Pulmonary embolism in an adolescent with COVID-19 pneumonia.

BACKGROUND: Pulmonary embolism (PE) is a complication reported in the adult population with coronavirus disease 2019 (COVID-19); however, its documentation in the pediatric population is limiteda. CASE REPORT: We report the case of a 15-year-old male with obesity and Down syndrome who was admitted for severe COVID-19 pneumonia. On day 7 of admission, he presented with chest pain, hemoptysis, respiratory distress, and marked elevation of D-dimer. Pulmonary CT angiography found an extensive thrombus in the right lower lobar artery. He received treatment with enoxaparin and rivaroxaban and had a favorable clinical outcome. In the tomographic control 1 month after treatment, thrombus was not evidenced and was successfully resolved. CONCLUSIONS: There are few reports of PE in children with COVID-19. Prompt diagnosis and early anticoagulant treatment are important to avoid life-threatening complications.

INTRODUCCIÓN: El tromboembolismo pulmonar es una complicación reportada en la población adulta con COVID-19; sin embargo, en la población pediátrica, su descripción es limitada. CASO CLÍNICO: Se reporta el caso de un varón de 15 años con antecedente de obesidad y síndrome de Down que fue hospitalizado por neumonía COVID-19 severa. En el séptimo día de hospitalización presentó dolor torácico, hemoptisis, dificultad respiratoria y elevación del dímero D. En la angiotomografía pulmonar se encontró un extenso trombo en la arteria lobar inferior derecha. Recibió tratamiento con enoxaparina y rivaroxabán evolucionando favorablemente. La resolución al mes de tratamiento fue existosa, ya que el control tomográfico no evidenció más el trombo. CONCLUSIONES: El tromboembolismo pulmonar es una complicación poco reportada en niños con neumonía COVID-19. El diagnóstico oportuno y tratamiento anticoagulante es importante para evitar complicaciones mortales.

Pulmonary embolism in an adolescent with COVID-19 pneumonia / Tromboembolismo pulmonar en un adolescente con neumonía COVID-19

Abstract Background: Pulmonary embolism (PE) is a complication reported in the adult population with coronavirus disease 2019 (COVID-19); however, its documentation in the pediatric population is limiteda. Case report: We report the case of a 15-year-old male with obesity and Down syndrome who was admitted for severe COVID-19 pneumonia. On day 7 of admission, he presented with chest pain, hemoptysis, respiratory distress, and marked elevation of D-dimer. Pulmonary CT angiography found an extensive thrombus in the right lower lobar artery. He received treatment with enoxaparin and rivaroxaban and had a favorable clinical outcome. In the tomographic control 1 month after treatment, thrombus was not evidenced and was successfully resolved. Conclusions: There are few reports of PE in children with COVID-19. Prompt diagnosis and early anticoagulant treatment are important to avoid life-threatening complications.

Resumen Introducción: El tromboembolismo pulmonar es una complicación reportada en la población adulta con COVID-19; sin embargo, en la población pediátrica, su descripción es limitada. Caso clínico: Se reporta el caso de un varón de 15 años con antecedente de obesidad y síndrome de Down que fue hospitalizado por neumonía COVID-19 severa. En el séptimo día de hospitalización presentó dolor torácico, hemoptisis, dificultad respiratoria y elevación del dímero D. En la angiotomografía pulmonar se encontró un extenso trombo en la arteria lobar inferior derecha. Recibió tratamiento con enoxaparina y rivaroxabán evolucionando favorablemente. La resolución al mes de tratamiento fue existosa, ya que el control tomográfico no evidenció más el trombo. Conclusiones: El tromboembolismo pulmonar es una complicación poco reportada en niños con neumonía COVID-19. El diagnóstico oportuno y tratamiento anticoagulante es importante para evitar complicaciones mortales.

[COVID-19-associated multisystem inflammatory syndrome in children: case series at a pediatric hospital in Peru]. / Síndrome inflamatorio multisistémico asociado a COVID-19 en niños: serie de casos en un hospital pediátrico de Perú.

During the COVID-19 pandemic, a new, severe and unusual condition called Multisystem Inflammatory Syndrome in children emerged, from which there is still much to learn. We report 8 children admitted to Instituto Nacional de Salud del Niño, in Lima, Perú. Their mean age was 5,1 years. Their clinical presentation included fever, acute gastrointestinal symptoms, ocular and mucocutaneous involvement. Four patients met criteria for classic Kawasaki Disease. All the patients had positive serology for SARS-CoV-2, abnormal complete blood counts and coagulation tests, and elevated inflammatory markers. Five had elevated liver enzymes and three had kidney involvement. Four patients met criteria for Macrophage Activation Syndrome. All of them received intravenous immune globulin, corticosteroids and aspirin. No coronary aneurysms were identified. Only one developed miocarditis, shock and was admitted to the Pediatric Intensive Care Unit. Most patients recovered successfully. Every child with fever, gastrointestinal and dermatological symptoms, associated with prior exposure to SARS-CoV-2, should be investigated for multi-systemic compromise.

La pandemia de COVID-19 ha traído una nueva afección grave e inusual denominada Síndrome Inflamatorio Multisistémico en niños, de la cual aún hay mucho por conocer. Presentamos una serie de 8 casos atendidos en el Instituto Nacional de Salud del Niño, Lima Perú. La edad media fue 5,1 años. La presentación clínica incluyó fiebre, problemas gastrointestinales agudos, afectación ocular y mucocutánea. Cuatro cumplieron criterios para Enfermedad de Kawasaki clásica. Todos tuvieron serología positiva para SARS-CoV-2, hemograma patológico, marcadores inflamatorios elevados y pruebas de coagulación alteradas. Cinco casos presentaron hipertransaminasemia y tres retención nitrogenada. Cuatro casos cumplieron criterios para Síndrome de Activación Macrófagica. Todos recibieron inmunoglobulina intravenosa, corticoides y ácido acetil salicílico. Ninguno desarrolló aneurismas coronarios. Solo uno presentó miocarditis, shock y requirió ingreso a Unidad de Cuidados Intensivos. La mayoría evolucionaron favorablemente. En todo niño con fiebre, síntomas gastrointestinales y dermatológicos; asociado a exposición al SARS-CoV-2, debe investigarse compromiso multisistémico.

Características clínicas, de laboratorio y radiológicas de pacientes pediátricos hospitalizados con COVID-19: serie de casos / Clinical, laboratory and radiological characteristics of pediatric patients hospitalized with COVID-19: case series

RESUMEN De toda la población infectada por el SARS-CoV-2, la población pediátrica representa del 1 al 5%, siendo un reto caracterizarla clínicamente. Presentamos cinco casos de pacientes pediátricos con diagnóstico de COVID-19; el rango de edad fue de 1 a 14 años, tuvieron manifestaciones clínicas variadas, tres de ellos presentaron fiebre, tos y dificultad respiratoria, otro fiebre y dermatosis, y un adolescente con diarrea y vómitos asociado al síndrome de Guillain-Barré. Los exámenes de laboratorio revelaron elevación de lactato deshidrogenasa, dimero-D y ferritina. El patrón radiológico más frecuente fue el engrosamiento peribronquial perihiliar. Todos los casos tuvieron evolución clínica y radiológica favorable. La diversidad en las presentaciones clínicas en niños debe considerarse para un diagnóstico temprano de la enfermedad.

ABSTRACT Children represent 1 to 5% of the entire SARS-CoV-2 infected population, and it is challenging to identify them based on clinical characteristics. We present 5 cases of pediatric patients diagnosed with COVID-19; the age range was from 1 to 14 years. They had different clinical characteristics, three of them presented fever, cough and respiratory distress, another one fever and dermatosis, and the other patient had diarrhea and vomiting associated with Guillain-Barre syndrome. Laboratory tests revealed elevated lactate dehydrogenase, D-dimer, and ferritin. The most frequent radiological pattern was perihilar peribronchial thickening. All cases had favorable clinical and radiological evolution. Diverse clinical characteristics should be considered for early diagnosis of COVID-19 in children.

Intranasal Dexamethasone Reduces Mortality and Brain Damage in a Mouse Experimental Ischemic Stroke Model.

Neuroinflammation triggered by the expression of damaged-associated molecular patterns released from dying cells plays a critical role in the pathogenesis of ischemic stroke. However, the benefits from the control of neuroinflammation in the clinical outcome have not been established. In this study, the effectiveness of intranasal, a highly efficient route to reach the central nervous system, and intraperitoneal dexamethasone administration in the treatment of neuroinflammation was evaluated in a 60-min middle cerebral artery occlusion (MCAO) model in C57BL/6 male mice. We performed a side-by-side comparison using intranasal versus intraperitoneal dexamethasone, a timecourse including immediate (0 h) or 4 or 12 h poststroke intranasal administration, as well as 4 intranasal doses of dexamethasone beginning 12 h after the MCAO versus a single dose at 12 h to identify the most effective conditions to treat neuroinflammation in MCAO mice. The best results were obtained 12 h after MCAO and when mice received a single dose of dexamethasone (0.25 mg/kg) intranasally. This treatment significantly reduced mortality, neurological deficits, infarct volume size, blood-brain barrier permeability in the somatosensory cortex, inflammatory cell infiltration, and glial activation. Our results demonstrate that a single low dose of intranasal dexamethasone has neuroprotective therapeutic effects in the MCAO model, showing a better clinical outcome than the intraperitoneal administration. Based on these results, we propose a new therapeutic approach for the treatment of the damage process that accompanies ischemic stroke.

Síndrome inflamatorio multisistémico asociado a COVID-19 en niños: serie de casos en un hospital pediátrico de Perú / COVID-19-associated multisystem inflammatory syndrome in children: case series at a pediatric hospital in Peru

RESUMEN La pandemia de COVID-19 ha traído una nueva afección grave e inusual denominada Síndrome Inflamatorio Multisistémico en niños, de la cual aún hay mucho por conocer. Presentamos una serie de 8 casos atendidos en el Instituto Nacional de Salud del Niño, Lima Perú. La edad media fue 5,1 años. La presentación clínica incluyó fiebre, problemas gastrointestinales agudos, afectación ocular y mucocutánea. Cuatro cumplieron criterios para Enfermedad de Kawasaki clásica. Todos tuvieron serología positiva para SARS-CoV-2, hemograma patológico, marcadores inflamatorios elevados y pruebas de coagulación alteradas. Cinco casos presentaron hipertransaminasemia y tres retención nitrogenada. Cuatro casos cumplieron criterios para Síndrome de Activación Macrófagica. Todos recibieron inmunoglobulina intravenosa, corticoides y ácido acetil salicílico. Ninguno desarrolló aneurismas coronarios. Solo uno presentó miocarditis, shock y requirió ingreso a Unidad de Cuidados Intensivos. La mayoría evolucionaron favorablemente. En todo niño con fiebre, síntomas gastrointestinales y dermatológicos; asociado a exposición al SARS-CoV-2, debe investigarse compromiso multisistémico.

ABSTRACT During the COVID-19 pandemic, a new, severe and unusual condition called Multisystem Inflammatory Syndrome in children emerged, from which there is still much to learn. We report 8 children admitted to Instituto Nacional de Salud del Niño, in Lima, Perú. Their mean age was 5,1 years. Their clinical presentation included fever, acute gastrointestinal symptoms, ocular and mucocutaneous involvement. Four patients met criteria for classic Kawasaki Disease. All the patients had positive serology for SARS-CoV-2, abnormal complete blood counts and coagulation tests, and elevated inflammatory markers. Five had elevated liver enzymes and three had kidney involvement. Four patients met criteria for Macrophage Activation Syndrome. All of them received intravenous immune globulin, corticosteroids and aspirin. No coronary aneurysms were identified. Only one developed miocarditis, shock and was admitted to the Pediatric Intensive Care Unit. Most patients recovered successfully. Every child with fever, gastrointestinal and dermatological symptoms, associated with prior exposure to SARS-CoV-2, should be investigated for multi-systemic compromise.

Phosphate starvation enhances phagocytosis of Mycobacterium bovis/BCG by macrophages.

BACKGROUND: Tuberculosis is an important health problem worldwide. The only available vaccine is M. bovis/BCG, an attenuated mycobacterium that activates the innate and the acquired immune system after being phagocytosed by macrophages and dendritic cells. Vaccination fails to prevent adult pulmonary tuberculosis although it may have a protective effect in childhood infection. Understanding how BCG interacts with macrophages and other immunocompetent cells is crucial to develop new vaccines. RESULTS: In this study we showed that macrophages phagocytose M. bovis/BCG bacilli with higher efficiency when they are cultured without phosphate. We isolated mycobacterial membranes to search for mycobacterial molecules that could be involved in these processes; by immunoblot, it was found that the plasma membranes of phosphate-deprived bacilli express the adhesins PstS-1, LpqH, LprG, and the APA antigen. These proteins are not detected in membranes of bacilli grown with usual amounts of phosphate. CONCLUSIONS: The interest of our observations is to show that under the metabolic stress implied in phosphate deprivation, mycobacteria respond upregulating adhesins that could improve their capacity to infect macrophages. These observations are relevant to understand how M. bovis/BCG induces protective immunity.

[Clinical, laboratory and radiological characteristics of pediatric patients hospitalized with COVID-19: case series]. / Características clínicas, de laboratorio y radiológicas de pacientes pediátricos hospitalizados con COVID-19: serie de casos.

Children represent 1 to 5% of the entire SARS-CoV-2 infected population, and it is challenging to identify them based on clinical characteristics. We present 5 cases of pediatric patients diagnosed with COVID-19; the age range was from 1 to 14 years. They had different clinical characteristics, three of them presented fever, cough and respiratory distress, another one fever and dermatosis, and the other patient had diarrhea and vomiting associated with Guillain-Barre syndrome. Laboratory tests revealed elevated lactate dehydrogenase, D-dimer, and ferritin. The most frequent radiological pattern was perihilar peribronchial thickening. All cases had favorable clinical and radiological evolution. Diverse clinical characteristics should be considered for early diagnosis of COVID-19 in children.

De toda la población infectada por el SARS-CoV-2, la población pediátrica representa del 1 al 5%, siendo un reto caracterizarla clínicamente. Presentamos cinco casos de pacientes pediátricos con diagnóstico de COVID-19; el rango de edad fue de 1 a 14 años, tuvieron manifestaciones clínicas variadas, tres de ellos presentaron fiebre, tos y dificultad respiratoria, otro fiebre y dermatosis, y un adolescente con diarrea y vómitos asociado al síndrome de Guillain-Barré. Los exámenes de laboratorio revelaron elevación de lactato deshidrogenasa, dimero-D y ferritina. El patrón radiológico más frecuente fue el engrosamiento peribronquial perihiliar. Todos los casos tuvieron evolución clínica y radiológica favorable. La diversidad en las presentaciones clínicas en niños debe considerarse para un diagnóstico temprano de la enfermedad.

Mycobacterial glycolipid Di-O-acyl trehalose promotes a tolerogenic profile in dendritic cells.

Due to prolonged coevolution with the human being, Mycobacterium tuberculosis has acquired a sophisticated capacity to evade host immunity and persist in a latent state in the infected individual. As part of this evolutive process, mycobacteria have developed a highly complex cell wall that acts as a protective barrier. Herein we studied the effects of Di-O-acyl trehalose, a cell-wall glycolipid of virulent mycobacteria on murine bone marrow-derived dendritic cells. We have demonstrated that Di-O-Acyl-trehalose promotes a tolerogenic phenotype in bone marrow-derived murine DCs activated with mycobacterial antigens and Toll-like receptor agonists. This phenotype included low expression of antigen presentation and costimulatory molecules and altered cytokine production with downregulation of IL-12 and upregulation of IL-10, an anti-inflammatory cytokine. Additional markers of tolerogenicity were the expression of Indoleamine 2,3-dioxygenase and CD25. Furthermore, Di-O-Acyl-Trehalose promoted the expansion of FoxP3+ regulatory T lymphocytes. A better understanding of mycobacterial cell-wall components involved in the evasion of immunity is a prerequisite to designing better strategies to fight tuberculosis.

Dendritic cells that phagocytose apoptotic macrophages loaded with mycobacterial antigens activate CD8 T cells via cross-presentation.

While homeostatic apoptosis is immunologically silent, macrophage apoptosis during Mycobacterium tuberculosis infection can potentially induce an immune response against the mycobacteria. To examine the role of dendritic cells in this response, macrophage apoptosis was induced by incubating the macrophage with cell wall extracts of mycobacteria expressing LpqH. The apoptogenic proteins of the cell wall extracts were engulfed by the macrophage and then were translocated from the cytosol to the nuclei of the dying cells. Dendritic cells that engulfed the apoptotic macrophages acquired an immunogenic phenotype that included upregulation of MHC-I, increased expression of the costimulatory molecules, CD40, CD80, and CD86, and increased production of IL-12, IL-10, TNF-α, and TGF-ß. In addition, the dendritic cells triggered a proliferative response of CD8+ T cells with IFN-γ production via cross-presentation. Taken together, these findings support a model in which phagocytosis of whole apoptotic cells carrying mycobacterial antigens promotes a potentially protective immune response.

The Mannose Receptor Is Involved in the Phagocytosis of Mycobacteria-Induced Apoptotic Cells.

Upon Mycobacterium tuberculosis infection, macrophages may undergo apoptosis, which has been considered an innate immune response. The pathways underlying the removal of dead cells in homeostatic apoptosis have been extensively studied, but little is known regarding how cells that undergo apoptotic death during mycobacterial infection are removed. This study shows that macrophages induced to undergo apoptosis with mycobacteria cell wall proteins are engulfed by J-774A.1 monocytic cells through the mannose receptor. This demonstration was achieved through assays in which phagocytosis was inhibited with a blocking anti-mannose receptor antibody and with mannose receptor competitor sugars. Moreover, elimination of the mannose receptor by a specific siRNA significantly diminished the expression of the mannose receptor and the phagocytosis of apoptotic cells. As shown by immunofluorescence, engulfed apoptotic bodies are initially located in Rab5-positive phagosomes, which mature to express the phagolysosome marker LAMP1. The phagocytosis of dead cells triggered an anti-inflammatory response with the production of TGF-ß and IL-10 but not of the proinflammatory cytokines IL-12 and TNF-α. This study documents the previously unreported participation of the mannose receptor in the removal of apoptotic cells in the setting of tuberculosis (TB) infection. The results challenge the idea that apoptotic cell phagocytosis in TB has an immunogenic effect.

Mycobacterial glycolipids di-O-acylated trehalose and tri-O-acylated trehalose downregulate inducible nitric oxide synthase and nitric oxide production in macrophages.

BACKGROUND: Tuberculosis (TB) remains a serious human health problem that affects millions of people in the world. Understanding the biology of Mycobacterium tuberculosis (Mtb) is essential for tackling this devastating disease. Mtb possesses a very complex cell envelope containing a variety of lipid components that participate in the establishment of the infection. We have previously demonstrated that di-O-acylated trehalose (DAT), a non-covalently linked cell wall glycolipid, inhibits the proliferation of T lymphocytes and the production of cytokines. RESULTS: In this work we show that DAT and the closely related tri-O-acylated trehalose (TAT) inhibits nitric oxide (NO) production and the inducible nitric oxide synthase (iNOS) expression in macrophages (MØ). CONCLUSIONS: These findings show that DAT and TAT are cell-wall located virulence factors that downregulate an important effector of the immune response against mycobacteria.

Identification of proteins associated with Mycobacterium tuberculosis virulence pathway by their polar profile.

With almost one third of the world population infected, tuberculosis is one of the most devastating diseases worldwide and it is a major threat to any healthcare system. With the mathematical-computational method named "Polarity Index Method", already published by this group, we identified, with high accuracy (70%), proteins related to Mycobacterium tuberculosis bacteria virulence pathway from the Tuberculist Database. The test considered the totality of proteins cataloged in the main domains: fungi, bacteria, and viruses from three databases: Antimicrobial Peptide Database (APD2), Tuberculist Database, Uniprot Database, and four antigens of Mycobacterium tuberculosis: PstS-1, 38-kDa, 19-kDa, and H37Rv ORF. The method described was calibrated with each database to achieve the same performance, showing a high percentage of coincidence in the identification of proteins associated with Mycobacterium tuberculosis bacteria virulence pathway located in the Tuberculist Database, and identifying a polar pattern regardless of the group studied. This method has already been used in the identification of diverse groups of proteins and peptides, showing that it is an effective discriminant. Its metric considers only one physico-chemical property, i.e. polarity.

Expression of autocrine prolactin and the short isoform of prolactin receptor are associated with inflammatory response and apoptosis in monocytes stimulated with Mycobacterium bovis proteins.

Increased levels of prolactin (PRL) have recently been associated with carcinogenesis and the exacerbation of autoimmune diseases, and might be involved in the progression of tuberculosis (TB). To investigate the relationship between PRL and prolactin receptor (PRLr) expression with inflammatory response and apoptosis in monocytes, we used THP-1 cells stimulated with antigens of the Mycobacterium bovis AN5 strain culture filtrate protein (CFP-M. bovis). Western blot (WB), real-time Polymerase chain reaction (PCR), and immunocytochemistry were performed to identify both PRL and PRLr molecules. PRL bioactivity and proinflammatory cytokine detection were assessed. The results showed that PRL and PRLr messenger RNA (mRNA) were synthesized in THP-1 monocytes induced with CFP-M. bovis at peaks of 176- and 404-fold, respectively. PRL forms of 60 and 80kDa and PRLr isoforms of 40, 50, and 65kDa were also identified as time-dependent, while 60-kDa PRL, as well as 40-, and 50-kDa PRLr, were found as soluble forms in culture media and later in the nucleus of THP-1 monocytes. PRL of 60kDa released by monocytes exhibited bioactivity in Nb2 cells, and both synthesized PRL and synthesized PRLr were related with nitrite and proinflammatory cytokine levels proapoptotic activity in CFP-M. bovis-induced monocytes. Our results suggest the overexpression of a full-autocrine loop of PRL and PRLr in monocytes that enhances the inflammatory response and apoptosis after priming with M. bovis antigens.

The 19 kDa Mycobacterium tuberculosis lipoprotein (LpqH) induces macrophage apoptosis through extrinsic and intrinsic pathways: a role for the mitochondrial apoptosis-inducing factor.

We describe the association of caspase-dependent and caspase-independent mechanisms in macrophage apoptosis induced by LpqH, a 19 kDa Mycobacterium tuberculosis lipoprotein. LpqH triggered TLR2 activation, with upregulation of death receptors and ligands, which was followed by a death receptor signaling cascade with activation of initiator caspase 8 and executioner caspase 3. In this caspase-mediated phase, mitochondrial factors were involved in loss of mitochondrial transmembrane potential (ΔΨm), release of cytochrome c, and caspase 9 activation. Interestingly, a caspase-independent pathway was also identified; by immunoblot, the mitochondrial apoptosis inducing factor (AIF) was demonstrated in nuclei and cytosol of LpqH-treated macrophages. Confocal microscopy revealed translocation of AIF to the nuclei of the majority of apoptotic cells. These findings emphasize the complex and redundant nature of the macrophage death response to mycobacteria.

New insights into protein O-mannosylation in actinomycetes.

Glycosylation is a common post-translational modification of surface exposed proteins and lipids present in all kingdoms of life. Information derived from bacterial genome sequencing, together with proteomic and genomic analysis has allowed the identification of the enzymatic glycosylation machinery. Among prokaryotes, O-mannosylation of proteins has been found in the actinomycetes and resembles protein O-mannosylation in fungi and higher eukaryotes. In this review we summarize the main features of the biosynthetic pathway of O-mannosylation in prokaryotes with special emphasis on the actinomycetes, as well as the biological role of the glycosylated target proteins.

Decreased expression of T-cell costimulatory molecule CD28 on CD4 and CD8 T cells of mexican patients with pulmonary tuberculosis.

Patients with tuberculosis frequently develop anergy, a state of T-cell hyporesponsiveness in which defective T-cell costimulation could be a factor. To know if the expression of T-cell costimulatory molecules was altered in tuberculosis, we analyzed the peripheral blood T-cell phenotype of 23 Mexican patients with pulmonary tuberculosis. There was severe CD4 (P < .001) and CD8 (P < .01) lymphopenia and upregulation of costimulatory molecule CD30 on CD4 and CD8 T cells (P < .05); this increase was higher in relapsing tuberculosis. The main finding was severe downregulation of the major costimulatory molecule CD28 on both CD8 and CD4 T cells (P < .001). Depletion of the CD4/CD28 subset, a hitherto undescribed finding, is relevant because CD4 T cells constitute the main arm of the cell-mediated antimycobacterial immune response.

Impact of opportunistic Mycobacterium tuberculosis infection on the phenotype of peripheral blood T cells of AIDS patients.

While the detrimental consequences of opportunistic tuberculosis (TB) in the course and outcome of HIV-1 infection are well studied, little information about the impact of the mycobacterial infection on the phenotype of T lymphocytes is available. In this study we analyzed by cytofluorimetry the peripheral blood T cell phenotype of 13 patients with AIDS, 23 HIV-1 negative patients with active pulmonary TB, nine HIV-1/Mycobacterium tuberculosis coinfected individuals, and 21 age- and sex-matched healthy controls. CD4+ T cells were equally depleted in AIDS and coinfection (P<0.001). The findings suggest a rescuing effect of the added mycobacterial infection. CD3 T cell loss was not observed in coinfection, whereas it was severe in AIDS (P<0.001). Similar (albeit less striking) effects were observed with other markers (CD45RA, CD45RO, and CD27) that were diminished in CD4+ T cells of AIDS patients. Apparent detrimental effects of the added mycobacterial infection were the increased expression of the proapoptotic molecule CD95 on CD4+ T cells, and decreased expression of the major costimulatory molecule CD28 on CD8+ T cells. In this work we show that M. tuberculosis infection modifies the T cell phenotype of the HIV-1 infected individual.

A microsatellite study of bovine solute carrier family 11 a1 (Slc11a1) gene diversity in Mexico in relation to bovine tuberculosis

Bovine tuberculosis, caused by Mycobacterium bovis, is a disease of socio-economic and public health importance and of significance to international trade regulation. Allelic variants of several genes have been implicated in the genetic susceptibility to tuberculosis in some human populations, but little is known in cattle. We surveyed 34 European, 18 Asian, 20 Creole and 23 hybrid bovines for polymorphisms of the bovine solute carrier family 11 a1(Slc11a1) gene, formerly known as natural resistance associated macrophage protein (Nramp1), gene by typing the cattle using two microsatellite loci closely linked to this gene. The microsatellites used were 311-22, located at the 3' untranslated region (3' UTR) of the Slc11a1 gene, and ARO28 situated about 0.6 cM upstream of the same gene Based on allele size in base pairs (bp) we determined five 311-223 locus variants (221, 223, 225, 227 and 229 bp) and 12 ARO28 loci. There was marked diversity and a very high level of heterozygosity in most of the cattle surveyed except the Europeans bovines and especially Holsteins in relation to the 3' UTR microsatellite locus.

The 19-kDa antigen of Mycobacterium tuberculosis is a major adhesin that binds the mannose receptor of THP-1 monocytic cells and promotes phagocytosis of mycobacteria.

Identification of mycobacterial adhesins is needed to understand better the pathogenesis of tuberculosis and to develop new strategies to fight this infection. In this work, THP-1 monocytic cells were incubated with Mycobacterium tuberculosis culture filtrate proteins labelled with biotin and a dominant 19-kDa adhesin was found. This adhesin was characterized as the glycosylated and acylated 19-kDa antigen (Rv 3763). These findings were confirmed in assays with culture filtrate proteins and cell-wall fractions from a recombinant Mycobacterium smegmatis strain that overexpresses the 19-kDa antigen. Further, fluorescent microspheres coated with recombinant culture filtrate proteins adhere to cells in higher numbers than microspheres coated with native M. smegmatis proteins. The binding of the 19-kDa antigen to cells was inhibited with mannose receptor competitor sugars, Ca(2+) chelators and with a monoclonal antibody to the human mannose receptor. Phagocytosis assays showed high-level binding of bacilli to THP-1 cells that was inhibited with alpha-methyl-mannoside, mannan, EDTA and mAbs to the mannose receptor and to the 19-kDa M. tuberculosis antigen. Immunoprecipitation, cell-surface ELISA and immunostaining confirmed the expression of the mannose receptor by THP-1 cells. In conclusion, here we show that the macrophage mannose receptor, considered a pathogen pattern recognition receptor, may interact with mannose residues of mycobacterial glycoproteins that could promote the phagocytosis of mycobacteria.