Excess of body weight is associated with accelerated T-cell senescence in hospitalized COVID-19 patients.

BACKGROUND: Several risk factors have been involved in the poor clinical progression of coronavirus disease-19 (COVID-19), including ageing, and obesity. SARS-CoV-2 may compromise lung function through cell damage and paracrine inflammation; and obesity has been associated with premature immunosenescence, microbial translocation, and dysfunctional innate immune responses leading to poor immune response against a range of viruses and bacterial infections. Here, we have comprehensively characterized the immunosenescence, microbial translocation, and immune dysregulation established in hospitalized COVID-19 patients with different degrees of body weight. RESULTS: Hospitalised COVID-19 patients with overweight and obesity had similarly higher plasma LPS and sCD14 levels than controls (all p < 0.01). Patients with obesity had higher leptin levels than controls. Obesity and overweight patients had similarly higher expansions of classical monocytes and immature natural killer (NK) cells (CD56+CD16-) than controls. In contrast, reduced proportions of intermediate monocytes, mature NK cells (CD56+CD16+), and NKT were found in both groups of patients than controls. As expected, COVID-19 patients had a robust expansion of plasmablasts, contrasting to lower proportions of major T-cell subsets (CD4 + and CD8+) than controls. Concerning T-cell activation, overweight and obese patients had lower proportions of CD4+CD38+ cells than controls. Contrasting changes were reported in CD25+CD127low/neg regulatory T cells, with increased and decreased proportions found in CD4+ and CD8+ T cells, respectively. There were similar proportions of T cells expressing checkpoint inhibitors across all groups. We also investigated distinct stages of T-cell differentiation (early, intermediate, and late-differentiated - TEMRA). The intermediate-differentiated CD4 + T cells and TEMRA cells (CD4+ and CD8+) were expanded in patients compared to controls. Senescent T cells can also express NK receptors (NKG2A/D), and patients had a robust expansion of CD8+CD57+NKG2A+ cells than controls. Unbiased immune profiling further confirmed the expansions of senescent T cells in COVID-19. CONCLUSIONS: These findings suggest that dysregulated immune cells, microbial translocation, and T-cell senescence may partially explain the increased vulnerability to COVID-19 in subjects with excess of body weight.

Spontaneous histopathology in New Zealand White rabbits: ten years of control data.

The historical control database of a multinational laboratory services provider was queried for all histopathologic findings in New Zealand White rabbits which were used as control animals during a ten-year period (2011-2020). The query included all evaluated tissues, with or without microscopic findings, in studies conducted for safety testing for regulatory approval by the U.S. Food and Drug Agency (FDA) or the U.S. Environmental Protection Agency. A second query included studies conducted in the United Kingdom for control rabbits used in studies compliant with the Healthcare Products Regulatory Agency (MHRA) and/or the European Medicines Agency (EMA), which provide regulatory oversight in the United Kingdom and European Union, respectively. Infiltrates of inflammatory (mixed or mononuclear) cells were commonly noted in various organs including heart, digestive tract, muscle, thyroid, kidney, urinary bladder, eyelid, ocular structures, harderian gland, lacrimal gland, and lung. Mineralization was noted in aorta, kidney, urinary bladder, and ovary. Also noted were degeneration/necrosis in the myocardium, and intramuscular injection sites of the skin, degeneration/regeneration of muscle and diaphragm, ectopic tissue in the pancreas and thyroid, basophilic foci in salivary gland, increased/decreased vacuolation in adrenal gland, increased/decreased lymphocytic cellularity of lymph nodes, intrasinusoidal erythrocytes in lymph nodes, thymic atrophy, increased adipocytes in bone marrow, inflammatory cell foci in the liver and gall bladder, lacrimal gland atrophy, renal tubule basophilia, degeneration/regeneration, and dilatation; oviduct cyst; in the testis, degeneration/atrophy, cellular debris, dilatation, decreased sperm and segmental hypoplasia of seminiferous tubules; and squamous metaplasia of the testis and seminal vesicle.

The role of O3 exposure and physical activity status on redox state, inflammation, and pulmonary toxicity of young men: A cross-sectional study.

The exposure to traffic-related air pollutants, such as NO2 and O3, are associated with detrimental health effects, becoming one of the greatest public health issues worldwide. Exercising in polluted environments could result in harmful outcomes for health and may blunt the physiological adaptations of exercise training. This study aimed to investigate the influence of physical activity and O3 exposure on redox status, an inflammatory marker, response to stress, and pulmonary toxicity of healthy young individuals. We performed a cross-sectional study with 100 individuals that, based on their exposure to O3 and physical fitness (PF) level, were distributed in four groups: Low PF + Low O3; Low PF + High O3; High PF + Low O3; High PF + High O3. We evaluated personal exposure to NO2 and O3, physical activity level, variables of oxidative stress (SOD, ROS, CAT, GSH, TBARS), pulmonary toxicity (CC16), and inflammatory mediators (IL-1ß, IL-4, IL-6, IL-10, TNF-α, HSP70). Spearman correlation test to check the association among the variables was used and to compare groups we used one-way ANOVA followed by Bonferroni's post hoc and Kruskal Wallis test followed by Dunn's post hoc. O3 levels correlated with physical activity (r = 0.25; p = 0.01) but not with age or markers of body composition (p > 0.05). The individuals with high physical fitness that were less exposed to O3 presented higher CAT activity (p < 0.001), lower TBARS (p < 0.01) and IL-1ß concentrations (p < 0.01), higher IL-6 (p < 0.05) and IL-10 concentrations (p < 0.05), lower IL-6:1L-10 ratio (p < 0.05), lower CC16 levels (p < 0.05), and higher HSP70 concentration (p < 0.05). Physical activity could result in higher exposure to O3 that could partially blunt some exercise adaptations, while high physical fitness improved the antioxidant defense system, systemic inflammatory mediators, and pulmonary toxicity.

Alterations in CD39/CD73 axis of T cells associated with COVID-19 severity.

Purinergic signaling modulates immune function and is involved in the immunopathogenesis of several viral infections. This study aimed to investigate alterations in purinergic pathways in coronavirus disease 2019 (COVID-19) patients. Mild and severe COVID-19 patients had lower extracellular adenosine triphosphate and adenosine levels, and higher cytokines than healthy controls. Mild COVID-19 patients presented lower frequencies of CD4+ CD25+ CD39+ (activated/memory regulatory T cell [mTreg]) and increased frequencies of high-differentiated (CD27- CD28- ) CD8+ T cells compared with healthy controls. Severe COVID-19 patients also showed higher frequencies of CD4+ CD39+ , CD4+ CD25- CD39+ (memory T effector cell), and high-differentiated CD8+ T cells (CD27- CD28- ), and diminished frequencies of CD4+ CD73+ , CD4+ CD25+ CD39+ mTreg cell, CD8+ CD73+ , and low-differentiated CD8+ T cells (CD27+ CD28+ ) in the blood in relation to mild COVID-19 patients and controls. Moreover, severe COVID-19 patients presented higher expression of PD-1 on low-differentiated CD8+ T cells. Both severe and mild COVID-19 patients presented higher frequencies of CD4+ Annexin-V+ and CD8+ Annexin-V+ T cells, indicating increased T-cell apoptosis. Plasma samples collected from severe COVID-19 patients were able to decrease the expression of CD73 on CD4+ and CD8+ T cells of a healthy donor. Interestingly, the in vitro incubation of peripheral blood mononuclear cell from severe COVID-19 patients with adenosine reduced the nuclear factor-κB activation in T cells and monocytes. Together, these data add new knowledge to the COVID-19 immunopathology through purinergic regulation.

Reversal of haloperidol-induced orofacial dyskinesia and neuroinflammation by isoflavones.

BACKGROUND: Schizophrenia is a mental illness and its pharmacological treatment consists in the administration of antipsychotics like haloperidol. However, haloperidol often causes extrapyramidal motor disorders such as tardive dyskinesia (TD). So far, there is no effective treatment against TD and alternatives for it have been sought. Isoflafones have been studied as neuroprotector and inhibitor of monoamine oxidase enzyme. Thus, the objective is to evaluate the possible protective effect of isoflavones against the induction of involuntary movements induced by haloperidol in an animal model. METHODS AND RESULTS: Male Wistar rats were treated with haloperidol (1 mg/kg/day) and/or isoflavones (80 mg/kg) for 28 days. Rats were submitted to behavioral evaluation to quantify vacuous chewing movements (VCM) and locomotor activity. In addition, the levels of pro-inflammatory cytokines were measured in the striatum. Haloperidol treatment reduced the locomotor activity and increased the number of VCM in rats. Co-treatment with isoflavones was able to reverse hypolocomotion and reduce the number of VCM. Besides, haloperidol caused significant increase in the proinflammatory cytokines (interleukin-1ß:IL-1ß, tumor necrosis factor-α: TNF-α and IL-6 and the co-treatment with isoflavones was able to reduce the levels of IL-1ß and TNF-α, but not IL-6. CONCLUSIONS: It is believed that the beneficial effect found with this alternative treatment is related to its anti-inflammatory potential and to the action on estrogen receptors (based on scientific literature findings). Finally, further studies are needed to elucidate the mechanisms of isoflavones in reducing motor disorders induced by antipsychotics.

Systemic redox imbalance in severe COVID-19 patients.

The aim of this study was to evaluate the systemic redox state and inflammatory markers in intensive care unit (ICU) or non-ICU severe COVID-19 patients during the hospitalization period. Blood samples were collected at hospital admission (T1) (Controls and COVID-19 patients), 5-7 days after admission (T2: 5-7 days after hospital admission), and at the discharge time from the hospital (T3: 0-72 h before leaving hospital or death) to analyze systemic oxidative stress markers and inflammatory variables. The reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) were analyzed in peripheral granulocytes and monocytes. THP-1 human monocytic cell line was incubated with plasma from non-ICU and ICU COVID-19 patients and cell viability and apoptosis rate were analyzed. Higher total antioxidant capacity, protein oxidation, lipid peroxidation, and IL-6 at hospital admission were identified in both non-ICU and ICU COVID-19 patients. ICU COVID-19 patients presented increased C-reactive protein, ROS levels, and protein oxidation over hospitalization period compared to non-ICU patients, despite increased antioxidant status. Granulocytes and monocytes of non-ICU and ICU COVID-19 patients presented lower MMP and higher ROS production compared to the healthy controls, with the highest values found in ICU COVID-19 group. Finally, the incubation of THP-1 cells with plasma acquired from ICU COVID-19 patients at T3 hospitalization period decreased cell viability and apoptosis rate. In conclusion, disturbance in redox state is a hallmark of severe COVID-19 and is associated with cell damage and death.

Exposure to fine particulate matter partially counteract adaptations on glucose metabolism, oxidative stress, and inflammation of endurance exercise in rats.

BACKGROUND: Long-term exposure to air pollution triggers metabolic alterations along with oxidative stress and inflammation, while exercise interventions are widely used to improve those parameters. OBJECTIVE: Our study aimed to determine the effects of subchronic exposure to particulate matter 2.5 (PM2.5) and endurance exercise training on glucose metabolism, oxidative stress, and inflammation of the heart and gastrocnemius muscle of rats. MATERIAL AND METHODS: Thirty-two male Wistar rats were assigned to 4 experimental groups: Untrained; Endurance training (ET); Untrained + PM2.5; Endurance training + PM2.5. Rats exposed to air pollution received 50 µg of PM2.5 via intranasal instillation daily for 12 weeks. Exercised groups underwent endurance training, consisting in running on an electronic treadmill (70% of maximal capacity, 5 days/week, 5 times/week) for 12 weeks. Glucose metabolism markers, redox state, and inflammatory variables were evaluated in the heart and gastrocnemius muscle. RESULTS: ET and ET + PM2.5 group had lower body mass gain and higher exercise capacity, and higher glycogen concentration in the heart and gastrocnemius muscle. In the heart, ET and ET + PM2.5 groups had higher levels of GSH, and lower TBARS and TNF-α concentrations. In the gastrocnemius muscle, the ET group showed higher leptin and lower TBARS and IL-1ß concentrations, ET and ET + PM2.5 showed higher superoxide dismutase activity and ROS content. CONCLUSION: PM2.5 exposure partially blunts metabolic and inflammatory adaptations in heart and gastrocnemius muscle tissues induced by exercise training.

O3 concentration and duration of exposure are factors influencing the environmental health risk of exercising in Rio Grande, Brazil.

Ozone (O3) represents a great threat to human health, contributing to respiratory diseases and premature mortality. This pollutant is often considered a critical pollutant in regions of southern Brazil. Exposure to this pollutant during vigorous physical activity should be the subject of thorough investigations due to the increased ventilation rate and altered breathing pattern present during vigorous physical activity that result in greater inhalation of O3. Thus, this study aimed to evaluate the health risk of exposure to low, mean, and high concentrations of O3 during different durations of exercise in the city of Rio Grande (southern Brazil). Healthy young men (n = 45) performed cardiopulmonary exercise testing, and ventilation rate data were collected to predict total ventilation and pollutant inhalation during a 5 km running session. The O3 concentration in the city of Rio Grande was obtained from data reported by the Copernicus Atmosphere Monitoring Service (CAMS). The environmental health risk was calculated based on the potential intake dose. The lowest, mean, and highest concentrations of O3 detected during the monitoring period were 32.5, 64.9, and 115.2 µg/m3, respectively. In all evaluated scenarios, there was a toxicological risk (RQ > 1), except when exercising when the O3 concentration was lowest for the shortest length of time (p < 0.001). As the concentration of O3 and the duration of the exposure increase, the health risk is increased. Therefore, O3 concentration and duration of exposure are factors influencing the health risk of exercising. These findings are extremely relevant in cities that have high levels of O3, such as the city of Rio Grande.

Differential effects of whole blood heat treatment on the ex vivo inflammatory profile of untrained and trained men.

This study evaluated the effects of heat stress on the ex vivo inflammatory profile in untrained and trained men. Whole blood samples from untrained (UT) and trained (TR) individuals were incubated for 2 h at 37 °C or 40 °C. The whole blood of a subsample of the participants (n = 5 in both TR and UT groups) were stimulated with lipopolysaccharide (LPS, 10 ng/mL) concomitant to heat treatment (37 °C versus 40 °C). Flow cytometry was used to assess the intracellular NF-κB activation in CD4+ T cells and CD14+ monocytes, the expression of Toll-Like Receptor-4 (TLR-4), the frequencies of CD4+CD25-CD39+ and CD4+CD25+CD39+ T cells and monocyte subsets (CD14+CD16-; CD14+CD16+; CD14-CD16+), the mitochondrial membrane potential (MMP) and the reactive oxygen species (ROS) production by lymphocytes and monocytes. The production of interleukin (IL)-6, IL-10, and tumor necrosis factor-alpha (TNF-α) by LPS-stimulated whole blood were also evaluated. Heat treatment (40 °C) increased the proportions of CD14+CD16- and CD14+CD16+ monocytes and the lymphocyte MMP in the UT group. The frequencies of CD14-CD16+ monocytes and the activation of NF-κB in CD14+ monocytes decreased in UT and TR groups after heat treatment, while a reduction in CD4+CD25-CD39+ T-cells was observed only in the UT group. Higher TLR-4 and NF-κB activation were found in LPS-stimulated monocytes of UT men concomitant with higher TNF-α production and diminished IL-10 production after heat treatment. TR individuals presented lower NF- κB activation in LPS-stimulated monocytes after heat treatment. Our data suggest that the training status of individuals may impact on the anti-inflammatory response of heat treatment.

The concomitant use of cannabis and cocaine coexists with increased LPS levels and systemic inflammation in male drug users.

Illicit drug use can cause a variety of effects including alterations in the immune system. The aim of this study was to investigate the effects of illicit drugs on circulating lipopolysaccharide (LPS), systemic inflammation and oxidative stress markers in drug users. We evaluated the levels of soluble CD14 (sCD14), LPS, inflammatory (TNF-α and IL-6) and regulatory (IL-10) cytokines, as well as C-reactive protein (CRP), lipid peroxidation (TBARS) and total thiols in the peripheral blood of 81 men included in groups of cannabis (n = 21), cocaine (n = 12), cannabis-plus-cocaine users (n = 27), and non-drug users (n = 21). The use of cannabis plus cocaine leads to higher systemic levels of LPS, CRP, IL-6 and higher IL-6/IL-10 ratio, characterizing a proinflammatory profile. In contrast, a regulatory profile as viewed by lower systemic TNF-α and IL-6 levels and lower TNF-α/IL-10 ratio were observed in cannabis users compared to the control group. Moreover, cocaine users presented a lower content of non-enzymatic antioxidant thiol compared to control group, cannabis group and cannabis plus cocaine group. In conclusion, our results indicate that the use of cannabis contributes to an anti-inflammatory/or regulatory profile while the concomitant cannabis plus cocaine consumption coexists with increased circulating amounts of LPS and proinflammatory status.

Incidences and Range of Spontaneous Microscopic Lesions in the Eye of Sprague-Dawley Rats and Han Wistar Rats Used in Toxicity Studies.

The incidence and range of spontaneous microscopic lesions were determined in the eyes of male and female control Sprague-Dawley and Han Wistar rats. Data were collected retrospectively from 1411, 817, 970, 658, and 3999 rats from control groups of 4-, 13-, 26-, 52-, and 104-week studies, respectively, carried out between 1997 and 2019. Microscopic lesions of the eye were rare in 4- and 13-week studies, uncommon in 26- and 52-week studies, and were of relatively higher incidence in 104-week studies. Neoplastic lesions were sporadic and were only observed in 104-week studies. In Sprague-Dawley rats, the most common lesions (>1% in 104-week studies) were retinal degeneration, retinal rosettes/folds, and lenticular degeneration. The Han Wistar rats presented a range of ocular lesions similar to the Sprague-Dawley rats. However, retinal degeneration occurred with an earlier onset and at higher incidences, ranging from >5% in 26-week studies up to 45.72% in 104-week studies. In both strains, females exhibited higher incidences and severities of retinal degeneration. It is hoped that reference to the incidences reported here will facilitate the differentiation of spontaneous lesions from test article-induced lesions in toxicology studies in these strains of rat.

Air pollution concentration and period of the day modulates inhalation of PM2.5 during moderate- and high-intensity interval exercise.

The increase in minute ventilation during exercise led to higher inhalation of air pollution and, consequently, to exacerbation of health issues. Therefore, the intensity of exercise and the air pollution concentration of the environment could be determinant variables to poor outcomes. This study aimed to investigate the inhaled dose of particulate matter 2.5 (PM2.5) during a moderate- and high-intensity interval exercise session performed in the morning and evening at different locations of Porto Alegre City. Eighteen individuals performed a cardiopulmonary exercise test, a moderate-intensity interval exercise (MIIE), and a high-intensity interval exercise (HIIE). Heart rate was monitored to estimate minute ventilation and total ventilation of the session. The concentration of PM2.5 was measured during the morning (6-8a.m.) and evening (6-8p.m.) by fixed-site monitors placed at five points of Porto Alegre City. The PM2.5 inhalation during MIIE and HIIE performed in the morning and evening in the monitoring points was estimated. HIIE showed higher minute ventilation (VE) (p = 0.0048) and total ventilation did not differ between groups (p = 0.4648). PM2.5 concentrations were higher during the mornings (p < 0.001). Monitored point 1 had higher levels of PM2.5 in the morning and evening (p < 0.001). The inhalation of PM2.5 in the morning showed no difference in MIIE (p = 0.8172) and HIIE (p = 0.7306) groups among the points. In the evening, the inhalation of PM2.5 was higher in point 1 in MIIE and HIIE group (p < 0.001). MIIE and HIIE had higher inhalation of PM2.5 in the morning than in the evening (p < 0.001). Total ventilation of exercise is a crucial factor that contributes to the inhalation dose of air pollution.

Physical fitness modulates the expression of CD39 and CD73 on CD4+ CD25- and CD4+ CD25+ T cells following high intensity interval exercise.

AIM: To investigate the impact of physical fitness on the mobilization of CD4+ CD25 - CD39 + and CD4 + CD25 + CD39 + T cells in response to acute exercise. METHODS: Fifteen high physical fitness (25.3 ± 1.4 years) and 15 low physical fitness (26.1 ± 1.9 years) men performed a single bout of high-intensity interval exercise (HIIE, 10 bouts of 60 seconds at 85% HRmax intercepted by 75 seconds of recovery at 50% HRmax). Blood lymphocytes were isolated before, immediately after and 1 hour after exercise for assessment of cell surface expression of CD25, CD39, and CD73 on CD4+ T cells. Effector memory T cells (mTeff) were identified by CD4 + CD25 - CD39 + coexpression, and memory regulatory T cells (mTReg) were defined as CD4 + CD25 + CD39 + T cells. RESULTS: Exercise increased CD4+ and CD4 + CD25 + T cell frequencies immediately after followed by a decrease bellow to baseline values at 1 hour after the bout in both low and high physical fitness groups. At baseline, the proportions of mTeff were higher, while mTreg were lower in low physical fitness individuals. The frequency of mTreg increased immediately after HIIE in both groups, and remained higher 1 hour after the bout. However, high physical fitness individuals presented higher mTreg frequency in all periods evaluated. A significantly mobilization of mTeff cells was identified in both groups immediately after HIIE. High physical fitness individuals displayed a decrease in mTeff cells bellow to baseline, while the frequency of mTeff remained higher in low physical fitness group 1 hour after the bout. The peripheral frequency of CD4 + CD25 + CD73 + T cells increased in a similar way immediately after the bout in both groups, returning to the baseline values 1 hour after exercise. No differences in CD4 + CD25 - CD73 + T cells were observed after HIIE in both groups. CONCLUSION: Our results highlight the impact of physical activity status in the redistribution of CD4+ T cells expressing ectonucleotidases in response to HIIE.

Cardiorespiratory fitness modulates the proportions of monocytes and T helper subsets in lean and obese men.

This study investigated the peripheral frequency of monocytes, CD4 + T cell subsets and the systemic levels of cytokines in lean and obese men with different levels of cardiorespiratory fitness (CRF). Mononuclear cells were obtained from 45 lean and 45 obese men who were assigned into six groups according to their body mass index and CRF (low, moderate, or high VO2Peak ) to analyze the frequency of monocyte subsets and subpopulations of CD4 + T cells (Treg cells, CD4 + CD25high CD127low ; mTeff, CD4 + CD25-CD39+; mTreg, CD4 + CD25+CD39+). The systemic levels of interleukin (IL)-6, IL-10, IL-17a, IL-33, leptin, and tumor necrosis factor-alpha (TNF-α) were also evaluated. Seven sedentary obese men performed one week of high-intensity interval training (HIIT, 3 sessions/week), and blood samples were collected before and 24 hours after the last session for phenotypic analysis of T cells and monocytes. Obese individuals presented an inflammatory profile characterized by lower frequencies of Treg and mTreg cells and higher proportions of proinflammatory monocytes. However, higher CRF status increased the frequencies of Treg cells and mTreg cells and decreased the percentage of CD4 + mTeff cells and intermediate and non-classical monocytes in the peripheral blood from lean and obese men. Systemic lower levels of proinflammatory (IL-6 and TNF-) cytokines and higher concentrations of IL-10 and IL-33 were observed in moderate and higher CRF in all subjects. HIIT increased the proportions of circulating mTreg and Treg cells in sedentary obese individuals. The immunoregulatory role of CRF contributes to the maintenance of low levels of inflammatory mediators.

Anti-Trypanosoma activity of bioactive metabolites from Photorhabdus luminescens and Xenorhabdus nematophila.

Only two drugs are currently available for the treatment of Chagas disease and their effectiveness are unsatisfactory. Photorhabdus luminescens and Xenorhabdus nematophila, two enteric bacteria highly pathogenic to a broad range of insects, have been studied as potential source for bioactive metabolites against protozoa causing neglected tropical diseases. Therefore, we tested the in vitro anti-Trypanosoma cruzi activity of secreted metabolites from these bacteria. The conditioned medium of X. nematophila and P. luminescens showed significant parasiticidal activity in a concentration-dependent manner (IC50XN = 0.34 mg/mL, IC50PL = 1.0 mg/mL). The parasiticidal compound was identified as a small molecule stable to heating and pH changes ranging from 2 to 12. Moreover, anti-Trypanosoma molecules secreted by both bacteria stimulate the trypanocidal activity of macrophages by a mechanism independent of nitric oxide. Summarizing, our studies reveal that P. luminescens and X. nematophila are potential sources of putative novel drugs against Chagas disease.

Nanoparticle vaccines against viral infections.

Despite numerous efforts, we still do not have prophylactic vaccines for many clinically relevant viruses, such as HIV, hepatitis C virus, Zika virus, and respiratory syncytial virus. Several factors have contributed to the current lack of effective vaccines, including the high rate of viral mutation, low immunogenicity of recombinant viral antigens, instability of viral antigenic proteins administered in vivo, sophisticated mechanisms of viral immune evasion, and inefficient induction of mucosal immunity by vaccine models studied to date. Some of these obstacles could be partially overcome by the use of vaccine adjuvants. Nanoparticles have been intensively investigated as vaccine adjuvants because they possess chemical and structural properties that improve immunogenicity. The use of nanotechnology in the construction of immunization systems has developed into the field of viral nanovaccinology. The purpose of this paper is to review and correlate recent discoveries concerning nanoparticles and specific properties that contribute to the immunogenicity of viral nanoparticle vaccines, bio-nano interaction, design of nanoparticle vaccines for clinically relevant viruses, and future prospects for viral nanoparticle vaccination.

Canine visceral leishmaniasis diagnosis: a comparative performance of serological and molecular tests in symptomatic and asymptomatic dogs.

Although serological assays have been widely used for the diagnosis of canine visceral leishmaniasis (CVL), they present different performances depending on the clinical profile of the dogs. This study evaluated the accuracy of serological tests, immunochromatographic (Dual Path Platform: DPP®) and enzyme-linked immunosorbent (ELISA EIE®), for CVL in relation to the detection of Leishmania DNA through real-time polymerase chain reaction (real-time PCR) in samples from symptomatic and asymptomatic dogs from a non-endemic area in the state of Rio Grande do Sul, Southern Brazil. Serum from 140 dogs (39 symptomatic and 101 asymptomatic) was tested by DPP and ELISA followed by real-time PCR. From a total of 140 samples evaluated, Leishmania DNA was detected by real-time PCR in 41.4% (58/140). Moreover, 67.2% of samples positive in real-time PCR were positive in both DPP and ELISA (39/58), showing moderate agreement between methods. In the symptomatic group, one sample non-reactive in both serological assays was positive in real-time PCR, whereas in the asymptomatic group, 17.8% non-reactive or undetermined samples in serological assays were positive in the molecular method. Leishmania DNA was not detected in 17.9% reactive samples by serological assays from the symptomatic group, and in 3.9% from asymptomatic dogs. Real-time PCR demonstrated greater homogeneity between symptomatic and asymptomatic groups compared with DPP and ELISA. The molecular method can help to establish the correct CVL diagnosis, particularly in asymptomatic dogs, avoiding undesirable euthanasia.

Entomopathogenic bacteria Photorhabdus luminescens as drug source against Leishmania amazonensis.

Leishmaniasis is a widely spread and zoonotic disease with serious problems as low effectiveness of drugs, emergence of parasite resistance and severe adverse reactions. In recent years, considerable attention has been given to secondary metabolites produced by Photorhabdus luminescens, an entomopathogenic bacterium. Here, we assessed the leishmanicidal activity of P. luminescens culture fluids. Initially, promastigotes of Leishmania amazonensis were incubated with cell free conditioned medium of P. luminescens and parasite survival was monitored. Different pre-treatments of the conditioned medium revealed that the leishmanicidal activity is due to a secreted peptide smaller than 3 kDa. The Photorhabdus-derived leishmanicidal toxin (PLT) was enriched from conditioned medium and its effect on mitochondrial membrane potential of promastigotes, was determined. Moreover, the biological activity of PLT against amastigotes was evaluated. PLT inhibited the parasite growth and showed significant leishmanicidal activity against promastigote and amastigotes of L. amazonensis. PLT also caused mitochondrial dysfunction in parasites, but low toxicity to mammalian cell and human erythrocytes. Moreover, the anti-amastigote activity was independent of nitric oxide production. In summary, our results highlight that P. luminescens secretes Leishmania-toxic peptide(s) that are promising novel drugs for therapy against leishmaniasis.

Phloroglucinol derivatives from Hypericum species trigger mitochondrial dysfunction in Leishmania amazonensis.

Bioactive molecules isolated from plants are promising sources for the development of new therapies against leishmaniasis. We investigated the leishmanicidal activity of cariphenone A (1), isouliginosin B (2) and uliginosin B (3) isolated from Hypericum species. Promastigotes and amastigotes of Leishmania amazonensis were incubated with compounds 1-3 at concentrations 1-100 µm for 48 h. The anti-promastigote effect of compounds was also tested in combinations. The cytotoxicity against macrophages and human erythrocytes were determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) method and hemolysis assay, respectively. The compounds 1-3 showed high leishmanicidal activity against promastigotes, IC50 values of 10.5, 17.5 and 11.3 µm, respectively. Synergistic interactions were found to the associations of compounds 1 and 2 [Σ fractional inhibitory concentration (FIC) = 0.41], and 2 and 3 (ΣFIC = 0.28) on promastigotes. All Hypericum compounds induced mitochondrial hyperpolarization and reactive oxygen species production in promastigotes. The compounds showed low cytotoxicity toward mammalian cells, high selectivity index and killed intracellular amastigotes probably mediated by oxidative stress. These results indicate that these compounds are promising candidates for the development of drugs against leishmaniasis.

Molecular Method Confirms Canine Leishmania Infection Detected by Serological Methods in Non-Endemic Area of Brazil.

In Brazil, visceral leishmaniasis (VL) is expanding and becoming urbanized, especially in non-endemic areas such as the State of Rio Grande do Sul. Considering that infected dogs are the main reservoir for zoonotic VL, this study evaluated the prevalence of canine visceral leishmaniasis (CVL) in the metropolitan area of Porto Alegre, a new area of expansion of VL in Brazil. Serum and plasma from 405 asymptomatic dogs from the municipalities of Canoas (n=107), São Leopoldo (n=216), and Novo Hamburgo (n=82) were tested for CVL using immunochromatographic (DPP®) and ELISA EIE® assays (2 assays officially adopted by the Brazilian government for the diagnosis of CVL) and real-time PCR to confirm the results. There was no agreement among serological and real-time PCR results, indicating that the Leishmania infection in asymptomatic animals with low parasite load, confirmed by negative parasitological tests (smears and parasite culture), need to be evaluated by molecular methods. The prevalence of LVC in the metropolitan region of Porto Alegre, confirmed by real-time PCR was 4% (5.6% in Canoas and 4.6% in São Leopoldo). The use of molecular method is essential for accurate diagnosis of CVL, especially in asymptomatic dogs in non-endemic areas.