The drug resistance mechanisms in Leishmania donovani are independent of immunosuppression.

The protozoan parasite L. donovani resides inside macrophages as amastigotes and inflicts a potentially lethal disease visceral leishmaniasis (VL). Due to absence of a vaccine, chemotherapy with antimonials, amphotericin B, miltefosine or paromomycin remains the only option for treating VL. Prolonged treatment with a single drug resulted in parasite strains resistant to each of these drugs. As immuno-suppression characterizes the disease, we examined whether eliciting immunosuppressive cytokines is a mechanism of manifestation of drug-resistance. We infected BALB/c mice with the clinical isolates of L. donovani- BHU1066 (sensitive), NS2 (antimony-resistant), BHU1064 (miltefosine-resistant), BHU919 (Amphotericin B-resistant) and BHU1020 (paromomycin-resistant)- from the respective drug-unresponsive patients and assessed splenic parasite load and production of pro-inflammatory and anti-inflammatory cytokines. Although the splenic parasite loads in the drug-resistant L. donovani-infected BALB/c mice were higher than that observed in the drug-sensitive parasites-infected mice, the cytokine profiles were not significantly different between these two sets of mice. The drug-resistance in L. donovani results from innate drug modulation but perhaps not from host immune-suppressive cytokines.

Th-1 biased immunomodulation and synergistic antileishmanial activity of stable cationic lipid-polymer hybrid nanoparticle: biodistribution and toxicity assessment of encapsulated amphotericin B.

To address issues related to Amphotericin B (AmpB) clinical applications, we developed macrophage targeted cationic stearylamine lipid-polymer hybrid nanoparticles (LPNPs) with complementary characteristics of both polymeric nanoparticles and liposomes, for enhancement of therapeutic efficacy and diminishing toxic effect of encapsulated AmpB. The LPNPs (size 198.3 ± 3.52 nm, PDI 0.135 ± 0.03, zeta potential +31.6 ± 1.91 mV) provide core-shell type structure which has the ability to encapsulate amphiphilic AmpB in higher amount (Encapsulation efficiency 96.1 ± 2.01%), sustain drug release and stabilize formulation tremendously. Attenuated erythrocytes and J774A.1 toxicity of LPNPs demonstrated safe applicability for parenteral administration. Elevated macrophage uptake of LPNPs, rapid plasma clearance and higher drug allocation in macrophage abundant liver and spleen illustrated admirable antileishmanial efficacy of AmpB-LPNPs in vitro (IC50, 0.16 ± 0.04 µg AmpB/ml) and in vivo (89.41 ± 3.58% parasite inhibition) against visceral leishmaniasis models. Augmentation in antileishmanial activity due to Th-1 biased immune-alteration mediated by drug-free LPNPs which elevated microbicidal mediators of macrophages. Moreover, minimal distribution to kidney tissues and low level of nephrotoxicity markers (creatinine and BUN) demonstrated the safety profile of AmpB-LPNPs. Conclusively, reliable safety and macrophage directed therapeutic performance of AmpB-LPNPs suggest it as promising alternative to commercial AmpB-formulations for the eradication of intra-macrophage diseases.

Early detection of systemic candidiasis in the whole blood of patients with hematologic malignancies.

Systemic candidiasis is a significant cause of morbidity and mortality in patients with hematologic disorders. The aim of this study was to determine the prevalence of systemic candidiasis and the efficiency of the polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELIZA) method for the early detection of Candida spp. in patients with hematologic malignancies. From 2004 to 2006, 194 patients with hematologic malignancies were evaluated for systemic candidiasis. Collected blood samples were assayed using the PCR-ELISA method for the presence of the bands on ethidium bromide stained gel, and for hybridization with Candida spp. as well. The female-to-male ratio was 61:133, the mean age was 33.7 years, and the mean hospitalization period was 21.2 days. Twenty-five patients (12.9%) had positive PCR-ELISA results for systemic candidiasis. The etiologic agents were Candida albicans (21 cases), C. tropicalis (3 cases), and C. krusei (1 case). The mean interval of PCR-ELISA positivity in blood samples before the manifestation of clinical signs was 12.6 days. Fungal PCR-ELISA assay became negative after 14 days when patients were treated successfully with amphotericin B, and the assay remained positive until death when the treatment failed. The PCR-ELISA method can potentially serve as a useful tool for the management of patients suffering from hematologic malignancies and at risk for systemic candidiasis.

Secretion of proinflammatory cytokines and chemokines during amphotericin B exposure is mediated by coactivation of toll-like receptors 1 and 2.

Amphotericin B (AmB) is a ligand of toll-like receptor 2 (TLR2). Here, we demonstrate the participation of TLR1 in AmB-induced cell activation that led to the secretion of tumor necrosis factor alpha, interleukin 6 (IL-6), and IL-8. Hence, TLR2-TLR1 coactivation serves as the underlying mechanism for the proinflammatory toxicities associated with AmB.

Amphotericin-induced stridor: a review of stridor, amphotericin preparations, and their immunoregulatory effects.

BACKGROUND: Various adverse effects have been reported with the use of amphotericin B. The respiratory adverse effects include dyspnea, tachypnea, bronchospasm, hemoptysis, and hypoxemia. Stridor has not been previously reported with the use of amphotericin B. OBJECTIVE: To review the mechanism of action and reports of respiratory adverse effects for amphotericin B, the liposomal preparations of amphotericin B, and the differential diagnosis of stridor. DATA SOURCES: A MEDLINE search from 1966 to 2002 was performed to review the current literature for possible mechanisms and immunoregulatory effects related to the infusion of amphotericin B. RESULTS: Amphotericin B has been shown to increase tumor necrosis factor alpha (TNF-alpha) concentrations in macrophages. In addition, it induces prostaglandin E2 synthesis and increases the production of interleukin 1beta (IL-1beta) in mononuclear cells. The immunoregulatory effects of amphotericin B include increases in apoptosis, production of monocyte chemoattractant protein 1, superoxide anion, nitric oxide, and intercellular adhesion molecule 1 expression. CONCLUSIONS: Amphotericin B induces the production of TNF-alpha, interferon-gamma, and IL-1beta, which may potentiate its toxic effects. Some liposomal preparations induced lower levels of TNF-alpha and nitric oxide and may be useful in patients unable to tolerate amphotericin B deoxycholate.

Candida albicans isoladas de pacientes com SIDA: sensibilidade "in vitro" aos agentes antifúngicos / Candida albicans from AIDS patients: susceptibility \"in vitro\" to antifungal agents

Resumo: Por meio da determinaçäo da CIM(Concentraçäo Inibitória Mínima) e da CFM(Concentraçäo Fungicoda Mínima), os autores verificaram a sensibilidade de candida albicans isoladas de pacientes com SIDA, frente a Anfotericina B, Nistatina, Cetoconazol e miconazol.Os autores näo verificaram a ocorrência de amostras resistente e discutem o fenômeno da resistência de C.albicans aos antifúngicos poliênicos e imidazólicos.