Metabolic abnormalities such as dyslipidemia, hyperinsulinemia, or insulin resistance and obesity play key roles in the induction and progression of type 2 diabetes mellitus (T2DM). The field of immunometabolism implies a bidirectional link between the immune system and metabolism, in which inflammation plays an essential role in the promotion of metabolic abnormalities (e.g., obesity and T2DM), and metabolic factors, in turn, regulate immune cell functions. Obesity as the main inducer of a systemic low-level inflammation is a main susceptibility factor for T2DM. Obesity-related immune cell infiltration, inflammation, and increased oxidative stress promote metabolic impairments in the insulin-sensitive tissues and finally, insulin resistance, organ failure, and premature aging occur. Hyperglycemia and the subsequent inflammation are the main causes of micro- and macroangiopathies in the circulatory system. They also promote the gut microbiota dysbiosis, increased intestinal permeability, and fatty liver disease. The impaired immune system together with metabolic imbalance also increases the susceptibility of patients to several pathogenic agents such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Thus, the need for a proper immunization protocol among such patients is granted. The focus of the current review is to explore metabolic and immunological abnormalities affecting several organs of T2DM patients and explain the mechanisms, whereby diabetic patients become more susceptible to infectious diseases.

Obesity is associated with chronic low‐grade inflammation of the adipose tissue (AT) that might develop into systemic inflammation, insulin resistance (IR) and an increased risk of type 2 diabetes mellitus (T2DM) in severe obese rodents and humans. In the lean state, small normal adipocytes and AT macrophages interact with each other to maintain metabolic homeostasis but during obesity, enlarged adipocytes secrete inflammatory mediators and express immune receptors to recruit immune cells and aggravate the inflammation. The better understanding of the obesity‐related inflammatory milieu and the sequential events leading to IR could be helpful in designing new preventive and therapeutic strategies. The present review will discuss the cellular and molecular abnormalities participating in the pathogenesis of obesity in obese individuals as well as high‐fat diet (HFD)‐fed mice, a mouse model of obesity.

The result of recent genome-wide association studies revealed that, in addition to HLA-B27, a few non-HLA genes are associated with susceptibility to ankylosing spondylitis (AS) in Caucasian populations. According to these studies, IL-23R is one of the genes that is associated with AS. In this study, we evaluated five important single nucleotide polymorphisms (SNPs) of the IL-23R gene which confers susceptibility to AS, and its effects on the severity of the disease in HLA-B27 positive and negative patients and several subtypes of HLA-B27. The study population consisted of 294 AS patients and 352 age-, sex-, and ethnicity-matched healthy controls. All patients were examined by rheumatologists, and met modified, New York criteria for the disease. Five SNPs (rs1004819, rs11209032, rs1495965, rs11465804, and rs1004819) of the IL-23R gene were genotyped using the Real-Time PCR TaqMan genotyping method. We found that only rs1004819 has a significant association with AS, and that the remaining four SNP alleles are not associated with AS. Also, there was no association between these five polymorphisms and BASDAI, BASFI, and BASMI indices. Two haplotypes, ACGAT and ACGAG, were found to be associated with the heritability of AS. In addition, two significant, protective diplotypes (D8, GCGAG/GTGGG ; and D9, ACGAG/GCGAG) were discovered. This study supported our previous findings regarding the differences between the genetic patterns of AS in Iranian patients compared with those in other parts of the world.

Multiple sclerosis (MS) is a chronic autoimmune neurodegenerative disease of the central nervous system (CNS) characterized by demyelination, neuronal loss, and permanent neu-rological impairments. The etiology of MS is not clearly understood, but genetics and environ-mental 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 abnormal-ities, hypertension, type 2 diabetes mellitus, reduced levels of vitamin D, and a systemic low-grade 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-in-flammatory 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 obesity‐related chronic inflammation and subsequent events leading to the dys-functional 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 per-meability 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.