Influenza infection reduces disease in a B-cell dependent EAE model of multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease characterized by demyelination of neurons and inflammation in the central nervous system. MS afflicts approximately 2.5 million people worldwide. Understanding how viral infection affects MS disease is of great importance because the immune-suppressive effects of some MS therapies can make patients more vulnerable to viral infections. The goal of our project is to elucidate the effect of respiratory viral infection in a B cell-driven experimental autoimmune encephalomyelitis (EAE), which models the immune pathology of MS. Here, we describe a comorbid animal model in which mice were immunized with hMOG1–125 to induce EAE and subsequently infected prior to disease onset with a sublethal dose of the H1N1 Influenza A mouse-adapted A/Puerto Rico/8/1934 virus (IAV). Our data show that comorbid mice have a less severe EAE paralysis phenotype than mice with EAE alone. Flow cytometry analyses show that the lungs of comorbid mice had increased neutrophil numbers and a reciprocal reduction in MHCII+ CD86+ inflammatory monocytes. Comorbid mice also had fewer germinal center B cells in the lungs and reduced levels of IAV-specific IgM and IgG antibodies compared to IAV-infected controls. Secondary IAV challenge of comorbid mice revealed deficits in immunological B cell memory. Overall, our data show that EAE disrupts the antiviral immune response, including by decreasing the IAV-specific B cell response. Paradoxically, viral infection decreased EAE severity, indicating that the antiviral immune response attenuates B cell-dependent neuroinflammation. Future studies will determine mechanisms by which inflammation induced by viral infection modulates neuroinflammatory diseases.

Supported by grants from  NIH (R01AI137047 and R01EY027346) A grant awarded to Dr. Kovats and Dr. Axtell from the Presbyterian Health Foundation

Impact of B-cell depletion therapy on respiratory viral infection

B cell depletion therapy with anti-CD20 antibodies ameliorates autoimmune diseases such as multiple sclerosis, rheumatoid arthritis as well as haematological malignancies. Anti-CD20 antibodies deplete pre-B cells, mature B cells and malignant B cells but do not reduce plasma cells. Recently, studies have associated anti-CD20 therapy with severe manifestation of SARS-CoV2 infection. However, the mechanism of this adverse effect of anti-CD20 therapy remains unclear.

This study was undertaken to investigate the effect of anti-CD20 therapy on respiratory viral infection. C57BL/6 mice were treated with anti-CD20 antibody to induce B cell depletion and then were infected intratracheally with H1N1 Influenza A mouse-adapted A/Puerto Rico/8/1934 virus (IAV). Our results show that B cell depletion therapy worsens lung infection with more severe and prolonged weight loss. Higher viral titers were found in the lungs of anti-CD20 treated mice, indicating impairment in virus clearance. Flow cytometry analysis showed no difference between groups in CD4+ and CD8+ PR8 antigen specific T cells on day 9 post-infection. However, higher numbers of inflammatory, SiglecF+ neutrophils were found in B cell depleted mice.

In summary, our data show that anti-CD20 therapy exacerbates the viral pathology in respiratory lung infections. We further have identified that B cell depletion therapy affects viral clearance and inflammatory neutrophils but has no effect on T cell numbers in the lung at the peak of infection. Our future studies will identify the mechanisms driving the severe pathology in influenza infection with B cell depletion.

Supported by grants from NIH (R01AI137047 and R01EY027346) A grant awarded to Dr. Kovatz and Dr Axtell from the Presbyterian Health Foundation

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.

Electronic supplementary material

The online version of this article (10.1186/s13099-019-0310-0) contains supplementary material, which is available to authorized users.

Microbial exposure and autoimmunity in the etiopathogenesis of Sarcoidosis

Sarcoidosis is an enigmatic inflammatory disease affecting multiple organs such as the lungs, lymph nodes, brain, heart, and skin. It is characterized by the occurrence of multiple non-caseating granulomas comprised of macrophages, giant cells, and CD4 T cells. Although genetic and environmental factors increase the risk for sarcoidosis, the etiology remains unknown. Recent studies have shown that HLA-DR3+ sarcoidosis patients harbor CD4+ T cells reactive with a vimentin peptide 424–443. However, whether autoimmunity is a cause or consequence of the disease is not known.

This study was undertaken to investigate the mechanisms responsible for activation of vimentin reactive T cells and determine their pathogenic role in sarcoidosis. For this purpose, we immunized the NOD-DR3 mice with the vimentin peptide 424–443 and induced a robust T cell response against the peptide. Fine epitope mapping using T cell hybridomas reactive with the peptide showed that both N-terminal and C-terminal amino acids were critical for T cell activation. Homology searches of microbial protein database identified a 100% homologous sequence in a protein from Klebsiella pneumoniae. Immunization of mice with this peptide, followed by intravenous transfer of peptide-coupled agarose beads induced granulomatous lesions in the lungs. Immunohistochemical analysis of these lesions showed the presence of CD4+ T cells, macrophages, and an upregulated MHC-II expression.

In summary, our data demonstrate for the first time that autoimmunity is involved in the pathogenesis of sarcoidosis. Furthermore, the demonstration of molecular mimicry between a lung infecting microbe and vimentin might explain the role of microbial exposures as a risk factor for sarcoidosis.

Host pathogen interactions in Helicobacter pylori related gastric cancer

Helicobacter pylori (H. pylori), discovered in 1982, is a microaerophilic, spiral-shaped gram-negative bacterium that is able to colonize the human stomach. Nearly half of the world's population is infected by this pathogen. Its ability to induce gastritis, peptic ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma has been confirmed. The susceptibility of an individual to these clinical outcomes is multifactorial and depends on H. pylori virulence, environmental factors, the genetic susceptibility of the host and the reactivity of the host immune system. Despite the host immune response, H. pylori infection can be difficult to eradicate. H. pylori is categorized as a group I carcinogen since this bacterium is responsible for the highest rate of cancer-related deaths worldwide. Early detection of cancer can be lifesaving. The 5-year survival rate for gastric cancer patients diagnosed in the early stages is nearly 90%. Gastric cancer is asymptomatic in the early stages but always progresses over time and begins to cause symptoms when untreated. In 97% of stomach cancer cases, cancer cells metastasize to other organs. H. pylori infection is responsible for nearly 60% of the intestinal-type gastric cancer cases but also influences the development of diffuse gastric cancer. The host genetic susceptibility depends on polymorphisms of genes involved in H. pylori-related inflammation and the cytokine response of gastric epithelial and immune cells. H. pylori strains differ in their ability to induce a deleterious inflammatory response. H. pylori-driven cytokines accelerate the inflammatory response and promote malignancy. Chronic H. pylori infection induces genetic instability in gastric epithelial cells and affects the DNA damage repair systems. Therefore, H. pylori infection should always be considered a pro-cancerous factor.