Hyperthermia is a promising potential adjunct to treating sporotrichosis: A refractory case of HIV sporotrichosis and in vitro experiments on Sporothrix spp.

BACKGROUND: Hyperthermia is a common monotherapy for sporotrichosis, but only in patients with special conditions, such as pregnancy and nursing. However, hyperthermia has not been used more widely for sporotrichosis in clinical practice. PATIENTS/METHODS: An HIV-positive adult male with lymphocutaneous sporotrichosis caused by Sporothrix globosa that did not respond to conventional itraconazole therapy lasting >2 months received adjunctive therapy with local hyperthermia. To simulate the effects of heat exposure on the growth and morphology of Sporothrix spp. in vitro, S. globosa, S. schenckii and S. brasiliensis were exposed to intermittent heat (42°C) for 1 h a day for 7 or 28 days and observed under transmission electron microscopy. RESULTS: Itraconazole combined with local hyperthermia significantly improved the lesions, and the patient was successfully cured of sporotrichosis, with no recurrence after 2 years of follow-up. Cultures of Sporothrix spp. treated with 7 days of daily heat exposure in vitro showed obvious decreases in colony diameters, but not numbers, compared with untreated cultures (p < .001). After 28 days of heat exposure in vitro, Sporothrix spp. were unable to thrive (p < .001), and ultrastructural alterations, including loose cell wall structure, incomplete cell membrane, disrupted vacuoles and fragmented nuclei, were noticeable. CONCLUSIONS: Our case findings and in vitro experiments on Sporothrix spp., together with a literature review of previous sporotrichosis cases, suggest that hyperthermia has a clinical role as a treatment adjunct. Large-scale clinical trials are required to examine the utility of hyperthermia in various forms of cutaneous sporotrichosis.

Melanin of Sporothrix globosa affects the function of THP-1 macrophages and modulates the expression of TLR2 and TLR4.

BACKGROUND: Melanin is an important virulence factor for Sporothrix globosa, the causative agent of sporotrichosis, a subcutaneous mycosis that occurs worldwide. Although previous research suggests that melanin is involved in the pathogenesis of sporotrichosis, little is known about its influence on the macrophages that represent the frontline components of innate immunity. OBJECTIVES: To evaluate the effects of melanin on phagocytic activity and the expression of Toll-like receptor (TLR)2 and TLR4 during S. globosa infection of macrophages in vitro. METHODS: To compare phagocytic activity and survival rates, THP-1 macrophages and primary mouse peritoneal macrophages were co-cultured with a wild-type S. globosa strain (Mel+), an albino mutant strain (Mel-), a tricyclazole-treated Mel + strain (TCZ-Mel+), or melanin ghosts extracted from S. globosa conidia. Reactive oxygen species (ROS), nitric oxide (NO) generation, tumor necrosis factor (TNF)-α and interleukin (IL)-6 were assayed in THP-1 cells infected with S. globosa conidia. Quantitative PCR and western blotting were used to observe the effect of melanin on TLR2 and TLR4 expression. Knockdown of TLR2/4 expression with small interfering RNA was performed to further verify the role of these receptors during infection. RESULTS: Macrophages infected with Mel + conidia showed a lower phagocytosis index and a higher survival rate than TCZ-Mel+ and Mel- in vitro. After incubation with S. globosa, the release of ROS, NO, TNF-α and IL-6 by THP-1 were decreased in the presence of melanin. Increased mRNA and protein expression of TLR2 and TLR4 occurred upon S. globosa infection in THP-1, whereas the presence of melanin suppressed TLR2 and TLR4. Moreover, TLR2 or TLR4 knockdown showed a trend toward reducing the pernicious effect of S. globosa conidia on THP-1 cells in vitro. CONCLUSIONS: Collectively, our results indicated that melanin inhibits the phagocytosis of S. globosa and guards against macrophage attack by providing protection from oxygen- and nitrogen-derived radicals, as well as suppressing the host pro-inflammatory cytokine response (TNF-α and IL-6). Melanin was also involved in modulating TLR2 and TLR4 receptor expression, weakening the killing efficiency of S. globosa.