Endocrine, Metabolic & Immune Disorders-Drug Targets (Formerly Current Drug Targets - Immune, Endocrine & Metabolic Disorders) - Volume 22, Issue 12, 2022

Coronavirus disease-19 (COVID-19) can be a fatal disease and is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). SARS-CoV2 is an enveloped virus that belongs to the Beta coronavirus subfamily. After entering into the target cells, this virus replicates rapidly and leads to cellular damage and uncontrolled pulmonary inflammation. Huge amounts of inflammatory cytokines and chemokines are produced by infected lung cells and are associated with monocyte recruitment and accumulation of inflammatory macrophages at the site of infection. Mitochondrial citrate carrier (CIC) expression increases in these macrophages, which results in elevated levels of cytosolic citrate and the production of inflammatory mediators. In this perspective article, we discuss the role of mitochondrial CIC in the metabolism of inflammatory macrophages and we propose that inhibition of this carrier might be a novel therapeutic approach for COVID-19 patients.

A new coronavirus pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been on the rise. This virus is fatal for broad groups of populations, including elderly, men, and patients with comorbidities among which obesity is a possible risk factor. The pathophysiologic connections between obesity/metainflammation and COVID-19 may be directly related to increasing soluble ACE2 (angiotensin-converting enzyme 2) levels which potentiate the viral entrance into the host cells, or indirectly related to dysregulation of immune system, microvascular injury and hypercoagulability. The SARS-CoV-2 S-glycoprotein interacts mainly with ACE2 or possibly DPP4 receptors to enter into the host cells. The host proteases, especially TMPRSS2 (transmembrane protease serine 2), support the fusion process and virus entry. While membranous ACE2 is considered a port of entry to the cell for SARSCoV- 2, it seems that soluble ACE2 retains its virus binding capability and enhances its entry into the cells. Interestingly, ACE2 on cell membrane may have protective roles by diminishing cytokine storm-related injuries to the organs. Applying medications that can reduce soluble ACE2 levels, antagonizing TMPRSS2 or blocking DPP4 can improve the outcomes of COVID-19. Metformin and statins through immunomodulatory activities, Orlistat by reducing viral replication, and thiazolidinediones by upregulating ACE2 expression have potential beneficial effects against COVID-19. However, the combination of dipeptidyl peptidase-4 (DPP4) inhibitors and spironolactone/ eplerenone seems to be more effective by reducing soluble ACE2 level, antagonizing TMPRSS2, maintaining ACE2 on cell membrane and reducing risk of viral entry into the cells.

Metabolites produced by bacteria can influence the immune system. These metabolites are produced by pathogenic bacteria as well as the friendly microbiota. This review sheds light on the major bacterial metabolites and their structures. It also describes the capacity of these molecules to stimulate and inhibit the immune responses in a way that affects their capacity to control different diseases.

Bilirubin is the main waste product of heme catabolism. At high concentrations, bilirubin may cause toxicity, especially in the brain, kidney, and erythrocytes. Membrane and mitochondrial dysfunction, oxidative stress, apoptosis, necrosis, endoplasmic reticulum stress, excitotoxicity, inflammation, and epigenetic modifications are the main mechanisms of toxicity triggered by bilirubin in susceptible organs. Many studies have shown that there is an interaction between bilirubin and epigenetic modifications in metabolic and immune diseases. In this review, we first outline the toxicity mediated by bilirubin and then summarize the current knowledge linking bilirubin and epigenetic modifications in metabolic and immunometabolic disorders.

Atherosclerosis is a chronic inflammatory disease of the arteries characterized by the accumulation of inflammatory cells in the arterial wall. Hypertension, dyslipidemia, and hyperglycemia are major risk factors of atherosclerosis. Rho-associated protein kinase (ROCK), a serine/threonine kinase, is a downstream effector of the small GTPase RhoA. ROCK is involved in different stages of atherosclerosis. Accumulating evidence has demonstrated that ROCK signaling plays vital roles in various cellular functions, such as contraction, migration, and proliferation of smooth muscle cells. Dysregulation of the ROCK pathway is associated with atherosclerosis and hypertension. Experimental studies have shown that ROCK inhibitors may have favorable effects in ameliorating atherosclerosis. ROCK signaling has a role in proteoglycan synthesis through transactivation of the TGF-β receptor Type I (TβRI) mediated by G-protein-coupled receptor (GPCR) agonists (endothelin-1, angiotensin II and …), and ROCK inhibitors could decrease proteoglycan synthesis and atherosclerotic plaque formation. Based on the hypothesis that targeting ROCK pathway may be effective in ameliorating atherosclerosis, we suggest that ROCK inhibitors may have a potential therapeutic role in inhibition or slowing atherogenesis. However, for this hypothesis more research is needed.

The initiation and progression of bladder cancer (BC) are dependent on its tumor microenvironment (TME). On the other hand, cancer cells shape and train TME to support their development, respond to treatment and migration in an organism. Immune cells exert key roles in the BC microenvironment and have complex interactions with BC cells. These complicated interplays result in metabolic competition in the TME, leading to nutrient deprivation, acidosis, hypoxia and metabolite accumulation, which impair immune cell function. Recent studies have demonstrated that immune cells functions are closely correlated with their metabolism. Immunometabolism describes the functional metabolic alterations that take place within immune cells and the role of these cells in directing metabolism and immune response in tissues or diseases such as cancer. Some molecules and their metabolites in the TME, including glucose, fatty acids and amino acids, can regulate the phenotype, function and metabolism of immune cells. Hence, here we describe some recent advances in immunometabolism and relate them to BC progression. A profound understanding of the metabolic reprogramming of BC cells and immune cells in the TME will offer novel opportunities for targeted therapies in future.

Multiple sclerosis (MS) is a chronic autoimmune neurodegenerative disease of the central nervous system (CNS) characterized by demyelination, neuronal loss, and permanent neurological impairments. The etiology of MS is not clearly understood, but genetics and environmental factors can affect the susceptibility of individuals. Obesity or a body mass index of (BMI) > 30 kg/m2 is associated with serious health consequences such as lipid profile abnormalities, hypertension, type 2 diabetes mellitus, reduced levels of vitamin D, and a systemic lowgrade inflammatory state. The inflammatory milieu can negatively affect the CNS and promote MS pathogenesis due in part to the increased blood-brain barrier permeability by the actions of adipose tissue-derived cytokines or adipokines. By crossing the blood-brain barrier, the pro-inflammatory adipokines such as leptin, resistin, and visfatin activate the CNS-resident immune cells, and promote the inflammatory responses; subsequently, demyelinating lesions occur in the white matter of the brain and spinal cord. Therefore, better knowledge of the adipokines’ role in the induction of obesity128;related chronic inflammation and subsequent events leading to the dysfunctional blood-brain barrier is essential. In this review, recent evidence regarding the possible roles of obesity and its related systemic low-grade inflammation, and the roles of adipokines and their genetic variants in the modulation of immune responses and altered blood-brain barrier permeability in MS patients, has been elucidated. Besides, the results of the current studies regarding the potential use of adipokines in predicting MS disease severity and response to treatment have been explored.