Cofilin-1, peroxiredoxin-1, and galectin-3: Major proteins released by macrophages infected with Corynebacterium pseudotuberculosis

TRIM21 interacts with IκBα and negatively regulates NF-κB activation in Corynebacterium pseudotuberculosis-infected macrophages

Corynebacterium pseudotuberculosis, a zoonotic intracellular bacteria, is responsible for abscesses and pyogranuloma formation of the infected host, which is essentially a chronic inflammatory response. Tripartite motif-containing protein 21 (TRIM21) negatively regulates pro-inflammatory cytokines production during C. pseudotuberculosis infection, the mechanism of which remains unclear. This study found that C. pseudotuberculosis infection in macrophages induced phosphorylation of IκB and p65. TRIM21 interacted with IκBα by PRY/SPRY domain, stabilizes IκBα and negatively regulates IκBα phosphorylation in macrophages during C. pseudotuberculosis infection. In addition, TRIM21 positively regulates the ubiquitination of IκBα via K48 linkage rather than K63 linkage in C. pseudotuberculosis-infected macrophages. In brief, our research confirmed that TRIM21 negatively regulates canonical NF-κB activation by interacting with IκBα and decreasing IκBα phosphorylation in macrophages during C. pseudotuberculosis infection. Preventing inflammation induced by C. pseudotuberculosis infection through regulation of the NF-κB pathway is a potential way to control this pathogen.

Lactobacillus acidophilus protects against Corynebacterium pseudotuberculosis infection by regulating the autophagy of macrophages and maintaining gut microbiota homeostasis in C57BL/6 mice

Corynebacterium pseudotuberculosis (C. p), a facultative intracellular bacterium, is an important zoonotic pathogen that causes abscesses and pyogenic granulomas. The relationship between gut microbiota and host health or diseases has received increasing attention. However, the role of gut microbiota in the process of C. p infection is still unclear. In this study, we established a C. p infection model in C57BL/6 mice and examined the impact of preemptive oral administration Lactobacillus acidophilus (L. acidophilus) on infection. Our findings revealed that C. p infection led to pronounced pathological alterations in the liver and kidneys, characterized by abscess formation, intense inflammatory responses, and bacterial overload. Remarkably, these deleterious effects were greatly relieved by oral administration of L. acidophilus before infection with C. p. Additionally, we further found that during C. p infection, peritoneal macrophages (PMs) of mice orally administered with L. acidophilus accumulated more rapidly at sites of infection. Furthermore, our results showed that PMs from mice with oral L. acidophilus administration showed a stronger C. p clearance effect, and this was mediated by high expression of LC3-II protein. Meanwhile, oral administration of L. acidophilus protected the gut microbiota disorder in C57BL/6 mice caused by C. p infection. In summary, our study demonstrates that oral administration of L. acidophilus confers effective protection against C. p infection in C57BL/6 mice by modulating macrophage autophagy, thereby augmenting bacterial clearance and preserving gut microbiota and function stability. These findings position L. acidophilus as a viable probiotic candidate for the clinical prevention of C. p infection.

IMPORTANCE

Corynebacterium pseudotuberculosis (C. p) is known to induce a range of chronic diseases in both animals and humans. Currently, clinical treatment for C. p infection mainly relies on antibiotic therapy or surgical intervention. However, excessive use of antibiotics may increase the risk of drug-resistant strains, and the effectiveness of treatment remains unsatisfactory. Furthermore, surgical procedures do not completely eradicate pathogens and can easily cause environmental pollution. Probiotic interventions are receiving increasing attention for improving the body's immune system and maintaining health. In this study, we established a C. p infection model in C57BL/6 mice to explore the impact of Lactobacillus acidophilus during C. p infection. Our results showed that L. acidophilus effectively protected against C. p infection by regulating the autophagy of macrophages and maintaining intestinal microbiota homeostasis. This study may provide a new strategy for the prevention of C. p infection.

TRIM21 negatively regulates Corynebacterium pseudotuberculosis-induced inflammation and is critical for the survival of C. pseudotuberculosis infected C57BL6 mice

Corynebacterium pseudotuberculosis, a facultative intracellular bacterium, is an important zoonotic pathogen responsible for chronic inflammatory diseases. TRIM21, an E3 ubiquitin-protein ligase, plays pivotal roles in inflammation regulation. However, its role during C. pseudotuberculosis infection is unclear. Here, we found that TRIM21 expression was significantly increased in C. pseudotuberculosis-infected macrophages. Following infection by C. pseudotuberculosis, we observed a significantly higher number of bacteria and a higher degree of LDH release from Trim21^-/- macrophages compared to wild-type (WT) macrophages, suggesting that TRIM21 limits C. pseudotuberculosis replication in macrophages and protects the infected cells from death. Further in vivo experiments showed a significantly higher mortality, higher bacterial load, much more severe abscess formation, and lesions in the organs of C. pseudotuberculosis-infected Trim21^-/- mice compared to those of the infected WT mice, suggesting that TRIM21 plays critical roles in protecting against C. pseudotuberculosis infection. Moreover, the secretory levels of IL-1α, IL-1β, IL-6, and TNF-α were significantly higher in C. pseudotuberculosis-infected Trim21^-/- macrophages compared to infected WT macrophages; the levels of these cytokines were also higher in the sera, organs, and ascites of C. pseudotuberculosis-infected Trim21^-/- mice compared to infected WT mice. These findings suggest that TRIM21 negatively regulates the secretion of pro-inflammatory cytokines in macrophages, sera, organs, and ascites of mice following C. pseudotuberculosis infection. Collectively, the present study demonstrates that TRIM21 plays a vital role in preventing C. pseudotuberculosis infection, which may be related to the negative regulation of pro-inflammatory cytokines production by TRIM21 during this pathogen infection.