Promising immunotherapeutic targets for treating candidiasis

Diagnostic and clinical management of Candida auris infections in immunocompromised patients

INTRODUCTION

Candida (Candidozyma) auris is an emerging fungal pathogen that poses a significant threat to immunocompromised patients. Its high mortality rates, resistance to multiple antifungal classes, and ability to spread rapidly in healthcare settings underscore the need for timely and accurate diagnosis to guide effective clinical management.

AREAS COVERED

This special report provides an updated overview of C. auris infections in immunocompromised hosts. It discusses current phenotypic and molecular diagnostic tools, antifungal susceptibility testing methods, and infection control strategies. Emerging therapies, including investigational antifungals and combination regimens, are also examined in light of evolving resistance patterns and clinical challenges.

EXPERT OPINION

Despite notable advances in diagnostics and treatment, major obstacles remain in the clinical management of C. auris, particularly in vulnerable populations. Barriers to guideline implementation, lack of standardized screening protocols, and limited access to novel antifungal agents continue to hinder effective response. Future efforts should focus on expanding diagnostic capacity, developing innovative therapies, and implementing targeted surveillance strategies to reduce the global burden of C. auris.

Biosimilars Targeting Pathogens: A Comprehensive Review of Their Role in Bacterial, Fungal, Parasitic, and Viral Infections

Biosimilars represent medicinal products that exhibit a high degree of similarity to an already sanctioned reference biologic agent, with negligible clinically significant disparities concerning safety, purity, or potency. These therapeutic modalities are formulated as economically viable substitutes for established biologics, thereby facilitating increased accessibility to sophisticated treatments for a range of medical conditions, including infectious diseases caused by bacterial, fungal, and viral pathogens. The current landscape of biosimilars includes therapeutic proteins, such as monoclonal antibodies, antimicrobial peptides, antiviral peptides, and antifungal peptides. Here, we discuss the obstacles inherent in the development of biosimilars, including the rapid mutation rates of pathogens. Furthermore, we discuss innovative technologies within the domain, including antibody engineering, synthetic biology, and cell-free protein synthesis, which exhibit potential for improving the potency and production efficiency of biosimilars. We end with a prospective outlook to highlight the importance and capacity of biosimilars to tackle emerging infectious diseases, highlighting the imperative need for ongoing research and financial commitment.

Extracellular fungal Hsp90 represents a promising therapeutic target for combating fungal infections

Heat shock protein 90 (Hsp90) is a pivotal virulence factor in pathogenic fungi, playing a significant role in conferring drug resistance. However, due to the high amino acid sequence similarity between fungal and mammalian Hsp90, targeting fungal intracellular Hsp90 therapeutically is associated with marked toxic side effects, thereby limiting clinical application. Studies have demonstrated that intracellular fungal Hsp90 can be secreted as extracellular Hsp90 (eHsp90), which plays a crucial role in fungal infections. Strategies targeting fungal eHsp90 have exhibited promising therapeutic outcomes. Unlike intracellular targeting, such antifungal approaches can operate without cell penetration, thereby circumventing the toxic side effects due to Hsp90's high conservation. This review summarizes the potential extracellular secretion pathways of fungal eHsp90, its roles in fungal pathogenesis, as well as the development of vaccines and antibodies targeting fungal eHsp90. The review underlines the significance of eHsp90 in fungal infections and suggests that eHsp90 represents a promising therapeutic target for fungal infection treatment.

Transcriptomics analysis reveals the effect of Pulsatilla decoction butanol extract on endoplasmic reticulum and peroxisome function of Candida albicans in hyphal state

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine formula known as Pulsatilla decoction was utilized to treat conditions such as bacterial dysentery, ulcerative colitis, and fungal infections like vulvovaginal candidiasis (VVC) caused by Candida albicans (C. albicans). In our prior research, it was shown that the n-butanol extract from Pulsatilla Decoction (BEPD) exhibited effective inhibition of C. albicans. Nevertheless, the exact mechanism by which BEPD hinders hyphal growth, a critical virulence factor of C. albicans, remains unclear.

AIM OF THE STUDY

In the present study, the inhibitory effect and mechanism of the BEPD on C. albicans hyphal growth was predicted by transcriptome analysis, and further verified by in vitro and in vivo experiments.

MATERIALS AND METHODS

The BEPD was prepared and C. albicans was cultured to induce the hyphal state. Transcriptome analysis was conducted to predict the significant difference in enrichment genes and signaling pathways in the inhibitory effect of BEPD on C. albicans hyphae. Various methods, such as spot assay, time-growth curve analysis, Confocal laser scanning microscope (CLSM), scanning electron microscope (SEM), transmission electron microscope (TEM), flow cytometry, and spectrophotometer, were used to assess the effect of BEPD on hyphal structure and growth activity, lipid peroxidation level, peroxidase (CAT) activity, superoxide dismutase (SOD) activity, and apoptosis of C. albicans. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was employed to examine the expression levels of genes associated with endoplasmic reticulum and peroxisome function. The VVC model was employed to evaluate the influence of BEPD on the growth of C. albicans hyphae in vivo.

RESULT

The growth of C. albicans hyphae on solid culture media was significantly inhibited by BEPD. CLSM showed that the length of C. albicans hyphae was decreased and their vitality was lowered. SEM indicated that the hyphae of C. albicans were fractured, while TEM revealed damage to the organelles within the cells. GO enrichment and KEGG pathways analysis from transcriptomic data demonstrated that BEPD effectively suppressed the functioning of the endoplasmic reticulum and peroxisomes in C. albicans hyphae. RT-qPCR verified the decreased expression of genes associated with endoplasmic reticulum and peroxisome function by BEPD. Investigation of the endoplasmic reticulum revealed that BEPD elevated levels of reactive oxygen species (ROS) and apoptosis, indicating endoplasmic reticulum stress, as well as malondialdehyde (MDA), a marker of oxidative stress. Additionally, BEPD was shown to lower the activities of catalase (CAT) and superoxide dismutase (SOD). In animal trials, BEPD effectively hindered the growth of C. albicans hyphae in the vaginas of mice with VVC, thus reducing immune inflammatory damage to the vaginal mucosa of these mice.

CONCLUSION

This study demonstrates that BEPD has an inhibitory effect on hyphae, which are an important virulence factor of C. albicans. This effect may be related to BEPD's inhibitory effect on endoplasmic reticulum (ER) and peroxisome function. The findings suggest that BEPD could potentially play a therapeutic role in C. albicans infectious diseases by inhibiting hyphae.

Extracellular Hsp90 of Candida albicans contributes to the virulence of the pathogen by activating the NF-κB signaling pathway and inducing macrophage pyroptosis

Strategies aimed at targeting fungal extracellular heat shock protein 90 (eHsp90) using vaccines and antibodies have demonstrated encouraging potential in the prevention and management of invasive fungal diseases (IFDs). However, the precise underlying mechanism by which eHsp90 contributes to the heightened virulence of Candida albicans (C. albicans) remains an enigma, awaiting further elucidation. In our current research, we have found that the 47-kDa fragment of C. albicans Hsp90 (CaHsp90), which serves as the primary antigenic determinant, is not degraded within C. albicans cells. Moreover, we have discovered that extracellular CaHsp90 (eCaHsp90) is derived from the components of lysed C. albicans cells. We also generated recombinant CaHsp90 in Escherichia coli, and found that eCaHsp90 spreads beyond the initial C. albicans colonization site, thereby enhancing the overall virulence of the organism. Our results further clarify that eCaHsp90 activates the nuclear factor kappa-B (NF-κB) signaling pathway and upregulates the expression of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3). This upregulation results in the activation of Gasdermin D (GSDMD) and subsequent macrophage pyroptosis, ultimately increasing the virulence of C. albicans. This study provides valuable insights into the mechanism by which eCaHsp90 contributes to the virulence of C. albicans, offering a pharmacological basis for antifungal strategies targeting fungal eHsp90.

Diagnostic and Therapeutic Challenge Caused by Candida albicans and Aspergillus spp. Infections in a Pediatric Patient as a Complication of Acute Lymphoblastic Leukemia Treatment: A Case Report and Literature Review

Fungal infections constitute a significant challenge and continue to be a predominant cause of treatment failure in pediatric leukemia cases. Despite the implementation of antifungal prophylaxis, these infections contribute to approximately 20% of cases in children undergoing treatment for acute lymphoblastic leukemia (ALL). The aim of this study is to highlight the diagnostic and therapeutic challenges associated with invasive fungal infections (IFIs). We also present a review of the epidemiology, risk factors, treatment, and a clinical presentation of IFI in patients with ALL. This case report details the clinical course of confirmed Candida albicans (C. albicans) and Aspergillus spp. infections during the consolidation phase of ALL treatment in a 5-year-old pediatric patient. This male patient did not experience any complications until Day 28 of protocol II. Then, the patient's condition deteriorated. Blood culture detected the growth of C. albicans. Despite the implementation of targeted therapy, the boy's condition did not show improvement. The appearance of respiratory symptoms necessitated a computed tomography (CT) of the chest, which revealed multiple nodular densities atypical for C. albicans etiology. In spite of ongoing antifungal treatment, the lesions depicted in the CT scans showed no regression. A lung biopsy ultimately identified Aspergillus species as the source of the infection. Overcoming fungal infections poses a considerable challenge; therefore, an accurate diagnosis and the prompt initiation of targeted therapy are crucial in managing these infections in patients with leukemia.

Isobavachalcone Exhibits Potent Antifungal Efficacy by Inhibiting Enolase Activity and Glycolysis in Candida albicans

Invasive fungal diseases (IFDs) are becoming increasingly acknowledged as a significant concern linked to heightened rates of morbidity and mortality. Regrettably, the available antifungal therapies for managing IFDs are constrained. Emerging evidence indicates that enolase holds promise as a potential target protein for combating IFDs; however, there is currently a deficiency in antifungal medications specifically targeting enolase. This study establishes that isobavachalcone (IBC) exhibits noteworthy antifungal efficacy both in vitro and in vivo. Moreover, our study has demonstrated that IBC effectively targets Eno1 in Candida albicans (CaEno1), resulting in the suppression of the glycolytic pathway. Additionally, our research has indicated that IBC exhibits a higher affinity for CaEno1 compared to human Eno1 (hEno1), with the presence of isoprenoid in the side chain of IBC playing a crucial role in its ability to inhibit enolase activity. These findings contribute to the comprehension of antifungal approaches that target Eno1, identifying IBC as a potential inhibitor of Eno1 in human pathogenic fungi.

Geldanamycin confers fungicidal properties to azole by triggering the activation of succinate dehydrogenase

AIMS

Azoles have been widely employed for the treatment of invasive fungal diseases; however, their efficacy is diminished as pathogenic fungi tolerate them due to their fungistatic properties. Geldanamycin (GdA) can render azoles fungicidal by inhibiting the ATPase and molecular chaperone activities of heat shock protein 90 (Hsp90). Nonetheless, the clinical applicability of GdA is restricted due to its cytotoxic ansamycin scaffold structure, its induction of cytoprotective heat shock responses, and the conservative nature of Hsp90. Hence, it is imperative to elucidate the mechanism of action of GdA to confer fungicidal properties to azoles and mitigate the toxic adverse effects associated with GdA.

MATERIALS AND METHODS

Through various experimental methods, including the construction of gene-deleted Candida albicans mutants, in vitro drug sensitivity experiments, Western blot analysis, reactive oxygen species (ROS) assays, and succinate dehydrogenase activity assays, we identified Hsp90 client proteins associated with the tolerance of C. albicans to azoles.

KEY FINDINGS

It was observed that GdA effectively hindered the entry of Hsp90 into mitochondria, resulting in the alleviation of inhibitory effect of Hsp90 on succinate dehydrogenase. Consequently, the activation of succinate dehydrogenase led to an increased production of ROS. within the mitochondria, thereby facilitating the antifungal effects of azoles against C. albicans.

SIGNIFICANCE

This research presents a novel approach for conferring fungicidal properties to azoles, which involves specifically disrupting the interaction of between Hsp90 and succinate dehydrogenase rather than employing a non-specific inhibition of ATPase activity of Hsp90.

Marine-Derived Metabolites Act as Promising Antifungal Agents

The incidence of invasive fungal diseases (IFDs) is on the rise globally, particularly among immunocompromised patients, leading to significant morbidity and mortality. Current clinical antifungal agents, such as polyenes, azoles, and echinocandins, face increasing resistance from pathogenic fungi. Therefore, there is a pressing need for the development of novel antifungal drugs. Marine-derived secondary metabolites represent valuable resources that are characterized by varied chemical structures and pharmacological activities. While numerous compounds exhibiting promising antifungal activity have been identified, a comprehensive review elucidating their specific underlying mechanisms remains lacking. In this review, we have compiled a summary of antifungal compounds derived from marine organisms, highlighting their diverse mechanisms of action targeting various fungal cellular components, including the cell wall, cell membrane, mitochondria, chromosomes, drug efflux pumps, and several biological processes, including vesicular trafficking and the growth of hyphae and biofilms. This review is helpful for the subsequent development of antifungal drugs due to its summary of the antifungal mechanisms of secondary metabolites from marine organisms.