Candida albicans triggers interleukin-6 and interleukin-8 responses by oral fibroblasts in vitro

Clinical significance of inflammatory markers for evaluating disease severity of mixed-pathogen bloodstream infections of both Enterococcus spp. and Candida spp

Objective

In recent decades, there has been a notable increase in the morbidity and mortality rates linked to bacteremia and candidemia. This study aimed to investigate the clinical significance of inflammatory markers in assessing the disease severity in critically ill patients suffering from mixed-bloodstream infections (BSIs) due to Enterococcus spp. and Candida spp.

Methods

In this retrospective research, patients diagnosed with BSIs who were admitted to the intensive care unit (ICU) during the period of January 2019 to December 2022 were analyzed. The patients were divided into two groups: a mixed-pathogen BSI group with both Enterococcus spp. and Candida spp., and a single-pathogen BSI group with only Enterococcus spp. The study examined the differences in inflammatory marker levels and disease severity, including Acute Physiology and Chronic Health Evaluation (APACHE) II scores, duration of ICU stay, and 30-day mortality, between the two groups. Furthermore, we sought to scrutinize the potential associations among these aforementioned parameters.

Results

The neutrophil-to-lymphocyte ratios (NLRs) and levels of plasma C-reactive protein (CRP), interleukin (IL)-6, IL-8, and tumor necrosis factor-α (TNF-α) in the mixed-pathogen BSI group were higher than those in the single-pathogen BSI group. Spearman's rank correlation analysis showed that NLRs and plasma CRP and IL-6 levels were positively correlated with disease severity in the mixed-pathogen BSI group. Further, the levels of plasma IL-8 and TNF-α were also positively correlated with ICU stay duration and 30-day mortality. In multivariate analysis, plasma CRP and IL-6 levels were independently associated with 30-day mortality.

Conclusion

Mixed-pathogen BSIs caused by Enterococcus spp. and Candida spp. may give rise to increased NLRs and plasma CRP, IL-6, IL-8, and TNF-α levels in comparison to BSI caused by Enterococcus spp. only, thus leading to elevated disease severity in critically ill patients.

Risk of candidiasis associated with interleukin-17 inhibitors: A real-world observational study of multiple independent sources

BACKGROUND

Biologics directed against the T-helper (Th)-17 pathway have been approved for several inflammatory diseases. Interleukin (IL)-17 is involved in anti- Candida host defense, and clinical trials suggested increased candidiasis incidence during IL-17 inhibitor therapy. We describe the worldwide epidemiology of candidiasis during Th17 inhibitor therapy, and immunological mechanisms involved in candidiasis susceptibility.

METHODS

A comprehensive analysis of multiple independent sources reporting Candida adverse events during biologics inhibiting the Th17 pathway was performed. Association between Th17 inhibitors and candidiasis was assessed using safety reports of (1) WHO and (2) EMA, (3) a population-based prescriptions registry, and (4) a psoriasis cohort. In a cohort of psoriasis patients experiencing candidiasis during Th17 inhibitors, Candida killing by immune cells and serum inflammatory proteome were analyzed.

FINDINGS

A strong association between IL-17 inhibitors and candidiasis (ROR 10·20) was found in the WHO database, particularly for cutaneous (ROR 12·28), oropharyngeal (ROR 19·18), and esophageal candidiasis (ROR 21·20). Risk was higher relative to TNF-α inhibitors (4-10-fold, depending on candidiasis type), confirmed by EMA reports (16-33-fold), prescriptions registry (2-42-fold), and a psoriasis cohort (3-25-fold). After start of IL-17 inhibitors, patients' risk of candidiasis requiring antifungals increased 2-16 fold. In the psoriasis cohort, 58% of IL-17 treatment episodes were associated with candidiasis. In Th17 inhibitor recipients, proteins involved in anti- Candida immunity and Candida killing by mononuclear leukocytes were impaired.

INTERPRETATION

IL-17 inhibitors are associated with an increased risk of oropharyngeal, esophageal, and cutaneous candidiasis, posing a significant disease burden for IL-17 inhibitor recipients.

FUNDING

RadboudUMC.

Effects of mechanical stress on human oral mucosa-derived cells

OBJECTIVES

Placement of a denture results in the application of mechanical stress (MS), such as occlusal force, onto the oral mucosa beneath the denture. To better understand the molecular mechanism underlying MS-induced inflammation in the oral mucosa, we examined the impact of MS on human oral epithelial cells (HO-1-N-1) and human fibroblasts (HGFs) in this study.

MATERIALS AND METHODS

MS was applied on HO-1-N-1 and HGFs using a hydrostatic pressure apparatus. The expression and production of inflammatory cytokines and growth factors were examined by real-time RT-PCR and ELISA. MS-induced intracellular signal transduction via MAP kinase (MAPK) was also examined.

RESULTS

1 MPa MS resulted in a significant increase in inflammatory cytokines, and 3 MPa MS resulted in a significant increase in FGF-2. MS also increased p-38 phosphorylation and the addition of a p-38 inhibitor significantly suppressed the production of inflammatory cytokines.

DISCUSSION

Our study suggested that MS applied through a denture increases the production of inflammatory cytokines from oral mucosal epithelial cells and fibroblasts via the p38 MAPK cascade. These responses to MS likely lead to inflammation of the mucosal tissue beneath dentures. On other hand, up-regulation of growth factors is likely a manifestation of the biological defense mechanism against excessive MS.

New insight of red seaweed derived Callophycin A as an alternative strategy to treat drug resistance vaginal candidiasis

Marine natural products are recognised as one among the major contributors of several important biological functions. The arguments has made to utilization of natural products against different kinds of infectious diseases. In the present study, Callophycin A was successfully prepared and its anti-candidal activity was evaluated through in-vitro and in-vivo methods. The in-vitro results revealed that, Callophycin A significantly inhibits the azole resistant and sensitive C. albicans. Further, in-vivo animal experiments have shown the effective reduction in CFU of C. albicans from its beginning day of the treatment as compared to the disease control group. At the end of Callophycin A administration, there was a decrease in inflammatory response and immune molecules such as IL-6, IL-12, IL-17, IL-22, TNF-α, macrophages, CD4 and CD8 cells were observed. Whereas the animals in the disease control group expressed all the parameters with the elevated level as compared to the control group. There are no hematological abnormalities such as neutropenia, lymphocytosis and eosinophilia was observed in any animal groups except the disease control group. Finally, the evidence based prediction of anti-candidal efficacious of Callophycin A was demonstrated.

Prevalence of Candida albicans in primary endodontic infections associated with a higher frequency of apical periodontitis in type two diabetes mellitus patients

To identify the prevalence of C. albicans in primary endodontic infections of type two diabetes mellitus (T2DM) patients and compare their clinical and radiographical characteristics with a non-diabetic control group, establishing the possible relationship between primary endodontic infection, T2DM, and C. albicans, since diabetes mellitus (DM), influences the development, course, and response to the treatment of apical periodontitis, but the presence of Candida albicans (C. albicans) has not been considered before. A total of 120 patients were selected and divided into two groups: 60 T2DM diagnosed patients and 60 non-diabetic controls. A clinical examination and radiographic analysis were performed to establish a periapical index score (PAI). Root canal samples were taken. Deoxyribonucleic acid (DNA) was extracted, and specific primers were used to identify C. albicans by polymerase chain reaction (PCR). A twofold increase in the prevalence of C. albicans in T2DM patients was observed in contrast to control patients (p = 0.0251). Sixty-five percent of T2DM patients with positive C. albicans scored a ≥ 3 PAI, while only 27% of the patients without C. albicans had a ≥ 3 PAI score (p = 0.0065). Long-term DM patients presented C. albicans more frequently (p < 0.0001). In this study, long-term T2DM patients carried C. albicans in their root canals more frequently when having a primary endodontic infection. Furthermore, this C. albicans presence seems to be related to a higher frequency of apical periodontitis.

Fibroblasts: The Unknown Sentinels Eliciting Immune Responses Against Microorganisms

Fibroblasts are present in all tissues but predominantly in connective tissues. Some of their functions include contractility, locomotion, collagen and elastin fiber production, and the regulation and degradation of the extracellular matrix. Also, fibroblasts act as sentinels to produce inflammatory mediators in response to several microorganisms. There is evidence that fibroblasts can synthesize toll-like receptors (TLRs), antimicrobial peptides, proinflammatory cytokines, chemokines, and growth factors, which are important molecules involved in innate immune response against microorganisms. Fibroblasts can express TLRs (TLR-1 to TLR-10) to sense microbial components or microorganisms. They can synthesize antimicrobial peptides, such as LL-37, defensins hBD-1, and hBD-2, molecules that perform antimicrobial activity. Also, they can produce proinflammatory cytokines, such as TNFα, INFγ, IL-6, IL-12p70, and IL-10; other chemokines, such as CCL1, CCL2, CCL5, CXCL1, CXCL8, CXCL10, and CX3CL1; and the growth factors granulocyte/macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) to induce and recruit inflammatory cells. According to their immunological attributes, we can conclude that fibroblasts are sentinel cells that recognize pathogens, induce the recruitment of inflammatory cells via cytokines and growth factors, and release antimicrobial peptides, complying with the characteristics of real sentinels.

The Host Cytokine Responses and Protective Immunity in Oropharyngeal Candidiasis

Over the last three decades, the prevalence of oropharyngeal fungal infections has increased enormously, mainly due to an increasing population of immunocompromised patients, including individuals with HIV infection, transplant recipients, and patients receiving cancer therapy. The vast majority of these infections are caused by Candida species. The presence of cytokines in infected tissues ultimately dictates the host defense processes that are specific to each pathogenic organism. During oral infection with Candida, a large number of pro-inflammatory and immunoregulatory cytokines are generated in the oral mucosa. The main sources of these cytokines are oral epithelial cells, which maintain a central role in the protection against fungal organisms. These cytokines may drive the chemotaxis and effector functions of innate and/or adaptive effector cells, such as infiltrating neutrophils and T-cells in immunocompetent hosts, and CD8+ T-cells in HIV+ hosts. Epithelial cells also have direct anti- Candida activity. Several studies have provided a potential link between lower levels of certain pro-inflammatory cytokines and susceptibility to oral C. albicans infection, suggesting that such cytokines may be involved in immune protection. The exact role of these cytokines in immune protection against oropharyngeal candidiasis is still incompletely understood and requires further investigation. Identification of such cytokines with the ability to enhance anti-fungal activities of immune effector cells may have therapeutic implications in the treatment of this oral infection in the severely immunocompromised host.

Reduced CX3CL1 Secretion Contributes to the Susceptibility of Oral Leukoplakia-Associated Fibroblasts to Candida albicans

Candida leukoplakia (OLK) is a kind of oral leukoplakia combined with chronic candidal infection, which plays an important role in the malignant transformation of OLK. However, little is known about the etiology, including susceptibility of leukoplakia to candidal adhesion, invasion and infection. Some antimicrobial peptides secreted by oral epithelial cells or fibroblasts potentially have antifungal activities against Candida albicans (C. albicans). In this study, we established three co-culture models to simulate different C. albicans-fibroblasts interactions during progression of candida leukoplakia. The susceptibility of oral leukoplakia-associated fibroblasts (LKAFs) to C. albicans and its underlying mechanism were determined. Samples of 14 LKAFs and 10 normal fibroblasts (NFs) were collected. The co-culture models showed that LKAFs had promoted the adhesion, invasion, and survival of C. albicans compared with NFs. CX3CL1, a chemokine with antifungal activity, was less abundant in LKAFs than NFs. Overexpression of CX3CL1 via transfection in LKAFs could partly restore the resistance to C. albicans. We also showed that inhibition of ERK could suppress CX3CL1 secretion. While phosphor-ERK was inhibited in LKAFs compared with NFs. Besides, the mRNA expression of a shedding enzyme for CX3CL1, disintegrin and metalloproteinase domain (ADAM) 17 was decreased in LKAFs than NFs. In conclusion, LKAFs produced and secreted less CX3CL1 by inhibiting the ERK signaling pathway, thereby contributing to impaired cell resistance to C. albicans.

Filament condition-specific response elements control the expression of NRG1 and UME6, key transcriptional regulators of morphology and virulence in Candida albicans

Candida albicans is the most frequently isolated human fungal pathogen and can cause a range of mucosal and systemic infections in immunocompromised individuals. Morphogenesis, the ability to undergo a reversible transition from budding yeast to elongated filaments, is an essential virulence trait. The yeast-to-filament transition is associated with expression of genes specifically important for filamentation as well as other virulence-related processes, and is controlled, in part, by the key transcriptional regulators Nrg1 and Ume6. Both of these regulators are themselves controlled at the transcriptional level by filament-inducing environmental cues, although little is known about how this process occurs. In order to address this question and determine whether environmental signals regulate transcription of UME6 and NRG1 via distinct and/or common promoter elements, we performed promoter deletion analyses. Strains bearing promoter deletion constructs were induced to form filaments in YEPD plus 10% serum at 37°C, Spider medium (nitrogen and carbon starvation) and/or Lee’s medium pH 6.8 (neutral pH) and reporter gene expression was measured. In the NRG1 promoter we identified several distinct condition-specific response elements for YEPD plus 10% serum at 37°C and Spider medium. In the UME6 promoter we also identified response elements for YEPD plus 10% serum at 37°C. While a few of these elements are distinct, others overlap with those which respond to Lee’s pH 6.8 medium. Consistent with UME6 possessing a very long 5’ UTR, many response elements in the UME6 promoter are located significantly upstream from the coding sequence. Our data indicate that certain distinct condition-specific elements can control expression of C. albicans UME6 and NRG1 in response to key filament-inducing environmental cues. Because C. albicans encounters a variety of host microenvironments during infection, our results suggest that UME6 and NRG1 expression can be differentially modulated by multiple signaling pathways to control filamentation and virulence in vivo.

Comparative evolution of morphological regulatory functions in Candida species

Morphological transitions play an important role in virulence and virulence-related processes in a wide variety of pathogenic fungi, including the most commonly isolated human fungal pathogen Candida albicans. While environmental signals, transcriptional regulators, and target genes associated with C. albicans morphogenesis are well-characterized, considerably little is known about morphological regulatory mechanisms and the extent to which they are evolutionarily conserved in less pathogenic and less filamentous non-albicans Candida species (NACS). We have identified specific optimal filament-inducing conditions for three NACS (C. tropicalis, C. parapsilosis, and C. guilliermondii), which are very limited, suggesting that these species may be adapted for niche-specific filamentation in the host. Only a subset of evolutionarily conserved C. albicans filament-specific target genes were induced upon filamentation in C. tropicalis, C. parapsilosis, and C. guilliermondii. One of the genes showing conserved expression was UME6, a key filament-specific regulator of C. albicans hyphal development. Constitutive high-level expression of UME6 was sufficient to drive increased filamentation as well as biofilm formation and partly restore conserved filament-specific gene expression in both C. tropicalis and C. parapsilosis, suggesting that evolutionary differences in filamentation ability among pathogenic Candida species may be partially attributed to alterations in the expression level of a conserved filamentous growth machinery. In contrast to UME6, NRG1, an important repressor of C. albicans filamentation, showed only a partly conserved role in controlling NACS filamentation. Overall, our results suggest that C. albicans morphological regulatory functions are partially conserved in NACS and have evolved to respond to more specific sets of host environmental cues.

A genome-wide transcriptional analysis of morphology determination in Candida albicans

Candida albicans, the most common cause of human fungal infections, undergoes a reversible morphological transition from yeast to pseudohyphal and hyphal filaments, which is required for virulence. For many years, the relationship among global gene expression patterns associated with determination of specific C. albicans morphologies has remained obscure. Using a strain that can be genetically manipulated to sequentially transition from yeast to pseudohyphae to hyphae in the absence of complex environmental cues and upstream signaling pathways, we demonstrate by whole-genome transcriptional profiling that genes associated with pseudohyphae represent a subset of those associated with hyphae and are generally expressed at lower levels. Our results also strongly suggest that in addition to dosage, extended duration of filament-specific gene expression is sufficient to drive the C. albicans yeast-pseudohyphal-hyphal transition. Finally, we describe the first transcriptional profile of the C. albicans reverse hyphal-pseudohyphal-yeast transition and demonstrate that this transition involves not only down-regulation of known hyphal-specific, genes but also differential expression of additional genes that have not previously been associated with the forward transition, including many involved in protein synthesis. These findings provide new insight into genome-wide expression patterns important for determining fungal morphology and suggest that in addition to similarities, there are also fundamental differences in global gene expression as pathogenic filamentous fungi undergo forward and reverse morphological transitions.

Expression of UME6, a key regulator of Candida albicans hyphal development, enhances biofilm formation via Hgc1- and Sun41-dependent mechanisms

Biofilm formation is associated with the ability of Candida albicans, the major human fungal pathogen, to resist antifungal therapies and grow on tissues, catheters, and medical devices. In order to better understand the relationship between C. albicans morphology and biofilm formation, we examined biofilms generated in response to expression of UME6, a key filament-specific transcriptional regulator. As UME6 levels rise, C. albicans cells are known to transition from yeast to hyphae, and we also observed a corresponding increase in the level of biofilm formation in vitro. In addition to forming a biofilm, we observed that a C. albicans strain expressing constitutive high levels of UME6 promoted tissue invasion in a reconstituted human three-dimensional model of oropharyngeal candidiasis. Confocal microscopy indicated that both the top and bottom layers of the biofilm generated upon high-level constitutive UME6 expression consist primarily of hyphal cells. UME6-driven biofilm formation was reduced upon deletion of Hgc1, a cyclin-related protein important for hyphal development, as well as Sun41, a putative cell wall glycosidase. Constitutive high-level UME6 expression was also able to completely bypass both the filamentation and biofilm defects of a strain deleted for Efg1, a key transcriptional regulator of these processes. Finally, we show that both Sun41 and Efg1 affect the ability of UME6 to induce certain filament-specific transcripts. Overall, these findings indicate a strong correlation between increased C. albicans hyphal growth and enhanced biofilm formation and also suggest functional relationships between UME6 and other regulators of biofilm development.

Experimental superficial candidiasis on tissue models

Candida species are common pathogens causing superficial mycoses primarily affecting the mucosa and the skin in humans. Crucial steps during pathogenesis of superficial candidiasis comprise fungal adhesion, colonisation and subsequent penetration of the respective tissues. Exploring these pathological events and perhaps fungal and tissue responses towards drug treatment is imperative in the management of this infection. Unfortunately, pathological biopsies of superficial candidiasis do not exhibit the early changes in the host-pathogen interaction as the tissues are already invaded by the fungi. In vivo experimental assessments of pathological processes of superficial candidiasis are also limited because of the difficulties in providing reproducible and comparable conditions in the host environment. Conversely, in vitro models have helped studying fungal-host interactions under more defined and controlled conditions. Some common in vitro models used to simulate superficial candidiasis are chick chorioallantoic membrane, mucosal explants and single layer or multiple layer cell cultures. Interestingly, these experimental approaches share advantages as well as disadvantages when compared with in vivo conditions. Hence, this review intends to discuss about the experimental superficial candidiasis produced in various tissue models and their advantages as well as disadvantages with a particular reference to further improvement of validity and reliability of such experiments.

Development of a highly reproducible three-dimensional organotypic model of the oral mucosa

In this report we describe the development of a standardized three-dimensional (3D) system of the human oral mucosa based on an immortalized human oral keratinocyte cell line (OKF6/TERT-2). The procedure takes approximately 2-3 weeks to complete and includes three main stages: preparation of collagen-embedded fibroblasts, addition of the mucosal component and airlifting of cultures to ensure adequate differentiation/stratification. This procedure results in a multilayer epithelial structure in which layers are organized similarly to the cells in native oral mucosa. Specifically, this model system consists of a stratum basale, having one layer of columnar to round cells, a relatively flattened stratum spinosum and stratum granulosum, and a non-keratinizing stratum corneum. This 3D system resembles the commercially available system based on the cell line TR146 (SkinEthic), with the exception that our model system does not contain dyskeratotic changes and has a submucosal component, and thus better represents the normal human mucosa and submucosa.

Development of a novel three-dimensional in vitro model of oral Candida infection

Oropharyngeal candidiasis is emerging as a serious health problem in the elderly as well as other chronically immunosuppressed patient populations. Several approaches have been used to study the interactions between Candida and the oral mucosa in vitro. Recently, three-dimensional organotypic systems of the oral mucosa have been developed, which provide an organizational complexity that is between the culture of single cell types and organ cultures in vivo. In this report we describe the development of a novel three-dimensional system of the human oral mucosa based on an immortalized oral keratinocyte cell line. Unlike the commercially available cell line systems, this system also contains a connective tissue cell component, which ensures the quality and resemblance of the tissue model to the human oral masticatory mucosa and submucosa. Using a panel of Candida albicans strains with variable virulence in vivo, we showed that the extent of tissue damage, fungal invasion and host inflammatory response in this system was proportional to the well-documented in vivo virulence potential of these strains. Therefore, this investigation has added another useful tool in the study of host pathogen interactions in oral candidiasis.

Bioactive interleukin-1alpha is cytolytically released from Candida albicans-infected oral epithelial cells

Oral epithelial cells are primary targets of Candida albicans in the oropharynx and may regulate the inflammatory host response to this pathogen. This investigation studied the mechanisms underlying interleukin-1alpha (IL-1alpha) release by oral epithelial cells and the role of IL-1alpha in regulating the mucosal inflammatory response to C. albicans. Infected oral epithelial cells released processed IL-1alpha protein in culture supernatants. The IL-1alpha generated was stored intracellularly and was released upon cell lysis. This was further supported by the fact that different C. albicans strains induced variable IL-1alpha release, depending on their cytolytic activity. IL-1alpha from C. albicans-infected oral epithelial cells upregulated proinflammatory cytokine secretion (IL-8 and GM-CSF) in uninfected oral epithelial or stromal cells. Our studies suggest that production of IL-1alpha, IL-8 and GM-CSF may take place in the oral mucosa in response to lytic infection of epithelial cells with C. albicans. This process can act as an early innate immune surveillance system and may contribute to the clinicopathologic signs of infection in the oral mucosa.

Deletion of the SSK1 response regulator gene in Candida albicans contributes to enhanced killing by human polymorphonuclear neutrophils

The isolation and partial functional characterization of the two-component response regulator SSK1 gene of Candida albicans was previously reported. Compared to wild-type (CAF2-1) and gene-reconstituted (SSK23) strains, the ssk1 null strain (SSK21) was avirulent in a murine model of hematogenously disseminated candidiasis and less able to adhere to human esophageal cells. More recent data indicate that SSK21 is sensitive to 4 to 8 mM H(2)O(2) in vitro than CAF2-1 and SSK23. Furthermore, microarray studies indicate that the regulation of two classes of genes, those encoding cell wall functions and stress adaptation, are altered in the ssk1 mutant. In the present study, the susceptibility of strains CAF2-1, SSK21, and SSK23 to killing by human polymorphonuclear neutrophils (PMNs) was assessed. Results are also described for a newly constructed ssk1 mutant (SSK24) in which the URA3 gene is integrated into its native locus. Our results indicate that killing of SSK21 and SSK24 was significantly greater than that of CAF2-1 and SSK23 (P < 0.01). In order to determine why Ssk1p at least partially protects the organism against the killing activity of human PMNs, we compared the signal transduction activity and the inflammatory response gene profiles of PMNs infected with either the wild type or the ssk1 mutant. Phosphorylation of the mitogen-activated protein kinases p42/44 and p38 from neutrophils infected with either CAF2-1 (wild type) or SSK21 (ssk1/ssk1) was similar, while expression and phosphorylation of the JNK mitogen-activated protein kinase was not observed following infection with either strain. On the other hand, we observed an upregulation of seven inflammatory response genes in PMNs infected with the SSK21 mutant only, while an increase in interleukin-10 expression was measured in PMNs infected with either strain. Downregulation of interleukin-2 was observed in PMNs infected with either strain. Verification of the transcriptional profiling was obtained by reverse transcription-PCR for three of the genes that were upregulated in neutrophils infected with the ssk1 mutant. Also, the sensitivity of strain SSK21 to human defensin-1, one of the nonoxidative, antimicrobial peptides of PMNs, was greater than that of CAF2-1, demonstrating that nonoxidative killing in PMNs may contribute to the increased susceptibility of the ssk1 mutant. Our results indicate that the Ssk1p response regulator protein may provide at least partial adaptive functions for the survival of C. albicans following its encounter with human neutrophils.

Oral opportunistic infections in HIV-positive individuals: review and role of mucosal immunity

Oral opportunistic infections in the HIV-positive individual have been documented since the first reports of the epidemic, with many lesions associated with reduced CD4(+) T lymphocyte cell count. The most common oral lesions seen in HIV disease prior to the advent of highly active antiretroviral therapy (HAART) were oropharyngeal candidiasis and oral hairy leukoplakia. However, since the advent of HAART while many oral lesions have decreased significantly the incidence of oral warts has surprisingly increased. Despite the correlation of diminished CD4(+) T lymphocyte count to the occurrence of these lesions, it is rare for the lesions to occur concurrently suggesting that each pathologic lesion type is associated with distinct host immune dysfunctions. To date, the oral opportunistic infection most frequently investigated is oropharyngeal candidiasis, where data suggests that both systemic and local immunity is important for protection against infection. In contrast, recent investigations into the host responses associated with oral hairy leukoplakia and oral warts show little to no evidence of systemic or mucosal immune responsiveness despite the presumed competence of several types of leukocytes other than CD4(+) T cells. Together these data are suggesting that susceptibility to oropharyngeal candidasis in HIV-positive persons is predominantly immune-based, whereas protection or susceptibility to oral hairy leukoplakia and oral warts may be more associated with factors other than mucosal immune function.

Candida albicans-induced inflammatory response in human keratinocytes. Candida albicans-induzierte Entzundungsantwort humaner Keratinozyten

Candida albicans strains 3153a, ATCC 48867, CBS 2730, DSM 70014, and Vir 13 were cultivated and sterile C. albicans filtrates were produced. The interaction of soluble Candida factors of these infiltrates with human HaCaT keratinocytes was assayed in vitro. The following parameters were analyzed: cell proliferation, protein synthesis, nuclear matrix protein (NMP) 41 release, cytokine release (IL-1beta, soluble IL-2 receptor, IL-6, and IL-8), and reactive oxygen species (ROS). Cell counts at 1, 12, and 24 h were significantly lower for C. albicans strains CBS 2730 and VIR 13 (P < 0.05). There was no significant change for the remaining strains. Neither the protein synthesis nor the NMP-41 release was significantly affected. IL-6 and IL-8 were stimulated by C. albicans filtrates to different amounts with higher levels in strains of low virulence. There was no effect on the other cytokines. The production of ROS by HaCaT keratinocytes was suppressed. The induction of an inflammatory keratinocyte response by soluble C. albicans factors may play a role among the host-yeast interactions.

Granulocyte-macrophage colony-stimulating factor responses of oral epithelial cells to Candida albicans

Candida albicans is the principal fungal species responsible for oropharyngeal candidiasis, the most frequent opportunistic infection associated with immune deficiencies. Cytokines, such as granulocyte-macrophage colony-stimulating factor (GM-CSF), are important in the generation of effective immunity to C. albicans. The purposes of this investigation were to determine whether C. albicans triggers secretion of GM-CSF by oral epithelial cells in vitro and to investigate mechanisms of host cell-fungal interactions that trigger such responses. Oral epithelial cell lines as well as primary oral mucosal epithelial cells were challenged with stationary phase viable C. albicans, added to human cell cultures at varying yeast:oral cell ratios. Yeast were allowed to germinate for up to 48 h and supernatants were analyzed for GM-CSF by ELISA. Fixed organisms, germination-deficient mutants and separation of yeast from epithelial cells using cell culture inserts were used to assess the effects of viability, germination and physical contact, respectively, on the GM-CSF responses of these cells. Two out of three cell lines and three out of six primary cultures responded to C. albicans with an increase in GM-CSF secretion. GM-CSF responses were contact-dependent, strain-dependent, required yeast viability and were optimal when the yeast germinated into hyphae.

Candida albicans triggers interleukin-8 secretion by oral epithelial cells

Oropharyngeal candidiasis is a frequent opportunistic infection associated with immunocompromised hosts. Candida albicans is the principal species responsible for this infection. Production of interleukin-8 (IL-8), by oral epithelial cells can be expected to play a major role in the recruitment and activation of professional phagocytes at the infected site. The purpose of this study was to determine whether C. albicans triggers secretion of IL-8 by oral epithelial cells in vitro and investigate mechanisms of host cell-fungal interactions that trigger such responses. Oral epithelial cell lines (SCC4, SCC15, and OKF6/TERT-2) as well as primary gingival epithelial cells were used. Epithelial cells were cocultured with C. albicans, strains SC5314, ATCC28366 or ATCC32077, for 24-48 hr, and supernatants were analyzed for IL-8 content by ELISA. A germination-deficient mutant (efg1/efg1 cph1/cph1), otherwise isogenic to strain SC5314, was used to assess the requirement for germination in triggering IL-8 responses. In order to ascertain whether direct contact of yeast with host cells is required to trigger cytokine production, epithelial cells were separated from yeast using cell culture inserts. To test whether IL-8 secretion is dependent on IL-1alpha activity, epithelial cells were challenged with viable C. albicans in the presence or absence of neutralizing anti-IL-1alpha antibody or IL-1ra, and IL-8 secretion was measured in the supernatants. All cell lines and primary cultures responded to C. albicans with an increase in IL-8 secretion. IL-8 responses were contact-dependent, strain-specific, required yeast viability and germination into hyphae, and were in part autoregulated by IL-1alpha.

Immunomodulatory and protective effects of moxifloxacin against Candida albicans-induced bronchopneumonia in mice injected with cyclophosphamide

In a previous study, moxifloxacin was shown to ameliorate immunosuppression and enhance cytokine production in several tissues, including the lungs of cyclophosphamide-injected mice. We examined here the effects of moxifloxacin on Candida albicans lung infection in cyclophosphamide-injected mice. Mice were injected on day 0 with 250 mg of cyclophosphamide/kg, and on days 1 to 4 they were given moxifloxacin at 22.5 mg/kg/day compared to controls given ceftazidime at 75 mg/kg/day or saline. On day 6, C. albicans (10 7 CFU/mouse) was inoculated intratracheally, and animals were observed for the development of bronchopneumonia, weight loss, mortality, the presence of C. albicans, and lung cytokine production. Histopathology on day 10 postinoculation revealed bronchopneumonia in 50, 67, and 0% of saline-, ceftazidime-, and moxifloxacin-treated mice, respectively (P < 0.05). The mortality rates were 28, 17, and 5%, respectively (P < 0.05), and weight loss occurred at 20, 32, and 0%, respectively (P < 0.05). By day 15, C. albicans was eliminated from all moxifloxacin-treated mice but was still isolated from lung homogenates of 50 to 60% of the saline- and ceftazidime-treated groups. Among the cytokines tested on days 0 to 15, we found an increased production of tumor necrosis factor alpha, KC (functional interleukin-8), and gamma interferon in the lungs of ceftazidime- and saline-treated controls compared to the moxifloxacin pretreatment that abolished their secretion. In conclusion, moxifloxacin protected cyclophosphamide-injected mice from C. albicans-induced lung infection and significantly reduced pneumonia, weight loss, and mortality despite the lack of direct antifungal activity. This is most likely due to an immunomodulating activity conferred by moxifloxacin, as shown in this model and in our previous studies. Its potential protective role should be studied in patients undergoing chemotherapy and immune suppression.

Cytokine and chemokine production by human oral and vaginal epithelial cells in response to Candida albicans

Oropharyngeal and vaginal candidiases are the most common forms of mucosal fungal infections and are primarily caused by Candida albicans, a dimorphic fungal commensal organism of the gastrointestinal and lower female reproductive tracts. Clinical and experimental observations suggest that local immunity is important in host defense against candidiasis. Accordingly, cytokines and chemokines are present at the oral and vaginal mucosa during C. albicans infections. Since mucosal epithelial cells produce a variety of cytokines and chemokines in response to microorganisms and since C. albicans is closely associated with mucosal epithelial cells as a commensal, we sought to identify cytokines and/or chemokines produced by primary oral and vaginal epithelial cells and cell lines in response to C. albicans. The results showed that proinflammatory cytokines were produced by oral and/or vaginal epithelial cells at various levels constitutively with considerable interleukin-1alpha (IL-1alpha) and tumor necrosis factor alpha, but not IL-6, produced in response to C. albicans. In contrast, Th1-type (IL-12 and gamma interferon) and Th2-type-immunoregulatory (IL-10 and transforming growth factor beta) cytokines and the chemokines monocyte chemoattractant protein 1 and IL-8 were produced in low to undetectable concentrations with little additional production in response to C. albicans. Taken together, these results indicate that cytokines and chemokines are variably produced by oral and vaginal epithelial cells constitutively, as well as in response to C. albicans, and are predominated by proinflammatory cytokines.