Localized Cutaneous Leishmaniasis Patients Research Articles

Senescence-related genes are associated with the immunopathology signature of American Tegumentary Leishmaniasis lesions and may predict progression to mucosal leishmaniasis.

The American Tegumentary Leishmaniasis (ATL) is caused by protozoans of the genus Leishmania and varies from mild localized cutaneous leishmaniasis (LCL) form to more severe manifestations such as the diffuse cutaneous leishmaniasis (DCL) form and the mucosal leishmaniasis (ML) form. Previously, we demonstrated the accumulation of senescent cells in skin lesions of patients with LCL. Moreover, lesional transcriptomic analyses revealed a robust co-induction of senescence and pro-inflammatory gene signatures, highlighting the critical role of senescent T cells in orchestrating pathology. In this work we hypothesized that senescent cells might operate differently among the ATL spectrum, potentially influencing immunopathological mechanisms and clinical outcome. We analysed previously published RNA-Seq datasets of skin biopsies of healthy subjects and lesional skin from DCL patients, LCL patients and LCL patients that, after treatment, progressed to mucosal leishmaniasis (MLP). Our findings demonstrate a robust presence of a CD8 T cell signature associated with both LCL and MLP lesions. Moreover, both inflammatory and cytotoxic signatures were significantly upregulated, showing a strong increase in MLP and LCL groups, but not DCL. The senescence signature was elevated between LCL and MLP groups, representing the only distinguishable signature of immunopathology between them. Interestingly, our analyses further revealed the senescence signature's capacity to predict progression from LCL to mucosal forms, which was not observed with other signatures. Both the senescence-signature score and specific senescence-associated genes demonstrated an increased capacity to predict mucosal progression, with correct predictions exceeding 97% of cases. Collectively, our findings contribute to a comprehensive understanding of immunosenescence in ATL and suggest that senescence may represent the latest and most important signature of the immunopathogenisis. This highlights its potential value in predicting disease severity.

Enhanced activation of blood neutrophils and monocytes in patients with Ethiopian localized cutaneous leishmaniasis in response to Leishmania aethiopica Neutrophil activation in Ethiopian cutaneous leishmaniasis

Recent studies suggest an essential role of the innate immune effector cells neutrophils and monocytes in protection or disease progression in the early course of Leishmania infection. In areas endemic for cutaneous leishmaniasis in Ethiopia most individuals are exposed to bites of infected sandflies. Still only a minor ratio of the inhabitants develops symptomatic disease. Neutrophils, followed by monocytes, are the first cells to be recruited to the site of Leishmania infection, the initial response of neutrophils to parasites appears to be crucial for the protective response and disease outcome. Our working hypothesis is that neutrophils and/or monocytes in localized cutaneous leishmaniasis (LCL) patients may have defects in function of innate immune cell that contribute to failure to parasite clearance that lead to establishment of infection.The response of cells in Ethiopian LCL patients and healthy controls to Leishmania aethiopica and to the Toll like receptor (TLR) agonists lipopolysaccharide (LPS) and macrophage activating lipopeptide-2 (MALP-2) was investigated by assessing the cell surface expression of CD62L (on neutrophil and monocyte) and CD66b (only on neutrophil), as well as reactive oxygen species (ROS) production by using whole blood-based assays in vitro. No impaired response of neutrophils and monocytes to the microbial constituents LPS and MALP-2 was observed. Neutrophils and monocytes from LCL patients responded stronger to Leishmania aethiopica in the applied whole blood assays than cells from healthy individuals. These experimental findings do not support the hypothesis regarding a possible dysfunction of neutrophils and monocytes in cutaneous leishmaniasis. On the contrary, these cells react stronger in LCL patients as compared to healthy controls. The differential response to L. aethiopica observed between LCL patients and healthy controls have the potential to serve as biomarker to develop FACS based diagnostic/ prognostic techniques for LCL.

Body location of “New World” cutaneous leishmaniasis lesions and its impact on the quality of life of patients in Suriname

Cutaneous leishmaniasis (CL) is a chronic skin infection caused by Leishmania parasites, causing single or multiple skin nodules and ulcers on the exposed body locations. Healing of lesions is followed by scar formation. Active and healed CL lesions may affect patient’s health related quality of life (HRQL). The aim of this study was to determine whether the body location of the leishmaniasis lesions affects the HRQL of localized CL patients in Suriname. The HRQL of 163 patients with CL was assessed by Skindex-29 and EQ-5D/VAS questionnaires. Forty-six patients out of the total study population also participated in a qualitative anthropological study involving in depth interviews. All patients were allocated in 4 groups in the following hierarchy: head and face, upper limbs, lower limbs and trunk. Patients with lesions on the lower limbs had significantly higher Skindex-29 scores, indicating worse HRQL, in the symptom scale compared to lesions on head/face and trunk. The lower limb group was more likely to report problems in the dimensions self-care, mobility, daily activities and pain/discomfort of the EQ-5D. Little to no social stigma was reported in the in-depth interviews. The findings of this study indicate that Surinamese patients with CL lesions located on the lower limbs had more impairment in HRQL than on other body locations. Stigma related to CL seems to be virtually absent in Suriname.

Resistance to inflammasome-mediated nitric oxide production is involved in Diffuse Cutaneous Leishmaniasis

Abstract Leishmania amazonensis is one of the etiological agents of Cutaneous Leishmaniasis in Brazil. Infected individuals can present different forms of the disease, such as the Localized Cutaneous Leishmaniasis (LCL), characterized by round papules in the skin and the Diffuse Cutaneous Leishmanisis (DCL), a more severe form of the disease, characterized by multiple nodules in the skin, which are full of parasites. We have reported the protective function of the NLRP3 inflammasome during L. amazonensis infection in mouse, thus we aimed to evaluate if the inflammasome is involved in the determination of the LCL or DCL disease. We observed that skin biopsies of patients with DCL lesions present upregulation of inflammasome genes such as ASC, CASP1 and IL18. However, IL-1b and IL-18 levels in the plasma of LCL and DCL patients were similar. We used in vitro and mouse models to evaluate if the inflammasome is involved in the determination of the LCL or DCL. Macrophages do not differ in their ability to produce inflammasome-dependent IL-1b after infection with LCL and DCL. The inflammasome is involved in the control of LCL proliferation, but DCL isolates bypass the restrictive function of this platform both in vitro and in vivo. Further analysis showed that DCL isolates are resistant to inflammasome-mediated nitric oxide production. These data suggest that the resistance to the inflammasome effector functions may underlie the development of controlled (LCL) or disseminated (DCL) Leishmaniasis. We conclude that parasite-intrinsic factors related to resistance to the inflammasome might determine the outcome L. amazonensis infection.

Inflammasome gene expression is associated with immunopathology in human localized cutaneous leishmaniasis

Localized cutaneous leishmaniasis (LCL) can ultimately progress to chronic ulcerated lesions with strong local inflammatory reactions. The functional role of certain inflammasomes in mediating inflammation caused by Leishmania braziliensis needs to be addressed. By combining PCR-array, quantitative real-time PCR and immunohistochemical analysis, we identified inflammasome genes, such as IL-1β, NLRP3, NLRP1, NLRC5, AIM2 and P2RX7, that were upregulated in LCL patients. Temporal gene expression studies showed that the early phase of LCL displayed increased NLRP3 and reduced AIM2 and NLRP1 expression, while the late stages showed increased AIM2 and NLRP1 and lower NLRP3 expression. Our findings also showed that AIM2, NLRP1, and P2RX7 promoted susceptibility to experimental L. braziliensis infection. These results highlight the importance of inflammasome machinery in human LCL and suggest that inflammasome machinery plays a role in the acute and chronic phases of the disease.

Annexin A1 Is Involved in the Resolution of Inflammatory Responses duringLeishmania braziliensisInfection

Leishmaniases are diseases caused by several Leishmania species. Leishmania (Viannia) braziliensis can cause localized cutaneous leishmaniasis (LCL), which heals spontaneously, or mucosal leishmaniasis (ML), characterized by chronic and intense inflammation and scanty parasitism. Annexin A1 (AnxA1) is a protein involved in modulation and resolution of inflammation through multiple mechanisms. In the present study, the role of AnxA1 was investigated in L. braziliensis-infected BALB/c mice. AnxA1 levels increased at the peak of tissue lesion and parasitism in infected mice. AnxA1 increased also after L. braziliensis infection of BALB/c (wild-type [WT]) bone marrow derived macrophages. Despite a lower parasite intake, parasite burden in bone marrow-derived macrophages from AnxA1-/- mice was similar to WT and associated with an early increase of TNF-α and, later, of IL-10. AnxA1-/- mice controlled tissue parasitism similarly to WT animals, but they developed significantly larger lesions at later stages of infection, with a more pronounced inflammatory infiltrate and increased specific production of IFN-γ, IL-4, and IL-10. AnxA1-/- mice also presented higher phosphorylation levels of ERK-1/2 and p65/RelA (NF-κB) and inducible NO synthase expression, suggesting that AnxA1 may be involved in modulation of inflammation in this model of experimental leishmaniasis. Finally, assessment of AnxA1 levels in sera from patients with LCL or ML revealed that ML patients had higher levels of serum AnxA1 than did LCL patients or control subjects. Collectively, these data indicate that AnxA1 is actively expressed during L. braziliensis infection. In the absence of AnxA1, mice are fully able to control parasite replication, but they present more intense inflammatory responses and delayed ability to resolve their lesion size.

Evaluation of anti-lived and anti-fixed Leishmania (Viannia) braziliensis promastigote IgG antibodies detected by flow cytometry for diagnosis and post-therapeutic cure assessment in localized cutaneous leishmaniasis

This study aims to investigate a flow cytometry performance–based methodology to detect anti-live (FC-ALPA-IgG) and anti-fixed (FC-AFPA-IgG) Leishmania (Viannia) braziliensis promastigote IgG as a means to monitor post-therapeutic cure of patients with localized cutaneous leishmaniasis (LCL). Serum samples from 30 LCL patients infected with L. (V.) braziliensis were assayed, comparing the IgG reactivity before and after specific treatment with pentavalent antimonial. Reactivities were reported as the percentage of positive fluorescent parasites (PPFP), using a PPFP of 60% as a cut-off value. In the serum dilution of 1:1024, the positive percentage of LCL serum sample for FC-ALPA-IgG and FC-AFPA-IgG was 86% and 90%, respectively, before treatment. Analysis of ∆PPFP that represents the difference between PPFP after and before treatment appeared as a new approach to monitor post-therapeutic IgG reactivity in LCL. Our data support the perspective of using FC-ALPA and FC-AFPA as a useful serologic tool for diagnosis and for post-therapeutic follow-up of LCL patients.

Transcriptome Patterns from Primary Cutaneous Leishmania braziliensis Infections Associate with Eventual Development of Mucosal Disease in Humans

IntroductionLocalized Cutaneous Leishmaniasis (LCL) and Mucosal Leishmaniasis (ML) are two extreme clinical forms of American Tegumentary Leishmaniasis that usually begin as solitary primary cutaneous lesions. Host and parasite factors that influence the progression of LCL to ML are not completely understood. In this manuscript, we compare the gene expression profiles of primary cutaneous lesions from patients who eventually developed ML to those that did not.MethodsUsing RNA-seq, we analyzed both the human and Leishmania transcriptomes in primary cutaneous lesions.ResultsLimited number of reads mapping to Leishmania transcripts were obtained. For human transcripts, compared to ML patients, lesions from LCL patients displayed a general multi-polarization of the adaptive immune response and showed up-regulation of genes involved in chemoattraction of innate immune cells and in antigen presentation. We also identified a potential transcriptional signature in the primary lesions that may predict long-term disease outcome.ConclusionsWe were able to simultaneously sequence both human and Leishmania mRNA transcripts in primary cutaneous leishmaniasis lesions. Our results suggest an intrinsic difference in the immune capacity of LCL and ML patients. The findings correlate the complete cure of L. braziliensis infection with a controlled inflammatory response and a balanced activation of innate and adaptive immunity.

Exposure of Phosphatidylserine on Leishmania amazonensis Isolates Is Associated with Diffuse Cutaneous Leishmaniasis and Parasite Infectivity

Diffuse cutaneous leishmaniasis (DCL) is a rare clinical manifestation of leishmaniasis, characterized by an inefficient parasite-specific cellular response and heavily parasitized macrophages. In Brazil, Leishmania (Leishmania) amazonensis is the main species involved in DCL cases. In the experimental model, recognition of phosphatidylserine (PS) molecules exposed on the surface of amastigotes forms of L. amazonensis inhibits the inflammatory response of infected macrophages as a strategy to evade the host immune surveillance. In this study, we examined whether PS exposure on L. amazonensis isolates from DCL patients operated as a parasite pathogenic factor and as a putative suppression mechanism of immune response during the infection. Peritoneal macrophages from F1 mice (BALB/c×C57BL/6) were infected with different L. amazonensis isolates from patients with localized cutaneous leishmaniasis (LCL) or DCL. DCL isolates showed higher PS exposure than their counterparts from LCL patients. In addition, PS exposure was positively correlated with clinical parameters of the human infection (number of lesions and time of disease) and with characteristics of the experimental infection (macrophage infection and anti-inflammatory cytokine induction). Furthermore, parasites isolated from DCL patients displayed an increased area in parasitophorous vacuoles (PV) when compared to those isolated from LCL patients. Thus, this study shows for the first time that a parasite factor (exposed PS) might be associated with parasite survival/persistence in macrophages and lesion exacerbation during the course of DCL, providing new insights regarding pathogenic mechanism in this rare chronic disease.

Hormone levels are associated with clinical markers and cytokine levels in human localized cutaneous leishmaniasis

Leishmaniasis is a serious health problem in several parts of the world, and localized cutaneous leishmaniasis (LCL) is the most frequent presentation of the tegumentary form of this disease cluster. Clinical presentations of leishmaniasis are influenced by both parasite and host factors, with emphasis on the host immune response. Alterations in plasma hormone levels have been described in many infections, and changes in hormone levels could be related to an imbalanced cytokine profile. In the present work, we evaluated a group of patients with LCL to determine changes in plasma hormone levels (cortisol, DHEA-S, estradiol, prolactin and testosterone) and their association with clinical markers of disease (lesion size, dose used to reach cure and time to cure) and with cytokines produced by PBMC stimulated by SLA (IFN-γ, IL-10 and TNF-α). Individuals with LCL exhibited lower plasma levels of DHEA-S, prolactin and testosterone compared with sex-matched controls, whereas levels of cortisol and estradiol were similar between patients and controls. Plasma levels of cortisol, estradiol or prolactin positively correlated with at least one clinical parameter. Cortisol and prolactin levels exhibited a negative correlation with levels of IFN-γ, whereas no correlation was observed with IL-10 or TNF-α levels. A decrease in DHEA-S levels was observed in male LCL patients when compared to male healthy controls. No other differences between the sexes were observed. Our results indicate a role for neuroendocrine regulation that restricts Th1 responses in human LCL. It is possible that, although impairing parasite killing, such neuroimmunomodulation may contribute to limiting tissue damage.

Chemokines and chemokine receptors coordinate the inflammatory immune response in human cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) includes different clinical manifestations displaying diverse intensities of dermal inflammatory infiltrate. Diffuse CL (DCL) cases are hyporesponsive, and lesions show very few lymphocytes and a predominance of macrophages. In contrast, localized CL (LCL) cases are responsive to leishmanial antigen, and lesions exhibit granulocytes and mononuclear cell infiltration in the early phases, changing to a pattern with numerous lymphocytes and macrophages later in the lesion. Therefore, different chemokines may affect the predominance of cell infiltration in distinct clinical manifestations. In lesions from LCL patients, we examined by flow cytometry the presence of different chemokines and their receptors in T cells, and we verified a higher expression of CXCR3 in the early stages of LCL (less than 30 days of infection) and a higher expression of CCR4 in the late stages of disease (more than 60 days of infection). We also observed a higher frequency of T cells producing IL-10 in the late stage of LCL. Using immunohistochemistry, we observed a higher expression of CCL7, CCL17 in lesions from late LCL, as well as CCR4 suggesting a preferential recruitment of regulatory T cells in the late LCL. Comparing lesions from LCL and DCL patients, we observed a higher frequency of CCL7 in DCL lesions. These results point out the importance of the chemokines, defining the different types of cells recruited to the site of the infection, which could be related to the outcome of infection as well as the clinical form observed.

The rK39 immunochromatic dipstick testing: A study for K39 seroprevalence in dogs and human leishmaniasis patients for possible animal reservoir of cutaneous and visceral leishmaniasis in endemic focus of Satluj river valley of Himachal Pradesh (India)

The newly recognized endemic focus of leishmaniasis in Satluj river valley of Himachal Pradesh (India) has both localized cutaneous leishmaniasis (LCL) and visceral leishmaniasis (VL) predominantly caused by Leishmania donovani. Rapid rK39 immunochromatographic dipstick test detects circulating antibodies to recombinant K39 antigen of L. donovani-infantum complex and is highly specific/sensitive in diagnosing symptomatic or asymptomatic infection in humans and dogs. The sera from two VL patients and 13 LCL patients, and 31 dogs were subjected to rK39 immunochromatographic dipstick testing with an aim to identify possible animal reservoir for leishmaniasis in this endemic focus. The positive rapid rK39 immunochromatographic dipstick test in 100% VL and 31.8% LCL patients, and 6.5% dogs suggests that both VL and LCL in this focus are apparently being caused by L. donovani-infantum and that reservoir infection is perhaps being chiefly maintained in asymptomatic dogs. However, it needs corroborative evidence in the form of in-vitro parasite cultivation and/or PCR studies for confirmation. A more elaborate study is recommended.

Characteristics of <italic>Leishmania spp.</italic> isolated from a mixed focus of cutaneous and visceral Leishmaniasis in Himachal Pradesh (India)

Background: A mixed endemic focus of cutaneous and visceral leishmaniasis has emerged along the Sutluj river valley of Himachal Pradesh (India). Methods: The laboratory work up of 218 new consecutive cases of localized cutaneous leishmaniasis (LCL) and 14 patients of visceral leishmaniasis (VL) from this focus is analyzed. Results: Tissue smears were positive in 44.42% of LCL and 78.57% of VL patients. Positivity was higher (73.97%) in LCL lesions of 6months duration. Only modified NNN medium supplemented with RPMI 1640 and 10% heat inactivated fetal bovine serum was found to be the most suitable for primary isolation of the parasite while other seven media used did not yield significant growth. Culture for the organism was positive in 38 of 112 (33.92%) patients of LCL and 9 of 14 (64.28%) patients of VL. The cultured organisms from 4 each of LCL and VL samples were identified by PCR as Leishmania donovani. Although subculture/bulk cultivation of this Leishmania spp. was unsuccessful in the various media tried, the two of the primary cultures could be maintained for 50 days by just replenishing the liquid overlay. Conclusion: This new focus of leishmaniasis appears peculiar where cutaneous and visceral forms co-exist, and both Leishmania donovani and Leishmania tropica are producing LCL all the while L. donovani being the predominant pathogen. The difficulty in culturing the isolates is also reminiscent of LCL caused by Leishmania infantum suggesting that these isolates, both from LCL and VL patients, perhaps belong to Leishmania donovani-infantum complex.

Cytokine profile in Montenegro skin test of patients with localized cutaneous and mucocutaneous leishmaniasis

American tegumentary leishmaniasis presents as two major clinical forms: localized cutaneous leishmaniasis (LCL) and mucocutaneous leishmaniasis (MCL). The immune response in leishmaniasis is efficiently evaluated by the response to Leishmania antigen through the Montenegro skin test (MST). Both LCL and MCL present positive response to MST, indicating that the patients present cell-mediated immunity against the parasite - Leishmania. In spite of the presence of immunity in MCL, this is not sufficient to stop disease progression and prevent resistance to treatment. In this study we demonstrated interleukin (IL) 2, 4, 5 and interferon (IFN) gamma expression in biopsies of MST of ten patients with American tegumentary leishmaniasis. The obtained results were compared between LCL (n = 5) and MCL (n = 5) patients. The MST of MCL patients displayed a higher expression of IL-2, IL-4 and IL-5, in comparison to LCL. There was no significant difference in IFN-gamma expression between groups. The obtained results suggest the role of IL-4 and IL-5 in the maintenance of the immunopathogenic mechanism of the destructive lesions that characterize MCL.

American tegumentary leishmaniasis: langerhans cells in montenegro skin test

This work analyzed the histopathology and epidermal Langerhans cells (LC) of Montenegro skin test (MST) in patients with American tegumentary leishmaniasis (ATL) in order to in situ characterize and compare the immunological reaction of the two major clinical forms of ATL, localized cutaneous leishmaniasis (LCL) and mucocutaneous leishmaniasis (MCL). MST histopathology of both LCL and MCL showed superficial and deep perivascular inflammatory infiltrate composed mainly of lymphocytes and histiocytes. Epidermal LC population was higher in MST biopsies taken from LCL patients when compared to MCL group, at 48 and 72 hours after antigen inoculation. Increased number of epidermal LC displayed in MST biopsies of LCL patients represents specific cellular immunity against parasites. The decrease of LC in MST biopsies of MCL patients does not necessarily indicate a worse specific cellular immunity in this clinical form of leishmaniasis.

Intralesional isotype profiles in human localized cutaneous leishmaniasis lesions.

This immunocytochemical study evaluates the presence of IgG1-4, IgA and IgE immunoglobulins in active lesions of 25 localized cutaneous leishmaniasis patients from three bioclimatic areas (Awa, Afa and Bsha) in Mérida State, Venezuela. All immunoglobulin isotypes except IgE were detected, with variable intensity, in one or more of the epidermal or dermal components of skin lesions. IgG1 and IgG2 were detected significantly more frequently than IgG3, IgG4 and IgA. The ranking of the isotypes according to frequency of detection was the same in all areas: IgG1 = IgG2 > IgG3 = IgG4 = IgA, but considered as whole, all isotypes were detected significantly more frequently in patients from the Awa area than in those from the Bsha area. The predominant expression of isotypes IgG1 and IgG2 suggests a preferential Th1 like immune response. Anti-Leishmania immunoserum stained only parasites and their debris, suggesting that most of the immunostaining was nonspecific.

Quantitative study ofLeishmania braziliensis braziliensisreactive T cells in peripheral blood and in the lesions of patients with American mucocutaneous leishmaniasis

A limiting dilution analysis (LDA) was utilized to estimate the frequency of L. braziliensis braziliensis reactive T cells (Lbb-T cells) in peripheral blood and in the lesions of patients with mild localized cutaneous leishmaniasis (LCL) or with severe mucosal leishmaniasis (MCL). The frequencies of Lbb-T cells in peripheral blood varied from 1:107300 to 1:3587 and were not significantly different in MCL and LCL patients. However, a significant difference was encountered (P less than 0.02) between the T cells frequencies in cutaneous (1:748 to 1:45) and mucosal lesions (1:152 to 1:13). A positive correlation was also observed between these frequencies and the magnitude of delayed-type hypersensitivity (DTH) (P less than 0.01) and the presence of fibrinoid necrosis and granulomatous reaction in the site of the lesions (P less than 0.05). The lack of correlation between the severity of disease (MCL or LCL) and the frequency of Lbb-T cells in peripheral blood gave no indications towards understanding the physiopathology of severe or mild disease. However, the correlation between high T cell frequencies in the site of the lesions, the magnitude of DTH, the fibrinoid necrosis and the severity of the disease (MCL lesions) points to the possibility that the presence of a strong T cell dependent cellular immune response in the site of the lesions may have a deleterious effect. However, a local well modulated T cell immune response might provide healing of the lesions.

In vitro infectivity of species of Leishmania (Viannia) responsible for American cutaneous leishmaniasis

There is little available information regarding the infectivity of New World Leishmania species, particularly those from the Amazonian Brazil, where there are six species of the subgenus Viannia causing American cutaneous leishmaniasis (ACL). The aim of this study was to compare, in vitro, the potential infectivity of the following Leishmania (Viannia) spp.: L. (V.) braziliensis from localized cutaneous leishmaniasis (LCL) and mucocutaneous leishmaniasis (MCL) patients, L. (V.) guyanensis, L. (V.) shawi, L. (V.) lainsoni and L. (V.) naiffi from LCL patients only, in cultured BALB/c mice peritoneal macrophage, as well as the production of NO by the infected cells. The infectivity of parasites was expressed by the infection index and, the nitric oxide (NO) production in the macrophage culture supernatant was measured by the Griess method. It was found that L. (V.) braziliensis from MCL, the more severe form of disease, showed the highest (p<or=0.05) infection index (397), as well as the lowest NO production (2.15 microM) compared with those of other species. In contrast, L. (V.) naiffi which is less pathogenic for the human showed the lowest infection index (301) and the highest NO production (4.11 microM). These results demonstrated a negative correlation between the infectivity and the ability of these parasites to escape from the microbicidal activity of the host cell.

Mixed cytokine profile during active cutaneous leishmaniasis and in natural resistance

Most studies on immune response in human cutaneous leishmaniasis evaluate patients with active disease in comparison with healthy uninfected controls or patients that have had the lesions healed, however, little is known about the immune response associated with natural resistance. In this paper we evaluate the cytokine expression patterns of T-cells and the plasmatic levels of nitrite and nitrate in patients with localized cutaneous leishmaniasis (LCL) as well as endemic non-infected individuals with positive (MST) and negative (NI) Montenegro skin test, without previous history of leishmanial lesions. Our results demonstrated an increased number of IFN-gamma+ and TNF-alpha+ T-cells and high level of plasma nitrite and nitrate in LCL patients. Moreover, we have observed that early in infection (LCL equal/less than 60 days of lesion evolution), Leishmania patients present predominance in IL-4+ and IL-10+ T-lymphocytes. However, this is a transitory phenomenon, since patients with older lesions (LCL more than 60 days of lesion evolution) show a predominant Type-1 immune profile, suggesting that disease development may depend on a transient deregulation of T-cell response, during the initial phase of infection. Interestingly MST displayed a basal mixed Type-0 cytokines profile. However, the low frequency of IL-4+ T-cells, high IFN-gamma+/IL-10+ cell ratio as well as elevated nitrite and nitrate plasma levels observed in MST, suggested that despite basal levels of cytokines, a high proportion of Type-1 over Type-2 cytokines would count to prevent parasite growth and lesion development.

Monocyte cytokine and costimulatory molecule expression in patients infected with Leishmania mexicana

Leishmania mexicana causes localized and diffuse cutaneous leishmaniasis. Patients with localized cutaneous leishmaniasis (LCL) develop a benign disease, whereas patients with diffuse cutaneous leishmaniasis (DCL) suffer from a progressive disease associated with anergy of the cellular response towards Leishmania antigens. We evaluated the production of the interleukins (IL) IL-12, IL-15, IL-18 and tumour necrosis factor-alpha (TNF-alpha) and the expression of the costimulatory molecules CD40, B7-1 and B7-2 in monocytes from LCL and DCL patients, stimulated in vitro with Leishmania mexicana lipophosphoglycan (LPG) for 18 h. LCL monocytes significantly increased TNF-alpha, IL-15 and IL-18 production, and this increase was associated with reduced amounts of IL-12. DCL monocytes produced no IL-15 or IL-18 and showed a decreasing tendency of TNF-alpha and IL-12 production as the severity of the disease increased. No difference was observed in the expression of CD40 and B7-1 between both groups of patients, yet B7-2 expression was significantly augmented in DCL patients. It remains to be established if this elevated B7-2 expression in DCL patients is cause or consequence of the Th2-type immune response that characterizes these patients. These data suggest that the diminished ability of the monocytes from DCL patients to produce cell-activating innate proinflammatory cytokines when stimulated with LPG is a possible cause for disease progression.