Purpose: Zinc oxide nanoparticles (ZnO-NPs) have exerted antimicrobial properties. However, there is insufficient evaluation regarding the in vivo antifungal activity of ZnO-NPs. This study aimed to investigate the efficacy and mechanism of ZnO-NPs in controlling Candida albicans in the invertebrate Galleria mellonella.Methods:Galleria mellonella larvae were injected with different doses of ZnO-NPs to determine their in vivo toxicity. Non-toxic doses of ZnO-NPs were chosen for prophylactic injection in G. mellonella followed by C. albicans infection. Then the direct in vitro antifungal effect of ZnO-NPs against C. albicans was evaluated. In addition, the mode of action of ZnO-NPs was assessed in larvae through different assays: quantification of hemocyte density, morphology observation of hemocytes, characterization of hemocyte aggregation and phagocytosis, and measurement of hemolymph phenoloxidase (PO) activity.Results: Zinc oxide nanoparticles were non-toxic to the larvae at relatively low concentrations (≤20 mg/kg). ZnO-NP pretreatment significantly prolonged the survival of C. albicans-infected larvae and decreased the fungal dissemination and burden in the C. albicans-infected larvae. This observation was more related to the activation of host defense rather than their fungicidal capacities. Specifically, ZnO-NP treatment increased hemocyte density, promoted hemocyte aggregation, enhanced hemocyte phagocytosis, and activated PO activity in larvae.Conclusion: Prophylactic treatment with lower concentrations of ZnO-NPs protects G. mellonella from C. albicans infection. The innate immune response primed by ZnO-NPs may be part of the reason for the protective effects. This study provides new evidence of the capacity of ZnO-NPs in enhancing host immunity and predicts that ZnO-NPs will be attractive for further anti-infection applications.

Talaromyces marneffei is a thermally dimorphic fungus endemic in south-east Asia. It predominantly occurs in both immunocompromised and immunosuppressed patients and can be fatal if diagnosis and treatment are delayed. The clinical manifestations of T. marneffei infection are nonspecific and rapid diagnosis of T. marneffei infection remains challenging. A 24-year-old man came to our outpatient department with the sign of common skin lesions. The lesions were cuticolor follicular papules with or without central umbilication, nodules and acne-like lesions, which are common in syringoma, steatocystoma multiplex and trichoepithelioma. A dermatoscopy examination was performed to differentiate these skin lesions. The dermatoscopic images revealed circular or quasi-circular whitish amorphous structure with a central brownish keratin plug, providing the diagnostic clues of T. marneffei infection. Therefore, a skin scrapings culture, skin biopsy and serological detection for human immunodeficiency virus (HIV) were performed. The final diagnosis of this patient was T. marneffei and HIV co-infection. Rapid diagnosis of T. marneffei infection is clinically challenging since presenting clinical manifestations are nonspecific with significant overlap with other common conditions. This case highlights that dermatoscopy is a promising tool for the rapid diagnosis of T. marneffei infection in patients with nonspecific skin lesions, assisting clinicians to avoid delayed diagnosis or misdiagnosis.

Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by recurrent eczematous lesions and severe pruritus. The economic burden and time penalty caused by the relapse of AD reduce patients' life quality. AD has complex pathogenesis, including genetic disorders, epidermal barrier dysfunction, abnormal immune responses, microbial dysbiosis of skin, and environmental factors. Recently, the role of innate immune cells in AD has attracted considerable attention. This review highlighted recent findings on innate immune cells in the onset and progression of AD.