Synchronous kinetics of CD4+ lymphocytes and viral load before the onset of oral candidosis and hairy leukoplakia in a cohort of Mexican HIV-infected patients

An observational, prospective, longitudinal cohort study was performed at the AIDS Clinic of a tertiary care institution in Mexico City to determine the association of viral load (VL) and CD4+ lymphocyte kinetics with the development of oral candidosis (OC) and hairy leukoplakia (HL). Participants were HIV-infected adult subjects, without a history of or current OC or HL, not receiving HAART. Oral examinations were performed at baseline and every month for evidence of OC or HL; CD4+ and VL determinations were done at baseline, at 6-month intervals, when oral lesions were detected, and 2 months later. Affected subjects (OL group) by OC or HL had clinical intervals defined before (antecedent), during (concurrent), and after their development. In the nonaffected individuals (NA group), 6-month intervals were determined. Differences (changes) along the clinical and study intervals were calculated for CD4+ and VL. The median study time was 178 (range: 31-924) days; 99 patients were included. The 2-year cumulative incidence of either oral lesion was 54% (49.5% for OC and 33.2% for HL). In the OL group (31 patients) a progressive and continuous decrease of CD4+ was found in the antecedent interval followed by a significant increase in VL in the concurrent period. The NA group showed a significant fall in CD4+ by semester 3, without a significant rise of VL in the following semester. The effect of CD4+ remained significant in a multivariate analysis. This study has shown that the onset of OC and/or HL is heralded by the sequence of a sustained reduction of CD4+, followed by a sharp increase of VL. In the multivariate analysis, the decrease in CD4+ lymphocytes appeared to be the predominant factor predicting the appearance of these oral lesions. Their potential use as markers of a recent change in the immunologic and virologic status of HIV-infected individuals is emphasized.

Enhanced clearance of Candida albicans from the oral cavities of mice following oral administration of Lactobacillus acidophilus

Orally administered live Lactobacillus acidophilus was assessed for its capacity to enhance clearance from the oral cavity of DBA/2 mice shown previously to be 'infection prone'. L. acidophilus fed to DBA/2 mice significantly shortened the duration of colonization of the oral cavity compared to controls. Enhanced clearance of Candida albicans correlated with both early mRNA gene expression for interleukin (IL)-4 and interferon (IFN)-gamma and expression of their secreted products in cultures of cervical lymph nodes stimulated with Candida antigen. In addition rapid clearance correlated with higher levels of IFN-gamma and nitric oxide in saliva. Delayed clearance, less pronounced levels of the cytokine response, saliva IFN-gamma and nitric oxide, and later mRNA expression for IL-4 and IFN-gamma relative to feeding with the L. acidophilus isolate were noted in mice fed a different Lactobacillus isolate (L. fermentum). These observations indicate significant variations in individual isolates to activate the common mucosal system.

Relationship between Candida infection and immune cellular response in inflammatory hyperplasia

OBJECTIVES

To analyze and quantify the CD8(+) and CD4(+) T-lymphocyte populations in inflammatory hyperplasia and to establish the relationship between the frequency and location of these cells and Candida infection.

METHODS

Samples of inflammatory hyperplasia were stained with PAS for evidence of Candida sp. and were classified in two groups, infected and control, according to the presence or absence of infection. After immunoreaction with specific anti-CD4 and anti-CD8 monoclonal antibodies, the distribution and frequency of the positive cells were analyzed in 41 cases (19 controls without Candida sp. and 22 infected cases). Lymphocytes were quantified in the three consecutive fields where the inflammatory infiltration was concentrated.

RESULTS

There was no relationship between the frequency and location of CD4(+) T cells and Candida sp. infection. The number of CD8(+) cells close to the fungi hyphae as well as the total number of CD8(+) T cells present in inflammatory hyperplasia were higher in the Candida sp. group than in the control noninfected group (P < 0.05).

CONCLUSION

Since the CD8(+) T cells were distributed according to the location of Candida sp. hyphae, and since a higher CD8(+)/total lymphocytes ratio was observed in the infected group, we suggest a role for CD8(+) T cells in the defense against Candida in oral infections associated with inflammatory hyperplasia in immunocompetent individuals.

Oro-facial lesions and CD4 counts associated with HIV/AIDS in an adult population in Oyo State, Nigeria

OBJECTIVE

The objective of this study was to define the oro-facial lesions associated with Human Immunodeficiency Virus (HIV)/Acquired Immune Deficiency Syndrome (AIDS) in an adult population in Oyo state, Nigeria and to relate these with the level of immune suppression as measured by the CD4 counts.

MATERIALS AND METHOD

The study population consisted of 679 consecutive subjects who were seen at the state-owned blood bank. Information on demography, medical and medication histories were obtained. Oro-facial examinations were carried out according to Greenspan et al [Oral Surg Oral Med Oral Pathol (1992)73:142-144]. HIV sero-prevalence status was determined for all patients. CD4+ T-lymphocyte count was carried out for those sero-positive for HIV and 31 randomly selected HIV-negative subjects. Data were analyzed using the chi-square test, Fisher's exact test, Student's t-test and odds ratio where appropriate.

RESULTS

Eighty-one (11.9%) of the entire study sample were confirmed HIV positive. The prevalence of specific oral lesions by HIV sero-status revealed that pseudomembranous oral candidiasis and angular cheilitis occurred significantly and more frequently in HIV-positive subjects (33.3 and 21% respectively) than those who were HIV negative (4.3 and 1.8% respectively, P < 0.05). The mean CD4 count of the HIV-positive subjects was 452 cells mm(-3), s.d. 137, while it was 602 cells mm(-3), s.d. 251, for the HIV negatives. The difference was statistically significant (P = 0.000). Forty-four (66.7%) subjects with CD4 counts <500 cells mm(-3) had oro-facial lesions whereas among those with CD4 counts >500 cells mm(-3) only 22 (33.3%) had oro-facial lesions (OR = 4.57).

CONCLUSION

The type of oro-facial lesions most commonly associated with HIV/AIDS in Oyo state, Nigeria, has been shown to be pseudomembranous oral candidiasis. This was followed by angular cheilitis. These lesions, although found in HIV-negative subjects, were in a lower proportion as compared with HIV-positive subjects. Mean CD4 counts were lower in HIV-positive subjects and this was associated with greater prevalence of oro-facial candidiasis and angular cheilitis.

Oral candidosis as a clinical marker of immune failure in patients with HIV/AIDS on HAART

Oral candidosis (OC) has been proposed as a clinical marker of highly active antiretroviral therapy (HAART) success or failure. The principal objective of this work was to assess whether the presence OC is associated with immunologic or virologic failure in patients with HIV/AIDS undergoing HAART. One hundred fifty-one patients with HIV/AIDS from Regional Hospital "Carlos Haya," Malaga, Spain, were examined orally. All patients had been undergoing HAART for a minimum of 6 months prior to oral examination. OC diagnosis was in accordance with World Health Organization-Centers for Disease Control (WHO-CDC) criteria. Age, gender, route of HIV infection, CD4 lymphocyte counts, and viral load were taken from the medical records. In regard to HAART response the patients were classified as: virologic- responders (viral load < 50 copies per milliliter), virologic nonresponders (viral load >50 copies per milliliter); immunologic responders (CD4 cells counts > 500 per milliliter), and immunologic nonresponders (CD4 cells counts < 500 per milliliter). Prevalence of OC was determined for each group. The presence of OC was closely related to immune failure (p 0.006; odds ratio [OR] 3.38 95% confidence interval [CI] 1.262-12.046) in patients with HIV/AIDS undergoing HAART. The probability of immune failure in the presence of OC was 91% for men who have sex with men, 95.5% for heterosexuals, and 96% for intravenous drug users. In conclusion, OC should be considered a clinical marker of immune failure in patients with HIV/AIDS undergoing HAART.

Candida Adherence and Biofilm Formation on Oral Surfaces

Candida albicans is the most common fungal opportunistic pathogen in humans. The AIDS epidemic, improved life-sustaining therapy, and aggressive anticancer therapy have contributed to a rise in the number of severely immunocompromised patients. This has led to an increase in oral and systemic fungal infection. Several factors, such as adherence, persistence, dimorphism, germ tube formation, and/or contact sensing, phenotypic switching, interference with the host defense system, synergism with bacteria, and the production of hydrolases or other metabolites, have been proposed to be virulence factors of this fungus. Among these virulence factors, adherence and persistence are thought to be the most important, since the colonization and subsequent biofilm formation of oral surfaces may serve as a reservoir for disseminated infections, such as aspiration pneumonia and gastrointestinal infection. In the review, we summarized the factors involved in the Candida albicans biofilm formation.

Dermatoses em pacientes infectados pelo HIV com a contagem de linfócitos CD4

OBJETIVO: Correlacionar a prevalência das doenças dermatológicas entre pacientes infectados pelo HIV com a contagem de linfócitos CD4. MÉTODOS: Estudo de série de casos realizado na região de Caxias do Sul, Estado do Rio Grande do Sul. Os dados foram coletados por meio da revisão de prontuários de pacientes com infecção pelo HIV internados em hospital público (198 pacientes, período de março de 1998 a junho de 2002) ou atendidos no ambulatório central universitário (40 pacientes, período de março a junho de 2002). As variáveis analisadas foram: idade, sexo, contagem de linfócitos CD4, carga viral e doenças dermatológicas apresentadas pelo paciente. Os testes estatísticos utilizados foram o Teste t de Student, o de Spearman e o do qui-quadrado. RESULTADOS: A freqüência de doença dermatológica foi de 67,2% entre os pacientes hospitalizados e de 75,0% entre os pacientes ambulatoriais. Candidíase oral foi a doença dermatológica mais prevalente. Na população hospitalar, a média de células CD4 foi menor entre os pacientes com doença dermatológica dos sem doença dermatológica (142,34 células/mm³ vs 512,35 células/mm³, respectivamente; p=0,018). O mesmo fenômeno foi observado na população ambulatorial (138,88 células/mm³ e 336,21 células/mm³, respectivamente; p=0,001). Verificou-se, em ambas as populações, uma correlação negativa entre a contagem de CD4 e o número total de doenças dermatológicas apresentadas pelo paciente (p=0,000, população hospitalar; p=0,000, população ambulatorial). CONCLUSÕES: As doenças dermatológicas são altamente prevalentes entre os pacientes infectados pelo HIV, sendo que a freqüência e o número dessas manifestações correlacionam-se bem com o status imunológico do paciente e com a progressão da doença.

Innate versus adaptive immunity in Candida albicans infection

Candida albicans is a common opportunistic pathogen, causing both superficial and systemic infection. Clinical observations indicate that mucocutaneous infections are commonly associated with defective cell-mediated immune responses, whereas systemic infection is more frequently seen in patients with deficiencies in neutrophil number or function. Analysis of mechanisms of host resistance against gastrointestinal and oral infection in mouse models has demonstrated an absolute dependence on CD4(+) T cells, although clearance also involves phagocytic cells. Both IL-12 and TNF-alpha appear to be important mediators, but mouse strain-dependent variations in susceptibility to infection may be related to T-cell enhancement of production of phagocytic cells by the bone marrow. In murine systemic infection, the role of innate and adaptive responses is less well defined. Studies in immunodeficient and T-cell-depleted mice suggest that clearance of the yeast may be predominantly a function of the innate response, whereas the adaptive response may either limit tissue damage or have the potential to cause immunopathology, depending on the host genetic context in which the infection takes place.

Immunopathogenesis of oropharyngeal candidiasis in human immunodeficiency virus infection

Oropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4(+) cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8(+) T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal.

Polymorphonuclear leukocytes (PMNs) induce protective Th1-type cytokine epithelial responses in an in vitro model of oral candidosis

The immune response and the anticandidal activity of keratinocytes and polymorphonuclear leukocytes (PMNs) play a key role in host defence against localized Candida albicans infection. An established model of oral candidosis based on reconstituted human oral epithelium (RHE) was supplemented with PMNs to study the effect of these immune cells during experimental oral candidosis. Infection of RHE with C. albicans induced a strong expression of the chemokine interleukin-8 (IL-8) and the cytokine granulocyte-macrophages colony-stimulating factor (GM-CSF), and a moderate stimulation of interleukin-1α (IL-1α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interferon γ (IFN-γ) and tumour necrosis factor α (TNF-α) by keratinocytes. This immune response was associated with chemoattraction of PMNs to the site of infection, whereas uninfected RHE failed to induce cytokine expression or to attract PMNs. Growth of the pathogen and tissue damage of C. albicans-infected RHE were significantly reduced when PMNs were applied to the apical epithelial surface or when PMNs migrated through a perforated basal polycarbonate filter of the model. Notably, protection against epithelial tissue damage was also observed when PMNs were placed on the basal side of non-perforated filters, which prevented PMN migration into the RHE. Addition of PMNs enhanced a Th1-type immune response (IFN-γ, TNF-α), down-regulated the expression of the Th2-type cytokine interleukin-10 (IL-10), and was associated with protection against Candida-induced tissue damage. This PMN-supplemented model of oral candidosis mimics the in vivo situation, and provides a promising tool for studying the immunological interactions between keratinocytes and C. albicans, as well as the influence of PMNs on C. albicans pathogenesis.

Involvement of interleukin-18 in the inflammatory response against oropharyngeal candidiasis

BACKGROUND

Oral candidiasis is a collective name for a group of disorders caused by the dimorphic fungus Candida albicans (C. albicans). Host defenses against C. albicans essentially fall into two categories: specific immune mechanisms and local oral mucosal epithelial cell defenses. The rationale of this study was to investigate the involvement of IL-18 in the inflammatory response against oral candidiasis.

MATERIAL/METHODS

We first used human oral mucosa tissue and saliva to assess the production of Il-18. Second, we engineered human oral mucosa using only normal human oral epithelial cells and fibroblasts. Tissues were infected with C. albicans at different time points.

RESULTS

Tissue and saliva analyses demonstrated that constitutively produced and secreted IL-18 was up-regulated following Candida-infection. With our engineered model, we showed that C. albicans significantly increased the secretion of active IL-18 by infected epithelial cells. Interestingly, a significant secretion of IFNg functionally supported the up-regulation of active IL-18 in C. albicans-infected tissues. We also showed that rhIL-18 increased the expression and production of endogenous IL-18 and ICE in C. albicans-infected tissues, which was paralleled by a significant increase in IFNg secretion.

CONCLUSIONS

These data suggest that (i) oral epithelial cells are involved in local host defenses against C. albicans infections, via IFNg induced-IL-18, and (ii) that IL-18 and IFNg secretions may be related to epithelial cells. Given that our experimental model closely mimics the natural interface between the oral mucosa and C. albicans, it appears that IL-18 meets the requirements of being a cytokine that epithelial cells use to control C. albicans infections.

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.

Tissue‐Associated Cytokine Expression in HIV‐Positive Persons with Oropharyngeal Candidiasis

Oropharyngeal candidiasis (OPC), caused by Candida albicans, is the most common infection in human immunodeficiency virus (HIV)-positive persons. Although CD4(+) T cells are considered to be important for host defense against C. albicans at the oral mucosa, a recent immunohistochemical evaluation of T cells in OPC lesions of HIV-positive persons with reduced CD4(+) T cells showed high numbers of CD8(+) T cells. The present study investigated tissue-associated expression of cytokine and chemokine mRNA at the site of infection. Results showed some effects of HIV (primarily increased chemokine mRNA levels) but little effect of blood CD4(+) T cells. In contrast, mRNA for several proinflammatory, T helper, and CD8(+) T cell-associated cytokines and chemokines were increased in subjects with OPC versus those without. These results support the presence of CD8(+) T cells in OPC lesions and suggest evidence for a response against OPC, despite reduced levels of CD4(+) T cells.

Effect of orally administered bovine lactoferrin on the immune response in the oral candidiasis murine model

Therapeutic activity against oral candidiasis of orally administered bovine lactoferrin (LF), a multifunctional milk protein, was shown in a previous report using an immunosuppressed murine model. In the present study, the influence of orally administered LF on immune responses relevant to this therapeutic effect was examined. Because mice were immunosuppressed with prednisolone 1 day before and 3 days after the infection with Candida, the numbers of peripheral blood leukocytes (PBL) and cervical lymph node (CLN) cells were reduced. LF feeding prevented the reduction in the numbers of PBL on day 1 and CLN cells on days 1, 5 and 6 in the Candida-infected mice. The number of CLN cells of individual mice on days 5 and 6 was inversely correlated with the Candida c.f.u. in the oral cavity. Increased production of IFN-gamma and TNF-alpha by CLN cells stimulated with heat-killed Candida albicans on day 6 was observed in LF-treated mice compared with non-treated mice. Concanavalin A (ConA)-stimulated CLN cells from LF-treated mice also showed a significant increase in the production of IFN-gamma and IL12 on day 5 and a tendency for increased production of IFN-gamma and TNF-alpha on day 6. The levels of cytokine production by ConA-stimulated CLN cells on day 6 were inversely correlated with the Candida c.f.u. in the oral cavity. In conclusion, the alleviation of oral candidiasis by LF feeding in this model may correlate with the enhancement of the number of leukocytes and their cytokine responses in regional lymph nodes against Candida infection.

Susceptibility pattern and molecular type of species-specific Candida in oropharyngeal lesions of Indian human immunodeficiency virus-positive patients

A study of oropharyngeal candidiasis (OPC) in Indian human immunodeficiency virus (HIV)/AIDS patients was conducted over a period of 15 months. This study revealed that 75% of the HIV/AIDS patients had OPC. MIC testing revealed that 5% of the Candida isolates were fluconazole resistant. A correlation between CD4(+)-T-cell counts and development of OPC in HIV/AIDS patients was also observed. Molecular typing of C. albicans isolates showed that all were genetically unrelated.

Salivary secretory leukocyte protease inhibitor and oral candidiasis in human immunodeficiency virus type 1-infected persons

Oropharyngeal candidiasis, typically caused by Candida albicans, is the most common oral disease associated with human immunodeficiency virus type 1 (HIV-1) infection. Secretory leukocyte protease inhibitor (SLPI), a 12-kDa antiprotease, suppresses the growth of C. albicans in vitro. To determine whether the mucosal protein plays a role in protecting oral tissues against fungal infection, we conducted a cross-sectional study investigating the oral and systemic health and salivary SLPI levels in 91 dentate HIV-1-infected adults receiving medical care in the southeastern United States. Participants with a self-reported history of clinical oropharyngeal candidiasis during the previous 2 years constituted the test group (n = 52), while the comparison group (n = 39) had no oropharyngeal candidiasis during that period. Data collected from medical records, oral examination, and SLPI enzyme-linked immunosorbent assay quantitation of whole saliva were analyzed by t test, analysis of variance, linear regression, and unconditional logistic regression. The test group had a significantly higher mean salivary SLPI level than the comparison group (1.9 microg/ml versus 1.1 microg/ml, P < 0.05). Linear regression modeling identified CD4 cell count and history of oropharyngeal candidiasis as key predictors of salivary SLPI and revealed a significant interaction (P < 0.05) between immunosuppression (CD4 cell count below 200 cells/ microl) and positive history of oropharyngeal candidiasis in predicting salivary SLPI level. By logistic regression modeling, a salivary SLPI level exceeding 2.1 microg/ml, low CD4 count, antiretroviral monotherapy, and smoking were key predictors of oropharyngeal candidiasis. These data support a key role for SLPI in the oral mucosal defense against C. albicans. The antimicrobial mucosal protein may serve as an indicator of previous oropharyngeal candidiasis infection among immunosuppressed persons.

In vitro analyses of tissue structure and interleukin-1β expression and production by human oral mucosa in response to Candida albicans infections

Clinical and experimental observations suggest that oral epithelial cells play a key role in host defenses against candidal infections through cytokines and chemokines. We thus attempted to determine whether oral epithelial cells convey IL-1beta as a pro-inflammatory cytokine in response to Candida albicans infections. We created engineered human oral mucosa (EHOM), put them in contact with live and heat-inactivated C. albicans (10(5) yeast/cm2), and measured the expression of IL-1beta mRNA and protein. Tissue structure and C. albicans morphology were also evaluated. Only live C. albicans modulated IL-1beta expression and secretion. IL-1beta mRNA expression significantly increased during the early stages of infection and decreased during the later stages. The modulatory effect of C. albicans on IL-1beta expression was confirmed by the fact that increased amounts of inactive IL-1beta (33 kDa) were detected early during the infection which then dropped dramatically. There was a significant and time-dependent increase in the amount of the active form of IL-1beta (17 kDa) secreted into the supernatant by epithelial cells infected with live C. albicans. Histological features revealed damage to infected tissues (separation of epithelial cells, edema, vacuolization, reduction in thickness) compared to uninfected ones. Morphological analyses showed that C. albicans changed from a blastospore to a hyphal form at later infection periods. This transformation was very pronounced at 8 and 24 h post-infection. These results provide additional evidence for the contribution of oral epithelial cells to local defenses against exogenous stimulations such as C. albicans infections.

Protective effects of human saliva on experimental murine oral candidiasis

The protective effects of human saliva, known to contain various proteinaceous factors that have anti- Candida activity in vitro on oral candidiasis in the mouse model, were examined in vivo. Oral candidiasis was established by oral inoculation of viable Candida albicans (C. albicans) cells to ICR mice, 24 h after administration of predonisolone. These mice received orally 0.1 ml human saliva or sterile distilled water into the oral cavity a total of five times at specific intervals: 3, 6, 12, 24, and 36 h after inoculation. Seventy-two hours after inoculation with C. albicans, viable C. albicans cells in the oral cavity of the mice were counted and a subjective score for the extent of white patches on the tongue surface determined. The results showed that viable counts were significantly lower in the human saliva group than in the distilled water group (P < 0.05). Scores for white patches on the tongue were also significantly lower in the saliva group than in the distilled water group (P < 0.05). These results suggest that administration of human saliva may inhibit the colonization of the oral cavity by C. albicans in mice and the subsequent onset of oral candidiasis.

Yeasts from the oral cavity of children with AIDS: exoenzyme production and antifungal resistance

The oral fungal microbiota of 30 children with AIDS, of both genders, aged from two to six years, receiving outpatient treatment, was evaluated and compared with that of a control group composed of 30 healthy subjects with matching ages and genders. Virulence factors, such as exoenzyme production, and susceptibility to five antifungal agents using an E-Test kit were evaluated. C. albicans predominated over other species in the AIDS group, showing a higher production of proteinase and phospholipase when compared with that observed in the control group. In this study few clinical manifestations of and low selectivity for C. albicans (23.3%) were observed in the AIDS group. The enzymatic studies showed that 53.8% of the AIDS strains were strongly positive whereas only 33.3% of the non-AIDS strains were positive. Amphotericin B was the most effective drug among the antifungal agents tested against C. albicans. The frequency, selectivity and level of exoenzyme production by C. albicans suggest a higher pathogenicity in the AIDS children than in the control children.

Chronic hyperplastic candidosis/candidiasis (candidal leukoplakia)

Chronic hyperplastic candidosis/candidiasis (CHC; syn. candidal leukoplakia) is a variant of oral candidosis that typically presents as a white patch on the commissures of the oral mucosa. The major etiologic agent of the disease is the oral fungal pathogen Candida predominantly belonging to Candida albicans, although other systemic co-factors, such as vitamin deficiency and generalized immune suppression, may play a contributory role. Clinically, the lesions are symptomless and regress after appropriate antifungal therapy and correction of underlying nutritional or other deficiencies. If the lesions are untreated, a minor proportion may demonstrate dysplasia and develop into carcinomas. This review outlines the demographic features, etiopathogenesis, immunological features, histopathology, and the role of Candida in the disease process. In the final part of the review, newer molecular biological aspects of the disease are considered together with the management protocols that are currently available, and directions for future research.

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.

Fungal susceptibility testing: where are we now?

Invasive fungal infections have been noted in increasing frequency in immunosuppressed patients and may be due to organisms that are less susceptible or frankly resistant to antifungal agents. Recently, standards have been established for testing both yeasts and moulds for susceptibility to antifungal agents. While these tests are increasingly available for clinical use, clinicians are faced with the challenge of whether these tests offer benefit in terms of management and when they should be obtained. In this review, the relevance of these tests is discussed, as are the clinical data, especially for yeasts, that support their use. In addition, the strategy of identifying yeasts to the species level as a means for predicting susceptibility is also discussed. While susceptibility testing of all fungal isolates is not necessary and not recommended, the judicious use of these tests and the role of the mycology laboratory in assisting in management of invasive fungal infection is also evaluated.

Immunohistochemical evaluation of T cells in oral lesions from human immunodeficiency virus-positive persons with oropharyngeal candidiasis

Oropharyngeal candidiasis (OPC), caused by Candida albicans, is the most frequent opportunistic fungal infection in human immunodeficiency virus (HIV)-positive persons. Although Th1-type CD4(+) T cells are considered important for host defense against mucosal C. albicans infections, there is a paucity of information regarding the presence and/or role of T cells in OPC lesions. In pursuit of this, initial chromophore immunohistochemical studies showed a majority of CD8(+) rather than CD4(+) cells equally distributed throughout the buccal mucosa of OPC(-) persons (HIV(-) or HIV(+)), irrespective of blood CD4(+) cell numbers. In contrast, CD8(+) cells in lesions from HIV(+) OPC(+) persons were in significantly higher numbers and concentrated at the lamina propria-epithelium interface, a considerable distance from the Candida at the outer epithelium. Dual fluorescence and confocal microscopy confirmed that the majority of CD8(+), but not CD4(+), cells were T cells by the presence or absence, respectively, of CD3 on each cell type. These results suggest that CD8(+) T cells may be important for oral host defense against OPC, especially when CD4 cell numbers are reduced, with a potential CD8 cell-specific dysfunction associated with susceptibility to OPC.

Role of complement C5 and T lymphocytes in pathogenesis of disseminated and mucosal candidiasis in susceptible DBA/2 mice

The aims of the study were to compare the pathogenesis of Candida albicans infection in various organs and anatomical regions of C5-deficient (DBA/2) and C5-sufficient (BALB/c) mice, and to evaluate the importance of complement C5 and T lymphocytes as factors that determine host susceptibility or resistance. The kidneys of DBA/2 mice showed higher colonisation and more severe tissue damage than those of BALB/c, but infection at other sites, including oral and vaginal mucosa, was generally similar in the two strains. Passive transfer of C5-sufficient serum into DBA/2 mice decreased the fungal burden in the kidney, and prolonged survival of the reconstituted animals. Depletion of CD4(+) and/or CD8(+) cells did not exacerbate either systemic or mucosal infection when compared to controls, and passive transfer of splenocytes from infected donors caused only a small and transient reduction in numbers of yeasts recovered from the kidney of sub-lethally infected recipients. It is concluded that the acute susceptibility of the kidneys in this mouse strain is due to C5 deficiency expressed on a susceptible genetic background. T lymphocytes, however, appear to have minimal influence on recovery from systemic infection with this isolate of C. albicans.