ITGA2+ Endoneurial Cells and Extracellular Periostin are Upregulated in Chronic Inflammatory Demyelinating Polyneuropathy

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) is an autoimmune disorder of the peripheral nervous system characterized by weakness, imbalance, sensory loss and pain. Previously, our lab showed that a strain of NOD mice with a dominant G228W mutation (NOD.AireGW/+ mice) develops spontaneous autoimmune peripheral neuropathy and is a model for CIDP. In the peripheral nerves of neuropathic mice, our lab observed an increase in a population of cells that expressed ITGA2 (a classical marker for NK T cells) and expressed 60-fold higher RNA transcripts of extracellular periostin compared to dendritic cells and T cells. We aimed to determine what types of cells are expressing ITGA2 and to determine whether periostin expression is upregulated in the sciatic nerves of neuropathic mice. Using immunofluorescence staining of ITGA2 and CD3 (a classical marker for T cells) in sciatic nerve sections from neuropathic mice, we found that the CD3+ cells did not co-localize with ITGA2 staining suggesting that the ITGA2+ cells are not infiltrating T cells or NK T cells. Additionally, we found that the ITGA2+ cells were enriched in the neuropathic mice compared to wild type mice. Using qRT-PCR, western blot, and immunofluorescence for periostin, we found that periostin was enriched at the mRNA and protein level in neuropathic mice as compared to the wild-type mice. These findings suggest a possible pathogenic or maintenance role of ITGA2+ cells and periostin in CIDP. Consequently, these findings may have important implications in the further study of the pathogenesis of CIDP and help guide more targeted therapeutics for CIDP in the future.Bachelor of Scienc

INVESTIGATION OF THE OUTER SURFACE PROTEIN, BBK19, AS A POTENTIAL COMPONENT OF A CHIMERIC ANTIGEN FOR DIAGNOSIS OF HUMAN LYME DISEASE

Lyme Disease (LD), caused by spirochetes of the genus Borreliella, is the most common tick-borne infection in North America and Europe. Borreliella plasmids have been shown to be essential for virulence, including B. burgdorferi B31 lp36. In this study, the lp36 encoded lipoprotein, BBK19, was characterized. Triton X-114 extraction and phase partitioning and size-exclusion chromatography revealed that BBK19 localizes to the outer membrane and is a monomer. A B. burgdorferi B31 gene deletion strain (B31-Δbbk19) displayed significantly attenuated chemotactic response and infectivity in mice via needle inoculation (n=7/group). ELISA analyses of experimentally infected mice (n=45) found BBK19 to be antigenic in murine infection. This work indicates that BBK19 may play a role in B. burgdorferi pathogenesis and may be a potential diagnostic antigen. The development of a single antigen-based diagnostic approach has been complicated by issues, including differential gene regulation, antigen diversity, and cross-reactivity. Therefore, this study developed a multi-protein chimeric antigen for diagnostic applications. The antigens DbpA, DbpB, BBK53, BBA73, and VlsE were identified as candidate diagnostic proteins based on their conservation and immunogenicity. Based on this work, two diagnostic chimeric proteins were designed with the most promising being HDFL4. Early (n=53) and late (n=16) stage human serum samples demonstrated comparable reactivity to HDFL4 compared to VlsE in early disease (45%) and increased reactivity in late disease (81% versus 63%, respectively). Serum from patients with cross-reactive diseases demonstrated no reactivity to HDFL4 (n=12). European human serum samples demonstrated reactivity to HDFL4 indicating its potential utility in a global market

Schwann cell-derived periostin promotes autoimmune peripheral polyneuropathy via macrophage recruitment

Chronic inflammatory demyelinating polyneuropathy (CIDP) and Guillain-Barre syndrome (GBS) are inflammatory neuropathies that affect humans and are characterized by peripheral nerve myelin destruction and macrophage-containing immune infiltrates. In contrast to the traditional view that the peripheral nerve is simply the target of autoimmunity, we report here that peripheral nerve Schwann cells exacerbate the autoimmune process through extracellular matrix (ECM) protein induction. In a spontaneous autoimmune peripheral polyneuropathy (SAPP) mouse model of inflammatory neuropathy and CIDP nerve biopsies, the ECM protein periostin (POSTN) was upregulated in affected sciatic nerves and was primarily expressed by Schwann cells. Postn deficiency delayed the onset and reduced the extent of neuropathy, as well as decreased the number of macrophages infiltrating the sciatic nerve. In an in vitro assay, POSTN promoted macrophage chemotaxis in an integrin-AM (ITGAM) and ITGAV-dependent manner. The PNS-infiltrating macrophages in SAPP-affected nerves were pathogenic, since depletion of macrophages protected against the development of neuropathy. Our findings show that Schwann cells promote macrophage infiltration by upregulating Postn and suggest that POSTN is a novel target for the treatment of macrophage-associated inflammatory neuropathies