Metformin: A review of its potential as enhancer for anti tuberculosis efficacy in diabetes mellitus-tuberculosis coinfection patients

Tuberculosis-diabetes comorbidities: Mechanistic insights for clinical considerations and treatment challenges

Tuberculosis (TB) remains a leading cause of death among infectious diseases, particularly in poor countries. Viral infections, multidrug-resistant and ex-tensively drug-resistant TB strains, as well as the coexistence of chronic illnesses such as diabetes mellitus (DM) greatly aggravate TB morbidity and mortality. DM [particularly type 2 DM (T2DM)] and TB have converged making their control even more challenging. Two contemporary global epidemics, TB-DM behaves like a syndemic, a synergistic confluence of two highly prevalent diseases. T2DM is a risk factor for developing more severe forms of multi-drug resistant-TB and TB recurrence after preventive treatment. Since a bidirectional relationship exists between TB and DM, it is necessary to concurrently treat both, and promote recommendations for the joint management of both diseases. There are also some drug-drug interactions resulting in adverse treatment outcomes in TB-DM patients including treatment failure, and reinfection. In addition, autophagy may play a role in these comorbidities. Therefore, the TB-DM comorbidities present several health challenges, requiring a focus on multidisciplinary collaboration and integrated strategies, to effectively deal with this double burden. To effectively manage the comorbidity, further screening in affected countries, more suitable drugs, and better treatment strategies are required.

Pulmonary tuberculosis and diabetes mellitus: Epidemiology, pathogenesis and therapeutic management (Review)

The dual burden of pulmonary tuberculosis (PTB) and diabetes mellitus (DM) is a major global public health concern. There is increasing evidence to indicate an association between PTB and DM. DM is associated with immune dysfunction and altered immune components. Hyperglycemia weakens the innate immune response by affecting the function of macrophages, dendritic cells, neutrophils, and natural killer cells, and also disrupts the adaptive immune response, thus promoting the susceptibility of PTB in patients with DM. Antituberculosis drugs often cause the impairment of liver and kidney function in patients with PTB, and the infection with Mycobacterium tuberculosis weaken pancreatic endocrine function by causing islet cell amyloidosis, which disrupts glucose metabolism and thus increases the risk of developing DM in patients with PTB. The present review discusses the association between PTB and DM from the perspective of epidemiology, pathogenesis, and treatment management. The present review aims to provide information for the rational formulation of treatment strategies for patients with PTB-DM.

Expression pattern of the autophagy related proteins Beclin1 and LC3B in tuberculous wound tissues

Tuberculous wound therapy is a major challenge in clinical practice, due to the protracted disease course, high recurrence rate, and an unclear pathogenesis. We explored the expression patterns of Beclin1 and LC3B in tuberculous wound tissues in human tuberculous chronic wound and normal tissues was assayed by immunohistochemistry. Rat models of tuberculous wounding were induced by the Bacillus Calmette-Guerin (BCG) method. Beclin1 and LC3B protein expression in human tuberculous wound tissues differed from that of normal skin and non-tuberculous chronic wound tissues.In rat tuberculous wound tissues, expression of Beclin1 and LC3B mRNA time-dependently changed post-infection. Abnormal fluctuation of autophagy protein in the development of tuberculosis wound could be one of the causes for the repeated occurrence and protracted disease course of the tuberculous wound.

[Metformin inhibits collagen production in rat biliary fibroblasts: the molecular signaling mechanism]

OBJECTIVE

To clarify the molecular signaling mechanism underlying the inhibitory effect of metformin on transforming growth factor-β1 (TGF-β1)-stimulated collagen I production in rat biliary fibroblasts.

METHODS

Primary biliary fibroblasts were isolated under aseptic condition from 50 Sprague-Dawley rats (half male and half female), and microscopic observation identified no obvious difference in the morphology or viability of the cells from rats with different sexes or body weight. The cells were treated with TGF-β1 (10 ng/mL), Smad3 siRNA+TGF-β1, CTGF siRNA+TGF-β1, metformin (10 mmol/L)+ TGF-β1, or Compound C (10 μmol/L)+metformin+TGF-β1. The expressions of CTGF and collagen I in the treated cells were determined using ELISA kit or Western blotting; the phorsphorylated and total Smad3 and AMPK expressions were detected using immunoblotting.

RESULTS

TGF-β1 time- and dose-dependently induced collagen I production in rat biliary fibroblasts. The activated AMPK by metformin dose-dependently inhibited TGF-β1-induced collagen I production. Pre-incubation of cells with the AMPK inhibitor Compound C restored the inhibitory effect of AMPK on TGF-β1-induced collagen I secretion (P < 0.01). Activation of AMPK by metformin significantly reduced TGF-β1-induced collagen I production by suppressing Smad3-driven CTGF expression (P < 0.01), and the application of Compound C reversed such changes in the fibroblasts (P < 0.01).

CONCLUSIONS

Metformin inhibits TGF-β1-stimulated collagen I production by activating AMPK and inhibiting Smad3- driven CTGF expression in rat biliary fibroblasts.