SARS-CoV-2-derived peptides define heterologous and COVID-19-induced T cell recognition.

T cell immunity is central for the control of viral infections. To characterize T cell immunity, but also for the development of vaccines, identification of exact viral T cell epitopes is fundamental. Here we identify and characterize multiple dominant and subdominant SARS-CoV-2 HLA class I and HLA-DR peptides as potential T cell epitopes in COVID-19 convalescent and unexposed individuals. SARS-CoV-2-specific peptides enabled detection of post-infectious T cell immunity, even in seronegative convalescent individuals. Cross-reactive SARS-CoV-2 peptides revealed pre-existing T cell responses in 81% of unexposed individuals and validated similarity with common cold coronaviruses, providing a functional basis for heterologous immunity in SARS-CoV-2 infection. Diversity of SARS-CoV-2 T cell responses was associated with mild symptoms of COVID-19, providing evidence that immunity requires recognition of multiple epitopes. Together, the proposed SARS-CoV-2 T cell epitopes enable identification of heterologous and post-infectious T cell immunity and facilitate development of diagnostic, preventive and therapeutic measures for COVID-19.

A COVID-19 peptide vaccine for the induction of SARS-CoV-2 T cell immunity.

T cell immunity is central for the control of viral infections. CoVac-1 is a peptide-based vaccine candidate, composed of SARS-CoV-2 T cell epitopes derived from various viral proteins1,2, combined with the Toll-like receptor 1/2 agonist XS15 emulsified in Montanide ISA51 VG, aiming to induce profound SARS-CoV-2 T cell immunity to combat COVID-19. Here we conducted a phase I open-label trial, recruiting 36 participants aged 18-80 years, who received a single subcutaneous CoVac-1 vaccination. The primary end point was safety analysed until day 56. Immunogenicity in terms of CoVac-1-induced T cell response was analysed as the main secondary end point until day 28 and in the follow-up until month 3. No serious adverse events and no grade 4 adverse events were observed. Expected local granuloma formation was observed in all study participants, whereas systemic reactogenicity was absent or mild. SARS-CoV-2-specific T cell responses targeting multiple vaccine peptides were induced in all study participants, mediated by multifunctional T helper 1 CD4+ and CD8+ T cells. CoVac-1-induced IFNγ T cell responses persisted in the follow-up analyses and surpassed those detected after SARS-CoV-2 infection as well as after vaccination with approved vaccines. Furthermore, vaccine-induced T cell responses were unaffected by current SARS-CoV-2 variants of concern. Together, CoVac-1 showed a favourable safety profile and induced broad, potent and variant of concern-independent T cell responses, supporting the presently ongoing evaluation in a phase II trial for patients with B cell or antibody deficiency.

Detection of IgE-autoantibodies to nuclear antigens in patients with systemic sclerosis and analysis of their clinical relevance.

OBJECTIVES: Antinuclear antibodies (ANA) of the IgE-type have been described in several connective tissue disorders (CTD) but not yet in systemic sclerosis (SSc). Aim of the study was, therefore, to establish an ELISA for the demonstration of IgE-autoantibodies to topoisomerase-I (topo-I) and the centromeric proteins A and B (CENP-A/B), to assess their prevalence and reactivity in SSc and to analyse their clinical relevance. METHODS: One hundred fifty-one patients with SSc and 88 with CREST-syndrome, 291 patients with other CTD, and 23 patients with fibromyalgia syndrome (FM) as a control collective were included into the study. Patients' sera were analysed by an in-house-ELISA for IgE autoantibodies against topo-I and CENP-A/B using recombinant antigens. Patients were assessed for median Rodnan skin score(mRSS), different organ and cutaneous manifestations. RESULTS: Of the patients with CREST syndrome, 67% had IgE-anti-CENP-A- and 77% IgE-anti-CENP-B-antibodies. IgE-anti-topo-I antibodies were found in 56% of patients with SSc. Prevalence and reactivity were significantly higher in CREST and SSc, respectively, than in other CTD or FM. IgE-reactivity strongly correlated with IgG-antibody reactivity. In CRESTsyndrome, IgE-anti-CENP-A (but not CENP-B)-antibodies were significantly higher and more prevalent in patients with skin ulcers, high mRSS, and more than four organ manifestations. They did not correlate with blood eosinophil counts. In contrast, for IgE-anti-topo-I antibodies no correlation with clinical manifestations was observed. CONCLUSIONS: IgE-autoantibodies against CENP-A/B and topo-I occur in SSc underlining the concept that SSc may be a T helper cell type 2 mediated disease. IgE-anti-CENP-A-antibodies correlated with disease activity, but this has to be confirmed in larger studies.

Autoantibodies to beta tubulin in autoimmune liver diseases - relation to pANCA and clinical relevance.

There was evidence that pANCA (perinuclear antineutrophil cytoplasmic antibodies) in autoimmune liver diseases react with human beta-tubulin-5 (TBB5). Here we re-evaluate the specificity and clinical relevance of anti-TBB5 antibodies. Patients with untreated autoimmune hepatitis (AIH; n=53), AIH under immunosuppressive therapy (AIH-IS; n=125), primary sclerosing cholangitis (PSC; n=40), primary biliary cholangitis (PBC; n=250), non-autoimmune liver diseases (n=158), inflammatory bowel diseases (IBD; n=30), and healthy individuals (n=62) were tested by enzyme linked immunosorbent assay (ELISA) for IgG- and IgA-antibodies against recombinant human TBB5. pANCA were detected by immunofluorescence test. Sera were absorbed with TBB5 coupled to cyanogen bromide-activated sepharose. Prevalence and reactivity of IgG anti-TBB5 were significantly higher in patients with untreated AIH (68%; arbitrary units [AU] median:369) than in PSC (28%; AU median:84, p<0.001), other liver diseases (14%; AU median:185, p<0.0001), IBD (3%; AU median:111, p<0.0001) and healthy controls (3%; AU median:135; p<0.0001). Anti-TBB5 did not correlate with pANCA, and immunoprecipitation with TBB5 did not abolish pANCA reactivity. In untreated AIH anti-TBB5-reactivity was significantly higher than in AIH-IS. Transaminases decreased under IS preferentially in anti-TBB5 negative patients. There was no correlation between anti-TBB5-reactivity and histological stages. IgA-anti-TBB5 was mainly found in alcohol-associated liver disease (ALD; 39%). Our data do not support TBB5 as an autoantigenic target of pANCA. However, IgG-anti-TBB5 showed high specificity for (untreated) AIH. While they did not correlate with histological and laboratory parameters, their presence may indicate a poor response to IS.

Functional autoantibodies in systemic sclerosis: influence of autologous stem cell transplantation and correlation with clinical outcome.

OBJECTIVES: To evaluate the effect of autologous stem cell transplantation (aSCT) on functional antibodies (abs) to the angiotensin II type-1-receptor (AT1R) and topoisomerase-I (topo-I) in SSc-patients and to analyse their prognostic relevance. MATERIAL AND METHODS: Forty-three SSc-patients in whom aSCT was performed were analysed. Thirty-one patients had a favourable outcome after aSCT (group 1), 12 patients showed no response or relapse (group 2). Patients' sera were tested for anti-AT1R and anti-topo-I antibodies by ELISA and in a luminometric assay (LA) using AT1R-expressing Huh7-cells for inhibitory or stimulatory anti-AT1R antibodies before and after aSCT (4-217 months, median 28 months). Anti-topo-I antibodies were also analysed for their capacity to inhibit enzyme function. RESULTS: A total of 70% of the SSc patients had anti-topo-I- and 51% anti-AT1R antibodies in the ELISA before aSCT. In all instances, anti-topo-I antibodies inhibited topo-I-enzyme function. In the LA, 40% had stimulatory and 12% inhibitory anti-AT1R antibodies. Anti-topo-I- and anti-AT1R-reactivity (ELISA) significantly decreased after aSCT. Before aSCT, anti-topo-I-reactivity was significantly higher in group 2 patients than in group 1 patients (P < 0.001), while there was no difference between both groups for anti-AT1R antibodies detected by ELISA. Stimulatory anti-AT1R antibodies detected by LA were confined to group 1-patients. CONCLUSIONS: Reactivity of functionally active anti-AT1R antibodies was not influenced by aSCT, while anti-topo-I antibodies decreased after aSCT. The fact that anti-topo-I antibodies inhibited enzyme function in all instances supports the hypothesis of a pathogenetic role of the topo-I antigen/antibody-system in SSc. High anti-topo-I reactivity before aSCT was associated with an unfavourable, presence of stimulatory anti-AT1R antibodies with a favourable course after aSCT.

CD19-Targeting CAR T Cells for Myositis and Interstitial Lung Disease Associated With Antisynthetase Syndrome.

Importance: Autoimmune disorders can affect various organs and if refractory, can be life threatening. Recently, CD19-targeting-chimeric antigen receptor (CAR) T cells were efficacious as an immune suppressive agent in 6 patients with refractory systemic lupus erythematosus and in 1 patient with antisynthetase syndrome. Objective: To test the safety and efficacy of CD19-targeting CAR T cells in a patient with severe antisynthetase syndrome, a complex autoimmune disorder with evidence for B- and T-cell involvement. Design, Setting, and Participants: This case report describes a patient with antisynthetase syndrome with progressive myositis and interstitial lung disease refractory to available therapies (including rituximab and azathioprine), who was treated with CD19-targeting CAR T cells in June 2022 at University Hospital Tübingen in Tübingen, Germany, with the last follow-up in February 2023. Mycophenolate mofetil was added to the treatment to cotarget CD8+ T cells, hypothesized to contribute to disease activity. Exposure: Prior to treatment with CD19-targeting CAR T cells, the patient received conditioning therapy with fludarabine (25 mg/m2 [5 days before until 3 days before]) and cyclophosphamide (1000 mg/m2 [3 days before]) followed by infusion of CAR T cells (1.23×106/kg [manufactured by transduction of autologous T cells with a CD19 lentiviral vector and amplification in the CliniMACS Prodigy system]) and mycophenolate mofetil (2 g/d) 35 days after CD19-targeting CAR T-cell infusion. Main Outcomes and Measures: The patient's response to therapy was followed by magnetic resonance imaging of the thigh muscle, Physician Global Assessment, functional muscle and pulmonary tests, and peripheral blood quantification of anti-Jo-1 antibody levels, lymphocyte subsets, immunoglobulins, and serological muscle enzymes. Results: Rapid clinical improvement was observed after CD19-targeting CAR T-cell infusion. Eight months after treatment, the patient's scores on the Physician Global Assessment and muscle and pulmonary function tests improved, and there were no detectable signs of myositis on magnetic resonance imaging. Serological muscle enzymes (alanine aminotransferase, aspartate aminotransferase, creatinine kinase, and lactate dehydrogenase), CD8+ T-cell subsets, and inflammatory cytokine secretion in the peripheral blood mononuclear cells (interferon gamma, interleukin 1 [IL-1], IL-6, and IL-13) were all normalized. Further, there was a reduction in anti-Jo-1 antibody levels and a partial recovery of IgA (to 67% of normal value), IgG (to 87%), and IgM (to 58%). Conclusions and Relevance: CD19-targeting CAR T cells directed against B cells and plasmablasts deeply reset B-cell immunity. Together with mycophenolate mofetil, CD19-targeting CAR T cells may break pathologic B-cell, as well as T-cell responses, inducing remission in refractory antisynthetase syndrome.

iNKT cells can effectively inhibit IL-6 production by B cells in systemic sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is a connective tissue disease with poorly understood pathogenesis and limited treatment options. Patient mortality is rooted predominantly in the development of pulmonary and cardiac complications. The overactivated immune system is assumed to sustain the inflammatory signature of this autoimmune disease. Here, we investigate the potential of immunoregulatory invariant natural killer T (iNKT) cells to inhibit proinflammatory B cell responses in an in vitro model of inflammation. METHODS: B cells from healthy volunteers (n = 17) and patients with SSc (n = 15) were used for functional testing upon lipopolysaccharide (LPS) stimulation in a co-culture system with third-party iNKT cells. Cytokine production was measured with antibody-based immunoassays (ELISA) and intracellular cytokine staining. RESULTS: iNKT cells strongly inhibited the production of proinflammatory interleukin-6 by B cells upon stimulation with LPS in both healthy volunteers and patients with SSc. In a Transwell assay, cell contact between B cells and iNKT cells proved necessary for this inhibitory effect. Similarly, blocking of CD1d on the surface of B cells abolished the immunoregulatory effect of iNKT cells on B cells. B cell subsets with higher expression of CD1d, namely unswitched memory B cells, were more susceptible to iNKT cell inhibition. CONCLUSION: Our in vitro data underline the potential of iNKT cells in the control of SSc and provide a rationale for the use of novel iNKT cell-based therapeutic strategies in the context of autoimmune diseases.

The HLA ligandome landscape of chronic myeloid leukemia delineates novel T-cell epitopes for immunotherapy.

Antileukemia immunity plays an important role in disease control and maintenance of tyrosine kinase inhibitor (TKI)-free remission in chronic myeloid leukemia (CML). Thus, antigen-specific immunotherapy holds promise for strengthening immune control in CML but requires the identification of CML-associated targets. In this study, we used a mass spectrometry-based approach to identify naturally presented HLA class I- and class II-restricted peptides in primary CML samples. Comparative HLA ligandome profiling using a comprehensive dataset of different hematological benign specimens and samples from CML patients in deep molecular remission delineated a panel of novel frequently presented CML-exclusive peptides. These nonmutated target antigens are of particular relevance because our extensive data-mining approach suggests the absence of naturally presented BCR-ABL- and ABL-BCR-derived HLA-restricted peptides and the lack of frequent tumor-exclusive presentation of known cancer/testis and leukemia-associated antigens. Functional characterization revealed spontaneous T-cell responses against the newly identified CML-associated peptides in CML patient samples and their ability to induce multifunctional and cytotoxic antigen-specific T cells de novo in samples from healthy volunteers and CML patients. Thus, these antigens are prime candidates for T-cell-based immunotherapeutic approaches that may prolong TKI-free survival and even mediate cure of CML patients.

Effects of Long-Term Storage on Serum Free Light Chain Stability.

BACKGROUND: Determination and quantification of serum free light chains (FLC) is essential for the diagnosis and monitoring of patients with monoclonal gammopathies. Currently, the Freelite assay (The Binding Site, United Kingdom) and the N Latex FLC assay (Siemens Healthineers, Germany) are available for FLC determination. Data concerning stability of FLC following long-term storage are limited. Therefore, the aim of the present study is to investigate the stability of FLC in frozen samples determined by the N latex FLC assay. METHODS: One hundred eighty-eight serum samples from 47 patients with monoclonal gammopathies were analyzed at the beginning and after long-term storage (-20°C, 193 - 568 days). Serum free light chain kappa (κFLC) and lambda (λFLC) concentrations were measured, and the corresponding kappa/lambda (κ/λ FLC) ratios were calculated. All samples were analyzed with the N latex FLC assay on a single BNII System. RESULTS: Comparison analyses between fresh and stored samples revealed very strong correlations for the determination of κFLC (r = 0.993), λFLC (r = 0.998) and the calculated κ/λ FLC ratio (r = 0.997). Median percentage changes of κFLC (-0.5%) and λFLC (-0.8%) measurements and the calculated κ/λ FLC ratios (-3.7%) were within the calculated analytical imprecision of the FLC assay. Changes of κFLC (r = 0.17, p = 0.02) and λFLC (r = 0.28, p < 0.01) concentrations and of the κ/λ FLC ratio (r = 0.18, p = 0.01) over time were very weak, but statistically significant. CONCLUSIONS: Serum free light chains in serum samples are sufficiently stable following long-term frozen storage and are therefore suitable to be measured with the N Latex FLC assay.

Molecular recognition patterns of anti-topoisomerase I-antibodies in patients with systemic sclerosis before and after autologous stem cell transplantation.

OBJECTIVES: To evaluate the effect of autologous stem cell transplantation (aSCT) on antibody (ab) reactivity towards linear epitopes of topoisomerase-I (topo-I/Scl70) in patients with systemic sclerosis (SSc) and to correlate antibody reactivities with clinical outcome after aSCT. METHODS: Fourteen anti-topo-I/Scl70-positive SSc-patients were analysed before and after non-myeloablative aSCT. Five patients showed ongoing good response (group 1), 9 had primarily responded but later relapsed or did not respond (group 2). Patients' sera were tested by ELISA against full length (fl) topo-I and 45 overlapping 25-mer peptides. Furthermore, for comparison sera from patients with anti-topo-I-negative SSc (n=12), other collagen disorders (n=6), and from 21 healthy controls (HC) were analysed. RESULTS: Anti-topo-I-positive SSc-sera showed significantly higher IgG-reactivity as compared to HC towards 34 of the 45 peptides. Especially peptide 39 (aa647-671) emerged as a immunodominant epitope being recognised predominantly by anti-topo-I-positive SSc-sera. Reactivity towards 17 of the 45 peptides decreased after aSCT in group 1- and 2-patients. Before aSCT, group 1-patients had lower antibody reactivity towards peptide 39 than group 2-patients. There was no change in peptide-specificity after aSCT. CONCLUSIONS: Reactivity towards topo-I-epitopes is heterogeneous in SSc, but peptide 39 (aa647-671) may be another immunodominant epitope besides the published epitope aa489-573. Antibody reactivity to this peptide 39 was higher in group 2- than in group 1-patients. Peptide recognition pattern did not change after aSCT.

Sulphite oxidase (SO) - a mitochondrial autoantigen as target for humoral and cellular immune reactions in primary sclerosing cholangitis.

BACKGROUND: In a recent study we had evidence that sulphite oxidase (SO) may be a relevant autoantigen in primary sclerosing cholangitis (PSC). Aim of the present study was, therefore, to analyse humoral and cellular immune-reactivity towards SO in these patients in more detail. METHODS: Sera from 53 patients with PSC (30 untreated and 23 treated with ursodeoxycholic acid [UDCA] at time of analysis), from 422 patients with different hepatic and non-hepatic disorders, and from 50 healthy individuals were tested by ELISA for antibodies against full-length-SO (SO-fl) and its three major domains expressed in E.coli (SO-I, SO-II, SO-III). For epitope-mapping, 29 overlapping peptides were used. Peripheral blood mononuclear cells (PBMC) were obtained from 33 PSC-patients and analysed for SO-induced proliferation, production of cytokines, and expression of the activation marker cluster of differentiation (CD) 69. RESULTS: 43% of the 30 untreated and 26% of the 23 treated PSC-patients had IgG anti-SO-antibodies predominantly reacting with SO-fl, SO-I and SO-II. Antibody-reactivity decreased after UDCA-treatment. Prevalence and reactivity of anti-SO-antibodies were significantly higher in PSC than in patients with other hepatic and non-hepatic disorders. Epitope mapping revealed no distinct immuno-dominant regions within SO. Incubation of PBMC from PSC-patients (but not from controls) with SO-antigens revealed an activation of B-cells and a T-helper cell type-2 reaction pattern (production of interleukin [IL]-13, IL-10). CONCLUSIONS: PSC-patients show humoral and cellular immune response towards SO. Antibodies may be predominantly directed against conformational epitopes. SO enhances in vitro especially T-helper cell type-2 immune-reactions, which may be pro-fibrotic. SO is a detoxifying enzyme present also in bacteria; further studies analysing its role in the aetiology and pathogenesis in PSC may, therefore, be important.

AAV8 Can Induce Innate and Adaptive Immune Response in the Primate Eye.

Ocular gene therapy has evolved rapidly into the clinical realm due to promising pre-clinical proof-of-concept studies, recognition of the high unmet medical need of blinding disorders, and the excellent safety profile of the most commonly used vector system, the adeno-associated virus (AAV). With several trials exposing subjects to AAV, investigators independently report about cases with clinically evident inflammation in treated eyes despite the concept of ocular immune privilege. Here, we provide a detailed analysis of innate and adaptive immune response to clinical-grade AAV8 in non-human primates and compare this to preliminary clinical data from a retinal gene therapy trial for CNGA3-based achromatopsia (ClinicalTrials.gov: 02610582).

Analysis of anti-topoisomerase I antibodies in patients with systemic sclerosis before and after autologous stem cell transplantation.

Objectives: To evaluate the effect of autologous stem cell transplantation (aSCTrans) on antibody (Ab) reactivity towards topo I in patients with SSc, and to see whether it may correlate with clinical outcome after aSCTrans. Methods: Eighteen anti-topo/Scl70-positive patients with SSc in whom non-myeloablative aSCTrans had been performed were analysed. Seven patients showed good response without relapse for several years (group 1), eight primarily responded but later relapsed and three did not respond (group 2). A total of 74 sera were analysed at different time points and tested by ELISA against full length ( fl ) topo I, truncated ( tr ) topo I and a previously identified immunodominant epitope covering amino acid 489-573. Results: Eighty-three percent had IgG Abs to topo fl and topo tr . Ab reactivity significantly decreased after aSCTrans, but remained positive in 10 of the 11 patients followed for up to 24 months. The decrease did not correlate with the clinical outcome after aSCTrans. Fifty-six percent of the patients reacted with topo489-573, and reactivity was nearly confined to group 2. There was no correlation between Ab reactivity towards topo fl or topo489-573 and the modified Rodnan Skin Score before aSCTrans or its decrease after aSCTrans. Conclusions: Although aSCTrans is a good treatment option in patients with progressive SSc, it does not abrogate Ab reactivity towards topo I. The presence of anti-topo489-573 Abs before aSCTrans may indicate a less favourable course after aSCTrans.

Chronic graft-versus-host-disease in CD34(+)-humanized NSG mice is associated with human susceptibility HLA haplotypes for autoimmune disease.

Chronic graft-versus-host disease (cGVHD) is a significant hurdle to long-term hematopoietic stem-cell transplantation success. Insights into the pathogenesis and mechanistical investigations of novel therapeutic strategies are limited as appropriate animal models are missing. The immunodeficient NSG mouse - when humanized with human bone marrow, fetal liver and thymus (BLT NSG) - is prone for cGVHD, yet mainly affects the skin. In contrast, the NSG mouse humanized exclusively with CD34(+)-selected, CD3(+)-depleted stem cells (CD34(+)NSG) has neither been described for acute nor chronic GVHD so far. This is the first report about the development of systemic autoimmune cGVHD ≥24 weeks post stem cell receipt involving lung, liver, skin, gingiva and intestine in two NSG cohorts humanized with CD34(+) grafts from different donors. Affected mice presented with sclerodermatous skin, fibrotic lung, severe hepatitis, and massive dental malformation/loss. CD4(+)-dominated, TH2-biased, bulky T-cell infiltrates featured highly skewed T cell receptor (TCR) repertoires, clonal expansions, and autoreactive TCRs. In affected tissues profibrotic IL-13 and -4 dominated over TH1 cytokines IFN-γ and TNF-α. Thus, the time point of manifestation and the phenotype match human systemic pleiotropic sclerodermatous GVHD. The CD34(+)NSG-model's intrinsic deficiency of thymus, thymus-derived regulatory T cells (nTreg) and B cells emphasizes the role of the genetic polymorphism and the cytokines in the pathogenesis of cGVHD. Importantly, the only factor discriminating diseased versus non-diseased CD34(+)NSG cohorts were two risk HLA haplotypes that in human mediate susceptibility for autoimmune disease (psoriasis). Thus, the CD34(+)NSG model may serve as a platform for addressing issues related to the pathophysiology and treatment of human autoimmunity and chronic GVHD.

Patients with systemic sclerosis and low CD4 numbers after autologous stem cell transplantation have a favorable outcome.

BACKGROUND: Treatment with high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (aHSCT) is an intensive treatment option for patients with severe forms of systemic sclerosis (SSc). Even though associated with a high treatment related mortality, the results in this high-risk population are generally favourable. The knowledge on the potential mechanism of action of this therapy and how it can improve patients with SSc is crucial to better select the right patients for aHSCT. METHODS: This is a monocentric retrospective study from Tübingen, Germany, including 32 patients who underwent aHSCT. Peripheral blood samples were analysed for different lymphocyte subsets at various timepoints before and after aHSCT. Patients were divided into responders and non-responders according to the modified Rodnan skin score and lung function test in the three years following aHSCT. RESULTS: Responders showed significantly lower levels of cluster of differentiation (CD)4 positive T cells in the first months after aHSCT (month 1 and 3), B cells (month 3 and 6 after aHSCT) and natural killer cells (month 1). Mantel-cox test showed a significant deviation of the probability curves, i.e. patients with lower CD4 + T cells and natural killer cells one month and B cells after 3 months after stem cell transplantation had a higher probability to belong to the responder group. CONCLUSIONS: Taken together, this study supports the theory that a profound CD4 + T cell and B cell lymphopenia is important for patients with SSc to achieve a sustained response after aHSCT.

Low performance in attention testing is associated with reduced grey matter density of the left inferior frontal gyrus in euthyroid patients with Hashimoto's thyroiditis.

Hashimoto's thyroiditis (HT) can casually co-occur with an encephalopathy associated with autoimmune thyroid disease. Recently we found an increased occurrence of weaknesses in sustained attention and response inhibition in a subgroup of euthyroid patients with HT as obtained by the d2 attention test. Previous studies in healthy subjects and patients with brain lesions demonstrated a pivotal role for the left inferior frontal gyrus (LIFG) in these skills. Therefore, we studied the association between the performance in the d2 test and grey matter (GM) density of the LIFG in 13 euthyroid patients with HT compared to a control group of 12 euthyroid patients with other thyroid diseases. A significant correlation between GM density and d2 test total score was detected for the opercular part of the LIFG in patients with HT (p<0.001), but not in the control group (p=0.94). Regression in patients with HT was significantly stronger than in the control group (p=0.02). Moreover, GM density was significantly reduced when comparing HT patients with control patients that scored in the lower third during d2 attention testing (p<0.05). It can be concluded that in HT performance in the d2 test correlated with GM density of the LIFG. Particularly low achievement was associated with reduced GM density of this brain region suggesting an influence of autoimmune processes on the frontal cortex in this disease. This could be due to not yet known antibodies affecting brain morphology or an influence of thyroid antibodies themselves.

The good and the bad of T cell cross-reactivity: challenges and opportunities for novel therapeutics in autoimmunity and cancer.

T cells are main actors of the immune system with an essential role in protection against pathogens and cancer. The molecular key event involved in this absolutely central task is the interaction of membrane-bound specific T cell receptors with peptide-MHC complexes which initiates T cell priming, activation and recall, and thus controls a range of downstream functions. While textbooks teach us that the repertoire of mature T cells is highly diverse, it is clear that this diversity cannot possibly cover all potential foreign peptides that might be encountered during life. TCR cross-reactivity, i.e. the ability of a single TCR to recognise different peptides, offers the best solution to this biological challenge. Reports have shown that indeed, TCR cross-reactivity is surprisingly high. Hence, the T cell dilemma is the following: be as specific as possible to target foreign danger and spare self, while being able to react to a large spectrum of body-threatening situations. This has major consequences for both autoimmune diseases and cancer, and significant implications for the development of T cell-based therapies. In this review, we will present essential experimental evidence of T cell cross-reactivity, implications for two opposite immune conditions, i.e. autoimmunity vs cancer, and how this can be differently exploited for immunotherapy approaches. Finally, we will discuss the tools available for predicting cross-reactivity and how improvements in this field might boost translational approaches.

TOFIMS mass spectrometry-based immunopeptidomics refines tumor antigen identification.

T cell recognition of human leukocyte antigen (HLA)-presented tumor-associated peptides is central for cancer immune surveillance. Mass spectrometry (MS)-based immunopeptidomics represents the only unbiased method for the direct identification and characterization of naturally presented tumor-associated peptides, a key prerequisite for the development of T cell-based immunotherapies. This study reports on the implementation of ion mobility separation-based time-of-flight (TOFIMS) MS for next-generation immunopeptidomics, enabling high-speed and sensitive detection of HLA-presented peptides. Applying TOFIMS-based immunopeptidomics, a novel extensive benignTOFIMS dataset was generated from 94 primary benign samples of solid tissue and hematological origin, which enabled the expansion of benign reference immunopeptidome databases with > 150,000 HLA-presented peptides, the refinement of previously described tumor antigens, as well as the identification of frequently presented self antigens and not yet described tumor antigens comprising low abundant mutation-derived neoepitopes that might serve as targets for future cancer immunotherapy development.

Autoantibodies targeting G protein-coupled receptors: An evolving history in autoimmunity. Report of the 4th international symposium.

G protein-coupled receptors (GPCR) are involved in various physiological and pathophysiological processes. Functional autoantibodies targeting GPCRs have been associated with multiple disease manifestations in this context. Here we summarize and discuss the relevant findings and concepts presented in the biennial International Meeting on autoantibodies targeting GPCRs (the 4th Symposium), held in Lübeck, Germany, 15-16 September 2022. The symposium focused on the current knowledge of these autoantibodies' role in various diseases, such as cardiovascular, renal, infectious (COVID-19), and autoimmune diseases (e.g., systemic sclerosis and systemic lupus erythematosus). Beyond their association with disease phenotypes, intense research related to the mechanistic action of these autoantibodies on immune regulation and pathogenesis has been developed, underscoring the role of autoantibodies targeting GPCRs on disease outcomes and etiopathogenesis. The observation repeatedly highlighted that autoantibodies targeting GPCRs could also be present in healthy individuals, suggesting that anti-GPCR autoantibodies play a physiologic role in modeling the course of diseases. Since numerous therapies targeting GPCRs have been developed, including small molecules and monoclonal antibodies designed for treating cancer, infections, metabolic disorders, or inflammatory conditions, anti-GPCR autoantibodies themselves can serve as therapeutic targets to reduce patients' morbidity and mortality, representing a new area for the development of novel therapeutic interventions.