Pepper Mild Mottle Virus, a Plant Virus Associated with Specific Immune Responses, Fever, Abdominal Pains, and Pruritus in Humans

Background: Recently, metagenomic studies have identified viable Pepper mild mottle virus (PMMoV), a plant virus, in the stool of healthy subjects. However, its source and role as pathogen have not been determined. Methods and Findings: 21 commercialized food products containing peppers, 357 stool samples from 304 adults and 208 stool samples from 137 children were tested for PMMoV using real-time PCR, sequencing, and electron microscopy. Anti-PMMoV IgM antibody testing was concurrently performed. A case-control study tested the association of biological and clinical symptoms with the presence of PMMoV in the stool. Twelve (57%) food products were positive for PMMoV RNA sequencing. Stool samples from twenty-two (7.2%) adults and one child (0.7%) were positive for PMMoV by real-time PCR. Positive cases were significantly more likely to have been sampled in Dermatology Units (p<10−6), to be seropositive for anti-PMMoV IgM antibodies (p = 0.026) and to be patients who exhibited fever, abdominal pains, and pruritus (p = 0.045, 0.038 and 0.046, respectively). Conclusions: Our study identified a local source of PMMoV and linked the presence of PMMoV RNA in stool with a specific immune response and clinical symptoms. Although clinical symptoms may be imputable to another cofactor, including spicy food, our data suggest the possibility of a direct or indirect pathogenic role of plant viruses in humans

Pattern of DAP12 Expression in Leukocytes from Both Healthy and Systemic Lupus Erythematosus Patients

DAP12 is an ITAM-bearing transmembrane adaptor originally identified on the surface of Natural Killer cells. A broad expression among other immune cells was later found in myeloid and lymphoid cells. However, data on DAP12 expression pattern rely only on immunoblot and microarray analysis. Here, we describe the generation and the characterization of an anti-DAP12 monoclonal antibody. Using this novel reagent, we show that DAP12 expression is restricted to innate immune cells in basal condition. Since a decreased expression of DAP12 has been suggested in NK cells of systemic lupus erythematosus patients, we have further investigated the NK cell receptor repertoire and leukocyte expression of DAP12 in these patients and no major changes were detectable when compared to controls

Pathologies Associated with Serum IgG4 Elevation

Statement of Purpose. IgG4-related disease (IgG4-RD) is usually associated to an increase of serum IgG4 levels. However other conditions have also been associated to high serum IgG4 levels. Methods. All IgG subclasses analyses performed in our hospital over a one-year period were analyzed. When IgG4 level were over 1.35 g/L, the patient’s clinical observation was analyzed and both final diagnosis and reason leading to IgG subclasses analysis were recorded. Only polyclonal increases of IgG4 were considered. Summary of the Results. On 646 IgG subclass analysis performed, 59 patients had serum IgG4 over 1.35 g/L. The final diagnosis associated to serum IgG4 increase was very variable. Most patients (25%) presented with repeated infections, 13.5% with autoimmune diseases, and 10% with IgG4-RD. Other patients presented with cancer, primary immune deficiencies, idiopathic interstitial lung disease, cystic fibrosis, histiocytosis, or systemic vasculitis and 13.5% presented with various pathologies or no diagnosis. Mean IgG4 levels and IgG4/IgG ratio were higher in IgG4-RD than in other pathologies associated to elevated IgG4 levels. Conclusions. Our study confirms that elevation of serum IgG4 is not specific to IgG4-RD. Before retaining IgG4-RD diagnosis in cases of serum IgG4 above 1.35 g/L, several other pathological conditions should be excluded

Increased serum levels of fractalkine and mobilisation of CD34+CD45− endothelial progenitor cells in systemic sclerosis

International audienceBackground: The disruption of endothelial homeostasis is a major determinant in the pathogenesis of systemic sclerosis (SSc) and is reflected by soluble and cellular markers of activation, injury and repair. We aimed to provide a combined assessment of endothelial markers to delineate specific profiles associated with SSc disease and its severity

Comparing HLA Shared Epitopes in French Caucasian Patients with Scleroderma

Although many studies have analyzed HLA allele frequencies in several ethnic groups in patients with scleroderma (SSc), none has been done in French Caucasian patients and none has evaluated which one of the common amino acid sequences, 67FLEDR71, shared by HLA-DRB susceptibility alleles, or 71TRAELDT77, shared by HLA-DQB1 susceptibility alleles in SSc, was the most important to develop the disease. HLA-DRB and DQB typing was performed for a total of 468 healthy controls and 282 patients with SSc allowing FLEDR and TRAELDT analyses. Results were stratified according to patient’s clinical subtypes and autoantibody status. Moreover, standardized HLA-DRß1 and DRß5 reverse transcriptase Taqman PCR assays were developed to quantify ß1 and ß5 mRNA in 20 subjects with HLA-DRB1*15 and/or DRB1*11 haplotypes. FLEDR motif is highly associated with diffuse SSc (χ2 = 28.4, p<10−6) and with anti-topoisomerase antibody (ATA) production (χ2 = 43.9, p<10−9) whereas TRAELDT association is weaker in both subgroups (χ2 = 7.2, p = 0.027 and χ2 = 14.6, p = 0.0007 respectively). Moreover, FLEDR motif- association among patients with diffuse SSc remains significant only in ATA subgroup. The risk to develop ATA positive SSc is higher with double dose FLEDR than single dose with respectively, adjusted standardised residuals of 5.1 and 2.6. The increase in FLEDR motif is mostly due to the higher frequency of HLA-DRB1*11 and DRB1*15 haplotypes. Furthermore, FLEDR is always carried by the most abundantly expressed ß chain: ß1 in HLA DRB1*11 haplotypes and ß5 in HLA-DRB1*15 haplotypes

Autoimmune encephalitis concomitant with SARS-CoV-2 infection: insight from 18 F-FDG PET imaging and neuronal autoantibodies

International audienceWe report the case of a 72-years-old man with concomitant autoimmune encephalitis and SARS-CoV-2 infection. Methods: Review of clinical examination, CT, PET, MRI imaging, and autoantibodies testing. Results: The patient presented subacute cerebellar syndrome and myoclonus several days after general infectious symptoms. The oropharyngeal swab test was positive for SARS-CoV-2. Brain MRI was normal. CSF testing showed normal cell counts, negative RT-qPCR and no oligoclonal banding. Brain 18F-FDG-PET showed diffuse cortical hypometabolism, associated with putaminal and cerebellum hypermetabolism, compatible with encephalitis, and especially cerebellitis. The immunological study revealed high titers of IgG autoantibodies in serum and CSF directed against the nuclei of Purkinje cells, striatal and hippocampal neurons. Search for neoplasia including whole-body 18F-FDG-PET and CT scans was negative. Treatment with steroids allowed a rapid improvement of symptoms. Conclusion: This clinical case brings arguments on the possible relationship between SARS-CoV-2 infection and autoimmune encephalitis, and on the interest of 18F-FDG-PET in such context

Natural killer cells in human autoimmune diseases

Natural killer (NK) cells have been implicated in tumour surveillance and in the early control of several microbial infections. In autoimmune disease their involvement in these processes has been evaluated in animal models, with conflicting results. Both a disease-controlling and a disease-promoting role have been suggested. In human autoimmune disease only a few studies, mainly descriptive, have demonstrated qualitative and quantitative modification of NK cells. These changes were observed on blood- or tissue-infiltrating NK cells. Taken together with our expanding knowledge of the genetical variability of NK cell receptors and NK cell physiology, these findings pave the way for the dissection of the role of NK cells in human autoimmune diseases. NK cells may be directly involved in these diseases through their potential autoreactivity or through their interaction with dendritic cells, macrophages or T lymphocytes, thereby inducing excessive inflammation or favouring the adaptive autoimmune response. Thus, NK cells may be implicated in the onset, the maintenance or the progression of autoimmune diseases. Some reports also suggest the involvement of NK cells in the treatment of human autoimmune disease by biotherapies. All these observations suggest that NK cells are involved in the complex processes of autoimmune diseases. Nevertheless, further careful analysis of NK cells at different steps of these diseases, in different tissues and through combined genetical and functional studies will contribute to a better understanding of their role in autoimmune diseases. This knowledge might allow the development of new therapeutic strategies based on NK cells for the treatment of some autoimmune diseases

Infliximab in the treatment of refractory vasculitis secondary to hepatitis C-associated mixed cryoglobulinaemia

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Repeated corticosterone injections in adult mice alter stress hormonal receptor expression in the cerebellum and motor coordination without affecting spatial learning

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