sRNA21, a novel small RNA, protects Mycobacterium abscessus against oxidative stress

Stealth in non-tuberculous mycobacteria: clever challengers to the immune system

Non-tuberculous Mycobacteria (NTM) are found extensively in various environments, yet most are non-pathogenic. Only a limited number of these organisms can cause various infections, including those affecting the lungs, skin, and central nervous system, particularly when the host's autoimmune function is compromised. Among these, Non-tuberculous Mycobacteria Pulmonary Diseases (NTM-PD) are the most prevalent. Currently, there is a lack of effective treatments and preventive measures for NTM infections. This article aims to deepen the comprehension of the pathogenic mechanisms linked to NTM and to formulate new intervention strategies by synthesizing current research and detailing the different tactics used by NTM to avoid elimination by the host's immune response. These intricate mechanisms not only affect the innate immune response but also successfully oppose the adaptive immune response, establishing persistent infections within the host. This includes effects on the functions of macrophages, neutrophils, dendritic cells, and T lymphocytes, as well as modulation of cytokine production. The article particularly emphasizes the survival strategies of NTM within macrophages, such as inhibiting phagosome maturation and acidification, resisting intracellular killing mechanisms, and interfering with autophagy and cell death pathways. This review aims to deepen the understanding of NTM's immune evasion mechanisms, thereby facilitating efforts to inhibit its proliferation and spread within the host, ultimately providing new methods and strategies for NTM-related treatments.

Insights into the complementation potential of the extreme acidophile's orthologue in replacing Escherichia coli hfq gene-particularly in bacterial resistance to environmental stress

Acidithiobacillus caldus is a typical extreme acidophile widely used in the biohydrometallurgical industry, which often experiences extreme environmental stress in its natural habitat. Hfq, an RNA-binding protein, typically functions as a global regulator involved in various cellular physiological processes. Yet, the biological functions of Hfq derived from such extreme acidophile have not been extensively investigated. In this study, the recombinant strain Δhfq/Achfq, constructed by CRISPR/Cas9-mediated chromosome integration, fully or partially restored the phenotypic defects caused by hfq deletion in Escherichia coli, including impaired growth performance, abnormal cell morphology, impaired swarming motility, decreased stress resistance, decreased intracellular ATP and free amino acid levels, and attenuated biofilm formation. Particularly noteworthy, the intracellular ATP level and biofilm production of the recombinant strain were increased by 12.2% and 7.0%, respectively, compared to the Δhfq mutant. Transcriptomic analysis revealed that even under heterologous expression, AcHfq exerted global regulatory effects on multiple cellular processes, including metabolism, environmental signal processing, and motility. Finally, we established a potential working model to illustrate the regulatory mechanism of AcHfq in bacterial resistance to environmental stress.