Role of FKS Gene in the Susceptibility of Pathogenic Fungi to Echinocandins.

Echinocandins are antifungal agents that specifically inhibit the biosynthesis of 1,3-ß-D-glucan, a major structural component of fungal cell walls. Echinocandins are recommended as first-line or alternative/salvage therapy for candidiasis and aspergillosis in antifungal guidelines of various countries. Resistance to echinocandins has been reported in recent years. The mechanism of echinocandin resistance involves amino acid substitutions in hot spot regions of the FKS gene product, the catalytic subunit of 1,3-ß-D-glucan synthase. This resistance mechanism contributes to not only acquired resistance in Candida spp., but also inherent resistance in some pathogenic fungi. An understanding of the echinocandin resistance mechanism is important to develop both effective diagnosis and treatment options for echinocandin-resistant fungal diseases.

Histological study of chronic pulmonary aspergillosis.

BACKGROUND: Chronic pulmonary aspergillosis (CPA) has been accepted the criteria for the diagnosis of pulmonary Aspergillus infection. Whereas, either pathophysiology or signs of CPA remains still controversial. METHODS: In this study, we histopathologically investigated 25 specimens of CPA, surgically resected. RESULTS: 21 (84 %) of that comprised male. There were 21 cases with mild impairment of the immune system and/or a scar mostly due to old tuberculosis. There is a tendency for a negative correlation between peripheral blood white cell numbers and value level of beta-(1,3)-D-glucan. Four cases showed a granular fluorescent signal in granulation tissue surrounding the cavity without the fungal aspects itself. CONCLUSIONS: In conclusion, acute inflammatory exudate along the terminal respiratory tract is most significant pathophysiolocial complication of the CPA, caused to organizing pneumonia, which derives fatal respiratory failure. In addition, the viability of fungus does not concern extension of exudative inflammation at the site of erosion along terminal airway.

Genomic Analysis of Single Nucleotide Polymorphisms Asp299Gly and Thr399Ile in Japanese Patients with Invasive Aspergillosis.

Single nucleotide polymorphisms (SNPs) 1063A/G (Asp299Gly) and 1363C/T (Thr399Ile) in the gene encoding Toll-like receptor 4 (TLR4) increase susceptibility to invasive aspergillosis. However, limited information is available on the prevalence of these SNPs in Japan. Therefore, we surveyed these TLR4 SNPs by using formalin-fixed and paraffin-embedded tissue blocks obtained from autopsies of patients with invasive pulmonary aspergillosis. Tissue samples of approximately 30% patients were included in genomic analysis. However, none of these samples showed the presence of TLR4 Asp299Gly and Thr399Ile polymorphisms. Thus, the present study provided information on the prevalence of TLR4 SNPs in Japanese patients with invasive aspergillosis and indicated that these SNPs played a minor role in increasing the susceptibility of Japanese individuals to invasive aspergillosis.

Evaluation of the safety and efficacy of micafungin in Japanese patients with deep mycosis: a post-marketing survey report.

The safety and efficacy of micafungin were evaluated in a Japanese post-marketing survey involving 1,142 patients with deep mycosis caused by Candida or Aspergillus. The overall clinical response was 83.0%, and the respective responses for patients with candidiasis or aspergillosis were 86.3 and 70.8%. With regard to drug reactions, 562 adverse reactions were observed in 28.5% of patients. Among the 83 serious adverse drug reactions reported by 53 patients, a causal relationship with micafungin was assessed as definite or probable for 6 reactions in 5 patients. Age and baseline hepatic and renal function status did not affect the incidence of adverse reactions, although incidence increased significantly in proportion to the severity of mycosis and daily dose (p < 0.01). In multiple logistic regression analysis, neither baseline hepatic impairment nor increased daily dose of micafungin affected the incidence of hepatobiliary disorders, however, the severity of mycosis was found to correlate significantly with hepatobiliary disorders (p = 0.031). Taken together, our post-marketing findings show that micafungin is effective against deep mycosis caused by Candida or Aspergillus in patients across a range of backgrounds.

FR209602 and related compounds, novel antifungal lipopeptides from Coleophoma crateriformis no.738. I. Taxonomy, fermentation, isolation and physico-chemical properties.

Novel antifungal lipopeptides, FR209602, FR209603 and FR209604, were isolated from the fermentation broth of a fungal strain No. 738 which was identified as Coleophoma crateriformis from morphological and physiological characteristics. The antibiotics were purified by solvent extraction, HP-20, YMC-ODS and silica gel column chromatography and lyophilization. These compounds were structurally similar to FR901379 previously reported by ourselves which had a sulfate residue in the cyclic peptide portion.

FR209602 and related compounds, novel antifungal lipopeptides from coleophoma crateriformis no. 738. II. In vitro and in vivo antifungal activity.

The biological activities of the novel echinocandin-like lipopeptides, FR209602, FR209603 and FR209604, were evaluated. These compounds showed antifungal activity against Candida albicans and Aspergillus fumigatus attributed to inhibition of 1,3-beta-glucan synthesis. The minimum effective concentrations of these compounds against C. albicans and A1. fumigatus ranged from 0.02 to 0.04 microg/ml by microbroth dilution assay, and the IC50 values on C. albicans 1,3-beta-glucan synthase were 0.49, 0.64 and 0.72 microg/ml, respectively. FR209602 and FR209603 showed good efficacy by subcutaneous injection against C. albicans in a murine systemic infection model, with ED50 values of 2.0 and 1.9 mg/kg, respectively.

FR227673 and FR190293, novel antifungal lipopeptides from Chalara sp. No. 22210 and tolypocladium parasiticum No. 16616.

Novel antifungal lipopeptides, FR227673 and FR190293, were isolated from the fermentation broths of fungal strains Chalara sp. No. 22210 and Tolypocladium parasiticum No. 16616, respectively. These compounds have the same cyclic peptide nuclear structure as FR901379, with different side chains, and showed antifungal activity against Aspergillus fumigatus and Candida albicans attributed to inhibition of 1,3-beta-glucan synthesis.

FR220897 and FR220899, novel antifungal lipopeptides from Coleophoma empetri no. 14573.

Novel antifungal lipopeptides, FR220897 and FR220899, were isolated from the fermentation broth of a fungal strain No. 14573. This strain was identified as Coleophoma empetri No. 14573 from morphological and physiological characteristics. FR220897 and FR220899 showed antifungal activities against Aspergillus fumigatus and Candida albicans attributed to inhibition of 1,3-beta-glucan synthesis. Furthermore, FR220897 was effective in a murine model of systemic candidiasis.

FR207944, an antifungal antibiotic from Chaetomium sp. No. 217 II. Isolation and structure elucidation.

We discovered FR207944 produced by Chaetomium sp. No. 217 in the course of screening for antifungal antibiotics from natural products. FR207944 is identical with fuscoatroside, described in the preceding paper as an anti-Aspergillus flavus agent. Determination of the relative stereochemistry of fuscoatroside was made formally by comparison with WF11605 (16-Oxo-FR207944). We confirmed the stereochemistry on the basis of single crystal X-ray analysis.

FR207944, an antifungal antibiotic from Chaetomium sp. no. 217 I. Taxonomy, fermentation, and biological properties.

An antifungal antibiotic, FR207944, was isolated from the culture broth of a fungal strain Chaetomium sp. no. 217. FR207944 is a triterpene glucoside with antifungal activity against Aspergillus fumigatus and Candida albicans. Specifically, FR207944 exhibits in vitro and in vivo antifungal activity against A. fumigatus. The effects of FR207944 on the morphology of A. fumigatus were shown to be similar to those of FR901379, a known 1,3-beta-glucan synthase inhibitor. The MECs of FR207944 against A. fumigatus FP1305 and C. albicans FP633 in micro-broth dilution test were 0.039 and 1.6 mug/ml respectively. FR207944 showed good potency by subcutaneous injection and oral administration against A. fumigatus in a murine systemic infection model, with ED(50)s of 5.7 and 17 mg/kg respectively.

FR227244, a novel antifungal antibiotic from Myrothecium cinctum No. 002 Taxonomy, fermentation, isolation and physico-chemical properties.

A novel antifungal antibiotic, FR227244, was isolated from the culture broth of a fungal strain No. 002. The strain was identified as Myrothecium cinctum from morphological and physiological characteristics. This compound was isolated from the culture broth by solvent extraction, HP-20 and YMC ODS gel column chromatographies, and n-hexane precipitation. FR227244 is a white powder which melts at 210 to approximately 211 degrees C and possesses the molecular formula C38H58O11. FR227244 is a novel triterpene glycoside with antifungal activity against Aspergillus fumigatus. The effects of FR227244 on the morphology of A. fumigatus were shown to be similar to those of FR901379 which is a known 1,3-beta-glucan synthase inhibitor.

FR227244, a novel antifungal antibiotic from Myrothecium cinctum No. 002. II. Biological properties and mode of action.

FR227244 is a novel triterpene glycoside that exhibits in vitro antifungal activity against filamentous fungi such as Aspergillus sp. and Trichophyton sp. and yeast such as Candida utilis and Candida parapsilosis but shows low activity against Candida albicans, Candida krusei and Candida tropicalis. Specifically, FR227244 exhibits in vitro and in vivo antifungal activity against Aspergillus fumigatus. The minimum effective concentration (MEC) of FR227244 against A. fumigatus FP1305 in a micro-broth dilution test was 0.031 microg/ml. FR227244 showed good efficacy by subcutaneous injection and oral administration against A. fumigatus in a murine systemic infection model, with ED(50)s of 1.9 and 18 mg/kg, respectively. FR227244 inhibited glucan synthesis in a 1,3-beta-glucan synthase assay weakly and in whole cells strongly, but did not effect other macromolecule synthesis, including protein, nucleic acids, mannan and chitin. These results and the effect on hyphal morphology of A. fumigatus suggested that FR227244 showed antifungal activity based on inhibition of glucan synthesis.

[Issues in the development of drugs for treating deep-seated mycosis].

This review is a collection of abstracts of seven papers presented at the panel discussion Issues in the Development of Drugs for Treating Deep-Seated Mycosis - From Drug Discovery to Clinical Studies held at the 45th Annual Meeting of the Japanese Society of Medical Mycology. The first three presentations concerned the discovery of new drugs. The first discussed the screening, analysis of chemical structure and elucidation of the mechanism of action of new antifungal agents focusing on aureobasidin A. The second was on the search for and development of novel agents with selective targets of action, specifically FK463 (micafungin) which inhibits (1-3)-beta-glucan synthase. The third described the development of novel derivatives based on the structure-activity correlation of triazole agents, with CS-758 as an example. The remaining four presentations discussed the status and issues of clinical studies targeting hematological disorders and respiratory diseases, as well as various problems from the company point of view on new drug development and those from the government side concerning the approval of new drugs. This type of meeting which provides an opportunity for discussion of various multi-faceted issues from the discovery of a new drug to its preclinical and clinical studies can contribute greatly to progress in the future development of new antifungal agents.