17-AAG Kills Intracellular Leishmania amazonensis while Reducing Inflammatory Responses in Infected Macrophages

Abstract

BackgroundLeishmaniasis is a neglected endemic disease with a broad spectrum of clinical manifestations. Pentavalent antimonials have been the treatment of choice for the past 70 years and, due to the emergence of resistant cases, the efficacy of these drugs has come under scrutiny. Second-line drugs are less efficacious, cause a range of side effects and can be costly. The formulation of new generations of drugs, especially in developing countries, has become mandatory.Methodology/Principal FindingsWe investigated the anti-leishmanial effect of 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), an HSP90 inhibitor, in vitro. This inhibitor is currently in clinical trials for cancer treatment; however, its effects against intracellular Leishmania remain untested. Macrophages infected with L. amazonensis were treated with 17-AAG (25–500 nM) and parasite load was quantified using optical microscopy. Parasite load declined in 17-AAG-treated macrophages in a dose- and time-dependent manner. Intracellular parasite death became irreversible after 4 h of treatment with 17-AAG, and occurred independent of nitric oxide (NO) and superoxide (O2 −) production. Additionally, intracellular parasite viability was severely reduced after 48 h of treatment. Interestingly, treatment with 17-AAG reduced pro-inflammatory mediator production, including TNF-α, IL-6 and MCP-1, yet IL-12 remained unaffected. Electron microscopy revealed morphological alterations, such as double-membrane vacuoles and myelin figures at 24 and 48 h after 17-AAG treatment.Conclusions/SignificanceThe HSP90 inhibitor, 17-AAG, possesses high potency under low dosage and reduces both pro-inflammatory and oxidative molecule production. Therefore, further studies are warranted to investigate this inhibitor’s potential in the development of new generations of anti-leishmanials.

Hsp90 blockade modulates bullous pemphigoid IgG-induced IL-8 production by keratinocytes

“…It remains unclear, why anti-BP IgG-induced IL-6 expression was not hampered in response to Hsp90 inhibition in our study, although NFκB is also known to be an important transcription factor for this cytokine and impairment of the inflammatory IL-6 pathway by Hsp90 blockade was previously demonstrated in various cell types (except keratinocytes) (Sato et al 2003;Wax et al 2003;Mitsiades et al 2006;Lang et al 2007;Ambade et al 2012;Petersen et al 2012;Shimp et al 2012a, b). Similar to our study, however, inhibition of NFκB by Bay-11-7082 suppressed the upregulation of different proinflammatory cytokines, but also did not compromise the IL-6 response in diaphragm muscle cells exposed to oxidative stress (Sigala et al 2011).…”

Low Resolution Structural Studies Indicate that the Activator of Hsp90 ATPase 1 (Aha1) of Leishmania braziliensis Has an Elongated Shape Which Allows Its Interaction with Both N- and M-Domains of Hsp90

“…The presence and importance of Hsp90 in trypanosomatids has been shown [3]–[6]. However little is known about the Hsp90 co-chaperones, including their in vivo presence and roles.…”

Wnt5a Signaling Promotes Host Defense againstLeishmania donovaniInfection

“…TEM evaluation of L. donovaniinfected mouse PMFs actually revealed an increased proportion of membranous vesicle homing to parasite-containing vacuoles upon Wnt5a pretreatment. TEM also demonstrated that these macrophages exhibit an increased proportion of PVs bearing a degradation phenotype characterized by the presence of laminated structures (39), as well as an overall diminished abundance of PVs. These findings are represented in Fig.…”