Filardy AA, Guimarães-Pinto K, Nunes MP, Zukeram K, Fliess L, Pereira L, Oliveira Nascimento D, Conde L, Morrot A. Human Kinetoplastid Protozoan Infections: Where Are We Going Next? Front Immunol. 2018 Jul 25;9:1493.
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Kinetoplastida trypanosomatidae microorganisms are protozoan parasites exhibiting a developmental stage in the gut of insect vectors and tissues of vertebrate hosts. During the vertebrate infective stages, these parasites alter the differential expression of virulence genes, modifying their biological and antigenic properties in order to subvert the host protective immune responses and establish a persistent infection. One of the hallmarks of kinetoplastid parasites is their evasion mechanisms from host immunity, leading to disease chronification. The diseases caused by kinetoplastid parasites are neglected by the global expenditures in research and development, affecting millions of individuals in the low and middle-income countries located mainly in the tropical and subtropical regions. However, investments made by public and private initiatives have over the past decade leveraged important lines of intervention that if well-integrated to health care programs will likely accelerate disease control initiatives. This review summarizes recent advances in public health care principles, including new drug discoveries and their rational use with chemotherapeutic vaccines, and the implementation of control efforts to spatially mapping the kinetoplastid infections through monitoring of infected individuals in epidemic areas. These approaches should bring us the means to track genetic variation of parasites and drug resistance, integrating this knowledge into effective stewardship programs to prevent vector-borne kinetoplastid infections in areas at risk of disease spreading.
Martin-Martin I, Chagas AC, Guimaraes-Costa AB, Amo L, Oliveira F, Moore IN, DeSouza-Vieira TS, Sanchez EE, Suntravat M, Valenzuela JG, Ribeiro JMC, Calvo E. Immunity to LuloHya and Lundep, the salivary spreading factors from Lutzomyia longipalpis, protects against Leishmania major infection. PLoS Pathog. 2018 May 3;14(5):e1007006.
DOI: 10.1371/journal.ppat.1007006
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Salivary components from disease vectors help arthropods to acquire blood and have been shown to enhance pathogen transmission in different model systems. Here we show that two salivary enzymes from Lutzomyia longipalpis have a synergist effect that facilitates a more efficient blood meal intake and diffusion of other sialome components. We have previously shown that Lundep, a highly active endonuclease, enhances parasite infection and prevent blood clotting by inhibiting the intrinsic pathway of coagulation. To investigate the physiological role of a salivary hyaluronidase in blood feeding we cloned and expressed a recombinant hyaluronidase from Lu. longipalpis. Recombinant hyaluronidase (LuloHya) was expressed in mammalian cells and biochemically characterized in vitro. Our study showed that expression of neutrophil CXC chemokines and colony stimulating factors were upregulated in HMVEC cells after incubation with LuloHya and Lundep. These results were confirmed by the acute hemorrhage, edema and inflammation in a dermal necrosis (dermonecrotic) assay involving a massive infiltration of leukocytes, especially neutrophils, in mice co-injected with hemorrhagic factor and these two salivary proteins. Moreover, flow cytometry results showed that LuloHya and Lundep promote neutrophil recruitment to the bite site that may serve as a vehicle for establishment of Leishmania infection. A vaccination experiment demonstrated that LuloHya and Lundep confer protective immunity against cutaneous leishmaniasis using the Lu. longipalpis—Leishmania major combination as a model. Animals (C57BL/6) immunized with LuloHya or Lundep showed minimal skin damage while lesions in control animals remained ulcerated. This protective immunity was abrogated when B-cell-deficient mice were used indicating that antibodies against both proteins play a significant role for disease protection. Rabbit-raised anti-LuloHya antibodies completely abrogated hyaluronidase activity in vitro. Moreover, in vivo experiments demonstrated that blocking LuloHya with specific antibodies interferes with sand fly blood feeding. This work highlights the relevance of vector salivary components in blood feeding and parasite transmission and further suggests the inclusion of these salivary proteins as components for an anti-Leishmania vaccine.
Firmino-Cruz L, Ramos TD, da Fonseca-Martins AM, Maciel-Oliveira D, Oliveira-Silva G, Pratti JES, Cavazzoni C, Chaves SP, Oliveira Gomes DC, Morrot A, Freire-de-Lima L, Vale AM, Freire-de-Lima CG, Decote-Ricardo D, de Matos Guedes HL. Immunomodulating role of IL-10-producing B cells in Leishmania amazonensis infection. Cell Immunol. 2018 Dec;334:20-30.
DOI: 10.1016/j.cellimm.2018.08.014
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This work aims to study the immunomodulation of B lymphocytes during L. amazonensis infection. We demonstrated in this study that follicular B cells from draining lymph nodes of infected wild type BALB/c mice are the major source of IL-10 during infection. We infected BALB/Xid mice that developed smaller lesions in comparison with the control, but the parasite load obtained from the infected tissues was similar in both groups. We observed a reduction in the number of follicular B cells from BALB/Xid mice in relation to WT mice and, consequently, lower levels of IgM, IgG, IgG1, IgG2a and IgG2b in the serum of BALB/Xid when compared with wild type mice. BALB/Xid mice also presented lower levels of IL-10 in the infected footpad, draining lymph nodes and in the spleen when compared with WT infected tissues. We did not detect differences in the number of IL-10 producing CD4+ and CD8+ T cells between WT and BALB/Xid mice; however, a strong reduction of IL-10 producing follicular B cells was noted in BALB/Xid mice. When analyzed together, our data indicate that B cells are related with lesion pathogenesis through the production of antibodies and IL-10.
Poggio HA, Antunes MA, Rocha NN, Kitoko JZ, Morales MM, Olsen PC, Lopes-Pacheco M, Cruz FF, Rocco PRM. Impact of one versus two doses of mesenchymal stromal cells on lung and cardiovascular repair in experimental emphysema. Stem Cell Res Ther. 2018 Nov 8;9(1):296.
DOI: 10.1186/s13287-018-1043-6
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A single administration of mesenchymal stromal cells (MSCs) has been shown to reduce lung inflammation in experimental elastase-induced emphysema; however, effects were limited in terms of lung-tissue repair and cardiac function improvement. We hypothesized that two doses of MSCs could induce further lung and cardiovascular repair by mitigating inflammation and remodeling in a model of emphysema induced by multiple elastase instillations. We aimed to comparatively investigate the effects of one versus two doses of MSCs, administered 1 week apart, in a murine model of elastase-induced emphysema.
Morrot A, da Fonseca LM, Salustiano EJ, Gentile LB, Conde L, Filardy AA, Franklim TN, da Costa KM, Freire-de-Lima CG, Freire-de-Lima L. Metabolic Symbiosis and Immunomodulation: How Tumor Cell-Derived Lactate May Disturb Innate and Adaptive Immune Responses. Front Oncol. 2018 Mar 23;8:81.
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The tumor microenvironment (TME) is composed by cellular and non-cellular components. Examples include the following: (i) bone marrow-derived inflammatory cells, (ii) fibroblasts, (iii) blood vessels, (iv) immune cells, and (v) extracellular matrix components. In most cases, this combination of components may result in an inhospitable environment, in which a significant retrenchment in nutrients and oxygen considerably disturbs cell metabolism. Cancer cells are characterized by an enhanced uptake and utilization of glucose, a phenomenon described by Otto Warburg over 90 years ago. One of the main products of this reprogrammed cell metabolism is lactate. “Lactagenic” or lactate-producing cancer cells are characterized by their immunomodulatory properties, since lactate, the end product of the aerobic glycolysis, besides acting as an inducer of cellular signaling phenomena to influence cellular fate, might also play a role as an immunosuppressive metabolite. Over the last 10 years, it has been well accepted that in the TME, the lactate secreted by transformed cells is able to compromise the function and/or assembly of an effective immune response against tumors. Herein, we will discuss recent advances regarding the deleterious effect of high concentrations of lactate on the tumor-infiltrating immune cells, which might characterize an innovative way of understanding the tumor-immune privilege.
Nascimento DO, Vieira-de-Abreu A, Arcanjo AF, Bozza PT, Zimmerman GA, Castro-Faria-Neto HC. Integrin αDβ2 (CD11d/CD18) Modulates Leukocyte Accumulation, Pathogen Clearance, and Pyroptosis in Experimental Salmonella Typhimurium Infection. Front Immunol. 2018 May 24;9:1128.
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β2 integrins are critical in host defense responses to invading pathogens and inflammation. Previously, we reported that genetic deficiency of integrin αDβ2 in mice altered outcomes in experimental systemic infections including accelerated mortality in animals infected with Salmonella enterica serovar Typhimurium. Here, we show that deficiency of αDβ2 results in impaired accumulation of leukocytes in response to peritoneal infection by S. Typhimurium, impaired pathogen clearance in vivo, defective bacterial elimination by cultured peritoneal macrophages, and enhanced pyroptosis, a cell death process triggered by Salmonella. Salmonella-infected animals deficient in αDβ2 had increased levels of peritoneal cytokines in addition to other markers of pyroptosis, which may contribute to inflammatory injury and increased mortality in the context of impaired bacterial killing. These observations indicate important contributions of leukocyte integrins to the host response in experimental Salmonella infection and reveal previous activities of αDβ2 in bacterial infection.
Lixa C, Mujo A, de Magalhães MTQ, Almeida FCL, Lima LMTR, Pinheiro AS. Oligomeric transition and dynamics of RNA binding by the HuR RRM1 domain in solution. J Biomol NMR. 2018 Dec;72(3-4):179-192.
DOI: 10.1007/s10858-018-0217-y
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Human antigen R (HuR) functions as a major post-transcriptional regulator of gene expression through its RNA-binding activity. HuR is composed by three RNA recognition motifs, namely RRM1, RRM2, and RRM3. The two N-terminal RRM domains are disposed in tandem and contribute mostly to HuR interaction with adenine and uracil-rich elements (ARE) in mRNA. Here, we used a combination of NMR and electrospray ionization–ion mobility spectrometry–mass spectrometry (ESI–IMS–MS) to characterize the structure, dynamics, RNA recognition, and dimerization of HuR RRM1. Our solution structure reveals a canonical RRM fold containing a 19-residue, intrinsically disordered N-terminal extension, which is not involved in RNA binding. NMR titration results confirm the primary RNA-binding site to the two central β-strands, β1 and β3, for a cyclooxygenase 2 (Cox2) ARE I-derived, 7-nucleotide RNA ligand. We show by 15N relaxation that, in addition to the N- and C-termini, the β2–β3 loop undergoes fast backbone dynamics (ps–ns) both in the free and RNA-bound state, indicating that no structural ordering happens upon RNA interaction. ESI–IMS–MS reveals that HuR RRM1 dimerizes, however dimer population represents a minority. Dimerization occurs via the α-helical surface, which is oppositely orientated to the RNA-binding β-sheet. By using a DNA analog of the Cox2 ARE I, we show that DNA binding stabilizes HuR RRM1 monomer and shifts the monomer–dimer equilibrium toward the monomeric species. Altogether, our results deepen the current understanding of the mechanism of RNA recognition employed by HuR.
