Patch-seq of mouse DRG neurons reveals candidate genes for specific mechanosensory functions.

A variety of mechanosensory neurons are involved in touch, proprioception, and pain. Many molecular components of the mechanotransduction machinery subserving these sensory modalities remain to be discovered. Here, we combine recordings of mechanosensitive (MS) currents in mechanosensory neurons with single-cell RNA sequencing. Transcriptional profiles are mapped onto previously identified sensory neuron types to identify cell-type correlates between datasets. Correlation of current signatures with single-cell transcriptomes provides a one-to-one correspondence between mechanoelectric properties and transcriptomically defined neuronal populations. Moreover, a gene-expression differential comparison provides a set of candidate genes for mechanotransduction complexes. Piezo2 is expectedly found to be enriched in rapidly adapting MS current-expressing neurons, whereas Tmem120a and Tmem150c, thought to mediate slow-type MS currents, are uniformly expressed in all mechanosensory neuron subtypes. Further knockdown experiments disqualify them as mediating MS currents in sensory neurons. This dataset constitutes an open resource to explore further the cell-type-specific determinants of mechanosensory properties.

Prevalence of Helicobacter pylori infection and antibiotic resistance profile in Armenia.

BACKGROUND: The prevalence of Helicobacter pylori infection was never assessed in Armenia, nor was the prevalence of H. pylori resistance against the main antibiotics concerned, despite the fact that these data are fundamental to establish evidence-based recommendations for management of this infection. We aimed to fill this gap by assessing prevalence of H. pylori among adult population in Armenia and resistance of H. pylori strains to clarithromycin and levofloxacin. METHODS: Helicobacter pylori seroprevalence was determined in 217 asymptomatic adult subjects submitted to a health checkup using an ELISA. Molecular methods were used to detect H. pylori in gastric biopsies from 91 adult dyspeptic patients [55 (60.4%) were positive] as well as the mutations associated with clarithromycin resistance by real-time PCR and with levofloxacin by sequencing the gyrA QRDR. RESULTS: Helicobacter pylori seropositivity was found to be 41.5% globally and increased with age from 13.6% (age 18-25 years) to 83.3% (age > 65 years). Only two cases were found with a A2142/43G mutation causing clarithromycin resistance, and 6 cases showed mutations associated with levofloxacin resistance. CONCLUSIONS: Helicobacter pylori infection is estimated to be about 42% among adults in Armenia and the low clarithromycin resistance allows the use of the standard triple therapy as a first line therapy.

Deregulation of MicroRNAs in Gastric Lymphomagenesis Induced in the d3Tx Mouse Model of Helicobacter pylori Infection.

Helicobacter pylori infection is considered as an excellent model of chronic inflammation-induced tumor development. Our project focuses on gastric MALT lymphoma (GML) related to H. pylori infection and mediated by the chronic inflammatory process initiated by the infection. Recently, microRNAs (miRNAs) have emerged as a new class of gene regulators, which play key roles in inflammation and carcinogenesis acting as oncogenes or tumor suppressors. Their precise characterization in the development of inflammation and their contribution in regulating host cells responses to infection by H. pylori have been little explored. Our goal was to analyze the changes in miRNAs in a GML mouse model using BALB/c mice thymectomized at day 3 post-birth (d3Tx model) and to clarify their implication in GML pathogenesis. PCR array followed by RT-qPCR identified five miRNAs (miR-21a, miR-135b, miR-142a, miR-150, miR-155) overexpressed in the stomachs of GML-developing d3Tx mice infected by H. pylori. The analysis of their putative targets allowed us to identify TP53INP1, an anti-proliferative and pro-apoptotic protein, as a common target of 4 of the 5 up-regulated miRNAs. We postulate that these miRNAs may act in synergy to promote the development of GML. miR-142a was also overexpressed in mouse sera samples and therefore could serve as a diagnostic marker. In situ hybridization on gastric samples with miR-142a revealed a global up-regulation of this miRNA by the tumor microenvironment at the lymphoma stage. Dysregulation of miR-21a, miR-135b, miR-142a, miR-150, miR-155 could play a critical role in the pathogenesis of GML and might offer potential applications as therapeutic targets and novel biomarkers for this disease.

A New Animal Model of Gastric Lymphomagenesis: APRIL Transgenic Mice Infected by Helicobacter Species.

APRIL is a member of the tumor necrosis factor cytokine family involved in the regulation of B-cell immunity. We present a study of the infection by Helicobacter species of transgenic (Tg) C57BL6 mice, ectopically expressing the human form of APRIL. Wild-type (WT) and APRIL Tg mice were infected with Helicobacter felis and Helicobacter pylori and compared with noninfected animals. Mice were euthanized 18 months after infection, and inflammatory responses and histologic alterations were analyzed. Flow cytometry results revealed that WT-infected mice had less leukocyte infiltration than APRIL Tg-infected mice. In WT-infected mice, infiltrates in gastric tissues were predominantly composed of T cells, mainly CD4+ for H. pylori and CD8+ for H. felis. In APRIL Tg-infected mice, leukocyte infiltrates were composed of B cells with few CD4+ T cells for both species. B cells expressed B surface markers compatible with a marginal zone origin. These results were confirmed by immunohistochemistry. B cells in particular were involved in lymphoepithelial lesions, a hallmark of gastric MALT lymphoma. Monoclonality was observed in a few infiltrates in the presence of lymphoepithelial lesions. These results confirm the importance of APRIL in the development of gastric lymphoid infiltrates induced by Helicobacter species in vivo. We believe that APRIL Tg mice infected by Helicobacter species may represent a novel animal model of gastric lymphomagenesis.

Regulatory T cells may participate in Helicobacter pylori persistence in gastric MALT lymphoma: lessons from an animal model.

It has been postulated that the emergence of autoimmune gastritis in neonatal thymectomised (d3Tx) BALB/c mice may be a consequence of post-surgery deficit in Tregs. In this study, previously obtained samples from d3Tx mice were used in order to determine whether thymectomy creates a deficit in this T cell subset thereby allowing the emergence of autoimmune phenomena as a prerequisite for GML. The splenic Treg reserve and the local recruitment of these cells in the gastric mucosa were investigated using complementary molecular and immunohistochemistry approaches. Higher Foxp3/CD3 ratios were found in the spleen of non-infected d3Tx mice compared to non-thymectomised (NTx) controls. These results indicate a relative enrichment of Tregs following thymectomy in adult mice. The absence of Treg depletion in d3Tx mice is in line with the absence of auto-immune gastritis in non-infected d3Tx mice. Higher levels of T cell and Treg infiltration were also found in the stomach of GML-developing d3Tx mice versus NTx mice. Surprisingly, inflammatory scores inversely correlated with the bacterial inoculum. The presence of a small Treg containing compartment among gastric biopsies of GML developing d3Tx mice may play a role in perseverance of a minimal bacterial numbers thereby maintaining an antigen-dependent stimulation and proliferation.

Characterisation of inflammatory processes in Helicobacter pylori-induced gastric lymphomagenesis in a mouse model.

Gastric MALT lymphoma (GML) can be induced by Helicobacter pylori infection in BALB/c mice thymectomised at day 3 post-birth (d3Tx). This represented a unique opportunity to investigate the inflammatory process involved in the recruitment, proliferation and structuration of lymphoid infiltrates in the gastric mucosa of mice developing GML. Complementary molecular and proteomic approaches demonstrated that Th1 and Th2 cytokines were upregulated, along with activators/regulators of the lymphoid response and numerous chemokines. Interleukin-4, interferon γ, lymphotoxin-α and -ß were significantly upregulated and correlated with the inflammatory scores for all the d3Tx mice. GML lesions in d3Tx mice infected with H. pylori were associated with the presence of the inflammatory response. The dysregulation of numerous members of the tumour necrosis factor superfamily was also evident and suggests that they could play an important role in GML pathology, especially in light of their ability to promote and control lymphocyte proliferation.