A Mouse Model of Ulcerative Cutaneous Leishmaniasis by Leishmania (Viannia) panamensis to Investigate Infection, Pathogenesis, Immunity, and Therapeutics.

A mouse model of cutaneous leishmaniasis (CL) by Leishmania (Viannia) panamensis (L(V)p) that reproduces the characteristics of the human disease remains elusive. Here we report the development of a CL model that uses a mouse-adapted L(V)p isolate to reproducibly induce a dermal disease with a remarkable similarity to human CL. BALB/c mice infected intradermally in the ear with 105 stationary UA-946 L(V)p promastigotes develop a progressive cutaneous disease that exhibits the typical ulcerated lesions with indurated borders observed in CL patients. Although most of parasites in the inoculum die within the first week of infection, the survivors vigorously multiply at the infection site during the following weeks, paralleling disease appearance and aggravation. Regional lymphadenopathy as well as lymphatic dissemination of parasites to draining lymph nodes (dLN) was evidenced early after infection. Viable parasites were also isolated from spleen at later timepoints indicating systemic parasitic dissemination, but, strikingly, no signs of systemic disease were observed. Increasing numbers of myeloid cells and T lymphocytes producing IFNγ and IL-4 were observed in the dLN as disease progressed. A mixed adaptive L(V)p-specific T cell-mediated response was induced, since ex vivo recall experiments using dLN cells and splenocytes revealed the production of type 1 (IFNγ, IL-2), type 2 (IL-4, IL-13), regulatory (IL-10), and inflammatory (GM-CSF, IL-3) cytokines. Humoral adaptive response was characterized by early production of IgG1- followed by IgG2a-type of L(V)p-specific antibodies. IFNγ/IL-4 and IgG2a/IgG1 ratios indicated that the initial non-protective Th2 response was redirected toward a protective Th1 response. In situ studies revealed a profuse recruitment of myeloid cells and of IFNγ- and IL-4-producing T lymphocytes to the site of infection, and the typical histopathological changes induced by dermotropic Leishmania species. Evidence that this model is suitable to investigate pharmacological and immunomodulatory interventions, as well as for antigen discovery and vaccine development, is also presented. Altogether, these results support the validity and utility of this novel mouse model to study the pathogenesis, immunity, and therapeutics of L(V)p infections.

Evaluation of the chemopreventive potentials of ezetimibe and aspirin in a novel mouse model of gallbladder preneoplasia.

Gallbladder stones (cholecystolithiasis) are the main risk factor for gallbladder cancer (GBC), a lethal biliary malignancy with poor survival rates worldwide. Gallbladder stones are thought to damage the gallbladder epithelium and trigger chronic inflammation. Preneoplastic lesions that arise in such an inflammatory microenvironment can eventually develop into invasive carcinoma, through mechanisms that are not fully understood. Here, we developed a novel gallbladder preneoplasia mouse model through the administration of two lithogenic diets (a low- or a high-cholesterol diet) in wild-type C57BL/6 mice over a period of 9 months. Additionally, we evaluated the chemopreventive potentials of the anti-inflammatory drug aspirin and the cholesterol absorption inhibitor ezetimibe. Both lithogenic diets induced early formation of gallbladder stones, together with extensive inflammatory changes and widespread induction of metaplasia, an epithelial adaptation to tissue injury. Dysplastic lesions were presented only in mice fed with high-cholesterol diet (62.5%) in late stages (9th month), and no invasive carcinoma was observed at any stage. The cholesterol absorption inhibitor ezetimibe inhibited gallbladder stone formation and completely prevented the onset of metaplasia and dysplasia in both lithogenic diets, whereas aspirin partially reduced metaplasia development only in the low-cholesterol diet setting. This model recapitulates several of the structural and inflammatory findings observed in human cholecystolithiasic gallbladders, making it relevant for the study of gallbladder carcinogenesis. In addition, our results suggest that the use of cholesterol absorption inhibitors and anti-inflammatory drugs can be evaluated as chemopreventive strategies to reduce the burden of GBC among high-risk populations.

Safety and immunogenicity evaluation of recombinant BCG vaccine against respiratory syncytial virus in a randomized, double-blind, placebo-controlled phase I clinical trial.

BACKGROUND: Respiratory syncytial virus (RSV) is responsible for most respiratory tract infections and hospitalizations in infants and represents a significant economic burden for public health. The development of a safe, effective, and affordable vaccine is a priority for the WHO. METHODS: We conducted a double-blinded, escalating-dose phase 1 clinical trial in healthy males aged 18-50 years to evaluate safety, tolerability, and immunogenicity of a recombinant Mycobacterium bovis BCG vaccine expressing the nucleoprotein of RSV (rBCG-N-hRSV). Once inclusion criteria were met, volunteers were enrolled in three cohorts in an open and successive design. Each cohort included six volunteers vaccinated with 5 × 103, 5 × 104, or 1 × 105 CFU, as well as two volunteers vaccinated with the full dose of the standard BCG vaccine. This clinical trial (clinicaltrials.gov NCT03213405) was conducted in Santiago, Chile. FINDINGS: The rBCG-N-RSV vaccine was safe, well-tolerated, and no serious adverse events related to the vaccine were recorded. Serum IgG-antibodies directed against Mycobacterium and the N-protein of RSV increased after vaccination, which were capable of neutralizing RSV in vitro. Additionally, all volunteers displayed increased cellular response consisting of IFN-γ and IL-2 production against PPD and the N-protein, starting at day 14 and 30 post-vaccination respectively. INTERPRETATION: The rBCG-N-hRSV vaccine had a good safety profile and induced specific cellular and humoral responses. FUNDING: This work was supported by Millennium Institute on Immunology and Immunotherapy from Chile (P09/016), FONDECYT 1190830, and FONDEF D11E1098.

Peripheral Blood Classical Monocytes and Plasma Interleukin 10 Are Associated to Neoadjuvant Chemotherapy Response in Breast Cancer Patients.

Worldwide, breast cancer (BC) is the leading cause of cancer death among women. For many patients the most effective treatment is a resection surgery that removes the tumor. Within this subset, patients sometimes receive chemotherapy treatment (CT) prior to surgery aiming to reduce tumor size in order to preserve healthy breast tissue. This strategy is commonly called neoadjuvant chemotherapy (NAC). This approach also offers an opportunity to determine treatment sensitivity, especially in aggressive tumors. Post NAC absence of residual disease is associated to long term survival in BC patients and is used to define the need of adjuvant therapy options. Studies suggest that NAC allows the recognition of tumor antigens by immune cells potentiating the eradication of the tumor. However, the dynamic changes in patients' immune cells under NAC remain unclear. Here, we assessed changes in leucocyte and cytokine profiles in order to determine its association to NAC response in BC patients. Peripheral blood patient samples were taken prior to each NAC cycle to assess the abundance of leukocyte subsets and serum cytokines in 20 patients. These immunological features were associated with clinical outcomes including pathological response. We found a positive correlation between plasma Interleukin 10 (IL-10) and classical monocytes in HER2+ BC patients under NAC. We also observed a trend between increased IL-10 and classical monocytes levels and lower rates of pathologic complete response at the end of NAC. These data support the notion that monocyte subsets and IL-10 could be applied as a novel indicator of NAC efficacy in HER2+ BC patients. Finally, we confirm a key role of the immune system in cancer progression and CT response.

Eplerenone Implantation Improved Adipose Dysfunction Averting RAAS Activation and Cell Division.

Introduction: Mineralocorticoid receptor (MR) activation within adipose tissue, triggers inflammation and metabolic syndrome development. The pharmacological blockade of MR provides beneficial effects for adipose tissue. Our study evaluates the impact of eplerenone implantation upon obesity. Experimental approach: A group of mice with implanted placebo pellets were fed using two types of diet, a normal (ND) or a high fat (HFD) diet. Additionally, a group of mice fed HFD were implanted with an eplerenone pellet. Metabolic and biochemical parameters were assessed in each animal group. Adipocyte size and lipid accumulation were investigated in the liver and adipose tissue. We evaluated the components of renin-angiotensin-aldosterone system (RAAS) locally in adipose tissue. Key results: Eplerenone reduced HFD-induced body weight gain, fasting glucose levels, fat accumulation, HFD-induced adipocyte size and liver lipid accumulation and improved glucose tolerance. In the adipose tissue, HFD significantly increased the mRNA levels of the RAAS molecules relative to the ND group. Eplerenone lowered RAAS mRNA levels, components of lipid metabolism and markers of inflammation in HFD-fed animals. Conclusion: MR antagonism with eplerenone diminishes insulin resistance that is related to obesity partly via a reduction of RAAS activation, inflammatory progression and cytokines induction. This suggests that eplerenone should be further studied as a therapeutic option for obesity and overweight.

A Mineralocorticoid Receptor Deficiency in Myeloid Cells Reduces Liver Steatosis by Impairing Activation of CD8+ T Cells in a Nonalcoholic Steatohepatitis Mouse Model.

Background and Aims: The mineralocorticoid receptor (MR) and renin-angiotensin-aldosterone system (RAAS) are implicated in non-alcoholic liver fatty disease (NALFD). However, inflammatory mechanisms linking MR and RAAS with disease pathology remain unclear. Here we aimed to evaluate the contribution of myeloid MR to the inflammatory response in an animal model of non-alcoholic steatohepatitis (NASH), induced with a methionine-choline deficient diet (MCD). Methods: Mice with a conditional deficiency of MR in myeloid cells (MyMRKO) and their counterpart floxed control mice (FC) were fed for 18 days with MCD or chow diet, respectively. Serum levels of aminotransferases and aldosterone levels were measured and hepatic steatosis, inflammation and fibrosis scored histologically. Hepatic triglyceride content (HTC) and hepatic mRNA levels of pro-inflammatory pro-fibrotic-associated genes were also assessed. Deep flow cytometric analysis was used to dissect the immune response during NASH development. Results: MyMRKO mice fed with an MCD diet exhibited reduced hepatic inflammation and lower HTC than controls. Absolute number and percentage of liver inflammatory infiltrate cells (except for CD8+ T lymphocytes) were similar in both MyMRKO and control mice fed with an MCD diet but expression of the costimulatory molecule CD86 by dendritic cells and the CD25 activation marker in CD8+ T cells were significantly reduced in MyMRKO. Conclusions: Proinflammatory cells are functionally suppressed in the absence of MR. We hypothesized that loss of MR in myeloid cells reduces lipid accumulation in the liver, in part through modulating the adaptive immune response, which is pivotal for the development of steatosis.

The role of myeloid-derived suppressor cells in chronic infectious diseases and the current methodology available for their study.

An effective pathogen has the ability to evade the immune response. The strategies used to achieve this may be based on the direct action of virulence factors or on the induction of host factors. Myeloid-derived suppressor cells (MDSCs) are immune cells with an incredible ability to suppress the inflammatory response, which makes them excellent targets to be exploited by pathogenic bacteria, viruses, or parasites. In this review, we describe the origin and suppressive mechanisms of MDSCs, as well as their role in chronic bacterial, viral, and parasitic infections, where their expansion seems to be essential in the chronicity of the disease. We also analyze the disadvantages of current MDSC depletion strategies and the different in vitro generation methods, which can be useful tools for the deeper study of these cells in the context of microbial infections.

Patterns of antibody response during natural hRSV infection: insights for the development of new antibody-based therapies.

INTRODUCTION: The human respiratory syncytial virus (hRSV) is the main cause of acute lower respiratory tract infection in susceptible population worldwide, such as young children and the elderly. Although hRSV is a major public health burden, there are no licensed vaccines and the only available therapy is palivizumab. During life, reinfections with hRSV are common, suggesting that the virus can impair the development of an efficient host immune response. This feature has hindered the development of efficient therapies. AREAS COVERED: This article focuses on research about the natural development of antibodies in humans after the exposure to hRSV. The difficulties of developing anti-hRSV therapies based on monoclonal antibodies have been recently associated to the relationship between the disease outcome and the pattern of antibody response. EXPERT OPINION: Development of monoclonal antibodies is a potentially successful approach to prevent the population from suffering severe respiratory diseases caused by hRSV infection, for which there are no available vaccines. Although the use of palivizumab is safe, its effectiveness is controversial. Recent data have prompted research to develop therapies targeting alternative viral antigens, rather than focusing only on the F protein, as well as the development of antibodies with a cell-mediated function.

Assessing the Importance of Domestic Vaccine Manufacturing Centers: An Overview of Immunization Programs, Vaccine Manufacture, and Distribution.

Vaccines have significantly reduced the detrimental effects of numerous human infectious diseases worldwide, helped to reduce drastically child mortality rates and even achieved eradication of major pathogens, such as smallpox. These achievements have been possible due to a dedicated effort for vaccine research and development, as well as an effective transfer of these vaccines to public health care systems globally. Either public or private institutions have committed to developing and manufacturing vaccines for local or international population supply. However, current vaccine manufacturers worldwide might not be able to guarantee sufficient vaccine supplies for all nations when epidemics or pandemics events could take place. Currently, different countries produce their own vaccine supplies under Good Manufacturing Practices, which include the USA, Canada, China, India, some nations in Europe and South America, such as Germany, the Netherlands, Italy, France, Argentina, and Brazil, respectively. Here, we discuss some of the vaccine programs and manufacturing capacities, comparing the current models of vaccine management between industrialized and developing countries. Because local vaccine production undoubtedly provides significant benefits for the respective population, the manufacture capacity of these prophylactic products should be included in every country as a matter of national safety.

Interleukin-10 Production by T and B Cells Is a Key Factor to Promote Systemic Salmonella enterica Serovar Typhimurium Infection in Mice.

Salmonella enterica serovar Typhimurium (S. Typhimurium) is a Gram-negative bacterium that produces disease in numerous hosts. In mice, oral inoculation is followed by intestinal colonization and subsequent systemic dissemination, which leads to severe pathogenesis without the activation of an efficient anti-Salmonella immune response. This feature suggests that the infection caused by S. Typhimurium may promote the production of anti-inflammatory molecules by the host that prevent efficient T cell activation and bacterial clearance. In this study, we describe the contribution of immune cells producing the anti-inflammatory cytokine interleukin-10 (IL-10) to the systemic infection caused by S. Typhimurium in mice. We observed that the production of IL-10 was required by S. Typhimurium to cause a systemic disease, since mice lacking IL-10 (IL-10-/-) were significantly more resistant to die after an infection as compared to wild-type (WT) mice. IL-10-/- mice had reduced bacterial loads in internal organs and increased levels of pro-inflammatory cytokines in serum at 5 days of infection. Importantly, WT mice showed high bacterial loads in tissues and no increase of cytokines in serum after 5 days of S. Typhimurium infection, except for IL-10. In WT mice, we observed a peak of il-10 messenger RNA production in ileum, spleen, and liver after 5 days of infection. Importantly, the adoptive transfer of T or B cells from WT mice restored the susceptibility of IL-10-/- mice to systemic S. Typhimurium infection, suggesting that the generation of regulatory cells in vivo is required to sustain a systemic infection by S. Typhimurium. These findings support the notion that IL-10 production from lymphoid cells is a key process in the infective cycle of S. Typhimurium in mice due to generation of a tolerogenic immune response that prevents bacterial clearance and supports systemic dissemination.

Modulating the function of the immune system by thyroid hormones and thyrotropin.

Accumulating evidence suggests a close bidirectional communication and regulation between the neuroendocrine and immune systems. Thyroid hormones (THs) can exert responses in various immune cells, e.g., monocytes, macrophages, natural killer cells, and lymphocytes, affecting several inflammation-related processes (such as, chemotaxis, phagocytosis, reactive oxygen species generation, and cytokines production). The interactions between the endocrine and immune systems have been shown to contribute to pathophysiological conditions, including sepsis, inflammation, autoimmune diseases and viral infections. Under these conditions, TH therapy could contribute to restoring normal physiological functions. Here we discuss the effects of THs and thyroid stimulating hormone (TSH) on the immune system and the contribution to inflammation and pathogen clearance, as well as the consequences of thyroid pathologies over the function of the immune system.

Endothelial-to-mesenchymal transition: Cytokine-mediated pathways that determine endothelial fibrosis under inflammatory conditions.

During the last decade, the endothelial-to-mesenchymal transition (EndMT) process has attracted considerable attention due to associations with the onset of certain diseases, such as organ fibrosis and cancer. Several studies have assessed the mechanisms and signaling pathways that regulate endothelial fibrosis in the context of human pathologies. A number of inflammatory mediators, including pro-inflammatory cytokines, growth factors, oxidative stress, and toxins, induce the conversion of endothelial cells into mesenchymal fibroblast-like cells that promote disease progression. This review is separated into five chapters that critically present current knowledge on EndMT in the context of pathology. First, the main characteristics of EndMT are summarized, with a focus on the endothelial protein pattern changes that modulate the expressions of endothelial/fibrotic markers and extracellular matrix proteins. These expressions could serve as mechanisms for explaining potential EndMT contributions to human pathologies in adults. Second, the main findings supporting a connection between EndMT-mediated endothelial fibrosis and inflammatory conditions are presented. These connections could be linked to the onset and progression of pathological conditions. Third, EndMT inducers are described in detail. This includes considerations on the actions of the first and most well-known EndMT inducer, TGF-ß; of the most prominent pro-inflammatory cytokines released during inflammation, such as IL 1-ß and TNF-α; and of the NF-κB transcription factor, a common player during inflammation-induced EndMT. Furthermore, thorough attention is given to EndMT induction by endotoxins in the context of bacterial infectious diseases. Additionally, the participation of the inflammatory oxidative stress environment in the EndMT induction was also reviewed. Fourth, the pathophysiological findings of inflammation-induced EndMT are presented, and, fifth, special focus is placed on associations with cancer onset and development. Altogether, this review highlights the important role of EndMT-mediated endothelial fibrosis during inflammation in human pathologies.

Role of the Renin-Angiotensin-Aldosterone System beyond Blood Pressure Regulation: Molecular and Cellular Mechanisms Involved in End-Organ Damage during Arterial Hypertension.

Arterial hypertension is a common condition worldwide and an important predictor of several complicated diseases. Arterial hypertension can be triggered by many factors, including physiological, genetic, and lifestyle causes. Specifically, molecules of the renin-angiotensin-aldosterone system not only play important roles in the control of blood pressure, but they are also associated with the genesis of arterial hypertension, thus constituting a need for pharmacological interventions. Chronic high pressure generates mechanical damage along the vascular system, heart, and kidneys, which are the principal organs affected in this condition. In addition to mechanical stress, hypertension-induced oxidative stress, chronic inflammation, and the activation of reparative mechanisms lead to end-organ damage, mainly due to fibrosis. Clinical trials have demonstrated that renin-angiotensin-aldosterone system intervention in hypertensive patients lowers morbidity/mortality and inflammatory marker levels as compared to placebo patients, evidencing that this system controls more than blood pressure. This review emphasizes the detrimental effects that a renin-angiotensin-aldosterone system (RAAS) imbalance has on health considerations above and beyond high blood pressure, such as fibrotic end-organ damage.

Aldosterona e IL-17 en la génesis de la hipertensión arterial mineralocorticoídea, un estudio ex vivo / Aldosterone and il-17 in the genesis of mineralocorticoid arterial hypertension: an ex vivo study

Background: Treatment of dendritic cells (DC) with aldosterone induces the secretion of IL-6 and TGF-beta. The polarization of naïve T cells to helper 17 T lymphocytes with DCs pre-incubated with aldosterone, has been described in vivo, generating an IL-17 hyper-secreting phenotype, a cytokine associated with cardiac and renal fibrosis. There are mineralocorticoid receptors (MR) in immune cells and their activation may determine the inflammatory (M1) or adaptive (M2) macrophage phenotype. Aldosterone levels could regulate immunogenic gene expression in these cells, modulating the liberation of specific cytokines. Aim: To assess in humans the association of aldosterone levels and IL-17 with inflammatory markers in peripheral blood mononuclear cells (PBMC). Material and Methods: In blood samples of 176 participants aged 18 to 67 years (61 percent women) with a body mass index of 27.1 +/- 4.8 kg/m2, aldosterone, plasma renin activity (ARP), cortisol, C reactive protein, andIL-17 were measured. mRNA was isolated from PBMCs to measure the expression of MR RAC-1, HO-1, TLR-4, CD-14, NGAL and IL-17 by real time polymerase chain reaction. Results: Aldosterone correlated positively with ARP and the expression of CD-14 in PBMCs. Plasma levels of IL-17 were positively associated with the expression of MR, Rac1a and NGAL. Conclusions: Aldosterone and IL-17 levels were associated with inflammatory activation markers in PBMC, which could activate MRand promote a subclinical inflammatory status inducing hypertension.

Interleukin-10 plays a key role in the modulation of neutrophils recruitment and lung inflammation during infection by Streptococcus pneumoniae.

Streptococcus pneumoniae is a major aetiological agent of pneumonia worldwide, as well as otitis media, sinusitis, meningitis and sepsis. Recent reports have suggested that inflammation of lungs due to S. pneumoniae infection promotes bacterial dissemination and severe disease. However, the contribution of anti-inflammatory molecules to the pathogenesis of S. pneumoniae remains unknown. To elucidate whether the production of the anti-inflammatory cytokine interleukin-10 (IL-10) is beneficial or detrimental for the host during pneumococcal pneumonia, we performed S. pneumoniae infections in mice lacking IL-10 (IL-10(-/-) mice). The IL-10(-/-) mice showed increased mortality, higher expression of pro-inflammatory cytokines, and an exacerbated recruitment of neutrophils into the lungs after S. pneumoniae infection. However, IL-10(-/-) mice showed significantly lower bacterial loads in lungs, spleen, brain and blood, when compared with mice that produced this cytokine. Our results support the notion that production of IL-10 during S. pneumoniae infection modulates the expression of pro-inflammatory cytokines and the infiltration of neutrophils into the lungs. This feature of IL-10 is important to avoid excessive inflammation of tissues and to improve host survival, even though bacterial dissemination is less efficient in the absence of this cytokine.