Association between Type 2 Diabetes, Obesity and Key Immunological Components of IgE-mediated Inflammation

Origins and functions of eosinophils in two non-mucosal tissues

Eosinophils are a type of granulocyte named after the presence of their eosin-stained granules. Traditionally, eosinophils have been best known to play prominent roles in anti-parasitic responses and mediating allergic reactions. Knowledge of their behaviour has expanded with time, and they are now recognized to play integral parts in the homeostasis of gastrointestinal, respiratory, skeletal muscle, adipose, and connective tissue systems. As such, they are implicated in a myriad of pathologies, and have been the target of several medical therapies. This review focuses on the lifespan of eosinophils, from their origins in the bone marrow, to their tissue-resident role. In particular, we wish to highlight the functions of eosinophils in non-mucosal tissues with skeletal muscle and the adipose tissues as examples, and to discuss the current understanding of their participation in diseased states in these tissues.

Mendelian randomization indicates that atopic dermatitis contributes to the occurrence of diabetes

BACKGROUND

An association has been indicated between atopic dermatitis (AD), a prevalent chronic inflammatory skin disease, and diabetes mellitus. However, the exact causal relationship between AD and both type 1 diabetes (T1D) and type 2 diabetes (T2D) remains controversial. This study aimed to explore the causal association between AD and diabetes by Mendelian Randomization (MR) approaches.

METHODS

Public genetic summary data for AD was obtained from EAGLE study. Single nucleotide polymorphisms of diabetes were retrieved from four genome-wide association studies that had been performed in European populations. Inverse variance weighted (IVW) in MR analysis was used as the primary means of causality estimation. Several complementary analyses and sensitivity analyses were performed to calculate MR estimates and to enhance the causal inference, respectively. The R package 'TwoSampleMR' was used for analysis.

RESULTS

Genetically predicted AD led to a higher risk of T1D (OR, 1.19; 95% CI, 1.05, 1.34; P = 0.006) and T2D (OR, 1.07; 95% CI, 1.02, 1.11; P = 0.003) based on random-effect IVW method. The complementary analyses provided similar positive results. Cochran's Q test and I2 statistics indicated moderate heterogeneity between AD and both T1D and T2D. No significant horizontal pleiotropy was detected by MR-Egger Intercept p except summary data from FinnGen consortium.

CONCLUSION

Genetically predicted AD is a risk factor for both T1D and T2D. These findings imply potential shared pathological mechanisms between AD and diabetes, thus suggesting the significance of early clinical diagnosis and prevention of AD in reducing the incidence of diabetes.

Plasma fatty acid profile is related to cognitive function in obese Chinese populations (35-64 years): A cross-sectional study

BACKGROUND

A fast-growing body of evidence suggests that dietary lipids influence cognition, but the effects of dietary fatty acid (FA) intake and plasma FA profile on cognitive function in obese populations are currently unclear. The present study aimed to investigate the dietary FA intakes and plasma FA composition and their association with cognitive functions in obese and overweight populations aged 35-64 years.

METHODS

A total of 672 subjects were recruited and divided into normal-weight, overweight, and obese groups based on their body mass index (BMI). Dietary information was collected using a semiquantified food frequency questionnaire. Plasma FAs composition was examined using gas chromatography. The mini-mental state examination and Montreal Cognitive Assessment scales were carried out to assess the cognitive performance of each participant. Dietary FA intake and plasma FA composition were compared with rank transformation followed by one-way ANOVA analysis across different BMI groups. Spearman rank correlation analysis was used to investigate the correlation between dietary FA intake and plasma FA composition and cognitive functions in normal-weight, overweight, and obese subjects, respectively.

RESULTS

Overweight and obese subjects consumed larger amounts of saturated fatty acids (SFAs) compared to normal-weight participants (p < .05). Obese populations also had higher plasma levels of total SFAs and total monounsaturated fatty acid (MUFAs) than normal-weight subjects (both p < .05). In addition, plasma levels of SFAs, polyunsaturated fatty acids (PUFAs), and MUFAs were negatively correlated with cognitive functions in obese subjects but showed no correlation in normal-weight and overweight subjects.

CONCLUSIONS

From current data, we found higher plasma levels of SFA, PUFA, and MUFA in obese populations, which were associated with declined cognition. Lowering plasma FA levels may help maintaining normal cognitive functions in obese people.

Intestinal Immunomodulatory Cells (T Lymphocytes): A Bridge between Gut Microbiota and Diabetes

Diabetes mellitus (DM) is one of the most familiar chronic diseases threatening human health. Recent studies have shown that the development of diabetes is closely related to an imbalance of the gut microbiota. Accordingly, there is increasing interest in how changes in the gut microbiota affect diabetes and its underlying mechanisms. Immunomodulatory cells play important roles in maintaining the normal functioning of the human immune system and in maintaining homeostasis. Intestinal immunomodulatory cells (IICs) are located in the intestinal mucosa and are regarded as an intermediary by which the gut microbiota affects physiological and pathological properties. Diabetes can be regulated by IICs, which act as a bridge linking the gut microbiota and DM. Understanding this bridge role of IICs may clarify the mechanisms by which the gut microbiota contributes to DM. Based on recent research, we summarize this process, thereby providing a basis for further studies of diabetes and other similar immune-related diseases.

Schistosoma Infection and Schistosoma-Derived Products Modulate the Immune Responses Associated with Protection against Type 2 Diabetes

Studies on parasite-induced immunoregulatory mechanisms could contribute to the development of new therapies for inflammatory diseases such as type 2 diabetes (T2D), which is a chronic inflammatory disease characterized by persistent elevated glucose levels due to insulin resistance. The association between previous Schistosoma infection and T2D has been confirmed—Schistosoma infection and Schistosoma-derived products modulate the immune system, including innate and acquired immune responses, contributing to T2D disease control. Schistosoma infections and Schistosoma-derived molecules affect the immune cell composition in adipose tissue, dampening inflammation and improving glucose tolerance. This protective role includes the polarization of immune cells to alternatively activated macrophages, dendritic cells, eosinophils, and group 2 innate lymphoid cells. Furthermore, Schistosoma infection and Schistosoma products are effective for the treatment of T2D, as they increase the number of type 2 helper T cells (Th2) and regulatory T cells (Tregs) and decrease type 1 helper T cells (Th1) and type 17 helper T cells (Th17) cells. Thus, our aim was to comprehensively review the mechanism through which Schistosoma infection and Schistosoma products modulate the immune response against T2D.