The Rip1 intramembrane protease contributes to iron and zinc homeostasis in Mycobacterium tuberculosis

Impact of vitamin C deficiency on imaging patterns and ventilatory function in pulmonary tuberculosis

Background

Studies have shown that vitamin C is essential for the immune response to tuberculosis (TB), and that its deficiency may elevate the risk of TB and related complications. This prospective study investigated the association between disease severity, imaging findings and vitamin C levels.

Methods

This study enrolled 109 patients with confirmed pulmonary tuberculosis based on Mycobacterium tuberculosis culture. Patients were divided into two groups based on serum vitamin C levels: 59 patients (54.13%) with normal levels and 50 (45.87%) with low levels.

Results

At baseline, patients in the low vitamin C group showed significantly higher bacillar loads, with 86.00% presenting loads of 2+ or higher compared with 59.32% in the normal group (p < 0.001). After 2 months of treatment, 83.05% of the normal vitamin C group achieved culture conversion, while only 28.00% of the low vitamin C group reached the same milestone (p < 0.001). CT imaging at baseline revealed that the low vitamin C group had a significantly higher mean frequency of the tree-in-bud pattern (2.66 vs. 2.05; p < 0.001). Cavitary lesions were more prevalent in the low vitamin C group, in the superior right lobe (0.34 vs. 0.13; p = 0.011) and superior left lobe (0.34 vs. 0.14; p = 0.012). After 6 months of treatment, the low vitamin C group exhibited a higher prevalence of bronchiectasis (mean involvement in both lungs: 0.58 vs. 0.16; p < 0.001), cavitary lesions (0.32 vs. 0.00; p = 0.002), and fibrosis (0.90 vs. 0.36; p < 0.001). Pulmonary function tests showed greater impairment in the low vitamin C group. The forced expiratory volume decreased by 5.77% compared to 3.59% in the normal group (p < 0.001), the forced vital capacity (FVC) decreased by 12.00% vs. 6.67% (p < 0.001), and the Tiffeneau index by 3.34 vs. 2.13 (p = 0.002). Receiver operating characteristic (ROC) analysis indicated that FVC (AUC = 0.826) and forced expiratory flow (AUC = 0.745) were stronger predictors of treatment success in patients with normal vitamin C levels.

Conclusion

Vitamin C deficiency is correlated with increased disease severity, delayed bacterial clearance, and persistent pulmonary damage in patients with tuberculosis. Vitamin C supplementation can enhance treatment outcomes in tuberculosis therapy.

The role of transcriptional regulators in metal ion homeostasis of Mycobacterium tuberculosis

Metal ions are essential trace elements for all living organisms and play critical catalytic, structural, and allosteric roles in many enzymes and transcription factors. Mycobacterium tuberculosis (MTB), as an intracellular pathogen, is usually found in host macrophages, where the bacterium can survive and replicate. One of the reasons why Tuberculosis (TB) is so difficult to eradicate is the continuous adaptation of its pathogen. It is capable of adapting to a wide range of harsh environmental stresses, including metal ion toxicity in the host macrophages. Altering the concentration of metal ions is the common host strategy to limit MTB replication and persistence. This review mainly focuses on transcriptional regulatory proteins in MTB that are involved in the regulation of metal ions such as iron, copper and zinc. The aim is to offer novel insights and strategies for screening targets for TB treatment, as well as for the development and design of new therapeutic interventions.