neurodegenerative diseases.

The antipsychotic drug pimozide inhibits IgE-mediated mast cell degranulation and migration

BACKGROUND

Mast cells (MCs) mediate a key role in allergic diseases. Detailed studies of how the neuroleptic drug pimozide affects MC activity are lacking. The aim of this study was to investigate pimozide inhibition of immunoglobulin E (IgE)-mediated MC activation and MC-mediated allergic responses.

METHOD

MCs were stimulated with anti-dinitrophenyl (DNP) IgE antibodies and DNP-horse serum albumin (HSA) antigen (Ag), and anti-allergic pimozide effects were detected by measuring β-hexosaminidase levels. Morphological changes were observed histologically. In vivo pimozide effects were assessed in passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-sensitized active systemic anaphylaxis mouse (ASA) model experiments. Levels of phosphorylated (p-) SYK (spleen tyrosine kinase) and MAPKs (mitogen-activated protein kinases) were detected in western blots.

RESULTS

We found that pimozide inhibited MC degranulation, reduced MC release of β-hexosaminidase dose-dependently in activated RBL-2H3 (IC₅₀: 13.52 μM) and bone marrow derived MC (BMMC) (IC₅₀: 42.42 μM), and reduced MC morphological changes. The IgE/Ag-induced migration effect was suppressed by pimozide treatment dose-dependently. Pimozide down-regulated IgE/Ag-induced phosphorylation of SYK and MAPKs in activated MCs. Moreover, pimozide attenuated allergic reactions in PCA and ASA model mice, and decreased MC populations among splenic cells.

CONCLUSIONS

The antipsychotic drug pimozide can suppress IgE-mediated MC activation in vitro and in vivo and should be considered for repurposing to suppress MC-mediated diseases.

Pterostilbene Inhibits FcεRI Signaling through Activation of the LKB1/AMPK Pathway in Allergic Response

In this study, the role and mechanism of pterostilbene (Pts) in mast cell degranulation in vitro and in vivo were investigated. The results showed that Pts inhibited mast cell-mediated local passive allergic reactions in mice. In addition, treatment with Pts reduced both histamine release and calcium influx in rat peritoneal mast cells and RBL-2H3 cells and reduced IgE-mediated mast cell activation. Furthermore, the mechanism underlying Pts inhibition of mast cell signaling was probed via studying the effects of Pts on liver kinase B1 (LKB1), including the use of the LKB1 activator metformin and siRNA knockdown of LKB1. The data showed that Pts reduced the release of inflammatory mediators such as tumor necrosis factor-α, interleukin-6, leukotriene C4, and prostaglandin D2 in mast cells by activating the LKB1/adenosine monophosphate (AMP)-activated protein kinase (AMPK) signaling pathway. Furthermore, Pts inhibited phosphorylation of FcεRI and FcεRI-mediated degranulation in RBL-2H3 cells. These effects were attenuated after LKB1 knockdown. Taken together, Pts could inhibit FcεRI signaling through activation of the LKB1/AMPK signaling pathway in IgE-mediated mast cell activation. Thus, Pts might be an effective therapeutic agent for mast cell-mediated allergic diseases.

FcεRI-HDAC3-MCP1 Signaling Axis Promotes Passive Anaphylaxis Mediated by Cellular Interactions

Anaphylaxis is an acute and life-threatening systemic reaction. Food, drug, aero-allergen and insect sting are known to induce anaphylaxis. Mast cells and basophils are known to mediate Immunoglobulin E (IgE)-dependent anaphylaxis, while macrophages, neutrophils and basophils mediate non IgE-dependent anaphylaxis. Histone deacetylases (HDACs) play various roles in biological processes by deacetylating histones and non-histones proteins. HDAC inhibitors can increase the acetylation of target proteins and affect various inflammatory diseases such as cancers and allergic diseases. HDAC3, a class I HDAC, is known to act as epigenetic and transcriptional regulators. It has been shown that HDAC3 can interact with the high-affinity Immunoglobulin E receptor (FcεRI), to mediate passive anaphylaxis and cellular interactions during passive anaphylaxis. Effects of HDAC3 on anaphylaxis, cellular interactions involving mast cells and macrophages during anaphylaxis, and any tumorigenic potential of cancer cells enhanced by mast cells will be discussed in this review. Roles of microRNAs that form negative feedback loops with hallmarks of anaphylaxis such as HDAC3 in anaphylaxis and cellular interactions will also be discussed. The roles of MCP1 regulated by HDAC3 in cellular interactions during anaphylaxis are discussed. Roles of exosomes in cellular interactions mediated by HDAC3 during anaphylaxis are also discussed. Thus, review might provide clues for development of drugs targeting passive anaphylaxis.

CDK4/6 inhibitor palbociclib suppresses IgE-mediated mast cell activation

BACKGROUND

Mast cell activation causes degranulation and release of cytokines, thereby promoting inflammation. The aim of this study was to investigate the inhibitory effect of CDK4/6 inhibition on mast cell activation in vitro and in vivo.

METHODS

RBL-2H3 rat basophilic leukemia cells (BLCs) and mouse bone marrow-derived mast cells (BMMCs) were sensitized with anti-dinitrophenol (DNP) immunoglobulin (Ig)E antibodies, stimulated with DNP-human serum albumin (HSA) antigens, and treated with the CDK4/6 inhibitor palbociclib. Histological stains were applied to reveal cytomorphological changes. Murine IgE-mediated passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) models were used to examine palbociclib effects on allergic reactions in vivo. Western blots were performed to detect the expression of cell signaling molecules associated with mast cell activation.

RESULTS

Activated BLCs and BMMCs released copious granule-related mediators (histamine and β-hexosaminidase), which was reduced by palbociclib in a concentration-dependent manner. Palbociclib inhibited expression of the mast cell activation marker CD63 in activated BLCs and inhibited granule release (visualized with toluidine blue staining) while preventing morphological changes, (elongated shape maintained) and filamentous actin (F-actin) reorganization. Palbociclib suppressed molecular Lyn and/or mitogen-activated protein kinase (MAPK) signaling associated with mast cell activation in stimulated BLCs and attenuated allergic reactions in PCA mice dose dependently. Palbociclib attenuated body temperature reduction and diminished serum histamine levels in ovalbumin OVA-challenged ASA mice.

CONCLUSION

Palbociclib suppresses IgE-mediated mast cell activation in vitro and in vivo, suggesting that it may be developed into a therapy for mast cell-mediated allergic diseases via inhibition of mast cell degranulation.