tretinoin and Tuberculosis

The scenario of tuberculosis has gone deadly due to its high prevalence and emergence of widespread drug resistance. It is now high time to develop novel antimycobacterial strategies and to understand novel mechanisms of existing antimycobacterial compounds so that we are equipped with newer tuberculosis controlling molecules in the days to come. Iron has proven to be essential for pathogenesis of tuberculosis and retinoic acid is known to influence the iron metabolism pathway. Retenoic acid is also known to exhibit antitubercular effect in in vivo system. Therefore there is every possibility that retinoic acid by affecting the iron metabolism pathway exhibits its antimycobacterial effect. These aspects are reviewed in the present manuscript for understanding the antimycobacterial role of retinoic acid in the context of iron metabolism and other immunological aspects.

Topics: Animals; Antitubercular Agents; Humans; Iron; Mycobacterium tuberculosis; Phagosomes; Tretinoin; Tuberculosis

Macrophages are a protective replicative niche for Mycobacterium tuberculosis (Mtb) but can kill the infecting bacterium when appropriately activated. To identify mechanisms of clearance, we compared levels of bacterial restriction by human macrophages after treatment with 26 compounds, including some currently in clinical trials for tuberculosis. All-

Topics: Acyl Coenzyme A; Cholesterol; Clustered Regularly Interspaced Short Palindromic Repeats; Humans; Macrophages; Mycobacterium tuberculosis; Tretinoin; Tuberculosis

Tuberculosis (TB) is the leading cause of death by a single infectious agent, Mycobacterium tuberculosis (Mtb). Alveolar macrophages and respiratory epithelial cells are the first cells exposed to Mtb during the primary infection, once these cells are activated, secrete cytokines and antimicrobial peptides that are associated with the Mtb contention and elimination. Vitamins are micronutrients that function as boosters on the innate immune system, however, is unclear whether they have any protective activity during Mtb infection. Thus, we investigated the role of vitamin A (retinoic acid), vitamin C (ascorbic acid), vitamin D (calcitriol), and vitamin E (alfa-tocopherol) as inductors of molecules related to mycobacterial infection in macrophages and epithelial cells. Our results showed that retinoic acid promotes the expression of pro- and anti-inflammatory molecules such as Thymic stromal lymphopoietin (TSLP), β-defensin-2, IL-1β, CCL20, β-defensin-3, Cathelicidin LL-37, TGF-β, and RNase 7, whereas calcitriol, ascorbic acid, and α-tocopherol lead to an anti-inflammatory response. Treatment of Mtb-infected epithelial cells and macrophage-like cells with the vitamins showed a differential response, where calcitriol reduced Mtb in macrophages, while retinoic acid reduced infection in epithelial cells. Thereby, we propose that a combination of calcitriol and retinoic acid supplementation can drive the immune response, and promotes the Mtb elimination by increasing the expression of antimicrobial peptides and cytokines, while simultaneously modulating inflammation.

Topics: Antimicrobial Peptides; Antineoplastic Agents; Autophagy; Bronchi; Cells, Cultured; Cytokines; Epithelial Cells; Humans; Macrophages; Mycobacterium tuberculosis; Tretinoin; Tuberculosis

Vitamin A deficiency strongly predicts the risk of developing tuberculosis (TB) in individuals exposed to Mycobacterium tuberculosis (Mtb). The burden of antibiotic-resistant TB is increasing globally; therefore, there is an urgent need to develop host-directed adjunctive therapies to treat TB. Alveolar macrophages, the niche cell for Mtb, metabolize vitamin A to all-trans retinoic acid (atRA), which influences host immune responses. We sought to determine the mechanistic effects of atRA on the host immune response to intracellular bacterial infection in primary human and murine macrophages. In this study, atRA promoted autophagy resulting in a reduced bacterial burden in human macrophages infected with Mtb and Bordetella pertussis, but not bacillus Calmette-Guérin (BCG). Autophagy is induced by cytosolic sensing of double-stranded DNA via the STING/TBK1/IRF3 axis; however, BCG is known to evade cytosolic DNA sensors. atRA enhanced colocalization of Mtb, but not BCG, with autophagic vesicles and acidified lysosomes. This enhancement was inhibited by blocking TBK1. Our data indicate that atRA augments the autophagy of intracellular bacteria that trigger cytosolic DNA-sensing pathways but does not affect bacteria that evade these sensors. The finding that BCG evades the beneficial effects of atRA has implications for vaccine design and global health nutritional supplementation strategies. The ability of atRA to promote autophagy and aid bacterial clearance of Mtb and B. pertussis highlights a potential role for atRA as a host-directed adjunctive therapy.

Topics: Antineoplastic Agents; Antitubercular Agents; Autophagy; Cells, Cultured; Humans; Macrophages, Alveolar; Mycobacterium tuberculosis; Tretinoin; Tuberculosis

Topics: Autophagy; Bacterial Infections; Humans; Tretinoin; Tuberculosis; Vitamin A

Immune-modulating drugs that target myeloid-derived suppressor cells or stimulate natural killer T cells have been shown to reduce mycobacterial loads in tuberculosis (TB). We aimed to determine if a combination of these drugs as adjunct immunotherapy to conventional antibiotic treatment could also increase therapeutic efficacy against TB. In our model of pulmonary TB in mice, we applied treatment with isoniazid, rifampicin, and pyrazinamide for 13 weeks alone or combined with immunotherapy consisting of all-trans retinoic acid, 1,25(OH)

Topics: Animals; Anti-Bacterial Agents; Antitubercular Agents; Cholecalciferol; Combined Modality Therapy; Disease Models, Animal; Female; Galactosylceramides; Immunity, Cellular; Immunotherapy; Lung; Mice, Inbred BALB C; Recurrence; Tretinoin; Tuberculosis; Tumor Necrosis Factor-alpha

Phagosomal maturation arrest is known to play a central role in the survival of pathogenic mycobacteria within macrophages. The maturation arrest of mycobacterial phagosome results from the retention of tryptophan-aspartate-containing coat protein (TACO) on this organelle, enabling successful replication of the pathogen. We have shown earlier that vitamin D(3) and retinoic acid (RA) down-regulate TACO gene transcription in a dose-dependent manner.. In this study, we analyzed the promoter region of TACO gene using bioinformatics tools and observed that the vitamin D receptor (VDR)/retinoid-X-receptor (RXR) response sequence was highly functional. We also evaluated the effect of treatment with vitamin D(3)/RA on Mycobacterium tuberculosis entry and survival in cultured human macrophages.. TACO gene down-regulation observed with vitamin D(3)/RA treatment occurred through modulation of this gene via the VDR/RXR response sequence present in the promoter region of TACO gene. Treatment of macrophages with vitamin D(3)/RA allows maturation of mycobacterial phagosome, leading to degradation of the pathogen.. Our results elucidate the mechanism of TACO gene down-regulation observed with vitamin D(3)/RA. Furthermore, the results revealed that vitamin D(3)/RA treatment inhibits mycobacterial entry as well as survival within macrophages, possibly through rescue of phagosome maturation arrest. The developing knowledge in this area suggests that vitamin D(3)/RA may be of importance in the treatment of intracellular infection, particularly tuberculosis.

Topics: Binding Sites; Cell Line, Tumor; Down-Regulation; Genes, Reporter; Humans; Macrophages; Microbial Viability; Microfilament Proteins; Mycobacterium tuberculosis; Phagocytosis; Response Elements; Transcription Factors; Transcription, Genetic; Tretinoin; Tuberculosis; Vitamin D

The immunologically active vitamin retinoic acid (RA) was tested for the ability to increase the resistance of cultured human macrophages (MP) to experimental infection with virulent Mycobacterium tuberculosis Erdman (tubercle bacilli [TB]). It was added to MP in various concentrations and addition regimens. Protection against TB was measured by counting live TB (CFU) in lysates of samples of MP taken at 0, 4, and 7 days after MP infection. RA was protective when added after infection at the pharmacologic concentration of 10(-5) M and when added before infection at the physiologic concentration of 10(-7) M. The protection lengthened intracellular generation times for TB, occasionally caused bacteriostasis, and regularly kept CFU counts at 7 days (end of the period of infection) 1 to 2 log10 CFU below control values. Significant protection was seen in a series of 16 experiments with MP from seven different donors, but the degree of protection varied considerably. The protection depended partly on and was inversely proportional to concentrations of a serum substitute or autologous serum used as a supplement in the RPMI 1640 MP culture medium. It was strongest at concentrations of serum below 1%. RA at concentrations used in the MP cultures did not inhibit TB in the absence of MP. These results suggest that RA (vitamin A), like vitamin D, may have some immunoprotective role against human tuberculosis, as historically intimated by the regular use of vitamin A- and D-rich cod liver oil for the treatment of tuberculosis before the introduction of modern chemotherapy.

Topics: Cells, Cultured; Culture Media; Dose-Response Relationship, Drug; Humans; In Vitro Techniques; Macrophages; Mycobacterium tuberculosis; Time Factors; Tretinoin; Tuberculosis