A Reliable Murine Model of Disseminated Infection Induced by Talaromyces Marneffei

The microbial damage and host response framework: lesson learned from pathogenic survival trajectories and immunoinflammatory responses of Talaromyces marneffei infection

The adverse outcomes of fungal infection in mammalian hosts depend on the complex interactions between the host immune system and pathogen virulence-associated traits. The main clinical problems arise when the host response is either too weak to effectively eliminate the pathogen or overly aggressive, resulting in host tissue damage rather than protection. This article will highlight current knowledge regarding the virulence attributions and mechanisms involved in the dual-sided role of the host immune system in the immunopathogenesis of the thermally dimorphic fungus Talaromyces marneffei through the lens of the damage response framework (DRF) of microbial pathogenesis model.

Autophagy benefits the in vitro and in vivo clearance of Talaromyces marneffei

Talaromycosis, namely Talaromyces marneffei infection, is increasing gradually and has a high mortality rate even under antifungal therapy. Although autophagy acts differently on different pathogens, it is a promising therapeutic strategy. However, information on autophagy in macrophages and animals upon infection by T. marneffei is still limited. Therefore, several models were employed here to investigate the role of autophagy in host defense against T. marneffei, including RAW264.7 macrophages as in vitro models, different types of Caenorhabditis elegans and BALB/c mice as in vivo models. We applied the clinical T. marneffei isolate SUMS0152 in this study. T. marneffei-infected macrophages exhibit increased formation of autophagosomes. Further, macrophage autophagy promoted by rapamycin or Earle's balanced salt solution (EBSS) inhibited the viability of intracellular T. marneffei. In vivo, compared with uninfected Caenorhabditis elegans, the wild-type nematodes upregulated the expression of the autophagy-related gene lgg-1 and atg-18, and nematodes carrying GFP reporter were induced to form autophagosomes (GFP::LGG-1) after T. marneffei infection. Furthermore, the knockdown of lgg-1 significantly reduced the survival rate of T. marneffei-infected nematodes. Likewise, the autophagy activator rapamycin reduced the fungal burden and suppressed lung inflammation in a mouse model of infection. In conclusion, autophagy is essential for host defense against T. marneffei in vitro and in vivo. Therefore, autophagy may be an attractive target for developing new therapeutics to treat talaromycosis.

Integration of metabolomics and transcriptomics analyses reveals sphingosine-1-phosphate-mediated S1PR2/PI3K/Akt pathway involved in Talaromyces marneffei infection of macrophages

Talaromycosis is a fatal mycosis caused by the thermally dimorphic fungus Talaromyces marneffei (T. marneffei). The pathogenic mechanisms of talaromycosis are still poorly understood. This work combined metabolomics, transcriptomics, and verification experiments in vivo and in vitro to detect metabolic profiles and differentially expressed genes (DEGs) in T. marneffei infected and uninfected macrophages to explore possible pathogenesis and underlying mechanisms. A total of 256 differential metabolites (117 up-regulated and 148 down-regulated) and 1320 DEGs (1286 up-regulated and 34 down-regulated) were identified between the two groups. Integrative metabolomics and transcriptomics analysis showed sphingolipid signaling pathway is the most influential. Verification experiments showed that compared with the control group, the production of sphingosine-1-phosphate (S1P) and the expression of the S1PR1, S1PR2, phosphor-PI3K, and phosphor-Akt genes involved in the sphingolipid signaling pathway have significantly increased in the T. marneffei infection group (p < 0.05). T. marneffei activates the S1PR2/PI3K/Akt pathways in J774A.1 macrophage, regulation of the S1P singling might serve as a promising therapeutic strategy for talaromycosis.

Talaromyces marneffei Infection: Virulence, Intracellular Lifestyle and Host Defense Mechanisms

Talaromycosis (Penicilliosis) is an opportunistic mycosis caused by the thermally dimorphic fungus Talaromyces (Penicillium) marneffei. Similar to other major causes of systemic mycoses, the extent of disease and outcomes are the results of complex interactions between this opportunistic human pathogen and a host’s immune response. This review will highlight the current knowledge regarding the dynamic interaction between T. marneffei and mammalian hosts, particularly highlighting important aspects of virulence factors, intracellular lifestyle and the mechanisms of immune defense as well as the strategies of the pathogen for manipulating and evading host immune cells.