Increased level of soluble adenosine deaminase in bone marrow of visceral leishmaniasis patients: an inverse relation with parasite load.

Adenosine deaminase (ADA) which degrades adenosine to inosine, is known to be pro-inflammatory molecule in many diseases. Adenosine suppresses the functioning of the immune system and thus promotes dissemination of the parasite. In our previous finding, the level of soluble ADA in serum of visceral leishmaniasis (VL) was found to be increased as compared to healthy controls. However, it cannot be fairly interpreted unless their level is demonstrated at the disease site, where the parasite resides. We designed this study to correlate the level of soluble ADA (sADA) with parasitic load at the disease site i.e. bone marrow (BM). We found increased levels of sADA in BM as compared to the unaffected BM. Furthermore, a significant inverse correlation is observed between the parasite load and level of sADA at the disease site.

Impaired expression of CD26 compromises T-cell recruitment in human visceral leishmaniasis.

An inefficient Th1 response, coupled with skewed Th2 cytokine production, has been implicated to increase susceptibility to visceral leishmaniasis (VL) infection. The expression of the dipeptidyl peptidase Cd26 by polarized Th1 activates a chemokine cascade that recruits Th1 recruitment to the pathologic site. Here, we studied 42 patients with confirmed VL (mean age 24.80 ± 16.26 years; range 3-70 years; 25 males and 17 females), 30 endemic controls, and 10 nonendemic controls. We observed a decrease in constitutive and antigen-induced expression of CD26 on the T cells of VL patients. Soluble CD26 (sCD26) levels in serum and BM were also found to be significantly lower in VL patients. Following successful therapy, increased sCD26 expression was observed. Tuberculosis pleural effusion derived CCR5(+) CXCR3(+) effector T cells showed enhanced chemokine-driven migration in the presence of posttreatment BM aspirate containing high levels of sCD26. Moreover, T-cell migration could be inhibited by blocking RANTES, IP-10, and CD26 signaling from the posttreatment aspirate with Ab. Our results indicate that, in VL patients, impaired expression and secretion of CD26 compromises chemokine activation and thus T-cell recruitment, eventually resulting in a deficient state of local immunity at pathologic sites.

Regulatory T cells suppress T cell activation at the pathologic site of human visceral leishmaniasis.

Suppression of T cell response is thought to be involved in the pathogenesis of visceral leishmaniasis (VL). Regulatory T cell (Treg) mediated immune-suppression is reported in animal models of Leishmania infection. However, their precise role among human patients still requires pathologic validation. The present study is aimed at understanding the frequency dynamics and function of Treg cells in the blood and bone marrow (BM) of VL patients. The study included 42 parasitologically confirmed patients, 17 healthy contact and 9 normal bone marrow specimens (NBM). We show i) the selective accumulation of Treg cells at one of the disease inflicted site(s), the BM, ii) their in vitro expansion in response to LD antigen and iii) persistence after successful chemotherapy. Results indicate that the Treg cells isolated from BM produces IL-10 and may inhibit T cell activation in IL-10 dependent manner. Moreover, we observed significantly higher levels of IL-10 among drug unresponsive patients, suggesting their critical role in suppression of immunity among VL patients. Our results suggest that IL-10 plays an important role in suppression of host immunity in human VL and possibly determines the efficacy of chemotherapy.

Phase 4 pharmacovigilance trial of paromomycin injection for the treatment of visceral leishmaniasis in India.

Background. A phase 3 study demonstrated the safety and efficacy of paromomycin (paromomycin IM injection) for treatment of VL in an inpatient setting. Methods. This phase 4 study was conducted to assess the safety and efficacy of paromomycin in children and adults in an outpatient setting in Bihar, India. Results. This study enrolled 506 adult and pediatric patients. Of the 494 patients in the intent-to-treat (ITT) population, 98% received a full course of treatment. The overall study completion rate was 94% (462/494) for the ITT population and 96% (461/479) for the efficacy-evaluable (EE) population. Initial clinical cure was 99.6%, and final clinical cure 6 months after treatment was 94.2%. Grade 3 or 4 adverse events occurred in 5% of patients; events with a frequency of ≥1% were increases in alanine aminotransferase and aspartate aminotransferase. Conclusions. This study confirms the safety and efficacy of paromomycin to treat VL in an outpatient setting.

Injectable paromomycin for Visceral leishmaniasis in India.

BACKGROUND: Visceral leishmaniasis (kala-azar) affects large, rural, resource-poor populations in South Asia, Africa, and Brazil. Safe, effective, and affordable new therapies are needed. We conducted a randomized, controlled, phase 3 open-label study comparing paromomycin, an aminoglycoside, with amphotericin B, the present standard of care in Bihar, India. METHODS: In four treatment centers for visceral leishmaniasis, 667 patients between 5 and 55 years of age who were negative for the human immunodeficiency virus and had parasitologically confirmed visceral leishmaniasis were randomly assigned in a 3:1 ratio to receive paromomycin (502 patients) at a dose of 11 mg per kilogram of body weight intramuscularly daily for 21 days or amphotericin B (165 patients) at a dose of 1 mg per kilogram intravenously every other day for 30 days. Final cure was assessed 6 months after the end of treatment; safety assessments included daily clinical evaluations and weekly laboratory and audiometric evaluations. Noninferiority testing was used to compare 6-month cure rates, with a chosen margin of noninferiority of 10 percentage points. RESULTS: Paromomycin was shown to be noninferior to amphotericin B (final cure rate, 94.6% vs. 98.8%; difference, 4.2 percentage points; upper bound of the 97.5% confidence interval, 6.9; P<0.001). Mortality rates in the two groups were less than 1%. Adverse events, which were more common among patients receiving paromomycin than among those receiving amphotericin B (6% vs. 2%, P=0.02), included transient elevation of aspartate aminotransferase levels (>3 times the upper limit of the normal range); transient reversible ototoxicity (2% vs. 0, P=0.20); and injection-site pain (55% vs. 0, P<0.001); and in patients receiving amphotericin B, as compared with those receiving paromomycin, nephrotoxicity (4% vs. 0, P<0.001), fevers (57% vs. 3%), rigors (24% vs. 0, P<0.001), and vomiting (10% vs. <1%, P<0.001). CONCLUSIONS: Paromomycin was shown to be noninferior to amphotericin B for the treatment of visceral leishmaniasis in India. (ClinicalTrials.gov number, NCT00216346.)

A phase II dose-ranging study of sitamaquine for the treatment of visceral leishmaniasis in India.

This randomized, open label, multicenter study assessed the dose-response and safety profile for oral sitamaquine in 120 Indian subjects with visceral leishmaniasis (VL). Patients aged 5-64 years (mean age 21.2 years) received one of four sitamaquine doses (1.5, 1.75, 2.0, or 2.5 mg kg(-1) day(-1)) daily for 28 days. At Day 180 in the intent-to-treat population, final cure (primary efficacy outcome) was achieved in 92 of 106 (87%) patients overall and 25 of 31 (81%), 24 of 27 (89%), 23 of 23 (100%), and 20 of 25 (80%) patients at doses of 1.5, 1.75, 2.0, or 2.5 mg kg(-1) day(-1) sitamaquine, respectively. Sitamaquine was generally well tolerated. The most common adverse events during the active treatment phase were vomiting (8% [10 of 120]), dyspepsia (8% [9 of 120]) and cyanosis (3% [4 of 120]). Nephrotic syndrome (3% [3 of 120]) and glomerulonephritis (2% [2 of 120]) were also reported and require further investigation. Oral sitamaquine demonstrated efficacy in Indian VL and was well tolerated.