The BCG vaccine and SARS-CoV-2: Could there be a beneficial relationship?

The COVID-19 disease continues to cause complications and deaths worldwide. Identifying effective immune protection strategies remains crucial to address this ongoing challenge. The Bacillus Calmette-Guérin (BCG) vaccine, developed initially to prevent pulmonary tuberculosis, has gained relevance due to its ability to induce cross-protection against other pathogens of the airways. This review summarizes research on the immunological protection provided by BCG, along with its primary clinical and therapeutic uses. It also explores the immunological features of COVID-19, the mechanisms implicated in host cell death, and its association with chronic pulmonary illnesses such as tuberculosis, which has led to complications in diagnosis and management. While vaccines against COVID-19 have been administered globally, uncertainty still exists about its effectiveness. Additionally, it is uncertain whether the utilization of BCG can regulate the immune response to pathogens such as SARS-CoV-2.

Major Depressive Disorder and Pulmonary Tuberculosis Comorbidity Exacerbates Proinflammatory Immune Response-A Preliminary Study.

BACKGROUND: Major depressive disorders (MDDs) occurs frequently in patients with tuberculosis (TB). Elevated serum pro-inflammatory cytokine levels in MDD patients is a well-established fact. Therefore, an integrated clinical practice should be considered. However, the inflammatory status of MDD-TB patients is unknown. In this study, we analyze cytokines in activated-cells and sera from MDD-TB, TB, MDD patients, and healthy controls. METHODS: Flow cytometry was used to evaluate the intracellular production of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-12, and IL-10 by peripheral blood mononuclear cells after a polyclonal stimulation. A Bio-Plex Luminex system was used to measure serum cytokine and chemokine levels in the study groups. RESULTS: We observed a 40.6% prevalence of MDD in TB patients. The proportion of IFN-gamma-producing cells was higher in MDD-TB patients than other pathological groups. Nevertheless, the percentage of TNF-alpha- and IL-12-producing cells was similar between MDD-TB and TB patients. Likewise, MDD-TB and TB patients showed similar serum pro-inflammatory cytokine and chemokine levels, which were significantly lower than those in MDD patients. By multiple correspondence analyses, we observed that low levels of serum IL-4, IL-10, and IL-13 were powerfully associated with TB comorbidities with MDD. CONCLUSIONS: A high frequency of IFN-γ-producing cells is associated with low levels of serum anti-inflammatory cytokines in MDD-TB patients.

National Burden and Trends for 29 Groups of Cancer in Mexico from 1990 to 2019: A Secondary Analysis of the Global Burden of Disease Study 2019.

The global burden of cancer is on the rise, with varying national patterns. To gain a better understanding and control of cancer, it is essential to provide national estimates. Therefore, we present a comparative description of cancer incidence and mortality rates in Mexico from 1990 to 2019, by age and sex for 29 different cancer groups. Based on public data from the Global Burden of Disease Study 2019, we evaluated the national burden of cancer by analyzing counts and crude and age-standardized rates per 100,000 people with 95% uncertainty intervals for 2019 and trends using the annual percentage change from 1990 to 2019. In 2019, cancer resulted in 222,060 incident cases and 105,591 deaths. In 2019, the highest incidence of cancer was observed in non-melanoma skin cancer, prostate cancer, and breast cancer. Additionally, 53% of deaths were attributed to six cancer groups (lung, colorectal, stomach, prostate, breast, and pancreatic). From 1990 to 2019, there was an increasing trend in incidence and mortality rates, which varied by 10-436% among cancer groups. Furthermore, there were cancer-specific sex differences in crude and age-standardized rates. The results show an increase in the national cancer burden with sex-specific patterns of change. These findings can guide national efforts to reduce health loss due to cancer.

Cytotoxic activity of Staphylococcus aureus isolates from a cohort of Mexican children with cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) is a genetic disease in which thick, sticky mucus is produced in the lungs (and other organs) that impairs ciliary clearance, leading to respiratory problems, increased chronic bacterial infections, and decreased lung function. Staphylococcus aureus is one of the primary bacterial pathogens colonizing the lungs of CF patients. This study aimed to characterize the genetic relatedness of S. aureus, its presence in children with CF, and its cytotoxic activity in THP1 cell-derived macrophages (THP1m). METHODS: Genetic relatedness of S. aureus isolates from a cohort of 50 children with CF was determined by pulsed-field gel electrophoresis (PFGE). The VITEK 2 automated system was used to determine antimicrobial susceptibility, and methicillin-resistance S. aureus (MRSA) was determined by diffusion testing using cefoxitin disk. The presence of mecA and lukPV genes was determined by the polymerase chain reaction and cytotoxic activity of S.aureus on THP1m by CytoTox 96® assay. RESULTS: From 51 S. aureus isolates from 50 children with CF, we identified 34pulsotypes by PFGE. Of the 50 children, 12 (24%) were colonized by more than one pulsotype, and 5/34 identified pulsotypes(14.7%) were shared between unrelated children. In addition, 3/34 pulsotypes (8.8%) were multidrug-resistant (MDR), and2/34 (5.9%) were MRSA. Notably, 30/34 pulsotypes (88.2%) exhibited cytotoxicity on THP1m cells and 14/34 (41.2%) alteredTHP1m monolayers. No isolate carried the lukPV gene. CONCLUSIONS: Although a low frequency of MRSA and MDR wasfound among clinical isolates, most of the S. aureus pulsotypes identified were cytotoxic on THP1m.

INTRODUCCIÓN: La fibrosis quística (FQ) es una enfermedad genética en la que se produce moco espeso y pegajoso en los pulmones (y otros órganos), lo que conduce a problemas respiratorios, incremento de las infecciones bacterianas crónicas y disminución de la función pulmonar. Staphylococcus aureus es uno de los principales patógenos que colonizan los pul-mones de los pacientes con FQ. El objetivo de este trabajo fue caracterizar la relación genética de S. aureus, su presencia en niños con FQ y su actividad citotóxica en macrófagos derivados de células THP1 (THP1m). MÉTODOS: La relación gené-tica de los aislados de S. aureus provenientes de una cohorte de 50 pacientes con FQ fue determinada por electroforesis en gel de campo pulsado (PFGE). La sensibilidad a los antimicrobianos se determinó mediante el sistema automatizado VITEK 2, y la resistencia a la meticilina (SARM) mediante la prueba de difusión utilizando discos de cefoxitina. La presen-cia de los genes mecA y lukPV se determinó mediante reacción en cadena de la polimerasa, y la actividad citotóxica de S. aureus sobre células THP1m mediante el ensayo CytoTox96®. RESULTADOS: A partir de 51 aislados de S. aureus provenientes de 50 niños con FQ se identificaron 34 pulsotipos por PFGE. De los 50 niños, 12 (24%) estaban colonizados por más de un pulsotipo y 5 de los 34 pulsotipos (14.7%) los compartían niños que no estaban relacionados. De los 34 pulsotipos, 3 (8.8%) presentaron multirresistencia (MDR) y 2 (5.9%) fueron SARM. Además, 30 pulsotipos (88.2%) fueron citotóxicos sobre células THP1m y 14 (41.2%) alteraron su monocapa. Ninguno de los pulsotipos presentó el gen lukPV. CONCLUSIONES: Aunque se encontró una baja frecuencia de SARM y MDR en los aislados, la mayoría de los pulsotipos de S. aureus identificados fueron citotóxicos para células THP1m.

Expression Dynamics of the O-Glycosylated Proteins Recognized by Amaranthus leucocarpus Lectin in T Lymphocytes and Its Relationship With Moesin as an Alternative Mechanism of Cell Activation.

T lymphocyte activation begins with antigen/MHC recognition by the TCR/CD3 complex followed by a costimulatory signal provided by CD28. The search for novel costimulatory molecules has been extensive due to their potential use as immunotherapeutic targets. Although some molecules have been identified, they are unable to provide sustainable signaling to allow for proper T cell activation and proliferation. It has been shown that the Amaranthus leucocarpus lectin (ALL) can be used as an in vitro costimulator of CD4+ lymphocytes in the presence of anti-CD3 mAb; this lectin specifically recognizes O-glycans of the Galß1-3GalNAc-O-Ser/Thr type, including a 70-kDa moesin-like protein that has been suggested as the costimulatory molecule. However, the identity of this molecule has not been confirmed and such costimulation has not been analyzed in CD8+ lymphocytes. We show herein that the expression kinetics of the glycoproteins recognized by ALL (gpALL) is different in CD4+ and CD8+ T cells, unlike moesin expression. Results from IP experiments demonstrate that the previously described 70-kDa moesin-like protein is an O-glycosylated form of moesin (O-moesin) and that in vitro stimulation with anti-CD3 and anti-moesin mAb induces expression of the activation molecules CD69 and CD25, proliferation and IL-2 production as efficiently as cells costimulated with ALL or anti-CD28. Overall, our results demonstrate that O-moesin is expressed in CD4+ and CD8+ T lymphocytes and that moesin provides a new costimulatory activation signal in both T cell subsets.

Bacterial Subversion of Autophagy in Cystic Fibrosis.

Cystic fibrosis (CF) is a genetic disease affecting more than 70,000 people worldwide. It is caused by a mutation in the cftr gene, a chloride ion transporter localized in the plasma membrane of lung epithelial cells and other organs. The loss of CFTR function alters chloride, bicarbonate, and water transport through the plasma membrane, promoting the production of a thick and sticky mucus in which bacteria including Pseudomonas aeruginosa and Burkholderia cenocepacia can produce chronic infections that eventually decrease the lung function and increase the risk of mortality. Autophagy is a well-conserved lysosomal degradation pathway that mediates pathogen clearance and plays an important role in the control of bacterial infections. In this mini-review, we describe the principal strategies used by P. aeruginosa and B. cenocepacia to survive and avoid microbicidal mechanisms within the autophagic pathway leading to the establishment of chronic inflammatory immune responses that gradually compromise the lung function and the life of CF patients.

Pseudomonas aeruginosa Isolates From a Cohort of Mexican Children With Cystic Fibrosis Show Adaptation to a Chronic Phenotype.

BACKGROUND: Long-term persistence of Pseudomonas aeruginosa in the lung of individuals with cystic fibrosis (CF) is associated with progressive selection of diverse genotypes and phenotypes. This bacterial adaptation leads to chronic infection and increased morbidity and mortality. The aim of this study was to establish the prevalence, clonal relatedness, antimicrobial susceptibility and virulence-associated phenotypes of P. aeruginosa isolates in a cohort of 50 Mexican children with CF-associated chronic lung infection. METHODS: Clonal relatedness of P. aeruginosa isolates was verified by pulsed-field gel electrophoresis. The antimicrobial susceptibility was determined by an automated system that performs bacterial identificación and antibiotic susceptibility testing (VITEK 2) and/or broth microdilution method. Biofilm formation was quantified with the crystal violet method; swarming motility was measured on soft agar, and susceptibility to normal human serum determined by reduction of colony formed units (CFUs). RESULTS: High prevalence of P. aeruginosa colonization among Mexican children with CF was confirmed; 20% (10/49) of clones identified showed a multidrug-resistant phenotype and 8.2% (4/49) an extensive drug resistance phenotype; 26.5% (13/49) of the isolates were resistant to colistin, 42.9% (21/49) presented a phenotype of adaptation associated with chronic infection and 79.6% (39/49) showed increased ability to survive in normal human serum. CONCLUSIONS: This cohort of children with CF reveals that colonizing P. aeruginosa strains predominantly display resistance to several first-line antibiotics, although most isolates were susceptible to meropenem and tobramycin; 42.9% of isolates showed a phenotype consistent with adaptation to chronic lung infection.

Draft Genome Sequence of a Pseudomonas aeruginosa Sequence Type 3351 Strain Exhibiting High-Level Resistance to Polymyxins in a Pediatric Patient with Cystic Fibrosis in Mexico.

Here, we present the draft genome sequence of a Pseudomonas aeruginosa isolate (strain CF16053) belonging to a novel sequence type (ST), ST3351, isolated from a pediatric patient with cystic fibrosis (CF). CF16053 shows high-level resistance to polymyxins associated with mutations in the pmrB gene. Biofilm, pyoverdine, exotoxin A, and type III secretion system (T3SS) genes were identified.

CD3+ Macrophages Deliver Proinflammatory Cytokines by a CD3- and Transmembrane TNF-Dependent Pathway and Are Increased at the BCG-Infection Site.

Macrophages are essential cells of the innate immune response against microbial infections, and they have the ability to adapt under both pro- and anti-inflammatory conditions and develop different functions. A growing body of evidence regarding a novel macrophage subpopulation that expresses CD3 has recently emerged. Here, we explain that human circulating monocytes can be differentiated into CD3+TCRαß+ and CD3+TCRαß- macrophages. Both cell subpopulations express on their cell surface HLA family molecules, but only the CD3+TCRαß+ macrophage subpopulation co-express CD1 family molecules and transmembrane TNF (tmTNF). CD3+TCRαß+ macrophages secrete IL-1ß, IL-6 IP-10, and MCP-1 by both tmTNF- and CD3-dependent pathways, while CD3+TCRαß- macrophages specifically produce IFN-γ, TNF, and MIP-1ß by a CD3-dependent pathway. In this study, we also used a mouse model of BCG-induced pleurisy and demonstrated that CD3+ myeloid cells (TCRαß+ and TCRαß- cells) are increased at the infection sites during the acute phase (2 weeks post-infection). Interestingly, cell increment was mediated by tmTNF, and the soluble form of TNF was dispensable. BCG-infection also induced the expression of TNF receptor 2 on CD3+ myeloid cells, which increased after BCG-infection, suggesting that the tmTNF/TNFRs axis plays an important role in the presence or function of these cells in tuberculosis.

Tuberculosis patients display a high proportion of CD8+ T cells with a high cytotoxic potential.

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb) and remains a major cause of morbidity and mortality worldwide. In the host's immune response system, T cells play a critical role in mediating protection against Mtb infection, but the role of CD8+ T cells is still controversial. We evaluated the phenotypical characterization and cytotoxic ability of CD8+ T cells by flow cytometry-based assay. Cytokine levels in serum were measured by multiplex cytokine assay. Our data show that cells from TB patients have an increased percentage of peripheral blood CD8+ αß+ T (p = 0.02) and CD56+ CD8+ T (p = 0.02) and a decreased frequency of NKG2D+ CD8+ T (p = 0.02) compared with healthy donors. Unlike CD8+ T cells from healthy donors, CD8+ T cells from TB patients exhibit greater cytotoxicity, mediated by HLA class I molecules, on autologous monocytes in the presence of mycobacterial antigens (p = 0.005). Finally, TB patients have a proinflammatory profile characterized by serum high level of TNF-α (p = 0.02) and IL-8 (p = 0.0001), but, interestingly, IL-4 (p = 0.002) was also increased compared with healthy donors. Our data show evidence regarding the highly cytotoxic status of CD8+ T cells in Mtb infection. These cytotoxic cells restricted to HLA-A, B, and C could be used to optimize strategies for designing new TB vaccines or for identifying markers of disease progression.

Circadian disruption promotes tumor growth by anabolic host metabolism; experimental evidence in a rat model.

BACKGROUND: Light at night creates a conflicting signal to the biological clock and disrupts circadian physiology. In rodents, light at night increases the risk to develop mood disorders, overweight, disrupted energy metabolism, immune dysfunction and cancer. We hypothesized that constant light (LL) in rats may facilitate tumor growth via disrupted metabolism and increased inflammatory response in the host, inducing a propitious microenvironment for tumor cells. METHODS: Male Wistar rats were exposed to LL or a regular light-dark cycle (LD) for 5 weeks. Body weight gain, food consumption, triglycerides and glucose blood levels were evaluated; a glucose tolerance test was also performed. Inflammation and sickness behavior were evaluated after the administration of intravenous lipopolysaccharide. Tumors were induced by subcutaneous inoculation of glioma cells (C6). In tumor-bearing rats, the metabolic state and immune cells infiltration to the tumor was investigated by using immunohistochemistry and flow cytometry. The mRNA expression of genes involved metabolic, growth, angiogenes and inflammatory pathways was measured in the tumor microenvironment by qPCR. Tumor growth was also evaluated in animals fed with a high sugar diet. RESULTS: We found that LL induced overweight, high plasma triglycerides and glucose levels as well as reduced glucose clearance. In response to an LPS challenge, LL rats responded with higher pro-inflammatory cytokines and exacerbated sickness behavior. Tumor cell inoculation resulted in increased tumor volume in LL as compared with LD rats, associated with high blood glucose levels and decreased triglycerides levels in the host. More macrophages were recruited in the LL tumor and the microenvironment was characterized by upregulation of genes involved in lipogenesis (Acaca, Fasn, and Pparγ), glucose uptake (Glut-1), and tumor growth (Vegfα, Myc, Ir) suggesting that LL tumors rely on these processes in order to support their enhanced growth. Genes related with the inflammatory state in the tumor microenvironment were not different between LL and LD conditions. In rats fed a high caloric diet tumor growth was similar to LL conditions. CONCLUSIONS: Data indicates that circadian disruption by LL provides a favorable condition for tumor growth by promoting an anabolic metabolism in the host.

CD3+ICOS+ T cells show differences in the synthesis of nitric oxide, IFN-γ, and IL-10 in patients with pulmonary tuberculosis or in healthy household contacts.

Evidence indicates that more than 90 % of infected individuals never develop active tuberculosis. This fact highlights the relevance of the immune response in tuberculosis control. The inducible co-stimulator (ICOS) is a regulator of the function, differentiation, proliferation, and activation of T cells. Moreover, T cells synthesise nitric oxide (NO), interferon gamma (IFN-γ), and interleukin (IL)-10, which help regulate the immune response to tuberculosis. Therefore, we assessed the synthesis of NO, IFN-γ, and IL-10 in CD3+ICOS+ T cells from healthy individuals, household contacts (HHC), and patients with active pulmonary tuberculosis (PTB), previously stimulated with the antigen H37Rv. Our results indicated a significant increase in both the percentage of ICOS+ cells and CD3+ICOS+ T cells producing NO, IFN-γ, and IL-10 in cells obtained from patients with PTB (p < 0.01). In addition, a high mitochondrial membrane potential (ΔΨ m) in CD3+ICOS+ T cells was observed in the cells from HHC and from PTB patients, and is associated with the activation of T cells. In conclusion, results show that the CD3+ICOS+ T cells obtained from PTB patients are the main producers of NO, IFN-γ, and IL-10. In addition, our results imply that NO is a modulator of ICOS expression of T cells from PTB patients.

O-glycosylation of NnTreg lymphocytes recognized by the Amaranthus leucocarpus lectin.

O-glycosidically-linked glycans have been involved in development, maturation, homing, and immune regulation in T cells. Previous reports indicate that Amaranthus leucocarpus lectin (ALL), specific for glycans containing galactose-N-acetylgalactosamine and N-acetylgalactosamine, recognizes human naïve CD27(+)CD25(+)CD4(+) T cells. Our aim was to evaluate the phenotype of CD4(+) T cells recognized by ALL in peripheral blood mononuclear cells obtained from healthy volunteers. CD4(+) T cells were isolated by negative selection using magnetic beads-labeled monoclonal antibodies; the expression of T regulatory cell phenotypic markers was assessed on ALL-recognized cells. In addition, IL-4, IL-10, IFN-γ, and TGF-ß intracellular production in ALL (+) cells was also evaluated. The analyses of phenotypic markers and intracellular cytokines were performed through flow cytometry. ALL-recognized CD4(+) T cells were mainly CD45RA(+), CCR7(+) cells. Although 52 ± 10% CD25(+)Foxp3(+) cells were positive to ALL, only 34 ± 4% of ALL (+) cells corresponded to CD25(+)Foxp3(-) cells. Intracellular cytokines in freshly obtained ALL (+)CD4(+) T cells exhibited 8% of IL-4, 15% of IL-10, 2% of IFN-γ, and 15% of TGF-ß, whereas ALL (-)CD4(+) T cells depicted 1% of IL-4, 2% of IL-10, <1% of IFN-γ, and 6% of TGF-ß. Our results show that galactose-N-acetylgalactosamine and N-galactosamine-bearing CD4(+) T cells expressed phenotypic markers of NnTreg cells.

Comparison of immune peripheral blood cells in tuberculin reactor cattle that are seropositive or seronegative for Mycobacterium bovis antigens.

Bovine tuberculosis (bTB) is a major economic problem in animal husbandry and is a public health risk in nonindustrialized countries. It is generally accepted that protection against TB is generated through cell-mediated immunity. Previous investigations have shown that WC1(+) γδ, CD4(+) and CD8(+) T-cell subpopulations are important in the immune response to bTB. It is known that changes in the immune balance from a dominant T helper 1 (Th1)-type response toward a more prominent Th2 response may be observed during disease progression. In this study, we aimed to investigate immune peripheral blood cells in tuberculin reactor cattle that are seropositive or seronegative for Mycobacterium bovis antigens, using flow cytometry and hematological analysis. The evaluation of the T cell subpopulations revealed a decrease in CD8(+) T cells of the seropositive and seronegative animals compared with the control animals (p=0.0001). Moreover, the seropositive group exhibited a lower percentage of CD8(+) T cells than the seronegative group. The percentage of B cells was significantly increased in the seropositive group compared with the seronegative group and the control group (p=0.0009). No difference was observed in the percentage of WC1(+) γδ and CD4(+) T cells among the groups. Furthermore, following 24h of peripheral blood culture with bovine purified protein derivative (PPD), both apparently infected groups showed an increase in the levels of cellular activation compared with the control group (p<0.0001). The seropositive group displayed a higher level of cellular activation than the seronegative group. In both apparently infected groups, the hematological analysis showed an increase in total leukocyte (p=0.0012), lymphocyte (p=0.0057), monocyte (p=0.0010) and neutrophil (p=0.0320) counts in comparison with the healthy animals. Our results demonstrated differences in immune peripheral blood cells of tuberculin reactor cattle that are seropositive or seronegative for M. bovis antigens, probably due to different stages of bTB among the groups. The percentages of CD8(+) T cells, B cells and the T cell activation levels may represent biomarkers for the progression of the disease. However, general characteristics shared by both apparently infected groups as lymphocytosis and monocytosis may also be indicative of the disease. Further experiments are required to understand the variations between cellular and humoral immunities throughout the course of bTB infection. A detailed knowledge of the peripheral blood cells involved in all stages of the bTB immune response of naturally infected cattle is essential for the optimal exploitation of diagnosis and vaccination models.

[Regulatory T cells in chronic obstructive pulmonary disease]. / Las células T reguladoras en la enfermedad pulmonar obstructiva crónica.

Exposition to tobacco smoke has been established as the main risk factor to develop chronic obstructive pulmonary disease (COPD), by inducing inflammation of the airways. Several cell populations participate in this inflammatory process. It has been accepted that a maladaptive modulation of inflammatory responses plays a critical role in the development of the disease. Regulatory T cells (Treg) are a subset of T CD4(+) lymphocytes that modulate the immune response through secretion of cytokines. The role of the Treg cells in chronic obstructive pulmonary disease is not clearly known, that is why it is important to focus in understanding their participation in the pathogenesis of the disease. To elaborate a systematic review of original articles in which we could describe Treg cells (their ontogeny, mechanisms of action) and their role in COPD, we made a systematic literature search in some data bases (MEDLINE, AMED, PubMed and Scielo) looking through the next keywords: "COPD and Regulatory T cells/EPOC y células T reguladoras", «Inflammation and COPD/Inflamación y EPOC¼, «Regulatory T cells/Células T reguladoras¼. We included basic science articles, controlled and non-controlled clinical trials, meta-analysis and guides. From this search we conclude that Treg cells are a subpopulation of T CD4(+) lymphocytes and their major functions are the suppression of immune responses and the maintenance of tolerance to self-antigens. A disruption in the regulatory mechanisms of the Treg cells leads to the development and perpetuation of inflammation in COPD.

Las células T reguladoras en la enfermedad pulmonar obstructiva crónica / Regulatory T cells in chronic obstructive pulmonary disease

La exposición al humo del tabaco induce inflamación de las vías aéreas y es el principal factor de riesgo para desarrollar la enfermedad pulmonar obstructiva crónica (EPOC). En este proceso inflamatorio participan varias poblaciones celulares. Algunas fallas en la modulación de la respuesta inflamatoria han sido aceptadas como un factor para el desarrollo de esta enfermedad. Las células T reguladoras (Treg) son un tipo de linfocitos T CD4+ que modulan la respuesta inmune mediante contacto directo con las células efectoras, así como por la secreción de citocinas inmunorreguladoras. El papel de las células Treg en la EPOC no se encuentra completamente comprendido, por lo cual es importante evaluar su participación en la inmunopatogénesis de la enfermedad. Con el objetivo de elaborar una revisión sistemática de artículos originales que nos permitiera describir las células Treg (su origen, características y mecanismos de acción) y su participación en la EPOC, realizamos una búsqueda intencionada en las siguientes bases electrónicas: MEDLINE, AMED, PubMed y Scielo; para ello usamos la combinación de las siguientes palabras clave: <

Exposition to tobacco smoke has been established as the main risk factor to develop chronic obstructive pulmonary disease (COPD), by inducing inflammation of the airways. Several cell populations participate in this inflammatory process. It has been accepted that a maladaptive modulation of inflammatory responses plays a critical role in the development of the disease. Regulatory T cells (Treg) are a subset of T CD4+ lymphocytes that modulate the immune response through secretion of cytokines. The role of the Treg cells in chronic obstructive pulmonary disease is not clearly known, that is why it is important to focus in understanding their participation in the pathogenesis of the disease. To elaborate a systematic review of original articles in which we could describe Treg cells (their ontogeny, mechanisms of action) and their role in COPD, we made a systematic literature search in some data bases (MEDLINE, AMED, PubMed and Scielo) looking through the next keywords: ''COPD and Regulatory T cells/EPOC y células T reguladoras'', <

Monocytes from tuberculosis patients that exhibit cleaved caspase 9 and denaturalized cytochrome c are more susceptible to death mediated by Toll-like receptor 2.

Experimental models have shown that lipoproteins from Mycobacterium tuberculosis induce apoptosis via Toll-like receptor 2 (TLR2) in the THP-1 cell line and in monocyte-derived macrophages from healthy volunteers. We found an increased percentage of circulating monocytes in patients with tuberculosis (TB) in comparison to healthy controls. Patients with TB showed a higher TLR2 and TLR4 expression density on monocytes, and a higher proportion of TLR2(+) monocytes, as well as increased serum tumour necrosis factor-α level. In culture, monocytes from TB patients were more susceptible to death than monocytes from healthy controls. Moreover, death-susceptible monocytes were positive to both TLR2 and TLR4 at the start of culture. Freshly obtained monocytes from TB patients exhibited cleaved caspase 9 and denaturalized cytochrome c. For levels of caspase 8, apoptosis-regulating signal kinase 1, and phospho-p38 mitogen-activated protein kinase there was no difference between samples from TB patients and from healthy controls. The culture filtrate antigen extract from M. tuberculosis H37Rv strain induced the death of monocytes from patient with TB after a 4-hr incubation, which was abrogated by neutralizing antibodies for TLR2 but not TLR4. Similarly, Pam3CSK4, a synthetic agonist triacylated ligand to TLR2, also induced the death of monocytes, although it did not increase levels of cleaved caspase 9. Our findings suggest that monocytes from TB patients are more susceptible to death, probably through mitochondrial damage, and that cell death increases in the presence of mycobacterial antigen by a TLR2-dependent pathway.

Amaranthus leucocarpus lectin (ALL) enhances anti-CD3-dependent activation of murine T cells and promotes cell survival.

The Galß1,3GalNAc-specific lectin from Amaranthus leucocarpus (ALL) shows a differential binding pattern on murine thymocytes, peripheral and activated CD4(+) and CD8(+) T cells. Although ALL detects activation-related changes in T cell surface carbohydrate moieties, no study has been performed to examine the effect of ALL on T cell activation. In this study, we analyzed the anti-CD3-dependent activation of murine T cells in the presence of ALL by measuring proliferation, surface activation marker expression, and IL-2 secretion using total cells from the lymph node. The results showed that ALL did not significantly induce T cell activation but did enhance anti-CD3-dependent activation of both CD4(+) and CD8(+) T cells. In addition, ALL protected T cells from spontaneous apoptosis and increased cell survival in serum-free culture conditions. Our findings indicate that ALL alone does not affect T cell activation, but do suggest that ALL has an anti-CD3-dependent co-stimulatory-like effect on T cell activation. Moreover, ALL promotes cell survival in regular and serum-free culture conditions. This study is the first report of a non-mitogenic T cell-binding lectin that can induce a possible costimulatory-like effect and provides a new tool for understanding how glycosylation impacts the T cell response.

The Amaranthus leucocarpus lectin enhances the anti-CD3 antibody-mediated activation of human peripheral blood CD4+ T cells.

Activation of CD4(+) T cells plays a main role in adaptive immune response by regulating cellular and humoral immunity via processes associated with changes in cell surface oligosaccharide receptors. Lectins are glycoproteins that specifically recognize oligosaccharides and have been used to characterize changes in oligosaccharides present on T cell surface and their effects on activation. A lectin from Amaranthus leucocarpus seeds (ALL) is specific for glycoprotein structures containing galactose-N-acetylgalactosamine and is able to bind to human and murine CD4(+) T cells, however, its effect on activation remains unclear. We examined the effect of ALL on the activation of peripheral blood human CD4(+) T cells and analyzed cell proliferation, expression of the activation-associated molecule CD25, secretion of the activation-dependent cytokine interleukin (IL)-2 and intracellular calcium influx changes using flow cytometry. CD4(+) T cells were stimulated with anti-CD3 antibodies that provided the first activation signal in the presence or absence of ALL. ALL alone did not induce CD4(+) T cell activation but when also stimulated with anti-CD3 antibodies, ALL up-regulated CD25 expression, cell proliferation, IL-2 secretion and an intracellular calcium influx in a dose-dependent manner. In addition, ALL recognized CD4(+) T cells expressing the CD69 and Ki67 molecules expressed only by activated T cells and induced production of the TH1-type cytokine interferon-gamma. Our findings indicate that ALL binds to human activated CD4(+) T cells and enhances the degree of activation of CD4(+) T cells that are stimulated with anti-CD3 antibodies. ALL provides a new tool for analyzing T cell activation mechanisms.

The interaction between Histoplasma capsulatum cell wall carbohydrates and host components: relevance in the immunomodulatory role of histoplasmosis.

Histoplasma capsulatum is an intracellular fungal pathogen that causes respiratory and systemic disease by proliferating within phagocytic cells. The binding of H. capsulatum to phagocytes may be mediated by the pathogen's cell wall carbohydrates, glucans, which consist of glucose homo and hetero-polymers and whose glycosydic linkage types differ between the yeast and mycelial phases. The alpha-1,3-glucan is considered relevant for H. capsulatum virulence, whereas the beta-1,3-glucan is antigenic and participates in the modulation of the host immune response. H. capsulatum cell wall components with lectin-like activity seem to interact with the host cell surface, while host membrane lectin-like receptors can recognize a particular fungal carbohydrate ligand. This review emphasizes the relevance of the main H. capsulatum and host carbohydrate-driven interactions that allow for binding and internalization of the fungal cell into phagocytes and its subsequent avoidance of intracellular elimination.