SUMMARY Aberrant hexanucleotide repeat expansions in C9orf72 are the most common genetic change underlying amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). RNA transcripts containing these expansions undergo repeat associated non-ATG (RAN) translation to form five dipeptide repeat proteins (DPRs). DPRs are found as aggregates throughout the CNS of C9orf72-ALS/FTD patients and some cause degeneration when expressed in vitro in neuronal cultures and in vivo in animal models. The spread of characteristic disease-related proteins drives the progression of pathology in many neurodegenerative diseases. While DPR toxic mechanisms continue to be investigated, the potential for DPRs to spread has yet to be determined. Utilizing different experimental cell culture platforms, including spinal motor neurons derived from induced pluripotent stem cells from C9orf72-ALS patients, we found evidence for cell-to-cell spreading of DPRs via exosome-dependent and independent pathways, which may potentially be relevant to disease.

OBJECTIVE-12/15-lipoxygenase (12/15-LO), one of a family of fatty acid oxidoreductase enzymes, reacts with polyenoic fatty acids to produce proinflammatory lipids. 12/15-LO is expressed in macrophages and pancreatic ␤-cells. It enhances interleukin 12 production by macrophages, and several of its products induce apoptosis of ␤-cells at nanomolar concentrations in vitro. We had previously demonstrated a role for 12/15-LO in ␤-cell damage in the streptozotocin model of diabetes. Since the gene encoding 12/15-LO (gene designation Alox15) lies within the Idd4 diabetes susceptibility interval in NOD mice, we hypothesized that 12/15-LO is also a key regulator of diabetes susceptibility in the NOD mouse. RESEARCH DESIGN AND METHODS-We developed NOD mice carrying an inactivated 12/15-LO locus (NOD-Alox15null ) using a "speed congenic" protocol, and the mice were monitored for development of insulitis and diabetes.RESULTS-NOD mice deficient in 12/15-LO develop diabetes at a markedly reduced rate compared with NOD mice (2.5 vs. Ͼ60% in females by 30 weeks). Nondiabetic female NOD-Alox15 null mice demonstrate improved glucose tolerance, as well as significantly reduced severity of insulitis and improved ␤-cell mass, when compared with age-matched nondiabetic NOD females. Disease resistance is associated with decreased numbers of islet-infiltrating activated macrophages at 4 weeks of age in NOD-Alox15 null mice, preceding the development of insulitis. Subsequently, islet-associated infiltrates are characterized by decreased numbers of CD4 ϩ T cells and increased Foxp3 ϩ cells.CONCLUSIONS-These results suggest an important role for 12/15-LO in conferring susceptibility to autoimmune diabetes in NOD mice through its effects on macrophage recruitment or activation.

We have examined the formation, participation and functional specialization of virus-reactive Foxp3+ regulatory T cells (Tregs) in a mouse model of influenza virus infection. “Natural” Tregs generated intra-thymically based on interactions with a self-peptide proliferated in response to a homologous viral antigen in the lungs, and to a lesser extent in the lung-draining mediastinal LN (medLN), of virus-infected mice. By contrast, conventional CD4+ T cells with identical TCR specificity underwent little or no conversion to become “adaptive” Tregs. The virus-reactive Tregs in the medLN and the lungs of infected mice upregulated a variety of molecules associated with Treg activation, and also acquired expression of molecules (T-bet, Blimp-1 and IL-10) that confer functional specialization to Tregs. Notably, however, the phenotypes of the T-bet+ Tregs obtained from these sites were distinct, since Tregs isolated from the lungs expressed significantly higher levels of T-bet, Blimp-1 and IL-10 than did Tregs from the medLN. Adoptive transfer of antigen-reactive Tregs led to decreased proliferation of anti-viral CD4+ and CD8+ effector T cells in the lungs of infected hosts, while depletion of Tregs had a reciprocal effect. These studies demonstrate that thymically-generated Tregs can become activated by a pathogen-derived peptide and acquire discrete T-bet+ Treg phenotypes while participating in and modulating an antiviral immune response.

Background-Recent literature has indicated the feasibility of microarray analysis in the characterization of chronic sinusitis. We hypothesized that previously unexplored inflammatory mechanisms would be involved in the pathophysiology of noneosinophilic chronic rhinosinusitis with nasal polyps (NE-CRSwNP) and that this technology could be used to identify the gene expression of these novel and previously known mediators.

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