Liposomal amphotericin B and amphotericin B-deoxycholate show different immunoregulatory effects on human peripheral blood mononuclear cells

Use of topical amphotericin in a case of refractory sino-orbital angioinvasive mucormycosis

The standard of care for treatment of sino-orbital mucormycosis involves aggressive surgical debridement and liposomal amphotericin, and the roles of adjunctive and topical therapies are less clear. Here we describe a case of severe refractory sino-orbital mucormycosis in an immunocompetent patient who responded to combination therapy with liposomal amphotericin, isavuconazole, micafungin, and topical amphotericin deoxycholate after failing to achieve negative surgical margins.

Impact of immunosuppressive and antifungal drugs on PBMC- and whole blood-based flow cytometric CD154+ Aspergillus fumigatus specific T-cell quantification

Flow cytometric quantification of CD154⁺ mould specific T-cells in antigen-stimulated peripheral blood mononuclear cells (PBMCs) or whole blood has been described as a supportive biomarker to diagnose invasive mould infections and to monitor therapeutic outcomes. As patients at risk frequently receive immunosuppressive and antifungal medication, this study compared the matrix-dependent impact of representative drugs on CD154⁺ T-cell detection rates. PBMCs and whole blood samples from healthy adults were pre-treated with therapeutic concentrations of liposomal amphotericin B, voriconazole, posaconazole, cyclosporine A (CsA) or prednisolone. Samples were then stimulated with an Aspergillus fumigatus lysate or a viral antigen cocktail (CPI) and assessed for CD154⁺ T-helper cell frequencies. Specific T-cell detection rates and technical assay properties remained largely unaffected by exposure of both matrices to the studied antifungals. By contrast, CsA and prednisolone pre-treatment of isolated PBMCs and whole blood adversely impacted specific T-cell detection rates and caused elevated inter-replicate variation. Unexpectedly, the whole blood-based protocol that uses additional α-CD49d co-stimulation was less susceptible to CsA and prednisolone despite prolonged drug exposure in the test tube. Accordingly, addition of α-CD49d during PBMC stimulation partially attenuated the impact of immunosuppressive drugs on test performance. Translating these results into the clinical setting, false-negative results of CD154⁺ antigen-specific T-cell quantification need to be considered in patients receiving T-cell-active immunosuppressive medication. Optimized co-stimulation regimes with α-CD49d could contribute to an improved feasibility of functional T-cell assays in immunocompromised patient populations.

Impact of Antifungal Compounds on Viability and Anti-Aspergillus Activity of Human Natural Killer Cells

Despite the availability of new antifungal compounds, invasive aspergillosis carries high morbidity and mortality in hematopoietic stem cell transplant recipients. In vitro studies and animal models suggest that the adoptive transfer of natural killer (NK) cells might be a promising immunotherapeutic option in this setting. As it is unclear whether the viability and function of human NK cells are affected by common antifungal agents, we analyzed the interaction of various concentrations of amphotericin B deoxycholate (AmB-D), liposomal amphotericin B, caspofungin, fluconazole, voriconazole, and posaconazole with human NK cells. When adding NK cells to therapeutic concentrations of antifungal agents, a significant increase in the antifungal effect was seen for caspofungin and voriconazole, whereas NK cells significantly decreased the hyphal damage of escalated doses of AmB-D. In contrast, therapeutic concentrations of all antifungal compounds tested did not have a negative effect on proliferation, viability, and the release of soluble immunomodulatory molecules of NK cells. These data indicate that therapeutic concentrations of the antifungal agents tested do not negatively affect the functional properties of human NK cells, which is a prerequisite for further studies evaluating NK cells as antifungal immunotherapy in immunocompromised patients suffering from invasive aspergillosis.

Leishmanicidal Activity of Piper nigrum Bioactive Fractions is Interceded via Apoptosis In Vitro and Substantiated by Th1 Immunostimulatory Potential In Vivo

Visceral leishmaniasis (VL) is a life-threatening protozoal infection chiefly impinging the rural and poor population in the tropical and sub-tropical countries. The deadly affliction is rapidly expanding after its association with AIDS, swiftly defying its status of a neglected disease. Despite successful formulation of vaccine against canine leishmaniasis, no licensed vaccine is yet available for human VL, chemotherapy is in appalling state, and the development of new candidate drugs has been painfully slow. In face of lack of proper incentives, immunostimulatory plant preparations owing antileishmanial efficacy bear potential to rejuvenate awful antileishmanial chemotherapy. We have earlier reported profound leishmanicidal activity of Piper nigrum hexane (PNH) seeds and P. nigrum ethanolic (PNE) fractions derived from P. nigrum seeds against Leishmania donovani promastigotes and amastigotes. In the present study, we illustrate that the remarkable anti-promastigote activity exhibited by PNH and PNE is mediated via apoptosis as evidenced by phosphatidylserine externalization, DNA fragmentation, arrest in sub G₀/G₁ phase, loss of mitochondrial membrane potential and generation of reactive oxygen species. Further, P. nigrum bioactive fractions rendered significant protection to L. donovani infected BALB/c mice in comparison to piperine, a known compound present in Piper species. The substantial therapeutic potential of PNH and PNE was accompanied by elicitation of cell-mediated immune response. The bioactive fractions elevated the secretion of Th1 (INF-γ, TNF-α, and IL-2) cytokines and declined IL-4 and IL-10. PNH and PNE enhanced the production of IgG2a, upregulated the expression of co-stimulatory molecules CD80 and CD86, augmented splenic CD4⁺ and CD8⁺ T cell population, induced strong lymphoproliferative and DTH responses and partially stimulated NO production. PNH and PNE were devoid of any hepatic or renal toxicity. These encouraging findings merit further exploration of P. nigrum bioactive fractions as a source of potent and non-toxic antileishmanials.

Novel immunomodulatory function of 1,3,4-thiadiazole derivatives with leishmanicidal activity

OBJECTIVES

Previously, some nitroheteroaryl-1,3,4-thiadiazole derivatives were identified to have potent activity against Leishmania sp. The present aim was to complete the in vitro analysis, thereby investigating the in vivo efficiency of the analogues 15a, 21a and 21b against infected BALB/c mice.

METHODS

Following parasite inoculation and intraperitoneal drug administration (5 and 20 mg/kg/day) for 5 days, the course and size of cutaneous lesions, histopathology of the liver, parasite loads in the spleen through limiting dilution assay as well as spleen cell activation assays through cytokine secretion profiles were studied in BALB/c mice, over a period of 23 and 30 days post-drug injections.

RESULTS

The analogues significantly decreased lesion size and progression of infection in the liver and spleen, and were associated with granuloma formation, which correlates with disease regression in the liver of murine hosts. Moreover, the analogues had immunomodulatory effects, stimulating interferon-γ expression and suppressing interleukin-10 and interleukin-5 production, favouring type-1 immune responses and resolution of the parasitic infection.

CONCLUSIONS

Our results highlight marked differences between the responses of key anatomical organs to the thiadiazole derivatives in comparison with the current antileishmanial drug, meglumine antimoniate. The in vivo observations provide further evidence on the efficiency of the compounds for Leishmania treatment. The immunomodulatory function plays an essential role in enhancing cell-mediated immunity for complete clearance of the pathogen.

Real-time reverse transcription-PCR quantification of cytokine mRNA expression in golden Syrian hamster infected with Leishmania infantum and treated with a new amphotericin B formulation

A real-time quantitative reverse transcription-PCR assay was developed for the quantification of cytokine mRNA expression in the golden Syrian hamster Mesocricetus auratus infected with Leishmania infantum and treated with amphotericin B (AMB) formulated in microspheres made of human serum albumin (HSA). Treatment was administered intravenously on days 69, 71, and 73 postinfection (p.i.) with 10(7) metacyclic promastigotes, at doses of 2 and 40 mg/kg of AMB. High infection levels were recorded for untreated animals by day 76 p.i., with parasite loads always about 2 log10 per gram higher in the liver than in the spleen. Treatment was highly effective with both doses, but at 40 mg/kg, almost complete parasite elimination was achieved. mRNA expression of gamma interferon (IFN-gamma) and, to a lesser extent, tumor necrosis factor alpha (TNF-alpha) and transforming growth factor beta (TGF-beta) in spleen cells was up-regulated in most animals of the untreated group. The mRNA expression of interleukin-4 was strongly down-regulated in untreated as well as treated infected animals. Treatment with the lower dose of AMB-HSA down-regulated the mRNA expression of IFN-gamma and TNF-alpha, with no effect on the deactivating cytokine TGF-beta. In contrast, treatment with the higher dose (40 mg/kg) of the formulation caused moderate up-regulation of IFN-gamma and TNF-alpha and strong suppression of TGF-beta. Treatment of noninfected animals did not alter the cytokine expression pattern with regard to untreated controls. Our results suggest that treatment of L. infantum-infected Syrian hamsters with highly effective nontoxic doses of AMB-HSA causes deactivation of the anti-inflammatory cytokine TGF-beta, which in turn results in up-regulation of the Th1 cytokines IFN-gamma and TNF-alpha.

Exposure of Candida albicans to antifungal agents affects expression of SAP2 and SAP9 secreted proteinase genes

OBJECTIVES

To ascertain the effects of subinhibitory concentrations of several antifungal agents on a virulence factor: secreted proteinase (Sap) activity and expression of SAP genes in Candida albicans.

METHODS

Enzyme assays and growth measurements, GFP-SAP2 promoter constructs and fluorescence measurement, transcript profiling and RT-PCR.

RESULTS

For seven of eight C. albicans isolates tested, exposure to fluconazole gave an increase in Sap specific activity; for one isolate, resistant to azoles and flucytosine, fluconazole exposure led to a fall in Sap activity. A similar relationship between growth reduction and increased Sap activity was seen with C. albicans cells treated with subinhibitory concentrations of itraconazole, miconazole, flucytosine and caspofungin. Transcript profiling indicated antifungal exposure was associated with increased expression of mRNA from SAP2 and SAP9 genes; this was confirmed for fluconazole and caspofungin exposure by RT-PCR.

CONCLUSIONS

Antifungal agents with three different mechanisms of action similarly generate a rise in expression of SAP2 and activity of the secreted Sap2 gene product, a known virulence factor, in most isolates of C. albicans. One isolate of the fungus showed an opposite response.

New agents for the treatment of systemic fungal infections – current status

Systemic antifungal chemotherapy is enjoying its most dynamic era. More antifungal agents are under development than ever before, including agents in entirely new classes. Major goals of current investigations are to identify compounds with a wide spectrum of activity, minimal toxicity and a high degree of target specificity. The antifungal drugs in development include new azoles {voriconazole, posaconazole (formerly SCH-56592), ravuconazole (formerly BMS-207147)}, lipid formulations of amphotericin B, a lipid formulation of nystatin, echinocandins {anidulafungin (formerly, LY-303366, VER-002), caspofungin (formerly MK-991), micafungin (formerly FK-463)}, antifungal peptides other than echinocandins, and sordarin derivatives. This discussion reviews the currently available antifungal agents and summarises the developmental issues that surround these new systemic antifungal drugs.

Amphotericin-B-mediated reactivation of latent HIV-1 infection

To date, attempts to eliminate HIV-1 infection from its latent reservoirs, a prerequisite for the development of a curative treatment strategy for HIV-1 infection, have been unsuccessful. We demonstrate that the FDA approved antifungal agent amphotericin B efficiently reactivates HIV-1 infection in THP89GFP cells, a model of HIV-1 latency in macrophages. Although amphotericin B does not directly reactivate latent HIV-1 infection in T cells (e.g., J89GFP), amphotericin-B-stimulated macrophages (THP89GFP cells or primary macrophages) when cocultured with J89GFP cells can induce HIV-1 reactivation in these cells in trans. Because of the close proximity of antigen presenting macrophages and T cells in the primary lymphoid organs, such interaction between antigen presenting macrophages and T cells are frequent, and it seems reasonable to assume that trans-reactivation strategies hold promise to also reactivate latent HIV-1 infection in vivo.

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.

Case report: effect of antileishmanial treatment on hepatitis C viraemia in avisceral leishmaniasis patient with chronic hepatitis C

We describe a case of Mediterranean visceral leishmaniasis (VL) in a patient with pre-existing chronic hepatitis C, which caused high hepatitis C virus (HCV) plasma concentration and was followed by a rapidly growing hepatocellular carcinoma (HCC). The high HCV load was drastically and persistently reduced soon after treatment with liposomal amphotericin B suggesting a cause-effect interaction. Some data suggest that liposomal amphotericin B may have an immunomodulatory effect. VL may directly affect the liver function, but HCC has never been reported as a consequence of the disease. This case suggests that VL causes an increase in HCV replication, but, although the growth of the HCC can be defined as exceptional, a relationship with VL is not proven.

Multidrug-resistant Trichosporon asahii infection of nongranulocytopenic patients in three intensive care units

Trichosporon asahii (Trichosporon beigelii) infections are rare but have been associated with a wide spectrum of clinical manifestations, ranging from superficial involvement in immunocompetent individuals to severe systemic disease in immunocompromised patients. We report on the recent recovery of T. asahii isolates with reduced susceptibility in vitro to amphotericin B (AMB), flucytosine, and azoles from six nongranulocytopenic patients who exhibited risk factors and who developed either superficial infections (four individuals) or invasive infections (two individuals) while in intensive care units. The latter two patients responded clinically and microbiologically to AMB treatment. All six isolates were closely related according to random amplified polymorphic DNA studies and showed 71% similarity by amplified fragment length polymorphism analysis, suggesting a common nosocomial origin. We also review the literature pertaining to T. asahii infections and discuss the salient characteristics of this fungus and recent taxonomic proposals for the genus.

Activities of hexadecylphosphocholine (miltefosine), AmBisome, and sodium stibogluconate (Pentostam) against Leishmania donovani in immunodeficient scid mice

In both scid and BALB/c mouse-Leishmania donovani models, hexadecyphosphocholine (miltefosine) and AmBisome had similar levels of activity. In contrast, sodium stibogluconate (Pentostam) was significantly less active against L. donovani in scid mice than in BALB/c mice. The in vitro anti-leishmanial activity of miltefosine was similar in peritoneal macrophages derived from both scid and BALB/c mice, whereas Pentostam and AmBisome were significantly more active in the latter.

PREEMPTIVE PROPHYLAXIS WITH A LIPID PREPARATION OF AMPHOTERICIN B FOR INVASIVE FUNGAL INFECTIONS IN LIVER TRANSPLANT RECIPIENTS REQUIRING RENAL REPLACEMENT THERAPY1

BACKGROUND

Posttransplant renal replacement therapy has been shown to be an independently significant risk factor for invasive fungal infections after liver transplantation. We assessed the efficacy of a lipid preparation of amphotericin B as prophylaxis for invasive fungal infections, directed toward liver transplant recipients requiring renal replacement therapy.

METHODS

A total of 148 patients transplanted between 1990 and 1997 received no antifungal prophylaxis. Since 1997, 38 patients underwent liver transplantation; antifungal prophylaxis with a lipid preparation of amphotericin B was used in patients requiring renal replacement therapy.

RESULTS

Fifteen percent (22 of 148) of the patients transplanted before 1997 required renal replacement therapy. In this cohort, the incidence of invasive fungal infections (36% vs. 7%, P=0.0007) and invasive aspergillosis (14% vs. 2%, P=0.02) was significantly higher in patients who required renal replacement therapy compared with those who did not. Since 1997, 29% (11 of 38) of the patients required renal replacement therapy and received antifungal prophylaxis. Invasive fungal infections occurred in 36% (8 of 22) of the patients who received no prophylaxis (patients before 1997), and 0% (0 of 11, P=0.03) in those who received antifungal prophylaxis (since 1997). Antifungal prophylaxis was independently associated with protection from fungal infection (P=0.017). No reduction in mortality with antifungal prophylaxis was documented.

CONCLUSION

Prophylaxis with a lipid preparation of amphotericin B was associated with a significant reduction in invasive fungal infections in high-risk liver transplant recipients, i.e., those requiring renal replacement therapy. However, no beneficial effect on survival could be documented.