The role of eicosanoids in the kidney damage induced by Candida albicans

Arachidonic acid stimulates cell growth and forms a novel oxygenated metabolite in Candida albicans

Infection of human tissues by Candida albicans has been reported to cause the release of arachidonic acid (AA), eicosanoids and other proinflammatory mediators from host cells. Therefore, we investigated the interaction of this pathogen with AA. AA stimulated cell growth at micromolar concentrations when used as a sole carbon source. Moreover, it selectively inhibited the antimycin A-resistant alternative oxidase. [1-(14)C]AA was completely metabolised by C. albicans. Only one-seventh of the radioactivity metabolised was found in CO(2), whereas two-thirds occurred in carbohydrates suggesting a predominant role of the glyoxalate shunt of citrate cycle. About 1% of radioactivity was found in polar lipids including eicosanoids. A novel AA metabolite, which revealed immunoreactivity with an antibody against 3(R)-hydroxy-oxylipins, was identified as 3, 18-dihydroxy-5,8,11,14-eicosatetraenoic acid. Using immunofluorescence microscopy, endogenous 3(R)-hydroxy-oxylipins were found in hyphae but not in yeast cells. Such compounds have recently been shown to be connected with the sexual stage of the life cycle of Dipodascopsis uninucleata. Together, we propose that infection-mediated release of AA from host cells may modulate cell growth, morphogenesis and invasiveness of C. albicans by several modes. A better understanding of its role is thus promising for novel approaches towards the treatment of human mycoses.

Effect of nordihydroguaretic acid and fluconazole on the LTC4/PGE2 ratio in the kidney of mice damaged by Candida albicans

The kidney is a major target organ in generalized candidiasis. When mice were infected with C.albicans, prostaglandin E2 (PGE2)-like activity was found to be significantly decreased while leukotriene C4 (LTC4)-like activity increased in the kidneys within 10 days. The aim of this study is to investigate the effect of nordihydroguaretic (NDGA) and fluconazole on the LTC4/PGE2 ratio in the mice kidneys infected by proteinase (+) C. albicans. The LTC4/PGE2 ratio was found to be significantly decreased both in NDGA and fluconazole-pretreated groups. These results indicate that pretreatment with the lipoxygenase inhibitor NDGA and the antifungal drug fluconazole, protect the kidney against C. albicans infection. These results also indicate a possible role of arachidonic acid metabolites (increase LTC4 and decrease PGE2) in kidney damage due to C. albicans infection.

Fluorometric determination of acid proteinase activity in vulvovaginal candidosis

Vulvovaginal candidosis is one of the most frequent disorders in obstetrics and gynaecology. Candida albicans is commonly considered to be the true vaginopathic agent. The secreted acid proteinase might be especially relevant in the pathogenesis of vulvovaginal candidosis. A fluorometric determination of acid proteinase activity of clinical C. albicans isolates was carried out during the present work using fluorescamine. L-Leucyl-L-alanine was included as an internal standard and the results were expressed as nmoles of leucylalanine equivalents h-1 per 2 x 10(4) cells. The 13 isolates were taken from non-diabetic, non-pregnant women aged 22-35 years with vulvovaginal candidosis. Candida albicans ATCC 44858 was used as a control. The proteinase activity in culture supernatants was detectable starting from the mid- to late- exponential phase of growth, peaked between 30 and 46 h, and then declined. The control had an activity of 2.72 nmol h-1 per 2 x 10(4) cells, whereas eight of the samples had a lower activity (1.05 nmol h-1 per 2 x 10(4) cells on average) and five of the samples had a higher activity (6.53 nmol h-1 per 2 x 10(4) cells on average). The fluorometric determination of acid proteinase activity was found to be more reproducible and sensitive than the previously used spectrophotometric determinations.

Acute renal failure associated with Candida albicans infection

A 16-year-old male with a long history of steroid-responsive nephrotic syndrome developed fever, abdominal pain, thrombocytopenia and acute renal failure. The clinical course and renal histology were similar to, but not typical of, haemolytic uremic syndrome. Positive cultures (throat, oesophagus, stool), an elevation in serum levels of specific antibody and fungal polysaccharide (1,3) beta-D-glucan and response to the antifungal therapy indicated an association between this syndrome and infection with Candida albicans.

Candida albicans stimulates arachidonic acid liberation from alveolar macrophages through alpha-mannan and beta-glucan cell wall components

Candida albicans is an increasingly important fungal pathogen. Alveolar macrophages respond to fungal components such as zymosan by releasing arachidonic acid (AA) and AA metabolites. However, few studies hypothesized that macrophages respond to C. albicans by releasing AA and generating AA metabolites as a consequence of interaction of mannose and beta-glucan receptors with fungal cell wall components. [14C]AA-labeled rabbit alveolar macrophages released AA following stimulation with either live or heat-killed C. albicans. High-pressure liquid chromatography analysis revealed that 55% of the AA released was metabolized via cyclooxygenase and lipoxygenase pathways. The metabolites consisted of prostaglandin E2, prostaglandin F2 alpha, 6-ketoprostaglandin F1 alpha, thromboxane B2, and leukotrienes B4 and D4. We further examined the roles of alpha-mannan and beta-glucan components of C. albicans in mediating these alterations of eicosanoid metabolism. Prior work in our laboratory has shown that soluble alpha-mannan and beta-glucan inhibit macrophage mannose and beta-glucan receptors, respectively. Incubation of alveolar macrophages with soluble alpha-mannan derived from C. albicans (1 mg/ml) resulted in 49.8% +/- 2.6% inhibition of macrophage AA release during stimulation with intact C. albicans (P = 0.0001 versus control). Macrophage AA release in response to C. albicans was also inhibited to a significant but lesser degree by soluble beta-glucan (36.2% +/- 1.3%; P = 0.008 versus control). These results indicate that C. albicans stimulates macrophage AA metabolism and that these effects are partly mediated by alpha-mannan and beta-glucan constituents of the fungus.