Alterations in the intestinal microbiota associated with active tuberculosis and latent tuberculosis infection

Gut bacterial diversity in bovines infected with Mycobacterium tuberculosis var. bovis: insights on tuberculosis pathogenesis

Bovine tuberculosis susceptibility and pathogenesis are influenced by host immunity, which may be modulated by the host microbiota. While intestinal microbiota composition affects pulmonary diseases in humans, its role in bovine tuberculosis remains unclear. This study explores the intestinal microbiota of cattle and its association with tuberculosis to better understand disease pathophysiology. A case-control study was conducted using small intestine content samples from cattle with and without tuberculosis, slaughtered in Rio Grande do Sul, Brazil. DNA extraction, 16S rRNA (V4) sequencing, and bioinformatics analyses assessed alpha and beta diversity, taxa characterization, differential abundance, and metabolic pathways. No significant differences in alpha and beta diversities between the groups were detected. However, the Bacillota/Bacteroidota ratio suggested dysbiosis associated with bovine tuberculosis. Differential abundance analysis showed that microorganisms belonging to the Bacillota phylum, the Eubacterium cellulosolvens group, Colidextribacter and Coprococcus genera were enriched in healthy cattle. Conversely, animals with tuberculosis showed higher abundances of Verrucomicrobiota phylum, Sphingomonadaceae and Eubacteriaceae families, and Solobacterium and Clostridia-UCG-014 genera. Moreover, metabolic pathways related to carbohydrate degradation were enriched in healthy animals, and biosynthetic pathways related to disease were enriched in tuberculosis animals. This study highlights associations between intestinal microbiota and bovine tuberculosis, providing insights into disease mechanisms.

Amoxicillin-induced bacterial gut dysbiosis decreases IL-1β and IL-6 expression but exacerbate lung inflammatory response against Mycobacterium bovis-Bacille Calmette-Guérin (BCG)

Tuberculosis is one of the leading causes of global mortality, and the standard, prolonged, and intensive treatment can affect intestinal homeostasis. This study investigated amoxicillin-induced bacterial gut dysbiosis and its impact on the immune response of C57BL/6 mice to pulmonary infection by Mycobacterium bovis-BCG. It was observed that amoxicillin treatment resulted in bacterial gut dysbiosis, characterized by an increase in the phylum Proteobacteria and a reduction in Bacteroidetes and Firmicutes. This alteration was associated with a decrease in the animals' body weight and a reduction in the expression of pro-inflammatory cytokines such as IL-1β and IL-6, suggesting a compromised immune response. Additionally, microstructural analysis revealed significant alterations in the caecum and pulmonary structure of the mice, indicating tissue damage associated with intestinal dysbiosis. The results indicate that amoxicillin-induced bacterial gut dysbiosis may negatively affect pulmonary immunity and exacerbate M. bovis-BCG infection, highlighting the need to consider the impacts of intestinal microbiota on the development and control of tuberculosis. This study contributes to the understanding of the interaction between intestinal microbiota, antibiotic treatment, and immunity in pulmonary infections.

Full-length 16S rDNA sequencing based on Oxford Nanopore Technologies revealed the association between gut-pharyngeal microbiota and tuberculosis in cynomolgus macaques

Tuberculosis (TB) is an infectious disease caused by the Mycobacterium tuberculosis complex (Mtbc), which develops from asymptomatic latent TB to active stages. The microbiome was purposed as a potential factor affecting TB pathogenesis, but the study was limited. The present study explored the association between gut-pharyngeal microbiome and TB stages in cynomolgus macaques using the full-length 16S rDNA amplicon sequencing based on Oxford Nanopore Technologies. The total of 71 macaques was divided into TB (-) control, TB (+) latent and TB (+) active groups. The differential abundance analysis showed that Haemophilus hemolyticus was decreased, while Prevotella species were increased in the pharyngeal microbiome of TB (+) macaques. In addition, Eubacterium coprostanoligenes in the gut was enriched in TB (+) macaques. Alteration of these bacteria might affect immune regulation and TB severity, but details of mechanisms should be further explored and validated. In summary, microbiota may be associated with host immune regulation and affect TB progression. The findings suggested the potential mechanisms of host-microbes interaction, which may improve the understanding of the role of microbiota and help develop therapeutics for TB in the future.