Search

COVID-19 vaccine evaluations are mainly focused on antibody analyses, but there is growing interest in measuring the cellular immune responses from the researchers evaluating these vaccines. The cellular responses to several COVID-19 vaccines have been studied using the enzyme-linked immunospot (ELISPOT) assay for IFN-γ. However, the ELISPOT assay is no longer used only for research purpose and so the performance of this assay must be validated. Since the bioanalytical validation of ELISPOT-IFN-γ is essential for evaluating the method's effectiveness and establishing confidence in a vaccine's immunogenicity, the present work validates the ELISPOT-IFN-γ assay's performance in determining the frequency of IFN-γ-producing cells after stimulation with the SARS-CoV-2 spike protein. The validation was performed in peripheral blood mononuclear cells from volunteers immunized with anti-COVID-19 vaccines. According to the findings, the LOD was 17 SFU and the LLOQ was 22 SFU, which makes the method highly sensitive and suitable for evaluating low levels of cellular responses. The procedure's accuracy is confirmed by the correlation coefficients for the spike protein and anti-CD3+, being 0.98 and 0.95, respectively. The repeatability and intermediate precision tests were confirmed to be reliable by obtaining a coefficient of variation of ≤25%. The results obtained in this validation enable the assay to be employed for studying antigen-specific cells and evaluating cellular responses to vaccines. [ABSTRACT FROM AUTHOR]

Chagas disease is a complex zoonosis. Clinically, it presents in two distinct phases, acute and chronic. The ability of patients to respond to Trypanosoma cruzi infection depends on the balance between inflammatory and anti-inflammatory responses, in which cytokines play a key regulatory role. In this review, we discuss the role of cytokines in regulating the host response and as mediators of cardiac injury by inducing profibrotic alterations. The importance of characterizing cytokine profiles as biomarkers of the evolution of cardiac damage in T.-cruzi-infected individuals is also emphasized. [ABSTRACT FROM AUTHOR]

Obstructive Sleep Apnea (OSA) is a respiratory disorder characterized by frequent breathing pauses during sleep. The apnea–hypopnea index is a measure used to assess the severity of sleep apnea and the hourly rate of respiratory events. Despite numerous commercial devices available for apnea diagnosis and early detection, accessibility remains challenging for the general population, leading to lengthy wait times in sleep clinics. Consequently, research on monitoring and predicting OSA has surged. This comprehensive paper reviews devices, emphasizing distinctions among representative apnea devices and technologies for home detection of OSA. The collected articles are analyzed to present a clear discussion. Each article is evaluated according to diagnostic elements, the implemented automation level, and the derived level of evidence and quality rating. The findings indicate that the critical variables for monitoring sleep behavior include oxygen saturation (oximetry), body position, respiratory effort, and respiratory flow. Also, the prevalent trend is the development of level IV devices, measuring one or two signals and supported by prediction software. Noteworthy methods showcasing optimal results involve neural networks, deep learning, and regression modeling, achieving an accuracy of approximately 99%. [ABSTRACT FROM AUTHOR]

Chagas disease is caused by the hemoflagellate protozoan Trypanosoma cruzi. The main transmission mechanism for the parasite in endemic areas is contact with the feces of an infected triatomine bug. Part of the life cycle of T. cruzi occurs in the digestive tract of triatomines, where vector and parasite engage in a close interaction at a proteomic–molecular level. This interaction triggers replication and differentiation processes in the parasite that can affect its infectivity for the vertebrate host. With the aim of compiling and analyzing information from indexed publications on transcripts, proteins, and glycoproteins in the guts of fasting, fed, and T. cruzi-infected triatomines in the period 2000–2022, a systematic review was conducted following the PRISMA guidelines. Fifty-five original research articles retrieved from PubMed and ScienceDirect were selected; forty-four papers reported 1–26,946 transcripts, and twenty-one studies described 1–2603 peptides/proteins. [ABSTRACT FROM AUTHOR]

Symptoms in the acute phase of Chagas disease are usually mild and nonspecific. However, after several years, severe complications like dilated heart failure and even death may arise in the chronic phase. Due to the lack of specific symptoms in the acute phase, the aim of this work was to describe and analyze the cardiac histopathology during this phase in a CD1 mouse model by assessing parasitism, fibrotic damage, and the presence and composition of a cellular infiltrate, to determine its involvement in the pathogenesis of lesions in the cardiac tissue. Our results indicate that the acute phase lasts about 62 days post-infection (dpi). A significant increase in parasitemia was observed since 15 dpi, reaching a maximum at 33 dpi (4.1 × 106). The presence of amastigote nests was observed at 15–62 dpi, with a maximum count of 27 nests at 35 dpi. An infiltrate consisting primarily of macrophages and neutrophils was found in the cardiac tissue within the first 30 days, but the abundance of lymphocytes showed an 8 ≥ fold increase at 40–62 dpi. Unifocal interstitial fibrosis was identified after 9 dpi, which subsequently showed a 16 ≥ fold increase at 40–60 dpi, along with a 50% mortality rate in the model under study. The increased area of fibrotic lesions revealed progression in the extent of fibrosis, mainly at 50–62 dpi. The presence of perivasculitis and thrombus circulation disorders was seen in the last days (62 dpi); finally, cases of myocytolysis were observed at 50 and 62 dpi. These histopathological alterations, combined with collagen deposition, seem to lead to the development of interstitial fibrosis and damage to the cardiac tissue during the acute phase of infection. This study provides a more complete understanding of the patterns of histopathological abnormalities involved in the acute phase, which could help the development of new therapies to aid the preclinical tests of drugs for their application in Chagas disease. [ABSTRACT FROM AUTHOR]

In Chagas disease, the mechanisms involved in cardiac damage are an active field of study. The factors underlying the evolution of lesions following infection by Trypanosoma cruzi and, in some cases, the persistence of its antigens and the host response, with the ensuing development of clinically observable cardiac damage, are analyzed in this review. [ABSTRACT FROM AUTHOR]

Trypanosoma cruzi is a parasite transmitted by the feces of triatomines. Many triatomine species are found in Mexico, and various T. cruzi variants have been isolated from these species, each showing very different virulence and cell tropism. The isolates were obtained from Meccus phyllosoma specimens in three localities in the state of Oaxaca, Mexico: Tehuantitla, Vixhana, and Guichivere. The virulence of each isolate was assessed by quantifying parasitemia, survival, and histopathologic findings. The lineage of each isolate was identified using the mini-exon gene. The expression of the tssa gene during infection was detected in the heart, esophagus, gastrocnemius, and brain. Our results show that the maximum post-infection parasitemia was higher for the Tehuantitla isolate. On genotyping, all isolates were identified as T. cruzi I. The amastigotes in the heart and gastrocnemius were verified for all isolates, but in the brain only for Tehuantitla and Vixhana. The tssa expression allowed us to detect T. cruzi isolates, for Tehuantitla, predominantly in the heart. For Vixhana, a higher tssa expression was detected in gastrocnemius, and for Guichivere, it was higher in the esophagus. Results show that virulence, tropism, and tssa expression can vary, even when the isolates are derived from the same vector species, in the same region, and at similar altitudes. [ABSTRACT FROM AUTHOR]

The physiological state of the human macrophage may impact the metabolism and the persistence of Mycobacterium tuberculosis. This pathogen senses and counters the levels of O2, CO, reactive oxygen species (ROS), and pH in macrophages. M. tuberculosis responds to oxidative stress through WhiB3. The goal was to determine the effect of NADPH oxidase (NOX) modulation and oxidative agents on the expression of whiB3 and genes involved in lipid metabolism (lip-Y, Icl-1, and tgs-1) in intracellular mycobacteria. Human macrophages were first treated with NOX modulators such as DPI (ROS inhibitor) and PMA (ROS activator), or with oxidative agents (H2O2 and generator system O2•−), and then infected with mycobacteria. We determined ROS production, cell viability, and expression of whiB3, as well as genes involved in lipid metabolism. PMA, H2O2, and O2•− increased ROS production in human macrophages, generating oxidative stress in bacteria and augmented the gene expression of whiB3, lip-Y, Icl-1, and tgs-1. Our results suggest that ROS production in macrophages induces oxidative stress in intracellular bacteria inducing whiB3 expression. This factor may activate the synthesis of reserve lipids produced to survive in the latency state, which allows its persistence for long periods within the host. [ABSTRACT FROM AUTHOR]

There is a sex bias in tuberculosis's severity, prevalence, and pathogenesis, and the rates are higher in men. Immunological and physiological factors are fundamental contributors to the development of the disease, and sex-related factors could play an essential role in making women more resistant to severe forms of the disease. In this study, we evaluated sex-dependent differences in inflammatory markers. Serum samples were collected from 34 patients diagnosed with pulmonary TB (19 male and 15 female) and 27 healthy controls (18 male and 9 female). Cytokines IL2, IL4, IL6, IL8, IL10, IFNγ, TNFα, and GM-CSF, and eicosanoids PGE2, LTB4, RvD1, and Mar1 were measured using commercially available immunoassays. The MDA, a product of lipidic peroxidation, was measured by detecting thiobarbituric-acid-reactive substances (TBARS). Differential inflammation patterns between men and women were observed. Men had higher levels of IL6, IL8, and TNFα than women. PGE2 and LTB4 levels were higher in patients than healthy controls, but there were no differences for RvD1 and Mar1. Women had higher RvD1/PGE2 and RvD1/LTB4 ratios among patients. RvD1 plays a vital role in resolving the inflammatory process of TB in women. Men are the major contributors to the typical pro-inflammatory profile observed in the serum of tuberculosis patients. [ABSTRACT FROM AUTHOR]

Background: COVID-19 is an infectious disease caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Many COVID-19 patients require invasive mechanical ventilation (IMV) while others, even with acute respiratory failure, do not (NIMV). Therefore, we aimed to evaluate serum levels of MMP-7 and molecules related to exhausted T-cells as potential biomarkers to differentiate between IMV and NIMV patients. Methods: 105 patients diagnosed with COVID-19 and confirmed by RT-PCR for SARS-CoV-2 were divided into two groups according to the requirement for IMV. Serum levels of sPD-L1, sPD-L2, sTIM-3, sGal-9 and sMMP-7 were quantified by ELISA and correlated with clinical data. Twelve patients were followed up after eight months to compare the levels of the biomarkers between acute disease and post-COVID-19. Results: IMV patients experienced a lower PaO2/FiO2 (p < 0.0001) and a longer hospital stay (p < 0.0001), and exhibited higher levels of sPD-L1 (p < 0.05), sTIM-3 (p < 0.01) and sMMP-7 (p < 0.0001) when compared with NIMV patients. According to a ROC analysis, sMMP-7 had the highest sensitivity (78%) and specificity (76%) with a cut point of 4.5 ng/mL, followed by sTIM-3 and sPD-L1. Eight months post-COVID-19, IMV patients displayed a significant decrease in the initially high levels of sPD-L1, sTIM-3 and sGal-9, while sPD-L2 was increased, and sMMP-7 was unchanged. Conclusion: Circulating levels of sPD-L1, sTIM-3 and sMMP-7 are potential biomarkers of disease severity to distinguish patients requiring IMV. MMP-7 could also be a marker for the persistence of lung lesions post-COVID-19. [ABSTRACT FROM AUTHOR]

Gluconacetobacter diazotrophicus is a N2-fixing bacterium endophyte from sugar cane. The oxidation of ethanol to acetic acid of this organism takes place in the periplasmic space, and this reaction is catalyzed by two membrane-bound enzymes complexes: the alcohol dehydrogenase (ADH) and the aldehyde dehydrogenase (ALDH). We present strong evidence showing that the well-known membrane-bound Alcohol dehydrogenase (ADHa) of Ga. diazotrophicus is indeed a double function enzyme, which is able to use primary alcohols (C2-C6) and its respective aldehydes as alternate substrates. Moreover, the enzyme utilizes ethanol as a substrate in a reaction mechanism where this is subjected to a two-step oxidation process to produce acetic acid without releasing the acetaldehyde intermediary to the media. Moreover, we propose a mechanism that, under physiological conditions, might permit a massive conversion of ethanol to acetic acid, as usually occurs in the acetic acid bacteria, but without the transient accumulation of the highly toxic acetaldehyde. [ABSTRACT FROM AUTHOR]

Vitamin D has an immunomodulatory function and is involved in eliminating pathogens. Vitamin D deficiencies reported in Type 2 diabetes mellitus (T2DM) patients make them more susceptible to developing tuberculosis (TB). The macrophages are the immune cells that control intracellular pathogens by producing the antimicrobial peptide cathelicidin-LL37. This pathway involves TLR activation by pathogens, vitamin D receptor (VDR) ligation, and the enzyme 1α-hydroxylase Cytochrome P450 Family 27 Subfamily B Member 1 (CYP27B1). However, it is not clear whether the biological actions of vitamin D are affected by high glucose concentrations. This study aimed to evaluate the vitamin D contribution in the expression of VDR and CYP27B1, involved in the conversion of an inactive to an active form of vitamin D in the infected macrophages using M. tuberculosis as an infection model. The expression of LL37 and the nucleus translocation of VDR were evaluated as the readout of the response of vitamin D and determined if those processes are affected by glucose concentrations. Macrophages from healthy donors were cultured under glucose concentrations of 5.5, 15, or 30 mM, stimulated with vitamin D in inactive (25(OH)D3) or active (1,25(OH)2D3) forms, and infected with M. tuberculosis. The vitamin D-dependent induction of LL37 and the expression of VDR and CYP27B1 genes were analyzed by qPCR, and VDR translocation was analyzed in nuclear protein extracts by ELISA. M. tuberculosis downregulated the expression of LL37 regardless of the glucose concentration, whereas VDR and CYP27B1 upregulated it regardless of the glucose concentration. After evaluating two concentrations of vitamin D, 1 nM or 1 μM, the high concentration (1 μM) was necessary to restore the induction of LL37 expression in M. tuberculosis-infected macrophages. High concentrations of the inactive form of vitamin D restore the infected macrophages' ability to express LL37 regardless of the glucose concentration. This finding supports the idea that vitamin D administration in patients with T2DM could benefit TB control and prevention. [ABSTRACT FROM AUTHOR]

In mycobacterial infections, the number of cells from two newly discovered subpopulations of CD3+ myeloid cells are increased at the infection site; one type expresses the T cell receptor (CD3+TCRαβ+) and the other does not (CD3+TCRαβ−). The role of Mycobacterium tuberculosis (Mtb) virulence in generating these subpopulations and the ability of these cells to migrate remains unclear. In this study, monocyte-derived macrophages (MDMs) infected in vitro with either a virulent (H37Rv) or an avirulent (H37Ra) Mtb strain were phenotypically characterized based on three MDM phenotypes (CD3−, CD3+TCRαβ+, and CD3+TCRαβ−); then, their migration ability upon Mtb infection was evaluated. We found no differences in the frequency of CD3+ MDMs at 24 h of infection with either Mtb strain. However, H37Rv infection increased the frequency of CD3+TCRαβ+ MDMs at a multiplicity of infection of 1 and altered the expression of CD1b, CD1c, and TNF on the surface of cells from both the CD3+ MDM subpopulations; it also modified the expression of CCR2, CXCR1, and CCR7, thus affecting CCL2 and IL-8 levels. Moreover, H37Rv infection decreased the migration ability of the CD3− MDMs, but not CD3+ MDMs. These results confirm that the CD3+ macrophage subpopulations express chemokine receptors that respond to chemoattractants, facilitating cell migration. Together, these data suggest that CD3+ MDMs are a functional subpopulation involved in the immune response against Mtb. [ABSTRACT FROM AUTHOR]

Tuberculosis (TB) is one of the highest infectious burdens worldwide. An excess of inflammation and inadequate antioxidant defense mechanisms are believed to lead to chronic inflammation and lung damage in tuberculosis (TB). However, circulating metabolites do not always replicate lung-associated biomarkers that define the pathobiology of the disease. The objective of this study was to determine the utility of exhaled breath condensate (EBC), a non-invasive and straightforward sample, to evaluate alveolar space-derived metabolites of redox state and inflammation. We assessed the levels of exhaled oxidant/antioxidant parameters (8-isoprostane, MDA, GSH), inflammatory markers, such as nucleosomes, cytokines (IL-2, IL-4, IL-6 and IL-8, IL-10, GM-CSF, TNF-α, and IFN-γ) and lipid mediators (PGE2, LTB4, RvD1, and Mar1), in patients with recently diagnosed pulmonary TB and healthy controls' EBC and serum. The TB patients showed 36% lower GSH levels, and 2-, 1.4-, 1.1-, and 50-fold higher levels of 8-isoprostanes, nucleosomes, IL-6, and LTB4, respectively, in EBC. There was no correlation between EBC and serum, highlighting the importance of measuring local biomarkers. Quantitation of local inflammatory molecules and redox states in EBC would help find biomarkers useful for pharmacological and follow-up studies in pulmonary tuberculosis. [ABSTRACT FROM AUTHOR]

Plant food production is severely affected by fungi; to cope with this problem, farmers use synthetic fungicides. However, the need to reduce fungicide application has led to a search for alternatives, such as biostimulants. Rare-earth elements (REEs) are widely used as biostimulants, but their mode of action and their potential as an alternative to synthetic fungicides have not been fully studied. Here, the biostimulant effect of gadolinium (Gd) is explored using the plant-pathosystem Arabidopsis thaliana–Botrytis cinerea. We determine that Gd induces local, systemic, and long-lasting plant defense responses to B. cinerea, without affecting fungal development. The physiological changes induced by Gd have been related to its structural resemblance to calcium. However, our results show that the calcium-induced defense response is not sufficient to protect plants against B. cinerea, compared to Gd. Furthermore, a genome-wide transcriptomic analysis shows that Gd induces plant defenses and modifies early and late defense responses. However, the resistance to B. cinerea is dependent on JA/ET-induced responses. These data support the conclusion that Gd can be used as a biocontrol agent for B. cinerea. These results are a valuable tool to uncover the molecular mechanisms induced by REEs. [ABSTRACT FROM AUTHOR]

In mycobacterial infections, the number of cells from two newly discovered subpopulations of CD3 + myeloid cells are increased at the infection site; one type expresses the T cell receptor (CD3 + TCRαβ + ) and the other does not (CD3 + TCRαβ - ). The role of Mycobacterium tuberculosis (Mtb) virulence in generating these subpopulations and the ability of these cells to migrate remains unclear. In this study, monocyte-derived macrophages (MDMs) infected in vitro with either a virulent (H37Rv) or an avirulent (H37Ra) Mtb strain were phenotypically characterized based on three MDM phenotypes (CD3 - , CD3 + TCRαβ + , and CD3 + TCRαβ - ); then, their migration ability upon Mtb infection was evaluated. We found no differences in the frequency of CD3 + MDMs at 24 h of infection with either Mtb strain. However, H37Rv infection increased the frequency of CD3 + TCRαβ + MDMs at a multiplicity of infection of 1 and altered the expression of CD1b, CD1c, and TNF on the surface of cells from both the CD3 + MDM subpopulations; it also modified the expression of CCR2, CXCR1, and CCR7, thus affecting CCL2 and IL-8 levels. Moreover, H37Rv infection decreased the migration ability of the CD3 - MDMs, but not CD3 + MDMs. These results confirm that the CD3 + macrophage subpopulations express chemokine receptors that respond to chemoattractants, facilitating cell migration. Together, these data suggest that CD3 + MDMs are a functional subpopulation involved in the immune response against Mtb.