Carmen Maldonado-Bernal

Mycobacterium tuberculosis lipids regulate cytokines, TLR-2/4 and MHC class II expression in human macrophages

The interaction of macrophages with Mycobacterium tuberculosis through Toll-like receptors is critical in defining the cytokine profile that may or may not control disease progression. Cell-wall lipids are the main pathogen-associated molecular ligands of mycobacteria, in this paper, we analysed how lipid fractions of three different strains of the M. tuberculosis complex (genotypes Canetti, Beijing and H37Rv) affected the innate immunity by regulating TNF-alpha and IL-10 secretion, TLR2, TLR4, and MHC class II expression of human monocyte-derived macrophages. Of note, lipid fractions from the Beijing genotype (hypervirulent phenotype) preferentially induced macrophages to secrete high amounts of TNF-alpha and IL-10, but downregulated TLR2, TLR4 and MHC class II expression. In contrast, lipids from M. tuberculosis Canetti induced lower amounts of TNF-alpha and IL-10, upregulated TLR2 and TLR4 without modifying MHC class II expression. These results indicate that the virulent mycobacterial genotype Beijing expresses lipids that negatively modified cytokine, TLR and MHC class II expression. These findings may help to unravel the complex mechanisms used by virulent mycobacteria to evade and subvert the immune response.

TLR4 single-nucleotide polymorphisms alter mucosal cytokine and chemokine patterns in Mexican patients with Helicobacter pylori-associated gastroduodenal diseases.

Helicobacter pylori is associated with peptic ulcer and gastric adenocarcinoma. Toll-like receptors (TLRs) participate in H. pylori recognition, and single-nucleotide polymorphisms (SNPs) in TLRs are associated with impaired immune response. We aimed to evaluate the association of TLR2/R753Q and TLR4/D299G/T399I SNPs with gastroduodenal diseases; and study the effect of SNPs on cytokine and chemokine expression in the gastric mucosa. Study included 450 Mexican patients with gastroduodenal diseases. SNPs in TLRs 2 and 4 genes were analyzed by allele-specific PCR. Cytokines and chemokines were assessed by qRT-PCR and immunoassay. TLR4/D299G/T399I polymorphisms were more frequent in duodenal ulcer and showed a trend in gastric cancer, when compared with non-atrophic gastritis. Patients with TLR4 polymorphisms expressed significantly lower levels of IL-1beta, IL-6, IL-8 and GRO-alpha; and higher levels of TNF-alpha, IL-10, MCP-1 and MIP-1alpha . SNPs in TLR4 gene had an association with severe H. pylori-associated disease and with modified pattern of inflammatory cytokines and chemokines in the gastric mucosa. These results suggest that TLR4 SNPs contributes importantly to the clinical outcome of H. pylori infection.

Low frequency of Toll-like receptors 2 and 4 gene polymorphisms in Mexican patients and their association with Type 2 diabetes

Type 2 diabetes (T2D) is characterized by a chronic low‐grade inflammatory state. SNP in Toll‐like receptor (TLR) genes has been associated with impaired inflammatory response. We genotyped the TLR4/D299G, TLR4/T399I and TLR2/R753Q polymorphisms. Low frequency was found with no association with T2D, nevertheless the TLR2 SNP was associated with lower levels in HDL‐cholesterol values.

Helicobacter pylori and neurological diseases: Married by the laws of inflammation

The purpose of this paper is to review current information about the role of inflammation caused by Helicobacter pylori (H. pylori) infection in neurological diseases such as Parkinsons disease, Alzheimers disease, Guillain-Barré syndrome, multiple sclerosis, and other inflammatory diseases including ischemic stroke. Infection with H. pylori usually persists throughout life, resulting in a chronic inflammatory response with local secretion of numerous inflammatory mediators including chemokines [interleukin (IL)-8, macrophage chemotactic protein (MCP)-1, growth-regulated oncogene (GRO)-α] and cytokines [IL-1β, tumor necrosis factor (TNF)-α, IL-6, IL-12, interferon (IFN)-γ], which can pass into the circulation and have a systemic effect. The persistence of detectable systemic and local concentrations of inflammatory mediators is likely to alter the outcome of neurological diseases. These proinflammatory factors can induce brain inflammation and the death of neurons and could eventually be associated to Parkinsons disease and also may be involved in the development of Alzheimers disease. However, most neurological diseases are the result of a combination of multiple factors, but the systemic inflammatory response is a common component and determinant in the onset, evolution, and outcome of diseases. However, more studies are needed to allow understanding of the effects and mechanisms by which the inflammatory response generated by H. pylori infection affects neurological diseases.

Activation of NLRP3 inflammasome in human neutrophils by Helicobacter pylori infection

TLRs and NLRs participate in the immune system recognition of Helicobacter pylori. However, little is known about the mechanisms leading to inflammasome activation by H. pylori and if NLRs in neutrophils are involved in the process. We studied how NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome components are involved in IL-1β maturation in human neutrophils in response to the infection and if they are dependent on T4SS (type IV secretion system) and TLRs. Human neutrophils were cultured and infected with the 26695 or the VirD4− H. pylori strains; the IL-1β concentration was analyzed by ELISA, and we also evaluated the activation of TLRs 2 and 4. The infection of neutrophils with both strains of H. pylori induced production of IL-1β and expression of the NLRP3 inflammasome components such as apoptosis-associated speck-like protein with CARD domain and NLRP3 protein. The infection also increased the activity of caspase-1, which is required for the maturation of IL-1β. Our study shows, for the first time, that H. pylori infection induces the expression and activation of components of NLRP3 inflammasomes in human neutrophils and that the activation is independent of a functional T4SS and TLR2 and TLR4.

Toll-like receptors and cytokines are upregulated during Helicobacter pylori infection in children.

Helicobacter pylori infection is mainly acquired during childhood, and establishes a chronic infection that may lead to peptic ulcer or gastric cancer during adulthood. Toll‐like receptors (TLRs) are expressed by distinct cell types throughout the gastrointestinal tract, and play an important role in regulation of the innate immune response. Few works have addressed TLRs expression in gastric epithelia of adults, and scarce studies have done it in children. The aim of this work was to analyze the expression of TLR2, TLR4, TLR5, TLR9, and IL‐8, IL‐10 and TNF‐α in the gastric mucosa of children with and without H. pylori infection.

Impact of cagPAI and T4SS on the Inflammatory Response of Human Neutrophils to Helicobacter pylori Infection

Helicobacter pylori contains a pathogenicity island, cagPAI, with genes homologous to components of the type IV secretion system (T4SS) of Agrobacterium tumefaciens. The T4SS components assemble a structure that transfers CagA protein and peptidoglycan into host epithelial cells, causing the increased release of interleukin 8 (IL8) from the cells. The Toll-like receptors on neutrophils recognize H. pylori, initiating signaling pathways that enhance the activation of NF-κB. However, the roles of cagPAI and T4SS in the inflammatory response of neutrophils are unknown. We evaluated the participation of cagPAI and T4SS in the response of human neutrophils to H. pylori infection. Neutrophils were isolated from the blood of healthy donors and infected with H. pylori cagPAI+, cagPAI–, and cagPAI mutant strains virB4 – and virD4 –. Whereas cagPAI+ strain 26695 induced the greatest IL8 production, a proinflammatory response, cagPAI– strain 8822 induced the greatest IL10 production, an anti-inflammatory response. In contrast, the virB4 – and virD4 – mutant strains produced significantly more of the two proinflammatory cytokines IL1β and tumor necrosis factor αthan the cagPAI+ strain 26695. We observed that H. pylori downregulated the expression of TLRs 2 and 5 but upregulated TLR9 expression in a cagPAI and T4SS-independent manner. These results show for the first time that the response of human neutrophils to H. pylori may vary from a pro-inflammatory to an anti-inflammatory response, depending on cagPAI and the integrity of T4SS.

Receptores tipo Toll, patogénesis y respuesta inmune a Helicobacter pylori

Helicobacter pylori colonize the gastric epithelial, most infected people are asymptomatic, 10 to 20% develop atrophic gastritis, peptic ulcer and less than 3% gastric cancer. These diseases are determined by the relationship between virulence factors of bacteria, host factors such as, genetic predisposition, and immune response. The innate immune response mainly represented by Toll-like receptors and Nod-like receptors that recognize their specific ligands, activate transcription factors as NF-kB, AP-1, CREB-1, inducing production of inflammatory cytokines such as IL -8, IL-12, IL-6, IL-1β, IL-18, TNF-α and IL-10. Chronic inflammation promotes gastric morphological changes, prevents apoptosis and allows angiogenesis generating neoplasic lesions and cancer. The aim of this review is to analyze the mechanisms proposed to date of the innate and adaptative immune response involved in H. pylori infection; remarking the mechanisms related in the elimination or persistence.

Infección, inflamación y cáncer gástrico

Existe una solida relacion entre la infeccion persistente, la inflamacion cronica y el cancer. Helicobacter pylori es la principal causa del cancer gastrico, con 900 000 casos nuevos registrados cada ano. Este patogeno estimula a las celulas del epitelio gastrico para secretar IL-8, un quimioatrayente de leucocitos que infiltra el tejido infectado de manera persistente. Tambien se observan concentraciones elevadas de citocinas inflamatorias que promueven la perdida de la homeostasis local debido a la alteracion de la proliferacion y apoptosis celular. No es claro el mecanismo por el cual esta reaccion inflamatoria lleva al cancer, pero los radicales libres de O2 y N2 podrian contribuir de modo directo al dano genomico de la mucosa. El virus de Epstein-Barr es otro microorganismo vinculado con el cancer gastrico. En esta revision se describen los mecanismos inflamatorios importantes que intervienen en el desarrollo de la tumoracion, tal vez compartidos con otros patogenos, lo cual es de gran relevancia ya que alrededor de 25% de los canceres se relaciona con infeccion.

El papel de la inmunidad innata en la obesidad

Obesity in Mexico is alarmingly increasing in prevalence in adults and children, and it is a risk factor for the development of insulin resistance, as well as, of other metabolic alterations. The discovery of the expression of the Toll-like receptors (TLRs) in adipocytes, suggests an important role in innate immunity. In different models of obesity, there has been observed an increase of TLRs expression in the fat tissue, therefore TLRs could be involved in systemic inflammation in this disease, and in the development of insulin resistance. TLR activation is mediated by fatty acids and their expression is regulated by leptin, adiponectin and PPARs. Knowledge of the role of TLRs in inflammation and adipocyte differentiation and their regulation, then it is important to try to develop new therapeutic anti-inflammatory targets that contribute in the treatment of obesity.