Leishmaniasis

Photodynamic inactivation of Leishmania braziliensis doubly sensitized with uroporphyrin and diamino-phthalocyanine activates effector functions of macrophages in vitro

Photodynamic inactivation of Leishmania has been shown to render them non-viable, but retain their immunological activities. Installation of dual photodynamic mechanisms ensures complete inactivation of species in the Leishmania subgenus, raising the prospect of their safe and effective application as whole-cell vaccines against leishmaniasis. Here, we report the successful extension of this approach to L. braziliensis in the Viannia subgenus, viz. genetic engineering of promastigotes for cytosolic accumulation of UV-sensitive uroporphyrin (URO) and their loading with red light excitable phthalocyanines (PC) that was cationized by chemical engineering. The transgenic strategy used previously produced L. braziliensis transfectants, which gave the same phenotype of aminolevulinate (ALA)-inducible uroporphyria as found in Leishmania subgenus, indicative of pre-subgenus evolutionary origin for similar genetic deficiencies in porphyrin/heme biosynthesis. In the present study, 12 independent clones were obtained and were invariably ALA-responsive, albeit to different extent for uroporphyrinogenesis and UV-inactivation. In a separate study, L. braziliensis was also found, like other Leishmania spp., to take up diamino-PC (PC2) for red light inactivation. In vitro interactions of a highly uroporphyrinogenic clone with primary macrophages were examined with the intervention of URO/PC2-medated double-photodynamic inactivation to ascertain its complete loss of viability. Doubly sensitized L. braziliensis transfectants were photo-inactivated before (Strategy #1) or after (Strategy #2) loading of macrophages. In both cases, macrophages were found to take up L. braziliensis and degrade them rapidly in contrast to live Leishmania infection. The effector functions of macrophages became upregulated following their loading with L. braziliensis photodynamically inactivated by both strategies, including CD86 expression, and IL6 and NO production. This was in contrast to the immunosuppressive infection of macrophages with live parasites, marked by IL10 production. The results provide evidence that photodynamically inactivated L. braziliensis are susceptible to the degradative pathway of macrophages with upregulation of immunity relevant cytokine and co-stimulatory markers. The relative merits of the two loading strategies with reference to previous experimental vaccination were discussed in light of the present findings with L. braziliensis.

Generation and Characterization of a Dual-Reporter Transgenic Leishmania braziliensis Line Expressing eGFP and Luciferase

In this study, we generated a transgenic strain of Leishmania braziliensis, an etiological agent associated with a diversity of clinical manifestations of leishmaniasis ranging from localized cutaneous to mucocutaneous to disseminated disease. Transgenic parasites expressing reporter proteins are valuable tools for studies of parasite biology, host-pathogen interactions, and anti-parasitic drug development. To this end, we constructed an L. braziliensis line stably expressing the reporters eGFP and luciferase (eGFP-LUC L. braziliensis). The integration cassette co-expressing the two reporters was targeted to the ribosomal locus (SSU) of the parasite genome. Transgenic parasites were characterized for their infectivity and stability both in vitro and in vivo. Parasite maintenance in axenic long-term culture in the absence of selective drugs did not alter expression of the two reporters or infection of BALB/c mice, indicating stability of the integrated cassette. Infectivity of eGFP-LUC, L. braziliensis, both in vivo and in vitro was similar to that obtained with the parental wild type strain. The possibility of L. braziliensis tracking and quantification using fluorescence and luminescence broadens the scope of research involving this neglected species, despite its importance in terms of public health concerning the leishmaniasis burden.

Saraca asoca seed extract treatment recovers the trace elements imbalances in experimental murine visceral leishmaniasis

Saraca asoca is an important plant species of India having variety of medicinal activity such as antiviral, anti-diabetic, antimicrobial, anti-inflammatory, anti-cancer etc. Indian Kala-azar (KA) or visceral leishmaniasis (VL) is a protozoan parasitic disease caused by Leishmania sp and is endemic in Indian subcontinent. VL mainly targets the poorest people who have been suffering from deficiency in protein, nutrients and essential trace elements which ultimately leads to immunodeficiency. Essential trace element, Zinc (Zn) controls multiple aspects of innate and adaptive immunity while Iron (Fe) is required for various cellular activities. Bromine (Br) is important for assembly of collagen IV scaffolds in tissue development and helps in signalling and Copper (Cu) performs several functions related to immune system. Intra-cardiac blood was collected from the experimental BALB/c mice groups including (a) healthy control, (b) infected control, (c) Saraca asoca seed extract (Sa-SE) treated groups. The trace elements level in blood of mice was measured by Energy Dispersive X-Ray Fluorescence technique. Interestingly, the decreased level of Zn, Fe and Br as well as increased level of Cu in diseased state came back to almost normal range upon treatment with Sa-SE. The trace elements imbalances thus were almost restored to normalcy by treating the experimental BALB/c mice with ethanolic seed extract of Saraca asoca.

Functional transcriptomics of wild-caught Lutzomyia intermedia salivary glands: identification of a protective salivary protein against Leishmania braziliensis infection

Background

Leishmania parasites are transmitted in the presence of sand fly saliva. Together with the parasite, the sand fly injects salivary components that change the environment at the feeding site. Mice immunized with Phlebotomus papatasi salivary gland (SG) homogenate are protected against Leishmania major infection, while immunity to Lutzomyia intermedia SG homogenate exacerbated experimental Leishmania braziliensis infection. In humans, antibodies to Lu. intermedia saliva are associated with risk of acquiring L. braziliensis infection. Despite these important findings, there is no information regarding the repertoire of Lu. intermedia salivary proteins.

Methods and Findings

A cDNA library from the Salivary Glands (SGs) of wild-caught Lu. intermedia was constructed, sequenced, and complemented by a proteomic approach based on 1D SDS PAGE and mass/mass spectrometry to validate the transcripts present in this cDNA library. We identified the most abundant transcripts and proteins reported in other sand fly species as well as novel proteins such as neurotoxin-like proteins, peptides with ML domain, and three small peptides found so far only in this sand fly species. DNA plasmids coding for ten selected transcripts were constructed and used to immunize BALB/c mice to study their immunogenicity. Plasmid Linb-11—coding for a 4.5-kDa protein—induced a cellular immune response and conferred protection against L. braziliensis infection. This protection correlated with a decreased parasite load and an increased frequency of IFN-γ-producing cells.

Conclusions

We identified the most abundant and novel proteins present in the SGs of Lu. intermedia, a vector of cutaneous leishmaniasis in the Americas. We also show for the first time that immunity to a single salivary protein from Lu. intermedia can protect against cutaneous leishmaniasis caused by L. braziliensis.

Sand fly saliva contains potent, biologically active proteins that allow the insect to stop host responses to acquire a blood meal. After repeated exposures, a number of these salivary proteins also induce a response in the host such as antibody production and/or cellular-mediated immunity. In animal models, these immune responses affect Leishmania infection. On one hand, immunity to Phlebotomus papatasi saliva protected animals against cutaneous leishmaniasis, while on the other hand, immunity to Lutzomyia intermedia saliva did not protect but exacerbated this disease. These differences are probably due to the types of proteins present in the saliva of these different sand fly species. The present work focused on isolation and identification of the secreted proteins present in the salivary glands of Lu. intermedia, an important vector of L. braziliensis, the agent of mucocutaneous leishmaniasis. Saliva from this sand fly contains a number of proteins not present in P. papatasi saliva and, with some exceptions; proteins that are homologous between the two species are very divergent. Furthermore, we identified one protein that, after vaccination, induced a cellular immune response able to protect mice against Leishmania braziliensis infection. This is the first evidence that a single salivary protein from Lu. intermedia can protect mice against this cutaneous leishmaniasis.

The presence of Tregs does not preclude immunity to reinfection with Leishmania braziliensis

Leishmania spp. cause a broad spectrum of diseases collectively known as leishmaniasis. Leishmania braziliensis is the main etiological agent of American cutaneous leishmaniasis and mucocutaneous leishmaniasis. During experimental infection with L. braziliensis, BALB/c mice develop an adaptive immune response that is associated with lesion healing and, in parallel, parasite persistence within draining lymph nodes (dLNs). In the Leishmania major model of cutaneous leishmaniasis, regulatory T cells (Tregs) play an important role in immune regulation, preventing pathological immune responses but at the same time precluding sterile cure. In this study we investigated the role of Tregs during experimental infection with L. braziliensis. CD4(+)CD25(+) T cells were detected throughout the duration of clinical disease both at the ear and in dLNs of infected mice. These cells expressed Treg markers such as glucocorticoid-induced TNF-receptor-related protein (GITR), the α chain of the αεβ7 integrin (CD103), and the forkhead/winged helix transcription factor, Foxp3, and were able to suppress the proliferation of CD4(+)CD25(-) cells. Importantly, a high frequency of Foxp3(+) cells accumulated at the site of infection and in dLNs. We next investigated the outcome of a reinfection with L. braziliensis in terms of Treg distribution and disease reactivation. Interestingly, a secondary inoculation with L. braziliensis did not preclude an efficient recall response to L. braziliensis at a distal site, despite the presence of Tregs. Within dLNs, reinfection did not promote parasite dissemination or a differential recruitment of either CD4(+)CD25(+)Foxp3(+) or CD4(+)IL-10(+) T cells. On the contrary, parasites were mainly detected in the LN draining the primary infection site where a high frequency of CD4(+)IFN-γ(+) T cells was also present. Collectively these data show that during experimental infection, Tregs are present in healed mice but this population does not compromise an effective immune response upon reinfection with L. braziliensis.

Characterization of the recent clinical isolates of Indian Kala-azar patients by RAPD-PCR method

Leishmaniasis is one of the most important vector borne diseases caused by kinetoplastid protozoa Leishmania sp. Among all forms of Leishmaniasis, Visceral leishmaniasis (VL) or Kala-azar is the severest form of the illness. VL is characterized by fever, hepatosplenomegaly, anaemia, edema, weight loss and invariably fatal if left untreated. Characterization of Leishmania sp. is extremely necessary to understand the epidemiology, taxonomy and population genetics of the parasites which ultimately helps in designing appropriate drug regimen to combat the disease. In this study, we aimed to type the clinical isolates of Leishmania species collected in the period 2006-2010 from patients (n = 9) diagnosed with Kala-azar and post Kala-azar dermal leishmaniasis (PKDL) by RAPD-PCR method using eight selected primers. Genome of the clinical isolates were amplified and electrophoresed in agarose gel. These were compared with the RAPD PCR profiles of WHO reference strains for L. donovani (DD8) and L. tropica (K27) respectively. We calculated the Jaccard's Similarity Coefficient and found one (study code T5) out of nine isolates as L. tropica while the rest were L. donovani. This pilot study supports the earlier single report claiming that both the species are responsible for Kala-azar in India and it also emphasizes the need for more systematic typing of clinical isolates of Indian Kala-azar.

Immunomodulation of human monocytes following exposure to Lutzomyia intermedia saliva

Background

Sand fly saliva contains potent and complex pharmacologic molecules that are able to modulate the host's hemostatic, inflammatory, and immune systems. In this study, we evaluated the effects of salivary gland sonicate (SGS) of Lutzomyia intermedia, the natural vector of Leishmania braziliensis, on monocytes obtained from the peripheral blood mononuclear cells (PBMC) of healthy volunteers. We investigated the effects of sand fly saliva on cytokine production and surface molecule expression of LPS-stimulated human monocytes uninfected or infected with L. braziliensis.

Results

Pre-treatment of non-infected human monocytes with L. intermedia SGS followed by LPS-stimulation led to a significant decrease in IL-10 production accompanied by a significant increase in CD86, CD80, and HLA-DR expression. Pre-treatment with SGS followed by LPS stimulation and L. braziliensis infection led to a significant increase in TNF-α, IL-6, and IL-8 production without significant alterations in co-stimulatory molecule expression. However, pre-treatment with L. intermedia SGS did not result in significant changes in the infection rate of human monocytes.

Conclusion

Our data indicate that L. intermedia saliva is able to modulate monocyte response, and, although this modulation is dissociated from enhanced infection with L. braziliensis, it may be associated with successful parasitism.

Primary Cutaneous Eosinophil-Rich Anaplastic Large Cell Lymphoma: Report of an Unusual Case and Literature Review

Background:

Cutaneous, neutrophil-rich anaplastic large cell lymphoma (ALCL) is an uncommon variant of ALCL that may be confused with inflammatory dermatoses.

Objective and methods:

We describe an eosinophil-rich variant of ALCL occurring on the left ear without systemic involvement. The lesion had inflammatory characteristics, which led initially to a histological diagnosis of an inflammatory process. Two months later, a second biopsy diagnosed eosinophil-rich variant of ALCL. The patient underwent radiation therapy, but due to the extensive deformation and mutilation of the ear, the patient elected to have the ear amputated. We discuss the clinicopathological findings and the differential diagnosis

Conclusions:

To the best of our knowledge, the occurrence of a cutaneous, eosinophil-rich variant of ALCL has not been previously reported. It is important to alert pathologists to this variant of ALCL so that this possibility may be considered in the early differential diagnosis of inflammatory cutaneous conditions.

Immune response to leishmania: paradox rather than paradigm

The leishmaniases are a group of diseases caused by protozoan parasites of the genus Leishmania. Various Leishmania species can cause human infection, producing a spectrum of clinical manifestations. It is estimated that 350 million people are at risk, with a global yearly incidence of 1-1.5 million for cutaneous and 500,000 for visceral leishmaniasis (VL). VL is a major cause of morbidity and mortality in East Africa and the Indian subcontinent. Coinfection with HIV enhances the risk of the disease. The only control measure currently available in India is case detection and treatment with antimonial drugs, which are expensive, not always available and cannot be self-administered. Newer drugs like oral miltefosine have not become widely available. Vector and reservoir control is difficult due to the elusive nature of the vector and the diversity of the animal reservoir. A detailed knowledge of immune response to the parasite would help in designing prophylactic and therapeutic strategies against this infection.

Leishmania infection impairs beta 1-integrin function and chemokine receptor expression in mononuclear phagocytes

Leishmania spp. are intracellular parasites that cause lesions in the skin, mucosa, and viscera. We have previously shown that Leishmania infection reduces mononuclear phagocyte adhesion to inflamed connective tissue. In this study, we examined the role of adhesion molecules and chemokines in this process. Infection rate (r = -0.826, P = 0.003) and parasite burden (r = -0.917, P = 0.028) negatively correlated to mouse phagocyte adhesion. The decrease (58.7 to 75.0% inhibition, P = 0.005) in phagocyte adhesion to connective tissue, induced by Leishmania, occurred as early as 2 h after infection and was maintained for at least 24 h. Interestingly, impairment of cell adhesion was sustained by phagocyte infection, since it was not observed following phagocytosis of killed parasites (cell adhesion varied from 15.2% below to 24.0% above control levels, P > 0.05). In addition, Leishmania infection diminished cell adhesion to fibronectin (54.1 to 96.2%, P < 0.01), collagen (15.7 to 83.7%, P < 0.05), and laminin (59.1 to 82.2%, P < 0.05). The CD11b(hi) subpopulation was highly infected (49.6 to 97.3%). Calcium and Mg(2+) replacement by Mn(2+), a treatment that is known to induce integrins to a high state of affinity for their receptors, reverted the inhibition in adhesion caused by Leishmania. This reversion was completely blocked by anti-VLA4 antibodies. Furthermore, expression of CCR4 and CCR5, two chemokine receptors implicated in cell adhesion, was found to be downregulated 16 h after infection (2.8 to 4.1 times and 1.9 to 2.8 times, respectively). Together, these results suggest that mechanisms regulating integrin function are implicated in the change of macrophage adhesion in leishmaniasis.

Characterization of the T-cell receptor Vbeta repertoire in the human immune response against Leishmania parasites

In order to explore a possible presence of hyperreactive T-cell clones in human cutaneous leishmaniasis (CL), we have investigated, by flow cytometry, the expression of Vbeta chains of T-cell receptors (TCRs) in the following types of cells: (i) peripheral blood mononuclear cells (PBMCs) from CL patients, which were then compared to those from normal volunteers; (ii) unstimulated and soluble Leishmania antigen-stimulated draining lymph node cells from CL patients; (iii) PBMCs from volunteers before versus after Leishmania immunization; and (iv) PBMCs from healthy volunteers that were primed in vitro with live Leishmania parasites. Our results show a modulation in the TCR Vbeta repertoire during CL and after antigen stimulation of patients' cells. Vaccination, however, leads to a broad expansion of different Vbeta TCRs. We also observed an association between TCR Vbeta12 expression, T-cell activation, and gamma interferon production upon in vitro priming with Leishmania. Collectively, these results both indicate that infection with live parasites or exposure to parasite antigen can modulate the TCR Vbeta repertoire and suggest that TCR Vbeta12 may be implicated in the response to Leishmania.

Frequent expansion of Epstein-Barr virus (EBV) infected cells in germinal centres of tonsils from an area with a high incidence of EBV-associated lymphoma

Burkitt's lymphoma (BL) and Hodgkin's disease (HD) occurring in developing regions are frequently associated with Epstein-Barr virus (EBV) infection and have a high incidence in childhood. Recent genotyping studies indicate that the tumour cells of both neoplasms represent B cells that contain somatically mutated immunoglobulin heavy chain genes. This implies that the precursors of these neoplasms have participated in the germinal centre (GC) reaction. We therefore presumed that normal lymphoid tissues from children living in developing regions would harbour an increased number of EBV-infected cells within the GC, when compared with children living in industrialized nations. To test this hypothesis, hyperplastic tonsils from 40 children living in Bahia (Brazil) and 40 from German children were analysed for the presence of EBV-encoded small nuclear RNA (EBER) and EBV-encoded proteins by in situ hybridization and immunohistology, respectively. Although the overall EBV infection rate was similar in both groups (50 per cent of Bahian vs. 45 per cent of German cases), a significantly higher number of EBER-positive lymphoid cells were found in the GCs of 8/20 EBV-positive tonsils from Brazil (9-89 cells/GC; mean: 14.5 cells/GC per case), while only 3/18 tonsils from Germany displayed a few EBER positive cells (1-9 cells/GC; mean: 0.5 cell/GC per case) in this compartment (p < 0.007). In addition, the EBV-infected GC cells in Bahian samples resembled centroblasts, exhibited mitotic activity, and in two cases showed expression of EBV-encoded latent membrane protein (LMP)-1, findings not present in German samples. These data show that latently EBV-infected cells participate more frequently in GC reactions in developing regions than in industrialized countries and may abnormally express the oncogenic protein LMP-1. This could in part explain the higher incidence in this region of EBV association with lymphomas related to GC cells or their progeny, such as BL and HD.

Tegumentary leishmaniasis in childhood

Very little has been published about tegumentary leishmaniasis in children and there are many controversies about this disorder in the literature. Therefore, we discuss the pathogenesis, clinical aspects, means to diagnosis, and treatment of this endemic disease.