Epithelial responses and Candida albicans pathogenicity are enhanced in the presence of oral streptococci

Abstract Experimental models that consider host-pathogen interactions are relevant for improving knowledge about oral candidiasis. The aim of this study was to assess the epithelial immune responses, Candida penetration of cell monolayers, and virulence during mixed species culture infections. Single species cultures of Candida albicans and mixed cultures (C. albicans, Streptococcus mutans, and Streptococcus sanguinis) were used to infect monolayers of HaCaT and FaDu ATCC HTB-43 cells for 12 h. After infection, IL-18 and IL-34 gene expression was measured to assess epithelial cell immune responses, and lactate dehydrogenase (LDH) activity was measured as an indicator of cell damage. Microscopy determined C. albicans morphology and penetration of fungal cells through the keratinocyte monolayer. Monolayers devoid of infection served as controls. Data were analyzed by an ANOVA one-way test followed by Tukey's post-hoc test (α = 0.05). The results found that IL-18 and IL-34 gene expression and LDH activity were significantly (p < 0.05) upregulated for both cell lines exposed to mixed species cultures compared with C. albicans alone. Candida albicans yeast and hyphae were evident in C. albicans only infections. In contrast, monolayers infected by C. albicans, S. mutans, and S. sanguinis exhibited higher microbial invasion with several hyphal aggregates detected. The presence of streptococci in C. albicans infection enhances the virulence and pathogenicity of the fungus with associated increased immune responses and tissue damage. Extrapolation of these findings to oral infection would indicate the added potential benefit of managing bacterial components of biofilms during treatment.

Resumo O objetivo deste estudo foi avaliar a resposta epithelial imune, a colonização da Candida albicans em monocamadas celulares e sua virulência em resposta a infecções de culturas de biofilme multiespécie. Culturas de biofilme monoespécie de C. albicans e culturas mistas (C. albicans, Streptococcus mutans e Streptococcus sanguinis) foram utilizadas para infectar monocamadas de células HaCaT e FaDu por 12 h. Após a infecção, a expressão dos genes IL-18 e IL-34 foi medida para avaliar as respostas imunes das células epiteliais. A atividade da lactato desidrogenase (LDH) foi medida como um indicador de dano celular. A microscopia determinou a morfologia de C. albicans e a penetração das células fúngicas através da monocamada de queratinócitos. Monocamadas em que não houve infecção serviram como controles. Os dados foram analisados por um teste ANOVA one-way seguido pelo teste post-hoc de Tukey (α = 0,05). Os resultados demonstraram que a expressão gênica de IL-18 e IL-34 e a atividade de LDH foram (p < 0,05) reguladas positivamente para ambas as linhagens de células expostas a culturas de espécies mistas em comparação com C. albicans isoladamente. Leveduras de C.albicans e hifas foram evidentes em infecções apenas por C. albicans. Entretanto, monocamadas infectadas por C. albicans, S. mutans e S. sanguinis exibiram maior invasão microbiana com vários agregados de hifas detectados. Dessa maneira, a presença de estreptococos na infecção por C. albicans aumentou a virulência e a patogenicidade do fungo com respostas imunes aumentadas associadas a danos nos tecidos. A extrapolação desses achados para a infecção oral indicaria o potencial benéfico do controle dos componentes bacterianos em biofilmes durante a terapia da candidíase

Demystifying interactions between micro organisms in oral candidiasis biofilm: the key to enhancing treatments

Introduction: candida albicans is a fungal pathogen that can provoke diseases ranging from oral infections to life-threatening systemic disorders. It is now recognized that oral bacteria, such as the genus Streptococcus, establish synergistic relationships with C. albicans, which could potentially increase the fungi's virulence and pathogenicity. Objective: this narrative review aimed to discuss the Candida-Streptococcus mechanisms of interactions and their contribution to increasing oral candidiasis severity. In addition, it provides a background of biofilm formation and potential therapeutical targets. Sources of Data: searches for papers in English were performed in the Pubmed database until May 2022. MeSH and free terms related to the field were used. In vitro studies were selected, tabulated, and qualitative and quantitative data were analyzed descriptively. Synthesis of Data: among the early colonizers bacteria, evidence pointed out that S. gordonnii and S. oralis have major implications in oral candidiasis, in which mixed biofilms increase the infection severity and challenge the host's defense. On the other hand, the outcomes of the interaction between C. albicans and S. mitis, S. sanguinis, or S. mutans remain little explored in the oral candidiasis scenario, albeit evidence pointed out an enhanced fungus population and virulence factors. Conclusion: overall, considering the polymicrobial profile of the infection and the potential to increase Candida-related disease severity, therapeutical strategies should also consider bacteria management.

Introdução: candida albicans é um patógeno fúngico que pode provocar doenças que variam de infecções orais a distúrbios sistêmicos com risco de vida. Hoje se reconhece que as bactérias orais, como o gênero Streptococcus, estabelecem relações sinérgicas com C. albicans, o que pode potencialmente aumentar a virulência e patogenicidade do fungo. Objetivo: esta revisão narrativa teve como objetivo discutir os mecanismos de interação Candida-Streptococcus e sua contribuição para o agravamento da candidíase oral. Além disso, fornece uma breve explanação sobre a formação do biofilme e potenciais alvos terapêuticos. Fonte dos dados: foi realizada pesquisa na base de dados Pubmed para a busca de artigos publicados em Inglês até maio de 2022. Para isso, foram utilizados descritores relacionados ao tema. Estudos in vitro foram selecionados, tabulados e seus resultados quantitativos e qualitativos analisados descritivamente. Síntese dos dados: entre as bactérias denominadas colonizadores iniciais, evidências apontam que S. gordonnii e S. oralis têm implicações importantes na candidíase oral, na qual biofilmes mistos aumentam a gravidade da infecção e desafiam a defesa do hospedeiro. Por outro lado, os desfechos das interações entre C. albicans e S. mitis, S. sanguinis ou S. mutans permanecem pouco explorados no cenário da candidíase oral, apesar de evidências apontarem um aumento dapopulação fúngica e de fatores de virulência. Conclusão: de maneira geral, considerando o perfil polimicrobiano da infecção e o potencial agravamento das doenças provocadas por Candida spp, as estratégias terapêuticas não devem estar focadas apenas no fungo, mas também devem considerar o manejo da bactéria.

Oral candidiasis and denture stomatitis in diabetic patients: Systematic review and meta-analysis

Abstract Here, the prevalence of oral candidiasis and denture stomatitis among diabetic patients compared to healthy ones was summarized through a systematic review with meta-analysis. Medline, Scopus, Web of Science, Lilacs, Cochrane Library, Embase, and the grey literature were searched without restriction, until May 2020. Eligibility criteria were established, data were extracted, and quality assessment was conducted by two trained examiners. Qualitative synthesis was based on the recommendations of Fowkes and Fulton. Two meta-analyses were performed on studies investigating patients with: a) oral candidiasis and b) denture stomatitis. Out of 6034 screened studies, seven were eligible for qualitative and quantitative synthesis; of these, three evaluated oral candidiasis and four evaluated denture stomatitis. Qualitative synthesis showed that the main methodological problems of the studies included sample size, source of controls, matching, and randomization. Diabetic patients had a similar chance of developing oral candidiasis to non-diabetic patients (OR1.40 [0.96; 2.04], p = 0.08, I2 = 94%). However, diabetic patients had a higher chance to present denture stomatitis compared to non-diabetic patients (OR 1.92 [1.42, 2.59] p < 0.0001, I2 = 0%). Therefore, diabetic patients have a higher chance of developing denture stomatitis compared to non-diabetic patients. However, for all analyses, the certainty of the evidence was considered to be very low.