Immune responses of mucosal-associated invariant T cells in infectious diseases / 中华微生物学和免疫学杂志

Mucosal-associated invariant T (MAIT) cells are highly conserved immune cells that could participate in innate and adaptive immune responses after being activated by major histocompatibility complex class 1-related molecule (MR1) pathway or cytokine pathway. At present, it has been confirmed that a large number of MAIT cells exist in human peripheral blood and specific tissues, and play an important role in infectious diseases. This review focused on the role of MAIT cells in immune responses to different pathogens. Additionally, the therapeutic methods and challenges of targeting MAIT cells in infectious diseases were also discussed.

Changes in the frequency, phenotype, and function of mucosal-associated invariant T lymphocytes in peripheral blood of children with metabolic associated fatty liver disease / 临床肝胆病杂志

Objective To investigate the change in mucosal-associated invariant T (MAIT) lymphocytes in peripheral blood of children with metabolic associated fatty liver disease (MAFLD) and its clinical significance. Methods A total of 18 children with MAFLD who attended Hunan Children's Hospital from March to May, 2022, were enrolled as MAFLD group, and 20 normal children who attended the hospital during the same period of time were enrolled as control group. Peripheral blood samples were collected, and flow cytometry was used to measure the percentages of MAIT lymphocytes (CD3 + CDl61 + TCRVα7.2 + cells), different MAIT lymphocyte subsets (CD4 + CD8 - MAIT cells, CD4 - CD8 - MAIT lymphocytes, CD4 - CD8 + MAIT lymphocytes, and CD4 + CD8 + MAIT lymphocytes), and MAIT lymphocytes expressing PD-1, CD69, perforin, CD107α, CXCR3, CXCR6, and CCR6. The correlation of MAIT lymphocyte frequency with liver inflammation, fat content, and fibrosis degree was analyzed. The t -test was used for comparison of normally distributed continuous data between two groups, and the Mann-Whitney U test was used for comparison of non-normally distributed continuous data between two groups. The Spearman correlation analysis was used for correlation analysis. Results Compared with the control group, the MAFLD group had significant increases in the percentage of MAIT lymphocytes in peripheral blood, the percentages of MAIT cells expressing PD-1, CD69, CD107α, CXCR3, CXCR6 and CCR6, and the percentages of CD4 + CD8 - MAIT cells and CD4 + CD8 + MAIT lymphocytes among MAIT cell subsets (all P < 0.05), as well as a significant reduction in the percentage of CD4 - CD8 + MAIT cells among MAIT cell subsets ( P < 0.001). The percentages of CD4 + CD8 + MAIT lymphocytes and CD107α-positive MAIT lymphocytes were negatively correlated with alanine aminotransferase ( r =-0.474 and -0.550, P =0.047 and 0.018). Conclusion The migration of peripheral blood MAIT lymphocytes to the liver plays a protective role against liver inflammation in children with MAFLD.

Mucosal-associated invariant T cells expression and its clinical significance in ankylosing spondylitis / 中华风湿病学杂志

Objective:To investigate the expression of Mucosal-associated invariant T (MAIT) cells in the peripheral blood of ankylosing spondylitis (AS) patients, and to analyze its clinical significance.Methods:Sixty-four AS patients from September 2020 to September 2022 in Fujian Provincial Hospital and 60 healthy controls were enrolled. The expression of MAIT cells and CD69 +MAIT cells were detected by immunofluorescence. Spondylarthritis research consortium of Canada (SPARCC) scores of sacroiliac joint magnetic resonance imaging (MRI) were calculated and were analyzed based on clinical data. The changes of MAIT cells were observed in 7 patients with AS after treatment. t test, variance analysis and Pearson correlation analysis were used for statistical analysis. Results:The expression of MAIT cells in the peripheral of AS patients was significantly lower than that in the controls [(2.81±0.27)% and (4.46±0.86)% respectively, t=2.33, P=0.022], while CD69 +MAIT cells were significantly higher [(12.0±1.0)% and (7.8±1.2)% respectively, t=2.31, P=0.024]. The level of CD69 +MAIT cells were significantly positively correlated with erythrocyte sedimentation rate (ESR) ( r=0.39, P=0.010), C-reactive protein (CRP) ( r=0.36, P=0.012), ASDAS ( r=0.35, P=0.013) and SPARCC scores ( r=0.38, P=0.006) of AS patients. ASDAS scores and CD69 +MAIT cells obviously decreased in 7 treated AS patients ( F=7.62, P=0.007 and F=4.97, P=0.027 respectively). Conclusion:The expression of peripheral MAIT cells in AS patients is lower than that in healthy controls, but the number of the activated MAIT cells is increased. Levels of activated MAIT cells may in some extent reflect the inflammatory state and disease activity of AS, as well as inflammatory destruction of sacroiliac joint, and therapeutic effect. MAIT cells may partially participate in the inflammatory response and play a role in the pathogenesis of AS.

Mucosal-associated invariant T cells and tumors / 中国药理学通报

Mucosal-assooiated invariant T(MAIT) cells are an evolutionarily highly conserved T lymphocyte subsets with the innate functions similar to innate natural killer T(iNKT) cells. MAIT cells are defined by their invariant T cell receptors (TCR)-alpha chain and restrictive major histocompatibility complex (MHC) related protein-! (MR1) , and identify antigens through the MR1, secreting a variety of cytokines after being activated, directly or indirectly involved in the body's immune re-sponses. MAIT cells are also abundant in human peripheral blood and many tissues. They are closely related to the occurrence and development of various infectious diseases, autoimmune diseases and malignant tumors. This article mainly reviews the research on MAIT cells in tumor diseases.

Deficiencies of Circulating Mucosal-associated Invariant T Cells and Natural Killer T Cells in Patients with Multiple Trauma

Mucosal-associated invariant T (MAIT) cells and natural killer T (NKT) cells are known to play important roles in autoimmunity, infectious diseases and cancers. However, little is known about the roles of these invariant T cells in multiple trauma. The purposes of this study were to examine MAIT and NKT cell levels in patients with multiple trauma and to investigate potential relationships between these cell levels and clinical parameters. The study cohort was composed of 14 patients with multiple trauma and 22 non-injured healthy controls (HCs). Circulating MAIT and NKT cell levels in the peripheral blood were measured by flow cytometry. The severity of injury was categorised according to the scoring systems, such as Acute Physiology and Chronic Health Evaluation (APACHE) II score, Simplified Acute Physiology Score (SAPS) II, and Injury Severity Score (ISS). Circulating MAIT and NKT cell numbers were significantly lower in multiple trauma patients than in HCs. Linear regression analysis showed that circulating MAIT cell numbers were significantly correlated with age, APACHE II, SAPS II, ISS category, hemoglobin, and platelet count. NKT cell numbers in the peripheral blood were found to be significantly correlated with APACHE II, SAPS II, and ISS category. This study shows numerical deficiencies of circulating MAIT cells and NKT cells in multiple trauma. In addition, these invariant T cell deficiencies were found to be associated with disease severity. These findings provide important information for predicting the prognosis of multiple trauma.

Clinical implications of circulating mucosal associated invariant T (MALT) cells in septic patients / 中国感染与化疗杂志

Objective To investigate the number and activation status of circulating mucosal associated invariant T (MAIT) cells in patients with sepsis.Methods Flow cytometric method was used to determine the number and percentage of MAIT cells and their expression of activation molecule CD69.Results The circulating MAIT cells dropped significantly at early stage of sepsis in septic patients.The MAIT cells in the sepsis group continued to express high levels of CD69 on day 1 and day 3 after admission to ICU.Conclusions Remarkable decrease of circulating MAIT cells may portend the possibility of sepsis in patients with severe infection.

Deficiencies of Circulating Mucosal-associated Invariant T Cells and Natural Killer T Cells in Patients with Acute Cholecystitis

Mucosal-associated invariant T (MAIT) cells and natural killer T (NKT) cells are known to play crucial roles in a variety of diseases, including autoimmunity, infectious diseases, and cancers. However, little is known about the roles of these invariant T cells in acute cholecystitis. The purposes of this study were to examine the levels of MAIT cells and NKT cells in patients with acute cholecystitis and to investigate potential relationships between clinical parameters and these cell levels. Thirty patients with pathologically proven acute cholecystitis and 47 age- and sex-matched healthy controls were enrolled. Disease grades were classified according to the revised Tokyo guidelines (TG13) for the severity assessment for acute cholecystitis. Levels of MAIT and NKT cells in peripheral blood were measured by flow cytometry. Circulating MAIT and NKT cell numbers were significantly lower in acute cholecystitis patients than in healthy controls, and these deficiencies in MAIT cells and NKT cell numbers were associated with aging in acute cholecystitis patients. Notably, a reduction in NKT cell numbers was found to be associated with severe TG13 grade, death, and high blood urea nitrogen levels. The study shows numerical deficiencies of circulating MAIT and NKT cells and age-related decline of these invariant T cells. In addition, NKT cell deficiency was associated with acute cholecystitis severity and outcome. These findings provide an information regarding the monitoring of these changes in circulating MAIT and NKT cell numbers during the course of acute cholecystitis and predicting prognosis.