Cellular infiltrate in cutaneous leishmaniasis lesions and therapeutic outcome

Abstract Background: The treatment of cutaneous leishmaniasis is a challenge. A better understanding of the in situ mechanisms involved in the evolution and cure of the disease is essential for the development of new therapies. Objective: Correlate histopathological and immunological characteristics of cutaneous leishmaniasis lesions with clinical outcome after different treatment regimens. Methods: The authors analyzed cellular infiltration and immunohistochemistry staining for CD4, CD8 and IL-17 in biopsy samples from 33 patients with cutaneous leishmaniasis before treatment. All patients were recruited in a randomized clinical trial at Corte de Pedra (Bahia-Brazil) and assigned to receive Glucantime®, Glucantime® + Oral Tamoxifen or Glucantime® + Topical Tamoxifen. Patients were followed for 2 to 6 months to define disease outcome. Results: A similar expression of CD4, CD8 and IL-17 was observed in lesion samples regardless of clinical outcome. In general, a higher amount of CD8 cells were observed compared with CD4 cells. An important observation was that all patients whose cellular infiltrate did not contain plasma cells were cured after treatment. Study limitations: Isolated quantification of TCD8 and IL-17 using immunohistochemistry is insufficient to analyze the role of these molecules in the immunopathogenesis of cutaneous leishmaniasis. In addition, the expansion of the immunohistochemistry panel would allow a more complete analysis of the immune response in situ. Conclusions: The absence of plasma cells in cutaneous leishmaniasis lesions was related to a favorable therapeutic outcome.

Cellular infiltrate in cutaneous leishmaniasis lesions and therapeutic outcome.

BACKGROUND: The treatment of cutaneous leishmaniasis is a challenge. A better understanding of the in situ mechanisms involved in the evolution and cure of the disease is essential for the development of new therapies. OBJECTIVE: Correlate histopathological and immunological characteristics of cutaneous leishmaniasis lesions with clinical outcome after different treatment regimens. METHODS: The authors analyzed cellular infiltration and immunohistochemistry staining for CD4, CD8 and IL-17 in biopsy samples from 33 patients with cutaneous leishmaniasis before treatment. All patients were recruited in a randomized clinical trial at Corte de Pedra (Bahia-Brazil) and assigned to receive Glucantime®, Glucantime® + Oral Tamoxifen or Glucantime® + Topical Tamoxifen. Patients were followed for 2 to 6 months to define disease outcome. RESULTS: A similar expression of CD4, CD8 and IL-17 was observed in lesion samples regardless of clinical outcome. In general, a higher amount of CD8 cells were observed compared with CD4 cells. An important observation was that all patients whose cellular infiltrate did not contain plasma cells were cured after treatment. STUDY LIMITATIONS: Isolated quantification of TCD8 and IL-17 using immunohistochemistry is insufficient to analyze the role of these molecules in the immunopathogenesis of cutaneous leishmaniasis. In addition, the expansion of the immunohistochemistry panel would allow a more complete analysis of the immune response in situ. CONCLUSIONS: The absence of plasma cells in cutaneous leishmaniasis lesions was related to a favorable therapeutic outcome.

A Double-blind, Randomized Trial to Evaluate Miltefosine and Topical Granulocyte Macrophage Colony-stimulating Factor in the Treatment of Cutaneous Leishmaniasis Caused by Leishmania braziliensis in Brazil.

BACKGROUND: The treatment of cutaneous leishmaniasis (CL) in Brazil using pentavalent antimony (Sbv) is associated with a high rate of failure. Miltefosine has proven efficacy for CL caused by L. braziliensis, with a cure rate (CR) of 75%. A combined treatment with granulocyte macrophage colony-stimulating factor (GM-CSF) and miltefosine could increase CR and decrease healing time. METHODS: A randomized, double-blind clinical trial to evaluate the efficacy of miltefosine combined with topical GM-CSF (M + GM) vs miltefosine and placebo (M + P) vs Sbv in 133 patients with CL caused by L. braziliensis in Bahia, Brazil. RESULTS: The final CR at 180 days after the initiation of treatment was 44.4% in the Sbv group, 76.6% in the M + P group (P = .003 vs Sbv), and 75.6% in the M + GM group (P = .004 vs Sbv). The median healing time for cure was 102 days for the Sbv group and 60 days for both miltefosine groups (P = .0009). During the 6-month follow-up period, 4 relapses were documented: 1 in the Sbv group, 1 in the M + P group, and 2 in the M + GM group. Mild adverse events occurred in 65% of patients from the Sbv group, 76% and 79% from the M + P and M + GM groups respectively. CONCLUSIONS: Miltefosine is more effective than Sbv for the treatment of CL caused by L. braziliensis in Brazil and accelerates the healing time. Association with GM-CSF does not improve therapeutic outcome. CLINICAL TRIALS REGISTRATION: NCT03023111.

Association of miltefosine with granulocyte and macrophage colony-stimulating factor (GM-CSF) in the treatment of cutaneous leishmaniasis in the Amazon region: A randomized and controlled trial.

OBJECTIVES: To compare topical granulocyte and macrophage colony-stimulating factor (GM-CSF) and miltefosine (G + M) versus placebo and miltefosine (P + M) or parenteral meglumine antimoniate (MA) in the treatment of 150 patients with cutaneous leishmaniasis (CL) caused by Leishmania guyanensis in the Amazon. DESIGN: A randomized and double-blinded clinical trial. RESULTS: At 90 days after the initiation of therapy, the cure rates were 66%, 58%, and 52% for the groups P + M, G + M, and MA, respectively (p > 0.05). Cure rates at 180 days did not differ. Healing time was similar in the 3 groups, but faster in the MA group as compared to the G + M group (p = 0.04). Mild and transitory systemic adverse events were frequent in all groups (above 85%). Nausea (85%) and vomiting (39%) predominated in the miltefosine groups and arthralgia (51%) and myalgia (48%) in the MA group. One patient (group MA) stopped treatment after presenting with fever, exanthema, and severe arthralgia. CONCLUSIONS: Miltefosine did not present a higher cure rate than MA, and the association of GM-CSF did not improve the therapeutic response. Nevertheless, because of its less toxicity, easier administration, and a similar cure rate when compared with MA, miltefosine should remain as one of the main drugs for treating CL due to L. guyanensis. (Clinicaltrials.gov Identifier NCT03023111).

Diabetes Modifies the Clinic Presentation of Cutaneous Leishmaniasis.

BACKGROUND: Cutaneous leishmaniasis (CL) caused by L. braziliensis is characterized by 1 or multiple well-limited ulcerated lesions. Diabetes mellitus (DM) impairs neutrophil and monocyte function, and there is a report of vegetative lesions in a patient with both diseases in Morocco. Here we evaluate the influence of DM on clinical manifestations, immune response, and in the treatment of CL. METHODS: The participants were 36 DM patients with CL and 36 patients with CL without DM, matched by age and gender. The diagnosis of CL was performed by documentation of DNA of L. braziliensis by polymerase chain reaction in the lesion biopsy and histopathologic findings. All patients were treated with Glucantime (Sanofi-Aventis) 20 mg/kg of weight per day for 20 days. RESULTS: There was no difference in the majority of the clinical variables between the groups, and the cure rate in patients with CL and DM (67%) was similar to that observed in CL patients (56%; P ˃ .05). The most important finding was the documentation that 36% of the patients with DM and CL had atypical cutaneous lesions characterized by large superficial ulcers without defined borders. High levels of interferon-γ, tumor necrosis facor, and interleukin-1ß were detected in the supernatants of mononuclear cells stimulated with Leishmania antigen in patients with DM and atypical CL. Moreover, while cure was observed in only 33% of the patients with DM and atypical CL lesions, it was observed in 85% of patients with typical lesions (P < .05). CONCLUSIONS: DM modifies the clinical presentation of CL, enhances pro-inflammatory cytokine production, and impairs response to antimony therapy.

Evaluation of the Ability of Miltefosine Associated with Topical GM-CSF in Modulating the Immune Response of Patients with Cutaneous Leishmaniasis.

Cutaneous leishmaniasis (CL) due to L. braziliensis is associated with an exaggerated inflammatory response and tissue damage. Miltefosine is more effective than pentavalent antimony (Sbv) in the treatment of CL, and here, we evaluate the ability of Sbv, miltefosine, and GM-CSF administered intravenously, orally, or topically, respectively, to modify the immune response. Patients were treated with miltefosine plus GM-CSF, miltefosine plus placebo, or Sbv. Mononuclear cells were stimulated with soluble Leishmania antigen (SLA) on day 0 and day 15 of therapy, and cytokine levels were determined in supernatants by ELISA. The lymphocyte proliferation and oxidative burst were evaluated by flow cytometry, and the degree of infection and Leishmania killing by optical microscopy. Proliferation of CD4+ T cells were enhanced in patients using miltefosine and in CD8+ T cells when GM-CSF was associated. Enhancement in the oxidative burst occurred in the miltefosine plus GM-CSF group on day 15 of therapy. Moreover, the number of L. braziliensis in infected monocytes on day 15 as well as the percentage of infected cells was lower after 48- and 72-hour culture in cells from patients treated with miltefosine plus GM-CSF. In addition to the ability of miltefosine to kill Leishmania, the changes in the immune response caused by miltefosine and GM-CSF may increase the cure rate of CL patients using these drugs.

Mononuclear Phagocyte Activation Is Associated With the Immunopathology of Psoriasis.

Psoriasis is a chronic, inflammatory disease affecting the skin and joints. The pathogenesis of this disease is associated with genetic, environmental and immunological factors, especially unbalanced T cell activation and improper keratinocyte differentiation. Psoriatic lesion infiltrate is composed of monocytes and T cells, and most studies have focused on the participation of T cells in the pathogenesis of this disease. Here we investigated the contribution of mononuclear phagocytes in the immunopathology observed in psoriatic patients. Significant increases in the levels of TNF, IL-1ß, CXCL9, as well as the soluble forms of CD14 and CD163, were observed within the lesions of psoriatic patients compared to skin biopsies obtained from healthy individuals. Moreover, we found an association between the levels of CCL2, a monocyte attractant chemokine, and disease severity. In conclusion, our findings suggest a potential role for mononuclear phagocytes in the pathogenesis of psoriasis.

Leishmania braziliensis Infection Enhances Toll-Like Receptors 2 and 4 Expression and Triggers TNF-α and IL-10 Production in Human Cutaneous Leishmaniasis.

Cutaneous leishmaniasis (CL) caused by infection with Leishmania braziliensis is characterized by an exaggerated inflammatory response that controls the parasite burden, but also contributes to pathology. While myeloid cells are required to eliminate the parasite, recent studies indicate that they may also participate in the inflammatory response driving disease progression. The innate immune response to leishmania is driven in part by the Toll-like receptors (TLRs) TLR2, TLR4, and TLR9. In this study, we used flow cytometric analysis to compare TLR2 and TLR4 expression in monocyte subsets (classical, intermediate, and non-classical) from CL patients and healthy subjects (HS). We also determined if there was an association of either the pro-inflammatory cytokine TNF or the anti-inflammatory cytokine IL-10 with TLR2 or TLR4 expression levels after L. braziliensis infection. In vitro infection with L. braziliensis caused CL monocytes to up-regulate TLR2 and TLR4 expression. We also found that intermediate monocytes expressed the highest levels of TLR2 and TLR4 and that infected monocytes produced more TNF and IL-10 than uninfected monocytes. Finally, while classical and intermediate monocytes were mainly responsible for TNF production, classical monocytes were the main source of IL-10. Collectively, our studies revealed that up-regulated TLR2/4 expression and TNF production by intermediate/inflammatory subsets of monocytes from patients correlates with detrimental outcome of cutaneous leishmaniasis.

Evaluation of monocyte subsets and markers of activation in leprosy reactions.

Understanding host immune pathways associated with tissue damage during reactions are of upmost importance to the development of immune intervention strategies. The participation of monocytes in leprosy reactions was evaluated by determining the frequency of monocyte subsets and the degree of cellular activation through the expression of MHCII and the co-stimulatory molecules CD40, CD80, CD86. Leprosy subjects with or without reactions were included in this cross-sectional study. Peripheral blood mononuclear cell were isolated and stained ex vivo to determine monocyte subsets and the degree of cellular activation by flow cytometry. Intermediate monocytes were increased in leprosy patients with reactions when compared to patients without reactions. Although no difference was detected in the frequency of monocyte subsets between type 1 and 2 reactions, the expression of CD80 was increased in monocytes from patients with type 1 reactions and CD40 was higher in paucibacillary subjects presenting type 1 reactions. Moreover, CD86 and MHC II expression were higher in intermediate monocytes when compared to the other subsets in leprosy reaction types 1 and 2. Intermediate monocyte activation with CD86 and MHCII expression is involved with both type 1 and 2 reactions, whereas CD80 and CD40 expression is related to type 1 reactions.

Early Suppression of Macrophage Gene Expression by Leishmania braziliensis.

Leishmania braziliensis is an intracellular parasite that resides mostly in macrophages. Both the parasite genome and the clinical disease manifestations show considerable polymorphism. Clinical syndromes caused by L. braziliensis include localized cutaneous (CL), mucosal (ML), and disseminated leishmaniasis (DL). Our prior studies showed that genetically distinct L. braziliensis clades associate with different clinical types. Herein, we hypothesized that: (1) L. braziliensis induces changes in macrophage gene expression that facilitates infection; (2) infection of macrophages with strains associated with CL (clade B), ML (clade C), or DL (clade A) will differentially affect host cell gene expression, reflecting their different pathogenic mechanisms; and (3) differences between the strains will be reflected by differences in macrophage gene expression after initial exposure to the parasite. Human monocyte derived macrophages were infected with L. braziliensis isolates from clades A, B, or C. Patterns of gene expression were compared using Affymetrix DNA microarrays. Many transcripts were significantly decreased by infection with all isolates. The most dramatically decreased transcripts encoded proteins involved in signaling pathways, apoptosis, or mitochondrial oxidative phosphorylation. Some transcripts encoding stress response proteins were up-regulated. Differences between L. braziliensis clades were observed in the magnitude of change, rather than the identity of transcripts. Isolates from subjects with metastatic disease (ML and DL) induced a greater magnitude of change than isolates from CL. We conclude that L. braziliensis enhances its intracellular survival by inhibiting macrophage pathways leading to microbicidal activity. Parasite strains destined for dissemination may exert a more profound suppression than less invasive L. braziliensis strains that remain near the cutaneous site of inoculation.

Tamoxifen and meglumine antimoniate combined therapy in cutaneous leishmaniasis patients: a randomised trial.

OBJECTIVES: There is a clear need for new strategies of leishmaniasis treatment. This work was conducted to evaluate the efficacy of the co-administration of tamoxifen and meglumine antimoniate (SbV ) in a phase II pilot clinical trial in localised cutaneous leishmaniasis patients. METHODS: A randomised controlled pilot clinical trial was conducted to evaluate the efficacy and safety of oral (40 mg/day for 20 days) or topical tamoxifen (0.1% tamoxifen citrate for 20 days) combined with meglumine antimoniate (20 mg SbV /kg/day for 20 days) vs. a standard SbV protocol (20 mg/kg/day for 20 days) for the treatment of cutaneous leishmaniasis. Primary outcome was complete epithelisation of the lesion 6 months after the end of treatment. Secondary outcomes were lesion healing 2 months after the end of treatment and frequency and severity of adverse events. RESULTS: A total of 38 subjects were included in the trial, 15 were treated with standard SbV and 23 with the combination of tamoxifen and SbV . Of the patients treated with the co-administration scheme, 12 received tamoxifen orally and 11 were treated with topical tamoxifen. Tamoxifen administered by the oral or topical routes was well tolerated. Cure rates 6 months after the end of treatment per intention to treat were 40% in the group treated with the standard SbV scheme, and 36.4% and 58%, respectively, for groups treated with SbV plus topical or oral tamoxifen. CONCLUSIONS: In the doses and schemes used in this study, co-administration of oral tamoxifen and SbV resulted in higher cure rates in comparison with the standard scheme of treatment, although not to statistically significant levels.

Viral Co-infection and Leprosy Outcomes: A Cohort Study.

BACKGROUND: The role of the host immunity in determining leprosy clinical forms and complications is well recognized, implying that changes in the immune status may interfere with several aspects of the disease. Therefore, we hypothesized that the presence of viral co-infections and associated immunological changes will have a clinical impact on leprosy outcomes. The aim of our study was to determine the clinical impact of human immunodeficiency virus (HIV), human T cell lymphotrophic virus type 1 (HTLV-1), hepatitis B virus (HBV) and hepatitis C virus (HCV) co-infection on the development of reactions, neuritis, neuropathy and relapses. METHODOLOGY/PRINCIPAL FINDINGS: Cohort study in 245 leprosy subjects from Bahia, Brazil. Patients were followed from the time of diagnosis until at least the end of multidrug therapy. Viral co-infection was detected in 36 out of the 245 patients (14.7%). Specific co-infection rates were 10.6% for HBV, 2.9% for HIV, 2.5% for HTLV-1 and 0.8% for HCV. All four groups of co-infected patients had higher rates of neuritis and nerve function impairment compared to non co-infected leprosy subjects. The relapse rate was also higher in the co-infected group (8.3%) versus patients without co-infection (1.9%); relative risk 4.37, 95% confidence interval 1.02-18.74. CONCLUSIONS/SIGNIFICANCE: Leprosy patients should be screened for HBV, HCV, HIV and HTLV-1 co-infections. Besides contributing to better health care, this measure will facilitate the early detection of severe complications through targeting of higher risk patients.

Intermediate monocytes contribute to pathologic immune response in Leishmania braziliensis infections.

Ulcer development in patients with cutaneous leishmaniasis (CL) caused by Leishmania braziliensis is associated with high levels of tumor necrosis factor (TNF). We found that early after infection, before ulcer development, the frequency of CD16(+) (both intermediate [CD14(+)CD16(+)] and nonclassical [CD14(dim)CD16(+)]) monocytes was increased in the peripheral blood of patients with L. braziliensis, compared with uninfected controls. These results suggest that CD16(+) monocytes might promote disease. Also, we found that intermediate monocytes expressed CCR2 and that increased levels of CCL2 protein were present in lesions from patients, suggesting that intermediate monocytes are more likely than nonclassical monocytes to migrate to the lesion site. Finally, we found that the intermediate monocytes produced TNF. Our results show that intermediate monocytes are increased in frequency soon after infection; express CCR2, which would promote their migration into the lesions; and, owing to their production of TNF, can enhance the inflammatory response.

Clinical and immunological outcome in cutaneous leishmaniasis patients treated with pentoxifylline.

Pentoxifylline is a tumor necrosis factor-α (TNF-α) inhibitor that also attenuates the immune response and decreases tissue inflammation. The association of pentoxifylline with antimony improves the cure rate of mucosal and cutaneous leishmaniasis. In this randomized and double blind pilot trial, cure rate was higher, although not significant, in patients who received antimony plus pentoxifylline than in those patients receiving antimony plus placebo. A significant decrease in TNF-α and interferon-γ (IFN-γ) levels during therapy was more pronounced in the antimony plus pentoxifylline group, whereas CCL-3 (Chemokine [C-C motif] ligand 3) decreased similarly in both groups. The increased levels of CXCL-9 (Chemokine [C-X-C motif] ligand 9) during therapy were lower in the antimony plus pentoxifylline group. Therapy with pentoxifylline modifies cytokines and chemokines production, which may be associated with therapeutic outcome.

Association of treatment of American cutaneous leishmaniasis prior to ulcer development with high rate of failure in northeastern Brazil.

Cure rates for American cutaneous leishmaniasis (ACL) range between 60% and 90%. Early evidence suggests lower cure rates for early ACL before the development of the ulceration. We evaluated risk factors for treatment failure in patients with early and classic ulcerative ACL. Patients (n = 136) were 13-60 years of age and had lesions with a duration of 15-90-days. Patients were treated with antimony (20 mg/kg/day for 20 days). The primary outcome was lesion cure by 90 days without recurrence. Patients with early ACL (n = 16) had papules, nodules, plaques, or superficial ulcerations with less than 30 days of illness. Patients with classic ulcerative ACL (n = 120) had ulcerated classic lesions, longer duration, larger lesions, and higher levels of interferon-gamma and tumor necrosis factor-alpha (P < or = 0.01 for all comparisons). Ulcerated lesions were associated with a lower treatment failure rate compared with early ACL (25.8% versus 75.0%; P < 0.001). Early treatment of ACL does not prevent lesion ulceration and is associated with higher rates of treatment failure.

Características da reação tipo 1 e associação com vírus B e C da hepatite na hanseníase / Type 1 reaction in leprosy: characteristics and association with hepatitis B and C viruses

O episódio reacional tipo 1 ou reação reversa é ocorrência inflamatória aguda que atinge a pele e nervos periféricos, encontrada em até 30 por cento dos pacientes com hanseníase, sendo causa comum de incapacidade física. Fatores de risco associados incluem uso de poliquimioterapia e infecções virais. Neste estudo, foram avaliados 620 pacientes com hanseníase. Reação reversa foi diagnosticada em 121 (19,5 por cento) casos, sendo mais freqüente nos indivíduos borderlines (48 por cento). Início da poliquimioterapia foi considerado fator de risco para reação reversa, com 52 por cento dos casos apresentando o primeiro episódio neste momento. Neurite foi documentada em 73 por cento dos casos. A presença de vírus B ou C da hepatite foi documentada em 9 por cento de 55 pacientes com reação reversa e em nenhum dos 57 pacientes sem reação (p = 0, 026; teste exato de Fisher), sugerindo possível papel destes agentes como fatores de risco para desenvolvimento de reação reversa na hanseníase.

Type 1 reaction or reversal reaction is an acute inflammatory episode in the skin and peripheral nerves that is found in up to 30 percent of leprosy patients and commonly causes physical disabilities. Multidrug chemotherapy and viral infections are associated risk factors. In this study, 620 leprosy patients were evaluated. Reversal reactions were diagnosed in 121 cases (19.5 percent) and were most frequently found in borderline patients (48 percent). Starting on multidrug chemotherapy was considered to be a risk factor for reversal reaction: 52 percent of the cases presented their first episode at this time. Neuritis was found in 73 percent of the cases. The presence of hepatitis B or C virus was documented in 9 percent of the 55 patients with reversal reaction, while it was not detected in any of the 57 patients without reaction (p = 0.026, Fisher’s exact test). This suggests that these agents may have a role as risk factors for developing reversal reactions.

Oral pentoxifylline combined with pentavalent antimony: a randomized trial for mucosal leishmaniasis.

BACKGROUND: Mucosal leishmaniasis is associated with intense tissue damage and high tumor necrosis factor-alpha production. Therapeutic failure occurs in up to 42% of cases; patients who experience treatment failure will require >1 pentavalent antimony (Sb(v)) course or alternative drugs to achieve a cure. We previously showed that an inhibitor of tumor necrosis factor-alpha (pentoxifylline) combined with Sb(v) cured 90% patients refractory to monotherapy with Sb(v). METHODS: A double-blind, placebo-controlled trial involving 23 patients with mucosal leishmaniasis evaluated the efficacy of pentoxifylline when administered in association with Sb(v), compared with Sb(v) treatment alone. Eleven patients were randomized to receive Sb(v) plus oral pentoxifylline for 30 days, and 12 patients received Sb(v) plus oral placebo. The criterion for cure was a complete healing of lesions. RESULTS: All patients in the pentoxifylline group experienced a cure with 1 course of Sb(v), whereas 5 (41.6%) of 12 patients in the placebo group required a second course of Sb(v) (P=.037). The healing time +/- standard deviation in the pentoxifylline group was 83+/-36 days, compared with 145+/-99 days in the placebo group (P=.049). No relapses were documented in either group at the 2-year follow-up visit. CONCLUSIONS: The addition of pentoxifylline to Sb(v) in mucosal leishmaniasis reduces the healing time significantly and prevents the need for further courses of Sb(v).

Differential effects of antigens from L. braziliensis isolates from disseminated and cutaneous leishmaniasis on in vitro cytokine production.

BACKGROUND: Disseminated leishmaniasis is an emerging infectious disease, mostly due to L. braziliensis, which has clinical and histopathological features distinct from cutaneous leishmaniasis. METHODS: In the current study we evaluated the in vitro production of the cytokines IFN-gamma, TNF-alpha, IL-5 and IL-10 by peripheral blood mononuclear cells (PBMC) from 15 disseminated leishmaniasis and 24 cutaneous leishmaniasis patients upon stimulation with L. braziliensis antigens genotyped as disseminated leishmaniasis or cutaneous leishmaniasis isolates. RESULTS: Regardless of the source of L. braziliensis antigens, PBMC from cutaneous leishmaniasis patients produced significantly higher IFN-gamma than PBMC from disseminated leishmaniasis patients. Levels of TNF-alpha by PBMC from cutaneous leishmaniasis patients were significantly higher than disseminated leishmaniasis patients only when stimulated by genotyped cutaneous leishmaniasis antigens. The levels of IL-5 and IL-10 production by PBMC were very low and similar in PBMCs from both disseminated leishmaniasis and cutaneous leishmaniasis patients. The immune response of each patient evaluated by the two L. braziliensis antigens was assessed in a paired analysis in which we showed that L. braziliensis genotyped as disseminated leishmaniasis isolate was more potent than L. braziliensis genotyped as cutaneous leishmaniasis isolate in triggering IFN-gamma and TNF-alpha production in both diseases and IL-5 only in cutaneous leishmaniasis patients. CONCLUSION: This study provides evidence that antigens prepared from genotypically distinct strains of L. braziliensis induce different degrees of immune response. It also indicates that both parasite and host play a role in the outcome of L. braziliensis infection.

Decreased in situ expression of interleukin-10 receptor is correlated with the exacerbated inflammatory and cytotoxic responses observed in mucosal leishmaniasis.

Human infection with Leishmania braziliensis can lead to cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML). We hypothesize that the intense tissue destruction observed in ML is a consequence of an uncontrolled exacerbated inflammatory immune response, with cytotoxic activity. For the first time, this work identifies the cellular sources of inflammatory and antiinflammatory cytokines, the expression of effector molecules, and the expression of interleukin-10 (IL-10) receptor in ML and CL lesions by using confocal microscopy. ML lesions displayed a higher number of gamma interferon (IFN-gamma)-producing cells than did CL lesions. In both ML and CL, CD4+ cells represented the majority of IFN-gamma-producing cells, followed by CD8+ cells and CD4- CD8- cells. The numbers of tumor necrosis factor alpha-positive cells, as well as those of IL-10-producing cells, were similar in ML and CL lesions. The effector molecule granzyme A showed greater expression in ML than in CL lesions, while inducible nitric oxide synthase did not. Finally, the expression of IL-10 receptor was lower in ML than in CL lesions. Thus, our data identified distinct cytokine and cell population profiles for CL versus ML patients and provide a possible mechanism for the development of ML disease through the demonstration that low expression of IL-10 receptor is present in conjunction with a cytotoxic and inflammatory profile in ML.

Mecanismos de resposta imune às infecções / Immune response mechanisms to infections

O conhecimento dos principais mecanismos de defesa imune contra os diversos agentes infecciosos permite a compreensão da patogênese das doenças infectoparasitárias e das várias estratégias do hospedeiro e do parasita. O sistema imunológico atua numa rede de cooperação, envolvendo a participação de muitos componentes estruturais, moleculares e celulares. Nesse cenário encontra-se o delicado equilíbrio entre a saúde e a doença, em que tanto a deficiência quanto o exagero resultam em dano tecidual. Este artigo explora esses aspectos e algumas abordagens terapêuticas que surgem desse entendimento.