Liposomal drug delivery systems for the treatment of leishmaniasis.

Human le ishmaniasis is a vector-borne, neglected infectious disease that is widely distributed in America, Africa, Europe, and Asia. Current therapy is based on old and toxic drugs, including antimonials, aminoglycosides, and amphotericin. As a neglected disease, investment in the development of new therapeutic molecules is scarce. Considering these aspects, the optimization of treatment through novel delivery systems for current therapeutic agents is an attractive alternative. The encapsulation into liposomes of drugs used in treating leishmaniasis increases the concentration of these molecules in macrophages, which may not only increase the chance of cure but also expand their therapeutic spectrum to include resistant Leishmania, as well as reducing toxicity since the drug is less exposed to healthy cells. The classical example is the liposomal formulation of amphotericin B, a well-established therapeutic option that uses liposomes to decrease the progression of renal failure in patients. However, loading other leishmanicidal drugs into liposomes, such as pentavalent antimonials, presents an opportunity for innovative and cheaper therapeutic options for the treatment of human leishmaniasis. This review aims to discuss liposomes as a drug delivery system for leishmanicidal drugs.

Case Report: In Situ and Systemic Immune Response to Mucosal Leishmaniasis in an HIV-Infected Patient.

In situ and systemic evaluations of the immune responses of HIV-infected patients to mucosal leishmaniasis have been poorly described. We describe a recently diagnosed HIV-infected patient with mucosal leishmaniasis who was characterized by a CD4 count of 85 cells/mm3 and nasal septum destruction resulting from pruritic and ulcerated nasal mucosa with crust formation and progression over 2 years. In situ and systemic immune evaluations of T cell activation, memory, and exhaustion were conducted using cytofluorometric assays, and sequencing of the Leishmania species was performed. The immune profile of HIV-infected patient with mucosal leishmaniasis shows a mixed Th1/Th2 pattern and an activated and exhausted status.

Lipid nanoparticles for amphotericin delivery in the treatment of American tegumentary leishmaniasis.

Leishmaniasis occurs in the five continents and represents a serious public health challenge, but is still a neglected disease, and the current pharmacological weaponry is far from satisfactory. Triglyceride-rich nanoparticles mimicking chylomicrons (TGNP) behave metabolically like native chylomicrons when injected into the bloodstream. Previously we have shown that TGNP as vehicle to amphothericin B (AB) for treatment of fungi infection showed reduced renal toxicity and lower animal death rates compared to conventional AB. The aim of the current study was to test the tolerability and effectiveness of the TGNP-AB preparation in a murine model of Leishmania amazonensis infection. The in vitro assays determined the cytotoxicity of TGNP-AB, AB, and TGNP in macrophages and promastigote forms and the leishmanicidal activity in infected macrophages. The in vivo toxicity tests were performed in healthy mice with increasing doses of TGPN-AB and AB. Then, animals were treated with 2.5 mg/kg/day of AB, 17.5 mg/kg/day of TGNP-AB, or TGNP three times a week for 4 weeks. TGNP-AB formulation was less cytotoxic for macrophages than AB. TGNP-AB was more effective than AB against the promastigotes forms of the parasite and more effective in reducing the number of infected macrophages and the number of amastigotes forms per cell. TGNP-AB-treated animals showed lower hepatotoxicity. In addition, TGNP-AB group showed a marked reduction in lesion size on the paws and parasitic load. The TGNP-AB preparation attained excellent leishmanicidal activity with remarkable lower drug toxicity at very high doses that, due to the toxicity-buffering properties of the nanocarrier, become fully tolerable.

Performance of a qualitative rapid chromatographic immunoassay to diagnose COVID-19 in patients in a middle-income country.

OBJECTIVES: We evaluated a rapid chromatographic immunoassay (IgG/IgM antibodies) and an ELISA assay to diagnose COVID-19 in patient sat two Brazilian hospitals. METHODS: A total of 122 subjects with COVID-19 were included: 106 SARS-COV-2 RT-PCR-positive patients and 16 RT-PCR-negative patients with symptoms and chest computed tomography (CT) consistent with COVID-19. Ninety-six historical blood donation samples were used as controls. Demographic and clinical characteristics were retrieved from electronic records. Sensitivity and specificity were calculated, as were their 95% binomial confidence intervals using the Clopper-Pearson method. All analyses were performed in R version 3.6.3. RESULTS: The sensitivity of the chromatographic immunoassay in all RT-PCR-positive patients, irrespective of the timing of symptom onset, was 85.8% (95% binomial CI 77.7% to 91.9%). This increased with time after symptom onset, and at >14 days was 94.9% (85.9% to 98.9%). The specificity was 100% (96.4% to 100%). 15/16 (94%) RT- PCR-negative cases tested positive. The most frequent comorbidities were hypertension and diabetes mellitus and the most frequent symptoms were fever, cough, and dyspnea. All RT-PCR-negative patients had pneumonia. The most frequent thoracic CT findings were ground glass changes (n = 11, 68%), which were bilateral in 9 (56%) patients, and diffuse reticulonodular infiltrates (n = 5, 31%). CONCLUSIONS: The COVID-19 rapid chromatographic immunoassay evaluated in this study had a high sensitivity and specificity using plasma, particularly after 14 days from symptom onset. ELISA and qualitative rapid chromatographic immunoassays can be used for the diagnosis of RT-PCR-negative patients.

Comparative study on liposomal amphotericin B and other therapies in the treatment of mucosal leishmaniasis: A 15-year retrospective cohort study.

BACKGROUND: Liposomal amphotericin B (L-AMB) has been used for mucosal leishmaniasis (ML), but comparative studies on L-AMB and other drugs used for the treatment of ML have not been conducted. The present study aimed to evaluate the outcome of patients with ML who were treated with L-AMB. METHODS: This is a 15-year retrospective study of Brazilian patients with a confirmed diagnosis of ML. The therapeutic options for the treatment of ML consisted of L-AMB, amphotericin B lipid complex (ABLC), deoxycholate amphotericin B (d-AMB), itraconazole, antimonial pentavalent, or pentamidine. Healing, cure rate and adverse effects (AEs) associated with the drugs used to treat this condition were analyzed. RESULTS: In 71 patients, a total of 105 treatments were evaluated. The outcome of the treatment with each drug was compared, and results showed that L-AMB was superior to other therapeutic regimens (P = 0.001; odds ratio [OR] = 4.84; 95% confidence interval [CI] = 1.78-13.17). d-AMB had worse AEs than other treatment regimens (P = 0.001, OR = 0.09; 95% CI = 0.09-0.43). Approximately 66% of the patients presented with AEs during ML treatment. Although L-AMB was less nephrotoxic than d-AMB, it was associated with acute kidney injury compared with other drugs (P <0.05). CONCLUSION: L-AMB was more effective than other therapies for the treatment of ML. However, a high incidence of toxicity was associated with its use. Therapeutic choices should be reassessed, and the development of new drugs is necessary for the treatment of ML.

Could kDNA-PCR in Peripheral Blood Replace the Examination of Bone Marrow for the Diagnosis of Visceral Leishmaniasis?

The aim of this study was to evaluate whether the molecular (kDNA-PCR) and parasitological diagnosis in peripheral blood (PB) could replace the invasive and painful bone marrow collection (BM) in the diagnosis of visceral leishmaniasis (VL). PB from suspected VL patients was evaluated by parasitological and molecular techniques using as the gold standard (GS) a combination of clinical, epidemiological, and immunochromatographic test (PB-rK39) results and parasitological examination of BM. Based on the GS, 38 samples from 32 patients were grouped: Group 1, 20 samples of VL cases, and Group 2, 18 samples of non-VL cases. In order to evaluate the parasitological and molecular techniques in PB, the samples were examined. From Group 1, PB kDNA-PCR was positive in 20 samples and in 19 of 20 in BM kDNA-PCR examination. However, the parasitological examination of buffy coat was insensitive, being able to detect only 4 cases from Group 1. All samples from Group 2 were negative. We concluded that, for the diagnosis of visceral leishmaniasis, the parasitological examination of peripheral blood was not useful; however, molecular diagnosis by kDNA-PCR, performed in peripheral blood, could be useful to replace the parasitological examination of bone marrow.

False-positive results of a rapid K39-based strip test and Chagas disease.

BACKGROUND: The definitive diagnosis of visceral leishmaniasis (VL) requires invasive procedures with demonstration of amastigotes in tissue or promastigotes in culture. Unfortunately, these approaches require laboratory materials not available in poor countries where the disease is endemic. The correct diagnosis of VL is important, and made more difficult by the fact that several common tropical diseases such as malaria, disseminated tuberculosis, and enteric fever share the same clinical presentation. Serological tests have been developed to replace parasitological diagnosis in the field. A commercially available K39-based strip test for VL has been developed for this purpose. The endemic area of leishmaniasis in Brazil overlaps the endemic area of Chagas disease, a disease that can cause false-positive serological test results. The aim of this study was to evaluate the incidence of false-positive exams using a rapid test for VL in patients with Chagas disease. METHODS: A rapid test based on the recombinant K39 antigen of Leishmania was used in: (1) 30 patients with confirmed Chagas disease, (2) 30 patients with a serological diagnosis of Chagas disease by ELISA, indirect immunofluorescence, indirect hemagglutination, and chemiluminescence, (3) 30 healthy patients from a non-endemic area as the control group, (4) 30 patients with confirmed VL, and (5) 20 patients with proved cutaneous leishmaniasis. RESULTS: The sensitivity and specificity of the rapid strip test were 100% when compared with healthy volunteers and those with confirmed Chagas disease. One false-positive result occurred in the group with Chagas disease diagnosed by serological tests (specificity of 96%). CONCLUSION: The rapid test based on recombinant K39 is a useful diagnostic assay, and a false-positive result rarely occurs in patients with a serological diagnosis of Chagas disease.