TLR-induced secretion of novel cytokine IL-27 is defective in newly diagnosed type-2 diabetic subjects

Immune-endocrine network in diabetes-tuberculosis nexus: does latent tuberculosis infection confer protection against meta-inflammation and insulin resistance?

Tuberculosis patients with diabetes, have higher sputum bacillary load, delayed sputum conversion, higher rates of drug resistance, higher lung cavitary involvement and extra-pulmonary TB infection, which is called as "Diabetes-Tuberculosis Nexus". However, recently we have shown a reciprocal relationship between latent tuberculosis infection and insulin resistance, which has not been reported before. In this review, we would first discuss about the immune-endocrine network, which operates during pre-diabetes and incipient diabetes and how it confers protection against LTBI. The ability of IR to augment anti-TB immunity and the immunomodulatory effect of LTBI to quench IR were discussed, under IR-LTB antagonism. The ability of diabetes to impair anti-TB immunity and ability of active TB to worsen glycemic control, were discussed under "Diabetes-Tuberculosis Synergy". The concept of "Fighter Genes" and how they confer protection against TB but susceptibility to IR was elaborated. Finally, we conclude with an evolutionary perspective about how IR and LTBI co-evolved in endemic zones, and have explained the molecular basis of "IR-LTB" Antagonism" and "DM-TB Synergy", from an evolutionary perspective.

Augmented Innate and Adaptive Immune Responses Under Conditions of Diabetes-Filariasis Comorbidity

Metainflammation, as seen in chronic diabetes subjects, impairs immunity and increases the susceptibility to infections. In the present study, the effect of diabetes on immune response against filariasis was studied. Both toll-like receptor (TLR)-mediated and crude antigen-induced immune responses were quantified, in whole blood cultures from filariasis-infected subjects (LF+), with and without diabetes. Blood cultures were stimulated with TLR ligands (TLR2 and TLR4) or filarial antigen or were left unstimulated (control) for 18 h. Cytokine, chemokine, and defensin secretion was quantified by ELISA. Expression of HLA-DR, B7-1, B7-2, activation marker (CD69), and Th (Th1, Th2, Th17, and Th9) phenotypes was quantified by flow cytometry. Expression of immunomodulatory effectors (Cox-2, HO-1, IDO-1, and p47Phox) and Th-polarizing transcription factors (T-bet, GATA3, and ROR-γt) was quantified by quantitative PCR. Secretion of IL-27, IL-1Ra, IL-12, IL-33, IL-9, and SDF-1 was increased under diabetes conditions with increased Th9 polarization and increased expression of Cox-2 and IDO. Overall, diabetes was found to augment both TLR-mediated and antigen-induced inflammation, which can promote chronic pathology in LF+ subjects.

Role of TLR4/MyD88/NF-κB signaling in heart and liver-related complications in a rat model of type 2 diabetes mellitus

Aims

To analyze expression of members of the Toll-like receptor (TLR)4/myeloid differentiation primary response 88 (MyD88)/nuclear factor (NF)-κB signaling pathway in the heart and liver in a rat model of type 2 diabetes mellitus (T2DM). Our overall goal was to understand the underlying pathophysiological mechanisms.

Methods

We measured fasting blood glucose (FBG) and insulin (FINS) in a rat model of T2DM. Expression of members of the TLR4/MyD88/NF-κB signaling pathway as well as downstream cytokines was investigated. Levels of mRNA and protein were assessed using quantitative real-time polymerase chain reaction and western blotting, respectively. Protein content of tissue homogenates was assessed using enzyme-linked immunosorbent assays.

Results

Diabetic rats had lower body weights, higher FBG, higher FINS, and higher intraperitoneal glucose tolerance than normal rats. In addition, biochemical indicators related to heart and liver function were elevated in diabetic rats compared with normal rats. TLR4 and MyD88 were involved in the occurrence of T2DM as well as T2DM-related heart and liver complications. TLR4 caused T2DM-related heart and liver complications through activation of NF-κB.

Conclusions

TLR4/MyD88/NF-κB signaling induces production of tumor necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1, leading to the heart- and liver-related complications of T2DM.

Anti-inflammatory cytokines IL-27, IL-10, IL-1Ra and TGF-β in subjects with increasing grades of glucose intolerence (DM-LTB-2)

Anti-inflammatory cytokines act as double edged swords- they can dampen inflammation but can also suppress immunity. The role played by these cytokines in latent TB infected (LTBI) subjects, with various grades of glucose intolerance was studied. Both serum levels and recall-secretion of IL-27, IL-10, IL-1Ra and TGF-β in Normal Glucose Tolerance (NGT), Pre-Diabetes (PDM), Newly diagnosed Diabetes (NDM) and Known Diabetes (KDM) subjects, both with and without LTBI (n = 382), were quantified by ELISA. All the subjects were screened for LTBI by QuantiFERON-TB Gold test. Serum levels of IL-27, IL-10 and IL-1Ra were significantly elevated in the LTB^-PDM, compared to LTB^-NGT group. Increased IL-27 and IL-10 levels and decreased levels of TGF-β were seen in the LTB^-NDM, compared to LTB^-NGT group. Decreased serum levels of IL-27 and increased levels of IL-1Ra and TGF-β were seen in the LTB^-KDM, compared to LTB^-NGT group. TB antigens induced the secretion of IL-1Ra in LTB⁺ subjects in the NGT, PDM and NDM groups, but not in the KDM group. Co-morbidity with LTBI brought about (diabetic) stage-specific modulation, in these cytokine levels. Major defects in the circulating levels and recall secretion of anti-inflammatory cytokines, as seen in LTB⁺KDM subjects, could fuel DM-TB synergy.