Impact of Type 2 Diabetes on the capacity of human macrophages infected with Mycobacterium tuberculosis to modulate monocyte differentiation through a bystander effect

Hyperglycemia modulates M1/M2 macrophage polarization in chronic diabetic patients with pulmonary tuberculosis infection

Increased susceptibility to bacterial infections like tuberculosis (TB) is one of the complications of type 2 diabetes, however the underlying mechanisms remains poorly characterized. To explore how chronic hyperglycemia in diabetes affects progression of active TB, we examined mRNA expression of M1 (proinflammatory) and M2 (anti-inflammatory) cytokines/markers, in monocyte-derived macrophages obtained from patients with PTB + DM (pulmonary TB + diabetes mellitus type 2), patients with DM alone, patients with PTB alone, and healthy individuals (controls). Our findings indicate a dysregulated cytokine response in patients with both PTB and DM, characterized by decreased expression levels of interferon-gamma (IFN-γ) and inducible nitric oxide synthase (iNOS), along with increased expression levels of interleukin-1 beta (IL-1β) and CD206. Furthermore, we observed a positive correlation of IL-1β and CD206 expression with levels of glycosylated hemoglobin (HbA1c) in both PTB + DM and DM groups, while IFN-γ showed a positive correlation with HbA1c levels, specifically in the PTB + DM group. Additionally, M1 cytokines/markers, IL-1β and iNOS were found to be significantly associated with the extent of sputum positivity in both PTB and PTB + DM groups, suggesting it to be a function of increased bacterial load and hence severity of infection. Our data demonstrates that tuberculosis in individuals with PTB + DM is characterized by altered M1/M2 cytokine responses, indicating that chronic inflammation associated with type 2 diabetes may contribute to increased immune pathology and inadequate control of tuberculosis infection.

The role of pathogens in diabetes pathogenesis and the potential of immunoproteomics as a diagnostic and prognostic tool

Diabetes mellitus (DM) is a group of metabolic diseases marked by hyperglycemia, which increases the risk of systemic infections. DM patients are at greater risk of hospitalization and mortality from bacterial, viral, and fungal infections. Poor glycemic control can result in skin, blood, bone, urinary, gastrointestinal, and respiratory tract infections and recurrent infections. Therefore, the evidence that infections play a critical role in DM progression and the hazard ratio for a person with DM dying from any infection is higher. Early diagnosis and better glycemic control can help prevent infections and improve treatment outcomes. Perhaps, half (49.7%) of the people living with DM are undiagnosed, resulting in a higher frequency of infections induced by the hyperglycemic milieu that favors immune dysfunction. Novel diagnostic and therapeutic markers for glycemic control and infection prevention are desirable. High-throughput blood-based immunoassays that screen infections and hyperglycemia are required to guide timely interventions and efficiently monitor treatment responses. The present review aims to collect information on the most common infections associated with DM, their origin, pathogenesis, and the potential of immunoproteomics assays in the early diagnosis of the infections. While infections are common in DM, their role in glycemic control and disease pathogenesis is poorly described. Nevertheless, more research is required to identify novel diagnostic and prognostic markers to understand DM pathogenesis and management of infections. Precise monitoring of diabetic infections by immunoproteomics may provide novel insights into disease pathogenesis and healthy prognosis.

Increased frequency of CD14+HLA-DR-/low cells in type 2 diabetes patients with poor glycemic control

AIMS

Type 2 diabetes (T2DM) is associated with alterations of the immune response and T2DM patients have an increased risk for infections and certain sorts of cancers. Although CD14⁺HLA-DR^-/low cells have emerged as important mediators of immunosuppression in several pathologies, including cancer and non-malignant diseases, the presence of these cells in T2DM is not fully characterized.

METHODS

In this study, we evaluated the frequency of CD14⁺HLA-DR^-/low cells in non-obese T2DM patients and their association with glycemic control. Peripheral blood mononuclear cells were isolated from healthy controls (HC, n = 24) and non-obese T2DM patients (n = 25), the population was evaluated by flow cytometry, and an analysis of correlation between cell frequencies and clinical variables was performed.

RESULTS

CD14⁺HLA-DR^-/low monocytes were expanded in patients with T2DM compared to HC regardless of weight. Among the subjects with T2DM, the frequency of CD14⁺HLA-DR^-/low was higher in patients with poor glycemic control (HbA1c > 9%) compared to those with better glycemic control (HbA1c < 9%) and, positively correlated with the years since the diagnosis of T2DM, the age of the patients and the glycemic index.

CONCLUSIONS

An increased frequency of CD14⁺HLA-DR^-/low cells in the blood of T2DM patients was recorded. The influence of hyperglycemia seems to be independent of obesity, but related to glycemic control and age.

Cellular Immunity of Patients with Tuberculosis Combined with Diabetes

Tuberculosis (TB) is one of humanity's three major infectious diseases. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia due to impaired insulin secretion or impaired insulin function. It has been reported that DM is a primary risk factor for TB disease. Given the increasing public health threat to people's health, more and more studies have focused on diabetes complicated by TB. Hyperglycemia can affect the function of human immune cells, promote primary infections and reactivation of TB, and increase the susceptibility and severity of TB. However, the immunological mechanism behind it is still not clear. By reviewing the related articles on tuberculosis complicated with diabetes published in recent years, this paper expounds on the effect of hyperglycemia on innate immunity and adaptive immunity of patients with TB. This review provides new insights for elucidating the immunological mechanism of TB complicated with DM and lays the foundation for finding potential targets for preventing and treating TB combined with DM.