Role of type I interferon in the bacillus Calmette-Guérin-induced expression of CXCL10 from human monocytes.

BACKGROUND: The proinflammatory chemokine CXCL10, in addition to its chemotactic properties, is also involved in the stimulation of natural killer and T-cell migration in Mycobacterium tuberculosis infection. In this study, our experiments were designed to determine the role of interferon (IFN)-alphabeta in the production of CXCL10 by human monocytes infected with Mycobacterium bovis bacillus Calmette-Guerin (BCG). METHODS: The concentrations of CXCL10 in culture supernatants of monocytes infected with M. bovis BCG were determined by enzyme-linked immunosorbent assay. CXCL10 mRNA levels were determined by the reverse transcription-polymerase chain reaction method. RESULTS: We have shown the induction of CXCL10 following infection with M. bovis BCG in a dose-dependent and time-dependent manner. Importantly, the secretion of CXCL10 in response to M. bovis was increased by IFN-alpha. These results were further confirmed by the fact that the addition of an anti-IFN-alphabeta neutralizing antibody completely reversed the stimulatory effect, whereas an isotype-matched control antibody had no significant effect on CXCL10 secretion. It is important to note that no significant effect of type I IFN on CXCL8 production in M. bovis-infected monocytes was observed. This was consistent with the finding by the reverse transcription-polymerase chain reaction method that treatment with anti-IFN-alpha/beta antibodies potentially inhibited CXCL10 mRNA levels, whereas no significant effect was observed on CXCL8 mRNA. Moreover, in THP-1 monocytes and THP-1 macrophages, the addition of exogenous IFN-alpha stimulated CXCL10 secretion. CONCLUSIONS: Collectively, these results indicate that the type I IFN may play an important role to modulate the expression of CXCL10 in M. bovis BCG infection. Studies on M. bovis-induced chemokine secretion could provide important insight into the regulation of the immune response against tuberculosis

Expression and Secretion of CXCL-8 and CXCL-10 From Mycobacterium Bovis BCG-Infected Human Epithelial Cells: Role of IL-4

CXC chemokine release can be modulated by Th2-derived cytokines. Interleukin(IL)-4 is one of the cytokines that are the hallmark of the Th-2 response, and plays an important role in human tuberculosis. In the current study, we investigated the effect of IL-4 on chemokine production by human epithelial cells infected with Mycobacterium bovis bacillus calmette-guérin (BCG). Gene expression of CXCL-8 and CXCL-10 was determined by the reverse transcription (RT)-polymerase chain reaction method. The levels of immunoreactive CXCL-8 and CXCL-10 were determined by enzyme-linked immunosorbent assay. We found that, although M. bovis BCG induced gene expression of CXCL-8 and CXCL-10 in M. bovis BCG-infected human epithelial cells, CXCL-8 mRNA level was significantly reduced by IL-4, whereas no significant effect of IL-4 was observed on CXCL10 mRNA level. In addition, IL-4 decreased CXCL-8 (in a graded and significant manner) but not CXCL-10 secretion. These results were further confirmed, since a significant reversion was obtained with a neutralizing antibody to human IL-4, whereas an isotype-matched control antibody had no significant effect on CXCL-8 secretion. Furthermore, we found a similar effect of IL-4 on M. bovis BCG-induced CXCL-8 and CXCL-10 secretion by using other human epithelial A549 cell line. Collectively, these data demonstrate that M. bovis BCG-infected human epithelial cells can have an active role in a local inflammatory immune response via the secretion of CXC chemokines which can be selectively regulated by Th2-derived cytokines

Secretion of interleukin-8 by human-derived cell lines infected with Mycobacterium bovis.

BACKGROUND: The variable efficacy of bacillus Calmette-Guérin (Mycobacterium bovis BCG) in protecting humans against tuberculosis has prompted a search for the mechanisms through which BCG induces chemokines. In this study, our experiments were designed to determine the role of the transcription factor nuclear factor-kappaB (NF-kappaB) and intracellular calcium in the production of interleukin (IL)-8, a main chemotactic factor, by human-derived monocytic cell line U937 and by a human epithelial HEp-2 cell line infected with M. bovis BCG. METHODS: The concentrations of IL-8 in culture supernatants of U937 cells or HEp-2 cells infected with M. bovis BCG were determined by enzyme-linked immunosorbent assay. We used sulfasalazine and curcumin, which are well-described inhibitors of NF-kappaB activity, and we used ethylenediamine tetraacetic acid to deplete extracellular Ca2+ or used the cell-permeable agent 1,2-bis (2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester to chelate releasable intracellular stores of Ca2+ in order to investigate the mechanisms through which M. bovis BCG induces IL-8 secretion in our system. RESULTS: The enzyme-linked immunosorbent assay showed that IL-8 protein secretion was elevated in M. bovis-infected cell lines. This effect was statistically significant (p < 0.01). When calcium influx was suppressed in M. bovis-infected cell lines, IL-8 secretion was inhibited. Notably, specific inhibitors of NF-kappaB (sulfasalazine and curcumin) inhibited M. bovis-induced IL-8 secretion from U937 cells or HEp-2 cells. CONCLUSIONS: Collectively, these results indicate that activation of NF-kappaB is an important signal transduction pathway in M. bovis-induced IL-8 secretion in monocytic or epithelial cells. Furthermore, the results showed that calcium influx had a direct effect on IL-8 secretion in U937 cells or HEp-2 cells infected with M. bovis

Prevalencia de la esteatosis hepática no alcohólica en población con hipertransaminasemia y grado de adecuación del diagnóstico registrado en atención primaria

La esteatosis hepática no alcohólica (EHNA) es la causa más frecuente de elevación de transaminasas en el adulto. Determinar la prevalencia de EHNA en pacientes con hipertransaminasemia mantenida, y conocer el grado de adecuación del diagnóstico registrado en Atención Primaria (AP). 1) Estudio descriptivo transversal con muestra aleatoria de pacientes con elevación de la enzima alanina aminotransferasa (ALT) mantenida (ALT > 32 durante ≥ 6 meses), descartadas otras causas de hepatopatía, siguiendo criterios clínicos, analíticos y ecográficos en AP, y 2) descriptivo transversal sobre todos los casos con diagnóstico de EHNA registrado (K76 - CIE10) con análisis de adecuación diagnóstica según criterios estándar. Se analizaron 290 pacientes: 76 fueron diagnosticados de EHNA (26,1%), 44 mujeres (57,9%). El análisis multivariado ajustado por edad y sexo mostró asociación entre EHNA y sexo masculino (OR: 0,5; IC 95%: 0,3-0,9), diabetes mellitus (DM) (OR: 2,42; IC 95%: 1,2-4,9) e hipertensión arterial (HTA) (OR: 3,07; IC 95%: 1,6-5,6). De los 209 con registro diagnóstico de EHNA: 51 (24,4%) cumplían criterios de EHNA. El resto carecían de registros suficientes. Destacan: 53,1% carecían de hipertransaminasemia mantenida; 48% de serologías víricas; 11% de ecografía abdominal compatible y 53,1% de registro del consumo de alcohol. La EHNA severa es frecuente entre los pacientes con hipertransaminasemia mantenida. La DM y la HTA incrementan significativamente el riesgo de EHNA. El diagnóstico de EHNA se registra sin considerar todos los criterios de EHNA y se hace mayoritariamente por ecografía. Se deberían unificar criterios diagnósticos en el registro de la EHNA

Host Antimicrobial Peptides: the promise of new treatment strategies against Tuberculosis

Tuberculosis (TB) continues to be a devastating infectious disease and remerges as a global health emergency due to an alarming rise of antimicrobial resistance to its treatment. Despite of the serious effort that has been applied to develop effective antitubercular chemotherapies, the potential of antimicrobial peptides (AMPs) remains underexploited. A large amount of literature is now accessible on the AMP mechanisms of action against a diversity of pathogens; nevertheless, research on their activity on mycobacteria is still scarce. In particular, there is an urgent need to integrate all available interdisciplinary strategies to eradicate extensively drug-resistant Mycobacterium tuberculosis strains. In this context, we should not underestimate our endogenous antimicrobial proteins and peptides as ancient players of the human host defense system. We are confident that novel antibiotics based on human AMPs displaying a rapid and multifaceted mechanism, with reduced toxicity, should significantly contribute to reverse the tide of antimycobacterial drug resistance. In this review, we have provided an up to date perspective of the current research on AMPs to be applied in the fight against TB. A better understanding on the mechanisms of action of human endogenous peptides should ensure the basis for the best guided design of novel antitubercular chemotherapeutics

Antimicrobial Peptides in Innate Immunity against Mycobacteria

Antimicrobial peptides/proteins are ancient and naturallyoccurring antibiotics in innate immune responses in a variety of organisms. Additionally, these peptides have been recognized as important signaling molecules in regulation of both innate and adaptive immunity. During mycobacterial infection, antimicrobial peptides including cathelicidin, defensin, and hepcidin have antimicrobial activities against mycobacteria, making them promising candidates for future drug development. Additionally, antimicrobial peptides act as immunomodulators in infectious and inflammatory conditions. Multiple crucial functions of cathelicidins in antimycobacterial immune defense have been characterized not only in terms of direct killing of mycobacteria but also as innate immune regulators, i.e., in secretion of cytokines and chemokines, and mediating autophagy activation. Defensin families are also important during mycobacterial infection and contribute to antimycobacterial defense and inhibition of mycobacterial growth both in vitro and in vivo. Hepcidin, although its role in mycobacterial infection has not yet been characterized, exerts antimycobacterial effects in activated macrophages. The present review focuses on recent efforts to elucidate the roles of host defense peptides in innate immunity to mycobacteria

The Stress-Response Factor SigH Modulates the Interaction between Mycobacterium tuberculosis and Host Phagocytes

The Mycobacterium tuberculosis stress response factor SigH plays a crucial role in modulating the pathogen's response to heat, oxidative-stress, envelope damage and hypoxia. We hypothesized that the lack of this key stress response factor would alter the interaction between the pathogen and its host cells. We compared the interaction of Mtb, Mtb:Δ-sigH and a strain where the mutation had been genetically complemented (Mtb: Δ-sigH:CO) with primary rhesus macaque bone marrow derived macrophages (Rh-BMDMs). The expression of numerous inducible and homeostatic (CCL) β-chemokines and several apoptotic markers was induced to higher levels in the cells infected with Mtb:Δ-sigH, relative to Mtb or the complemented strain. The differential expression of these genes manifested into functional differences in chemotaxis and apoptosis in cells infected with these two strains. The mutant strain also exhibited reduced late-stage survival in Rh-BMDMs. We hypothesize that the product of one or more SigH-dependent genes may modulate the innate interaction of Mtb with host cells, effectively reducing the chemokine-mediated recruitment of immune effector cells, apoptosis of infected monocytes and enhancing the long-term survival and replication of the pathogen in this milieu The significantly higher induction of Prostaglandin Synthetase 2 (PTGS2 or COX2) in Rh-BMDMs infected with Mtb relative to Mtb: Δ-sigH may explain reduced apoptosis in Mtb-infected cells, as PTGS2 is known to inhibit p53-dependent apoptosis.The SigH-regulon modulates the innate interaction of Mtb with host phagocytes, perhaps as part of a strategy to limit its clearance and prolong its survival. The SigH regulon appears to be required to modulate innate immune responses directed against Mtb