The effect of antifungal agents and human monocytes on in vitro galactomannan release by Aspergillus spp. in liquid culture medium.

Invasive pulmonary aspergillosis is increasing in incidence in immunosuppressed patients. Diagnosis of this infection is problematic, relying on clinical suspicion and computerized tomography of the thorax and sinuses. An assay capable of detecting the fungal cell wall component galactomannan (GM) as a sign of Aspergillus infection is in use in patients with hematological malignancies. The aim of this study was to investigate the release of GM during growth of two medically important species, Aspergillus fumigatus and Aspergillus terreus, in liquid medium, including interaction with fluconazole, amphotericin B, liposomal amphotericin B and itraconazole, as well as human monocytes. Our results showed that for both species, amphotericin B deoxycholate, liposomal amphotericin B and itraconazole reduced the concentrations of GM to very low levels at the lowest doses tested (1, 3 and 4 microg/L, respectively). High doses of fluconazole had negligible effect on GM release by A. terreus, as expected. However, fluconazole at 128 microg/L increased GM concentrations released by A. fumigatus without reduction in visible growth. Co-incubation with human monocytes had no significant effect on GM release. The effects of antifungal agents on GM release may have diagnostic implications.

Inteferon gamma and granulocyte-macrophage colony-stimulating factor augment the antifungal activity of human polymorphonuclear leukocytes against Scedosporium spp.: comparison with Aspergillus spp.

While Aspergillus spp. have been the most frequent filamentous fungi causing infections in immunocompromised patients, Scedosporium spp. are emerging as life-threatening pathogens. We studied the effects of interferon gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF) alone or combined on the antifungal activities of human polymorphonuclear leukocytes (PMN) against Scedosporium apiospermum and Scedosporium prolificans. We paralleled these activities to those against Aspergillus fumigatus and Aspergillus flavus. Incubation of PMN with IFN-gamma and GM-CSF for 22 h enhanced PMN-induced hyphal damage of both Aspergillus spp. and S. prolificans (p < 0.05) but not of S. apiospermum. However, hyphae of S. apiospermum were damaged significantly more after incubation with PMN that had been treated with IFN-gamma and GM-CSF for 2 h. In addition, incubation of PMN with GM-CSF for 2 h enhanced PMN oxidative burst measured as superoxide anion (O2-) production in response to nonopsonized hyphae of A. flavus and Scedosporium spp. (p < 0.05). In contrast, after 2 h, IFN-gamma and GM-CSF alone did not enhance PMN O2- in response to opsonized hyphae of A. flavus and Scedosporium spp.; however, the combination of IFN-gamma and GM-CSF showed significant enhancement against these species. Thus, IFN-gamma and GM-CSF, particularly in combination, demonstrate a species- and time-dependent augmentation of PMN responses to Scedosporium spp.

Effects of interleukin-15 on antifungal responses of human polymorphonuclear leukocytes against Fusarium spp. and Scedosporium spp.

Fusarium spp. and Scedosporium spp. have emerged as important fungal pathogens that are frequently resistant to antifungal compounds. We investigated the effects of human interleukin-15 (IL-15) on human polymorphonuclear leukocyte (PMNL) activity against Fusarium solani and Fusarium oxysporum as well as Scedosporium prolificans and Scedosporium apiospermum. IL-15 (100 ng/ml) significantly enhanced PMNL-induced hyphal damage of both Fusarium spp. and S. prolificans after incubation for 22 h (P < 0.01) but not S. apiospermum. In addition, IL-15 enhanced PMNL oxidative respiratory burst evaluated as superoxide anion production in response to S. prolificans but not to the other fungi after 2 h incubation. IL-15 increased interleukin-8 (IL-8) release from PMNLs challenged with hyphae of F. solani and S. prolificans (P< or = 0.04). Release of tumor necrosis factor-alpha was not affected. The species-dependent enhancement of hyphal damage and induction of IL-8 release suggest that IL-15 plays an important role in the immunomodulation of host response to these emerging fungal pathogens.

Interferon- gamma and granulocyte-macrophage colony-stimulating factor augment the activity of polymorphonuclear leukocytes against medically important zygomycetes.

Zygomycetes cause serious invasive infections, predominantly in immunocompromised and diabetic patients with poor prognoses and limited therapeutic options. We compared the antifungal function of human polymorphonuclear leukocytes (PMNLs) against hyphae of Rhizopus oryzae and R. microsporus, the most frequently isolated zygomycetes, with that against the less frequently isolated Absidia corymbifera. We then evaluated the effects of interferon (IFN)- gamma and granulocyte-macrophage colony-stimulating factor (GM-CSF), alone or combined, on PMNL antifungal function against these zygomycetes. Both PMNL oxidative burst in response to hyphae and PMNL-induced hyphal damage were significantly lower in response to Rhizopus species than in response to A. corymbifera. Incubation of PMNLs with IFN- gamma and GM-CSF alone or combined for 22 h increased the PMNL-induced hyphal damage of all 3 species. The treatment of PMNLs with the combination of IFN- gamma and GM-CSF significantly increased the release of tumor necrosis factor- alpha in response to R. microsporus and A. corymbifera hyphae. IFN- gamma significantly reduced interleukin-8 release in response to all zygomycetes. Although Rhizopus species demonstrate a decreased susceptibility to the antifungal activity of human PMNLs, in comparison with A. corymbifera, IFN- gamma and GM-CSF augment the hyphal damage of all 3 zygomycetes, suggesting a role for IFN- gamma and GM-CSF in the management of invasive zygomycosis.

Transforming growth factor-beta1 in the urine of young children with urinary tract infection.

Urinary tract infection (UTI) is a frequent cause of morbidity during the first years of life and may lead to renal insufficiency. Transforming growth factor-beta1 (TGF-beta) is both immunoregulatory and an important mediator of interstitial fibrosis. TGF-beta was detected in the urine of 52% of 48 children aged 1-24 months with a first episode of UTI (94% due to Escherichia coli) and no obstructive nephropathy compared with 0 of 20 healthy young children (P<0.001). TGF-beta was detected in the urine only during the early stage (<1 day) after initiation of treatment. It was detected more frequently (P=0.06) and in significantly higher concentrations (P=0.046) in children with a normal (99m )Tc-dimercaptosuccinic acid scan compared with those with abnormal scans performed 3-14 days after the diagnosis of UTI, suggesting a regulatory role in fibrogenesis and outcome of pyelonephritis in childhood.

Selective effects of interleukin (IL)-15 on antifungal activity and IL-8 release by polymorphonuclear leukocytes in response to hyphae of Aspergillus species.

The effects of interleukin (IL)-15 on human polymorphonuclear leukocyte (PMNL) activity against Aspergillus fumigatus and Aspergillus flavus were investigated. Pretreatment with IL-15 for 2 h increased PMNL oxidative burst, as measured by superoxide anion (O(2)(-)) release in response to A. fumigatus (P<.05) but not to A. flavus. However, after 22-h, but not 2-h, treatment with IL-15, there was significant enhancement in PMNL-mediated hyphal damage to A. fumigatus. Furthermore, 22-h exposure to IL-15 mediated an enhanced release of IL-8 from PMNLs challenged with hyphae of A. fumigatus and A. flavus (P<.05). In contrast, IL-15 treatment did not affect the release of tumor necrosis factor-alpha from PMNLs. The selective time- and species-dependent enhancement of O(2)(-) production and hyphal damage, as well as its induction of IL-8 release, suggest that IL-15 may play an important role in the immunomodulation of host response to invasive aspergillosis.

Interactions of human phagocytes with moulds Fusarium spp. and Verticillium nigrescens possessing different pathogenicity.

Fusarium spp. are emerging as important causes of invasive fungal infections. They tend to have decreased susceptibility to antifungal agents, making host defences very important. The ability of human phagocytes to cause damage to hyphae of Fusarium solani, F. oxysporum and Verticillium nigrescens, a mould with very low pathogenicity, was assessed using the 2,3-bis[2-methoxy-4-nitro-5-sulphophenyl]2H-tetrazolium-5-carboxanilide (XTT) metabolic assay. The oxidative burst, evidenced as superoxide anion (O2-) production, of phagocytes in response to hyphae was also investigated, as well as phagocytosis of conidia by monocyte (MNC)-derived macrophages (MDM). Hyphal damage by polymorphonuclear leukocytes (PMNL) and MNC showed a linear trend increasing with effector cell:target cell (E:T) ratio. Although no significant differences were observed for PMNL, MNC-induced damage to F. solani hyphae was lower than that seen with F. oxysporum hyphae at an E:T ratio of 20:1 and with V. nigrescens hyphae at ratios of 1:1, 5:1 and 20:1 (P < 0.05). In contrast, levels of O2- production by phagocytes in response to F. oxysporum were lower than those induced in response to the other fungi (P < 0.01). The average number of V. nigrescens conidia ingested by MDM was higher than that of conidia of the other fungi (P < 0.01). Phagocytes respond to the test fungi differentially, with F. solani being the least susceptible to damage by MNC. This may correlate with the observation that, compared to the other fungi studied, it causes a relatively high incidence of infections in neutropenic patients.