Successful Amplification of DNA Specific for Finnish Borrelia burgdorferi Isolates in Erythema Chronicum Migrans but Not in Circumscribed Scleroderma Lesions

Early diagnosis of Borrelia burgdorferi infection, hampered by the absence of detectable antibodies in most patients with erythema chronicum migrans is important to prevent late-stage neurologic, rheumatologic, and skin disorders. Furthermore, B. burgdorferi has been claimed to be the causative agent in localized scleroderma (morphea). We used PCR amplification to search for B. burgdorferi outer surface protein OspA–specific sequences in DNA obtained from lesional skin biopsies on Finnish patients with clinically suspect erythema chronicum migrans, lymphocytoma, morphea, or with diverse skin manifestations and persistent high antibodies to B. burgdorferi flagellar antigen. Seronegative patients with other skin lesions served as controls. The amplicons obtained with primers specific for B. burgdorferi type strain B31 ospA sequence did not hybridize to the corresponding probes, and thus the DNA amplified from a Finnish B. burgdorferi erythema chronicum migrans skin isolate was sequenced. This 98-nucleotide sequence of ospA (332–429) showed 11% to 14% nucleotide divergence compared with the North American type strain (B31), several European strains, and an East Siberian tick strain. The sequence was almost identical (99%) to a Swedish isolate from acrodermatitis chronica atrophicans. Using oligonucleotides specific for the Finnish strain, a positive polymerase chain reaction – based hybridization was obtained in six of seven untreated erythema chronicum migrans patients infected in Finland or in Estonia, and in the lymphocytoma patient. Only two of the erythema chronicum migrans patients had IgG or IgM antibodies to flagellin. However, all seven morphea lesions as well as the other lesions were polymerase chain reaction negative. Polymerase chain reaction – based hybridization ofB. burgdoferi OspA gene from skin-derived DNA thus provides a sensitive and specific diagnostic tool. In conditions not unequivocally known to be caused by B. burgdorferi in morphea, this assay was negative. We also demonstrate that peri-Baltic B. burgdorferi isolates show homology in their OspA genes but differ from geographically more distant isolates

Response to comment on 'AIRE-deficient patients harbor unique high-affinity disease-ameliorating autoantibodies'

In 2016, we reported four substantial observations of APECED/APS1 patients, who are deficient in AIRE, a major regulator of central T cell tolerance (Meyer et al., 2016). Two of those observations have been challenged. Specifically, 'private' autoantibody reactivities shared by only a few patients but collectively targeting >1000 autoantigens have been attributed to false positives (Landegren, 2019). While acknowledging this risk, our study-design included follow-up validation, permitting us to adopt statistical approaches to also limit false negatives. Importantly, many such private specificities have now been validated by multiple, independent means including the autoantibodies ' molecular cloning and expression. Second, a significant correlation of antibody-mediated IFN a neutralization with an absence of disease in patients highly disposed to Type I diabetes has been challenged because of a claimed failure to replicate our findings (Landegren, 2019). However, flaws in design and implementation invalidate this challenge. Thus, our results present robust, insightful, independently validated depictions of APECED/APS1, that have spawned productive follow-up studies.Non peer reviewe

The autoimmune regulator PHD finger binds to non-methylated histone H3K4 to activate gene expression

Mutations in the gene autoimmune regulator (AIRE) cause autoimmune polyendocrinopathy candidiasis ectodermal dystrophy. AIRE is expressed in thymic medullary epithelial cells, where it promotes the expression of tissue-restricted antigens. By the combined use of biochemical and biophysical methods, we show that AIRE selectively interacts with histone H3 through its first plant homeodomain (PHD) finger (AIRE–PHD1) and preferentially binds to non-methylated H3K4 (H3K4me0). Accordingly, in vivo AIRE binds to and activates promoters containing low levels of H3K4me3 in human embryonic kidney 293 cells. We conclude that AIRE–PHD1 is an important member of a newly identified class of PHD fingers that specifically recognize H3K4me0, thus providing a new link between the status of histone modifications and the regulation of tissue-restricted antigen expression in thymus

IL-22 Paucity in APECED Is Associated With Mucosal and Microbial Alterations in Oral Cavity

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is caused by recessive mutations in the AIRE gene. The hallmark of the disease is the production of highly neutralizing autoantibodies against type I interferons and IL-22. Considering the importance of IL-22 in maintaining mucosal barrier integrity and shaping its microbial community, we sought to study potential changes in the oral cavity in this model of human IL-22 paucity. We found that besides known Th22 cell deficiency, APECED patients have significantly fewer circulating MAIT cells with potential IL-22 secreting capacity. Saliva samples from APECED patients revealed local inflammation, the presence of autoantibodies against IFN-α and IL-22, and alterations in the oral microbiota. Moreover, gene expression data of buccal biopsy samples suggested impaired antimicrobial response and cell proliferation, both of which are processes regulated by IL-22. Our data complement the knowledge gained from mouse models and support the concept of IL-22 being a critical homeostatic cytokine in human mucosal sites

Cytotoxic CD8+ Temra cells show loss of chromatin accessibility at genes associated with T cell activation

As humans age, their memory T cell compartment expands due to the lifelong exposure to antigens. This expansion is characterized by terminally differentiated CD8+ T cells (Temra), which possess NK cell-like phenotype and are associated with chronic inflammatory conditions. Temra cells are predominantly driven by the sporadic reactivation of cytomegalovirus (CMV), yet their epigenomic patterns and cellular heterogeneity remain understudied. To address this gap, we correlated their gene expression profiles with chromatin openness and conducted single-cell transcriptome analysis, comparing them to other CD8+ subsets and CMV-responses. We confirmed that Temra cells exhibit high expression of genes associated with cytotoxicity and lower expression of costimulatory and chemokine genes. The data revealed that CMV-responsive CD8+ T cells (Tcmv) were predominantly derived from a mixed population of Temra and memory cells (Tcm/em) and shared their transcriptomic profiles. Using ATAC-seq analysis, we identified 1449 differentially accessible chromatin regions between CD8+ Temra and Tcm/em cells, of which only 127 sites gained chromatin accessibility in Temra cells. We further identified 51 gene loci, including costimulatory CD27, CD28, and ICOS genes, whose chromatin accessibility correlated with their gene expression. The differential chromatin regions Tcm/em cells were enriched in motifs that bind multiple transcriptional activators, such as Jun/Fos, NFkappaB, and STAT, whereas the open regions in Temra cells mainly contained binding sites of T-box transcription factors. Our single-cell analysis of CD8+CCR7loCD45RAhi sorted Temra population showed several subsets of Temra and NKT-like cells and CMC1+ Temra populations in older individuals that were shifted towards decreased cytotoxicity. Among CD8+CCR7loCD45RAhi sorted cells, we found a decreased proportion of IL7R+ Tcm/em-like and MAIT cells in individuals with high levels of CMV antibodies (CMVhi). These results shed new light on the molecular and cellular heterogeneity of CD8+ Temra cells and their relationship to aging and CMV infection

The Autoimmune Regulator AIRE in Thymoma Biology: Autoimmunity and Beyond

Abstract:Thymomas are tumors of thymic epithelial cells. They associate more often than any other human tumors with various autoimmune diseases; myasthenia gravis is the commonest, occurring in 10–50% of thymoma patients, depending on the World Health Organization-defined histologic subtype. Most thymomas generate many polyclonal maturing T lymphocytes but in disorganized microenvironments Failure to induce self-tolerance may be a key factor leading to the export of potentially autoreactive CD4+ progeny, thus predisposing to autoimmune diseases. Normally, the master Autoimmune Regulator promotes expression of peripheral tissue-restricted antigens such as insulin by medullary thymic epithelial cells and induction of tolerance to them. The failure of ∼95% of thymomas to express autoimmune regulator is another feature potentially contributing to autoimmunity

Inactive disease in patients with lupus is linked to autoantibodies to type I interferons that normalize blood IFNα and B cell subsets

Systemic lupus erythematosus (SLE) is characterized by increased expression of type I interferon (IFN)-regulated genes in 50%-75% of patients. We report that out of 501 patients with SLE analyzed, 73 (14%) present autoantibodies against IFNα (anti-IFN-Abs). The presence of neutralizing-anti-IFN-Abs in 4.2% of patients inversely correlates with low circulating IFNα protein levels, inhibition of IFN-I downstream gene signatures, and inactive global disease score. Hallmarks of SLE pathogenesis, including increased immature, double-negative plasmablast B cell populations and reduction in regulatory B cell (Breg) frequencies, were normalized in patients with neutralizing anti-IFN-Abs compared with other patient groups. Immunoglobulin G (IgG) purified from sera of patients with SLE with neutralizing anti-IFN-Abs impedes CpGC-driven IFNα-dependent differentiation of B cells into immature B cells and plasmablasts, thus recapitulating the neutralizing effect of anti-IFN-Abs on B cell differentiation in vitro. Our findings highlight a role for neutralizing anti-IFN-Abs in controlling SLE pathogenesis and support the use of IFN-targeting therapies in patients with SLE lacking neutralizing-anti-IFN-Abs

Autoantibody Repertoire in APECED Patients Targets Two Distinct Subgroups of Protiens

High titer autoantibodies produced by B lymphocytes are clinically important features of many common autoimmune diseases. APECED patients with deficient autoimmune regulator (AIRE) gene collectively display a broad repertoire of high titer autoantibodies, including some which are pathognomonic for major autoimmune diseases. AIRE deficiency severely reduces thymic expression of gene-products ordinarily restricted to discrete peripheral tissues, and developing T cells reactive to those gene-products are not inactivated during their development. However, the extent of the autoantibody repertoire in APECED and its relation to thymic expression of self-antigens are unclear. We here undertook a broad protein array approach to assess autoantibody repertoire in APECED patients. Our results show that in addition to shared autoantigen reactivities, APECED patients display high inter-individual variation in their autoantigen profiles, which collectively are enriched in evolutionarily conserved, cytosolic and nuclear phosphoproteins. The APECED autoantigens have two major origins; proteins expressed in thymic medullary epithelial cells and proteins expressed in lymphoid cells. These findings support the hypothesis that specific protein properties strongly contribute to the etiology of B cell autoimmunity.Peer reviewe

Koroonaviiruse omikrontüve vastane antikehade kaitse ja T-rakuline immuunvastus pärast BNT162b2-vaktsiini tõhustusdoosi saamist

Eesti Arst 2023; 102(2):11

Anti-CD45RC antibody immunotherapy prevents and treats experimental autoimmune polyendocrinopathy-candidiasis- ectodermal dystrophy syndrome

Targeted monoclonal antibody (mAb) therapies show great promise for the treatment of transplant rejection and autoimmune diseases by inducing more specific immunomodulatory effects than broadly immunosuppressive drugs routinely used. We recently described the therapeutic advantage of targeting CD45RC, expressed at high levels by conventional T (Tconv) cells (CD45RC(hi)), their precursors, and terminally differentiated T (TEMRA) cells, but not by regulatory T cells (Tregs; CD45RC(lo/-)). We demonstrated efficacy of anti-CD45RC mAb treatment in transplantation, but its potential has not been examined in autoimmune diseases. Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare genetic syndrome caused by loss-of-function mutations of autoimmune regulator (AIRE), a key central tolerance mediator, leading to abnormal autoreactive T cell responses and autoantibody production. Herein, we show that, in a rat model of APECED syndrome, anti-CD45RC mAb was effective for both prevention and treatment of autoimmune manifestations and inhibited autoantibody development. Anti-CD45RC mAb intervention depleted CD45RC(hi) T cells, inhibited CD45RC(hi) B cells, and restored the Treg/Tconv cell ratio and the altered Treg transcriptomic profile. In APECED patients, CD45RC was significantly increased in peripheral blood T cells, and lesioned organs from APECED patients were infiltrated by CD45RC(hi) cells. Our observations highlight the potential role for CD45RC(hi) cells in the pathogenesis of experimental and human APECED syndrome and the potential of anti-CD45RC antibody treatment.Peer reviewe