Atypical cutaneous manifestation of HSV-2 with Candida albicans co-infection in a patient with HIV-1

Candida albicans as a Trailblazer for Herpes Simplex Virus-2 Infection Against an In Vitro Reconstituted Human Vaginal Epithelium

Little is known about the complex events driving host-pathogen and pathogen-pathogen interplay in polymicrobial infections. Using an in vitro model of a reconstituted vaginal epithelium (RVE) employing the A-431 cell line supplemented with synthetic vaginal fluid (SVF), we studied the consequences of single versus dual infections with Candida albicans and/or Herpes Simplex Virus-2 (HSV-2). Our data show (a) a relevant, SVF-enhanced expression of the differentiation marker cytokeratin 5/6 in the RVE; (b) the ability of Candida albicans to enhance HSV-2 in the dual infection model, with the virus titer almost doubling in the presence of SVF; (c) RVE damage (>20%), mostly attributable to Candida albicans and related to oxidative stress whether SVF is present; (d) the dysregulation of mucin-1, the production of which is enhanced (from 13 to 21 ng/mL) or impaired (from 21 to 10 ng/mL) in response to either SVF or infection, respectively; and (e) a partial-to-negligible cytokine response from the RVE, depending upon SVF presence. In conclusion, using an in vitro RVE model upgraded through the addition of synthetic vaginal fluid, we provide details on epithelial cell-pathogen-pathogen interaction, contributing to a better comprehension of the pathogenesis of polymicrobial infections at a mucosal level.

High calcium, ATP, and poly(I:C) augment the immune response to β-glucan in normal human epidermal keratinocytes

β-Glucans are pathogen-associated molecular patterns of fungi such as Candida albicans. Here, we studied their effects on normal human epidermal keratinocytes (NHEKs) from neonatal foreskin, and with high calcium to induce keratinocyte differentiation, danger signals, and pathogen-associated compounds such as adenosine 5'-triphosphate (ATP), poly(I:C), and lipopolysaccharide (LPS). β-Glucan stimulation significantly increased IL-8, IL-6, and IL-1α production by NHEKs. Well-differentiated NHEKs produced elevated IL-8 levels, whereas ATP, a danger signal, significantly increased IL-8 and IL-6 production, and the pathogen-associated compound, poly(I:C), augmented IL-1α production by β-glucan-stimulated NHEKs. No response to LPS from Escherichia coli was seen. Dectin-1 is known as the major receptor for β-glucans on phagocytes and dendritic cells. Dectin-1 mRNA was detected in NHEKs by reverse transcription-PCR. Flow-cytometric analyses confirmed the NHEK cell surface expression of dectin-1. Immunoblotting showed that β-glucan induced dual phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) (extracellular signal-regulated kinase (ERK)1/2), and p38 MAPK in NHEKs; these signaling pathways are known to be associated with dectin-1. Treatment with the ERK inhibitor PD98059 and with the p38 kinase inhibitor SB203580 effectively suppressed β-glucan-induced IL-8 production by NHEKs. Thus, high calcium, ATP, and poly(I:C) augment the cytokine and chemokine production by β-glucan-stimulated NHEKs. Dectin-1 is present on NHEKs and may have an important role in cell response to β-glucan.