Therapeutic effectiveness of type I interferon in vulvovaginal candidiasis

Fungal vaccines and adjuvants: a tool to reveal the interaction between host and fungi

Fungal infections are incurring high risks in a range from superficial mucosal discomforts (such as oropharyngeal candidiasis and vulvovaginal candidiasis) to disseminated life-threatening diseases (such as invasive pulmonary aspergillosis and cryptococcal meningitis) and becoming a global health problem in especially immunodeficient population. The major obstacle to conquer fungal harassment lies in the presence of increasing resistance to conventional antifungal agents used in newly clinically isolated strains. Although recombinant cytokines and mono-/poly-clonal antibodies are added into antifungal armamentarium, more effective antimycotic drugs are exceedingly demanded. It is comforting that the development of fungal vaccines and adjuvants opens up a window to brighten the prospective way in the diagnosis, prevention and treatment of fungal assaults. In this review, we focus on the progression of several major fungal vaccines devised for the control of Candida spp., Aspergillus spp., Cryptococcus spp., Coccidioides spp., Paracoccidioides spp., Blastomyces spp., Histoplasma spp., Pneumocystis spp. as well as the adjuvants adopted. We then expound the interaction between fungal vaccines/adjuvants and host innate (macrophages, dendritic cells, neutrophils), humoral (IgG, IgM and IgA) and cellular (Th1, Th2, Th17 and Tc17) immune responses which generally experience immune recognition of pattern recognition receptors, activation of immune cells, and clearance of invaded fungi. Furthermore, we anticipate an in-depth understanding of immunomodulatory properties of univalent and multivalent vaccines against diverse opportunistic fungi, providing helpful information in the design of novel fungal vaccines and adjuvants.

SLC7A11 as a therapeutic target to attenuate phthalates-driven testosterone level decline in mice

INTRODUCTION

Phthalates exposure is a major public health concern due to the accumulation in the environment and associated with levels of testosterone reduction, leading to adverse pregnancy outcomes. However, the relationship between phthalate-induced testosterone level decline and ferroptosis remains poorly defined.

OBJECTIVES

Herein, we aimed to explore the mechanisms of phthalates-induced testosterone synthesis disorder and its relationship to ferroptosis.

METHODS

We conducted validated experiments in vivo male mice model and in vitro mouse Leydig TM3 cell line, followed by RNA sequencing and metabolomic analysis. We evaluated the levels of testosterone synthesis-associated enzymes and ferroptosis-related indicators by using qRT-PCR and Western blotting. Then, we analyzed the lipid peroxidation, ROS, Fe2+ levels and glutathione system to confirm the occurrence of ferroptosis.

RESULTS

In the present study, we used di (2-ethylhexyl) phthalate (DEHP) to identify ferroptosis as the critical contributor to phthalate-induced testosterone level decline. It was demonstrated that DEHP caused glutathione metabolism and steroid synthesis disorders in Leydig cells. As the primary metabolite of DEHP, mono-2-ethylhexyl phthalate (MEHP) triggered testosterone synthesis disorder accompanied by a decrease in the expression of solute carri1er family 7 member 11 (SLC7A11) protein. Furthermore, MEHP synergistically induced ferroptosis with Erastin through the increase of intracellular and mitochondrial ROS, and lipid peroxidation production. Mechanistically, overexpression of SLC7A11 counteracts the synergistic effect of co-exposure to MEHP-Erastin.

CONCLUSION

Our research results suggest that MEHP does not induce ferroptosis but synergizes Erastin-induced ferroptosis. These findings provide evidence for the role of ferroptosis in phthalates-induced testosterone synthesis disorder and point to SLC7A11 as a potential target for male reproductive diseases. This study established a correlation between ferroptosis and phthalates cytotoxicity, providing a novel view point for mitigating the issue of male reproductive disease and "The Global Plastic Toxicity Debt".

A New Phenotype in Candida-Epithelial Cell Interaction Distinguishes Colonization- versus Vulvovaginal Candidiasis-Associated Strains

Vulvovaginal candidiasis (VVC) affects nearly 3/4 of women during their lifetime, and its symptoms seriously reduce quality of life. Although Candida albicans is a common commensal, it is unknown if VVC results from a switch from a commensal to pathogenic state, if only some strains can cause VVC, and/or if there is displacement of commensal strains with more pathogenic strains. We studied a set of VVC and colonizing C. albicans strains to identify consistent in vitro phenotypes associated with one group or the other. We find that the strains do not differ in overall genetic profile or behavior in culture media (i.e., multilocus sequence type [MLST] profile, rate of growth, and filamentation), but they show strikingly different behaviors during their interactions with vaginal epithelial cells. Epithelial infections with VVC-derived strains yielded stronger fungal proliferation and shedding of fungi and epithelial cells. Transcriptome sequencing (RNA-seq) analysis of representative epithelial cell infections with selected pathogenic or commensal isolates identified several differentially activated epithelial signaling pathways, including the integrin, ferroptosis, and type I interferon pathways; the latter has been implicated in damage protection. Strikingly, inhibition of type I interferon signaling selectively increases fungal shedding of strains in the colonizing cohort, suggesting that increased shedding correlates with lower interferon pathway activation. These data suggest that VVC strains may intrinsically have enhanced pathogenic potential via differential elicitation of epithelial responses, including the type I interferon pathway. Therefore, it may eventually be possible to evaluate pathogenic potential in vitro to refine VVC diagnosis. IMPORTANCE Despite a high incidence of VVC, we still have a poor understanding of this female-specific disease whose negative impact on women's quality of life has become a public health issue. It is not yet possible to determine by genotype or laboratory phenotype if a given Candida albicans strain is more or less likely to cause VVC. Here, we show that Candida strains causing VVC induce more fungal shedding from epithelial cells than strains from healthy women. This effect is also accompanied by increased epithelial cell detachment and differential activation of the type I interferon pathway. These distinguishing phenotypes suggest it may be possible to evaluate the VVC pathogenic potential of fungal isolates. This would permit more targeted antifungal treatments to spare commensals and could allow for displacement of pathogenic strains with nonpathogenic colonizers. We expect these new assays to provide a more targeted tool for identifying fungal virulence factors and epithelial responses that control fungal vaginitis.

Ferroptosis is critical for phthalates driving the blood-testis barrier dysfunction via targeting transferrin receptor

The global rate of human male infertility is rising at an alarming rate owing to environmental and lifestyle changes. Phthalates are the most hazardous chemical additives in plastics and have an apparently negative impact on the function of male reproductive system. Ferroptosis is a recently described form of iron-dependent cell death and has been linked to several diseases. Transferrin receptor (TfRC), a specific ferroptosis marker, is a universal iron importer for all cells using extracellular transferrin. We aim to investigate the potential involvement of ferroptosis during male reproductive toxicity, and provide means for drawing conclusions on the effect of ferroptosis in phthalates-induced male reproductive disease. In this study, we found that di (2-ethylhexyl) phthalate (DEHP) triggered blood-testis barrier (BTB) dysfunction in the mouse testicular tissues. DEHP also induced mitochondrial morphological changes and lipid peroxidation, which are manifestations of ferroptosis. As the primary metabolite of DEHP, mono-2-ethylhexyl phthalate (MEHP) induced ferroptosis by inhibiting glutathione defense network and increasing lipid peroxidation. TfRC knockdown blocked MEHP-induced ferroptosis by decreasing mitochondrial and intracellular levels of Fe²⁺. Our findings indicate that TfRC can regulate Sertoli cell ferroptosis and therefore is a novel therapeutic molecule for reproductive disorders in male patients with infertility.

Phthalate-induced testosterone/androgen receptor pathway disorder on spermatogenesis and antagonism of lycopene

Male infertility is an attracting growing concern owing to decline in sperm quality of men worldwide. Phthalates, in particular to di (2-ethylhexyl) phthalate (DEHP) or its main metabolite mono-2-ethylhexyl phthalate (MEHP), affect male reproductive development and function, which mainly accounts for reduction in male fertility. Lycopene (LYC) is a natural antioxidant agent that has been recognized as a possible therapeutic option for treating male infertility. Testosterone (T)/androgen receptor (AR) signaling pathway is involved in maintaining spermatogenesis and male fertility. How DEHP causes spermatogenesis disturbance and whether LYC could prevent DEHP-induced male reproductive toxicity have remained unclear. Using in vivo and vitro approaches, we demonstrated that DEHP caused T biosynthesis reduction in Leydig cell and secretory function disorder in Sertoli cell, and thereby resulted in spermatogenic impairment. Results also showed that MEHP caused mitochondrial damage and oxidative damage, which imposes a serious threat to the progress of spermatogenesis. However, LYC supplement reversed these changes. Mechanistically, DEHP contributed to male infertility via perturbing T/AR signaling pathway during spermatogenesis. Overall, our study reveals critical role for T/AR signal transduction in male fertility and provides promising insights into the protective role of LYC in phthalate-induced male reproductive disorders.

The network interplay of interferon and Toll-like receptor signaling pathways in the anti-Candida immune response

Fungal infections represent a major global health problem affecting over a billion people that kills more than 1.5 million annually. In this study, we employed an integrative approach to reveal the landscape of the human immune responses to Candida spp. through meta-analysis of microarray, bulk, and single-cell RNA sequencing (scRNA-seq) data for the blood transcriptome. We identified across these different studies a consistent interconnected network interplay of signaling molecules involved in both Toll-like receptor (TLR) and interferon (IFN) signaling cascades that is activated in response to different Candida species (C. albicans, C. auris, C. glabrata, C. parapsilosis, and C. tropicalis). Among these molecules are several types I IFN, indicating an overlap with antiviral immune responses. scRNA-seq data confirmed that genes commonly identified by the three transcriptomic methods show cell type-specific expression patterns in various innate and adaptive immune cells. These findings shed new light on the anti-Candida immune response, providing putative molecular pathways for therapeutic intervention.

Candida pathogens induce protective mitochondria-associated type I interferon signalling and a damage-driven response in vaginal epithelial cells

Vaginal candidiasis is an extremely common disease predominantly caused by four phylogenetically diverse species: Candida albicans; Candida glabrata; Candida parapsilosis; and Candida tropicalis. Using a time course infection model of vaginal epithelial cells and dual RNA sequencing, we show that these species exhibit distinct pathogenicity patterns, which are defined by highly species-specific transcriptional profiles during infection of vaginal epithelial cells. In contrast, host cells exhibit a homogeneous response to all species at the early stages of infection, which is characterized by sublethal mitochondrial signalling inducing a protective type I interferon response. At the later stages, the transcriptional response of the host diverges in a species-dependent manner. This divergence is primarily driven by the extent of epithelial damage elicited by species-specific mechanisms, such as secretion of the toxin candidalysin by C. albicans. Our results uncover a dynamic, biphasic response of vaginal epithelial cells to Candida species, which is characterized by protective mitochondria-associated type I interferon signalling and a species-specific damage-driven response.

Type I Interferons Ameliorate Zinc Intoxication of Candida glabrata by Macrophages and Promote Fungal Immune Evasion

Host and fungal pathogens compete for metal ion acquisition during infectious processes, but molecular mechanisms remain largely unknown. Here, we show that type I interferons (IFNs-I) dysregulate zinc homeostasis in macrophages, which employ metallothionein-mediated zinc intoxication of pathogens as fungicidal response. However, Candida glabrata can escape immune surveillance by sequestering zinc into vacuoles. Interestingly, zinc-loading is inhibited by IFNs-I, because a Janus kinase 1 (JAK1)-dependent suppression of zinc homeostasis affects zinc distribution in macrophages as well as generation of reactive oxygen species (ROS). In addition, systemic fungal infections elicit IFN-I responses that suppress splenic zinc homeostasis, thereby altering macrophage zinc pools that otherwise exert fungicidal actions. Thus, IFN-I signaling inadvertently increases fungal fitness both in vitro and in vivo during fungal infections. Our data reveal an as yet unrecognized role for zinc intoxication in antifungal immunity and suggest that interfering with host zinc homeostasis may offer therapeutic options to treat invasive fungal infections.