Genetic deletion of dectin-1 does not affect the course of murine experimental colitis.

BACKGROUND: It is believed that inflammatory bowel diseases (IBD) result from an imbalance in the intestinal immune response towards the luminal microbiome. Dectin-1 is a widely expressed pattern recognition receptor that recognizes fungi and upon recognition it mediates cytokine responses and skewing of the adaptive immune system. Hence, dectin-1 may be involved in the pathogenesis of IBD. METHODS: We assessed the responses of dectin-1 deficient macrophages to the intestinal microbiota and determined the course of acute DSS and chronic Helicobacter hepaticus induced colitis in dectin-1 deficient mice. RESULTS: We show that the mouse intestinal microbiota contains fungi and the cytokine responses towards this microbiota were significantly reduced in dectin-1 deficient macrophages. However, in two different colitis models no significant differences in the course of inflammation were found in dectin-1 deficient mice compared to wild type mice. CONCLUSIONS: Together our data suggest that, although at the immune cell level there is a difference in response towards the intestinal flora in dectin-1 deficient macrophages, during intestinal inflammation this response seems to be redundant since dectin-1 deficiency in mice does not affect intestinal inflammation in experimental colitis.

Fungemia due to Rhodotorula mucilaginosa in an immunocompetent, critically ill patient.

Infections due to the yeast Rhodotorula are rare in humans. R. mucilaginosa is responsible for the majority of human cases, and immunocompromised individuals with central venous catheters are at greatest risk. There are few reports of bloodstream infections due to R. mucilaginosa in immunocompetent patients. We present a case report of fungemia due to R. mucilaginosa in an immunocompetent, critically ill patient, with good evolution with catheter removal and fluconazole therapy. We briefly review the spectrum of infections due to R. mucilaginosa and the management of bloodstream infections due to this yeast.

A vacuolar serine protease (Rho m 2) is a major allergen of Rhodotorula mucilaginosa and belongs to a class of highly conserved pan-fungal allergens.

BACKGROUND: Rhodotorula mucilaginosa is one of the most frequently encountered species of yeasts in our environment. We reported here a major allergen of R. mucilaginosa. METHODS: A major R. mucilaginosa allergen (Rho m 2) was characterized by two-dimensional (2D) immunoblotting, protein sequencing, cDNA cloning and IgE cross-reactivity with fungal serine proteases. RESULTS: Fourty-four sera (28%) from 157 bronchial asthmatic patients showed IgE-immunoblot reactivity against R. mucilaginosa extract. Among these 44 sera, 25 (57%) demonstrated IgE binding against a 31-kDa protein of R. mucilaginosa. Protein sequencing results suggest that it is a vacuolar serine protease. The corresponding cDNA clone encoding a mature protein of 312 residues was isolated. It shares 67-68% sequence identity with vacuolar serine protease allergens from three different Penicillium species (Pen ch 18, Pen o 18 and Pen c 18) and designated as Rho m 2 by the Allergen Nomenclature Committee. The native and recombinant Rho m 2 react with IgE antibodies and monoclonal antibody (MoAb) FUM20 against fungal serine proteases. IgE cross-reactivity between nRho m 2 and nPen ch 18 was observed. It was also detectable between rRho m 2 and rPen o 18. CONCLUSION: Our results suggest that R. mucilaginosa may also be a significant causative agent of human respiratory allergic disorders. We identified a vacuolar serine protease as a major allergen of R. mucilaginosa (Rho m 2) and a pan allergen of prevalent airborne fungal species. We detected IgE cross-reactivity among these highly conserved serine protease pan-fungal allergens.

Characterization of enolase allergen from Rhodotorula mucilaginosa.

Rhodotorula mucilaginosa (also known as R. rubra) is among the most commonly found yeast strains in our environment. However, allergens from R. mucilaginosa have not yet been characterized at the molecular level. The purpose of this study was to characterize the enolase allergen from R. mucilaginosa and examine the allergenic/antigenic cross-reactivity among fungal enolases. The full-length cDNA encoding the R. mucilaginosa enolase was isolated through the reverse transcriptase-polymerase chain reaction in conjunction with the 5'-end and 3'-end rapid amplification cDNA end reactions. The corresponding natural enolase from R. mucilaginosa was identified using two-dimensional gel electrophoresis and N-terminal amino acid sequence analysis. The results showed that the enolase from R. mucilaginosa is a protein of 439 residues and is encoded by a cDNA of 1497 bp. It shares high sequence identity with enolase allergens from Candida albicans (85%), Saccharomyces cerevisiae (76%), Penicillium citrinum (76%), Aspergillus fumigatus (76%), Cladosporium herbarum (76.5%), and Alternaria alternata (74%). A 47-kD component in the R. mucilaginosa extracts was found to react with IgE or rabbit anti-enolase antiserum and has an N-terminal amino acid sequence identical to that deduced from the isolated enolase cDNA. Sera from three (21%) of 14 allergic patients sensitized to R. mucilaginosa showed IgE binding to this 47-kD R. mucilaginosa component and the His-tagged recombinant enolase. A rabbit antiserum against the P. citrinum enolase and a monoclonal antibody (MoAb; Afueno 8) against the A. fumigatus enolase reacted with all 5 fungal enolases tested. However, an MoAb (E2a) generated by using the Saccharomyces enolase as antigen could only recognize the immunizing enolase. In addition, heterogeneity in immunoblot profiles of IgE antibodies in serum samples from 9 allergic patients against 5 different fungal enolases tested was also observed. The presence of IgE cross-reactivity among enolase allergens from R. mucilaginosa, C. albicans and P. citrinum was detected by immunoblot inhibition. In conclusion, a new and cross-reactive enolase allergen from R. mucilaginosa (Rho m 1) was identified. Although enolases are highly conserved allergens among different fungal species, most of the allergic patients examined in this study differed in their IgE reactivity to the 5 different fungal enolases tested. The results obtained will be of value in understanding the role of enolase allergen in clinical mould allergy.

Utilization of exocellular mannan from Rhodotorula glutinis as an immunoreactive antigen in diagnosis of leptospirosis.

Previously, Rhodotorula glutinis was reported to produce a large amount of exocellular mannan, having a repeating unit of -->3)-D-Manp-(1-->4)-D-Manp-(1-->. Recently, we found that antigenic polysaccharides of Leptospira biflexa serovar patoc strain Patoc I have the same repeating unit and cross-react with antisera raised against extended strains of other leptospires (K. Matsuo, E. Isogai, and Y. Araki, Carbohydr. Res., in press). This structural identity and the difficulty of producing and isolating antigens led us to confirm the usefulness of Rhodotorula mannan as an immunoreactive antigen in a serological diagnosis of leptospirosis. In the present investigation, we confirmed the structural identity of an exocellular mannan isolated from R. glutinis AHU 3479 and tried to use it as an immunoreactive antigen in a serological diagnosis of leptospirosis. From its chemical analysis and (1)H- and (13)C-labeled nuclear magnetic resonance spectrometry, the Rhodotorula mannan was confirmed to consist of the same disaccharide units. Furthermore, such a preparation was shown to immunoreact to various sera from patients suffering with leptospirosis as well as to most rabbit antiserum preparations obtained from immunization with various strains of pathogenic leptospires. Therefore, the Rhodotorula mannan preparation is useful as an immunoreactive antigen in the serological diagnosis for leptospirosis.

Cross-reacting IgE and IgG antibodies to Pityrosporum ovale mannan and other yeasts in atopic dermatitis.

Atopic dermatitis (AD) patients often demonstrate positive skin prick test results and serum IgE antibodies to a range of different yeasts. This has been thought to be due to cross-reactivity. In this study, the cross-reactivity of IgE and IgG antibodies between mannan and crude antigens of Pityrosporum ovale, Candida albicans, and Saccharomyces cerevisiae and crude antigens of Cryptococcus albidus and Rhodotorula rubra was examined by RAST and ELISA inhibition with two serum pools of AD patients. We found cross-reacting IgE and IgG antibodies. In the IgE response, the main cross-reacting pattern was the mannan region, although inhibition could be achieved also with crude antigens of C. albicans, S. cerevisiae, and, to some extent, C. albidus. P. ovale was the most potent inhibitor of IgE-binding components, and against it the highest IgE antibody levels were detected in AD serum pools. In contrast, C. albicans was found to be the most important inducer of IgG antibodies, since the IgG level against P. ovale mannan in both AD serum pools was very low. Cross-reacting antibodies were also seen in ELISA inhibition with both crude and mannan antigens, but since the IgG antibody level of P. ovale mannan in AD serum pools was low, further studies are needed to confirm the IgG results.

A crossreactivity at the immunoglobulin E level of the cell wall mannoproteins of Candida albicans with other pathogenic Candida and airborne yeast species.

BACKGROUND: Candida albicans crossreacts with Saccharomyces cerevisiae or Pityrosporum ovale at the IgE level. However, the extent of crossreactivity of C. albicans with other yeast species is not known. OBJECTIVE: The crossreactivity at the immunoglobulin E (IgE) level of Candida albicans with other pathogenic Candida species and to the airborne yeast species Cryptococcus and Rhodotorula was studied by immunoblot analysis. METHODS: Crude antigens, designated as heat extract, were prepared from 13 different yeast species and a dot blot test was performed to detect IgE antibodies against each of the heat extracts in 349 patients with allergies who were positive for IgE antibodies against C. albicans in a CAP system. RESULTS: In the dot blot test, most of the sera reacted with the heat extracts of not only C. albicans but also those prepared from the other yeast species. The sera of 41 of the 349 patients (11.7%) reacted with the heat extracts of all 13 yeast species. The extent of the binding of IgE antibodies to multiple yeast species correlated with both the fluorescence intensities measured in the CAP system and the intensities of dots generated by the heat extract of C. albicans in the dot blot test. In an inhibition dot blot test, mannoproteins, but not proteins, of C. albicans strongly inhibited the subsequent binding of IgE antibodies to all yeast species. CONCLUSION: Our data suggest that the C. albicans mannoproteins are responsible for the crossreactivity among these yeast species at the IgE level.

[Fungal involvement of the penis in patients with penile condylomata acuminata]. / Hefebefall des Penis bei Patienten mit penilen Condylomata acuminata.

In a study on 129 patients with penile condylomata acuminata we recognised an incidence of 32% penile yeast affection. Candida was found in 54%, Torulopsis in 30% and Rhodotorula in 17% of all cases. The high rate of yeasts not belonging to the candida species is remarkable. There was no correlation between our test results regarding the cell-mediated immunity against candida albicans and the local yeast infection.