Medical Microbiology and Immunology最新文献

Toxoplasma gondii is a globally prevalent zoonotic parasite responsible for toxoplasmosis. Accurate serological diagnosis remains challenging due to the lack of standardized, high-performance antigens. In this study, we designed a recombinant multi-epitope protein (ME-TG) by selecting B-cell epitopes from four immunodominant antigens: SAG1, GRA7, GRA4, and GRA14. The ME-TG construct was expressed in E. coli, purified, and evaluated using ELISA across 189 serum samples, including acute (n = 45), chronic (n = 38), healthy controls (n = 62), and individuals with other parasitic or bacterial infections (n = 42). The ME-TG-based ELISA demonstrated 98% sensitivity for both IgG and IgM detection, and 100% specificity, with no observed cross-reactivity. These findings highlight the diagnostic potential of ME-TG as a standardized serological marker for human toxoplasmosis. Further validation using larger, geographically diverse cohorts and additional T. gondii antigens is recommended to enhance clinical applicability.

Myeloid cells, such as monocytes, are central in the immune response to infections. However, limited knowledge exists regarding the inflammatory response to Gram-positive anaerobic cocci (GPAC).To explore the ability of GPACs to induce monocyte activation, we compared two GPAC species, Parvimonas micra and Peptoniphilus harei, with E. coli, a major cause of bloodstream infections. We stimulated whole blood with heat-killed bacteria or conditioned medium (CM) and analysed monocytes for signs of activation by flow cytometry. The mechanisms were explored using anti-CD14- or anti-TLR2 antibodies. Finally, to investigate potential pathogen-associated molecular patterns in CM, we performed mass spectrometry (MS).Our findings revealed that P. harei significantly induced activation of monocytes, as evidenced by increased expression of activation markers (PDL1, HLA-DR and CD11b), phosphorylation of members of signalling pathways (NFκBp65, p38 and Akt) and production of cytokines (IL-1β, TNF, IL-6). Interestingly, P. micra had minimal impact on monocyte activation, and we thus focused on P. harei. Pre-treatment with anti-CD14 attenuated the activation of monocytes by heat-killed P. harei. Moreover, P. harei CM also induced clear monocyte activation, though, in contrast to heat-killed P. harei, this activation was dependent on TLR2 signalling. MS analysis of CM primarily identified four proteins possibly associated with monocyte activation. Finally, we also explored neutrophil activation and found a similar activation pattern to that of monocytes, suggesting that our observations are not exclusive to monocytes.Our study demonstrates that P. harei induce prominent activation of monocytes in blood, highlighting a pathogenic potential of these otherwise harmless perceived bacteria.

Yersinia enterocolitica (Ye) typically causes gastroenteritis and mesenteric lymphadenitis and can also spread extra-intestinally. Yersinia outer protein P (YopP) has been shown to induce cytotoxicity and suppress pro-inflammatory responses in in vitro studies. However, the role of YopP during in vivo Ye infection remains incompletely understood. Here, we show that, contrary to expectations for a virulence factor, a YopP-deficient strain (Ye ΔyopP) increases bacterial dissemination from Peyer's patches (PP) to mesenteric lymph nodes (MLN) and the spleen in intragastrically infected mice. Additionally, inhibition of cytotoxicity by suramin treatment in mice promoted wild-type Ye (Ye WT) dissemination to levels comparable to Ye ΔyopP. Moreover, the absence of YopP enhanced neutrophil and macrophage infiltration and increased pro-inflammatory cytokine production in PP, while decreasing IL-10 levels in PP, MLN and the spleen. Notably, the CD11b⁺ dendritic cell (DC) subpopulation in PP following Ye ∆yopP infection did not reach the levels observed in Ye WT. However, Ye-carrying DCs were significantly elevated after infection with GFP-expressing Ye ∆yopP (Ye ∆yopP GFP⁺). Blocking DC migration by FTY720 treatment in Ye ΔyopP-infected mice significantly reduced the MLN bacterial burden, indicating that YopP regulates Ye-transporting DCs from PP to MLN. Overall, our findings provide insights into how YopP participates in host-pathogen interactions, seemingly benefiting the host while simultaneously facilitating bacterial evasion from early immune clearance. These findings contribute to understanding the impact of YopP on the clinical outcome of Ye infection.

Mycobacterium tuberculosis (M. tb), the etiological agent of tuberculosis (TB), subverts host immune responses to establish persistent infection by influencing cytokine production. An effective and balanced cytokine response is crucial for eliminating the pathogen, whereas disruptions in this balance can lead to increased vulnerability to infection. Therefore, developing immunomodulatory agents to steer host immunity toward the adequate clearance of M. tb offers a promising strategy for limiting TB. This study investigates the immunomodulatory effects of Furamidine in response to regulating mycobacterial infection in differentiated THP-1 cells by activating Interleukin-23 (IL-23) signaling. Initially, we checked the immunoregulatory effect of Furamidine and found a substantial increase in the expression of IL-23 at mRNA and protein levels in uninfected and mycobacteria-infected dTHP-1 cells. Neutralization of IL-23 led to a rise in bacterial survival in the cells, confirming the physiological role of IL-23 in clearing mycobacteria in Furamidine-treated macrophages. It was further elucidated that Furamidine increased the receptors IL-12Rβ1 and IL-23R, essential for IL-23 signaling. IL-23R activation, in turn, phosphorylated its downstream effectors TYK2 and STAT3, which regulated the intracellular Ca²⁺ level. Neutralization of IL-23 or pharmacological inhibition of TYK2 and STAT3 by Deucravacitinib and Stattic hampered the process of autophagy by hindering the IL-23 signaling and leading to an increase in the survival of mycobacteria, pointing to the essential role of IL-23 in response to mycobacteria elimination from the cells. These findings revealed that Furamidine promotes host defense in mycobacterial infection by enhancing IL-23-mediated autophagy via the IL-23R/pTYK2/pSTAT3-Ca²⁺ pathway.

Carbapenem-resistant Enterobacteriaceae (CRE), known for their extensive antibiotic resistance, pose a severe global medical threat. Therefore, developing novel therapeutics beyond conventional antibiotics is urgently needed, and the importance of microbiome therapeutics is increasingly being recognized. This study explores the expanded systemic efficacy of PMC101, a microbiome therapeutic, beyond intestinal CRE infections and investigates its mechanism of action from a microbiome perspective. First, the genetic characteristics of the novel strain were identified through whole-genome analysis, and a scalable cultivation process was established as part of the overall development of this microbiome therapeutic. PMC101 increased the survival rate to 100%, significantly reduced disease severity scores, and prevented weight loss in CRE-infected mice treated with antibiotics. These effects are attributed to the inhibition of CRE growth in stool and the reduced detection of CRE in the lungs and kidneys, indicating suppression of systemic translocation. Metagenomic analysis revealed that PMC101 prevented the reduction in microbial population caused by antibiotics and CRE infection, restored species diversity indices, and mitigated dysbiosis while promoting eubiosis. This CRE translocation suppression was closely associated with increased CRE translocation-microbiome index, defined as the ratio of Bacteroidetes to Proteobacteria. This relationship was further confirmed through simulations using a human intestinal microbial ecosystem model. Additionally, increases in short-chain fatty acids, reductions in excessive inflammatory responses, and decreases in tissue damage were observed, all of which contribute to preventing CRE translocation. Finally, pathogen inhibition effects and safety tests were conducted, confirming the prophylactic potential of PMC101 as a microbiome therapeutic. These findings strongly support PMC101 as a promising candidate for future microbiome-based therapies against CRE infections.