Improvement of humoral immunity by repeated dose-intensified COVID-19 vaccinations in primary non- to low-responders and B cell deficient rheumatic disease patients.

OBJECTIVE: To determine whether repeated, dose-intensified mRNA vaccinations against COVID-19 increase humoral immunity in previously low-responding patients with autoimmune rheumatic diseases (AIRD), including rituximab-treated and B cell depleted patients. METHODS: Of 308 AIRD patients receiving basic immunization, 98 had a low serological response against SARS-CoV-2 with a neutralizing capacity of < 70% using surrogate neutralization assay. 38 patients received a third vaccination with 30 µg BNT162b2 16 weeks after second vaccination. If neutralizing serum capacity was below 70% four weeks after the last vaccination, then the fourth vaccination (n = 19) and the fifth (n = 4) vaccination with 100 µg mRNA-1273 took place eight weeks after the last vaccination. RESULTS: Each of the three booster vaccinations resulted in a significant increase of mean serum neutralizing capacity (3rd: Δ = 42%, p < 0.001; 4th: Δ = 19%, p = 0.049 and 5th: Δ = 51%, p = 0.043) and produced a significant proportion of high-responders (3rd: 34%; 4th: 32% and 5th: 75%). Low B cell counts (p = 0.047), lower previous antibody response (p < 0.001) and rituximab therapy (p = 0.021) were negatively associated with successful response to the third but not to the fourth vaccination. Remarkably, substantial increases in neutralization capacity of up to 99% were observed after repeated vaccinations in B cell depleted patients. CONCLUSION: AIRD patients with low humoral response benefited from up to three repeated dose-intensified mRNA booster vaccinations - despite low B cell count and previous rituximab therapy. Each additional vaccination substantially reduced the number of low-responding, vulnerable patients.

Distinct Effects of Interleukin-1ß Inhibition upon Cytokine Profile in Patients with Adult-Onset Still's Disease and Active Articular Manifestation Responding to Canakinumab.

Adult-onset Still's disease (AOSD) is a systemic auto-inflammatory disease characterized by the presence of immunologically mediated inflammation and deficient resolution of inflammation. Canakinumab is an approved IL-1ß inhibitor in the treatment of AOSD with a balanced efficacy and safety profile. Since inflammatory cytokines play a major role in the pathogenesis of AOSD, we investigated the effects of canakinumab on the cytokine profile of AOSD patients from a randomized controlled trial. Multiplex analysis and ELISA were used to test the concentrations of several cytokines at three time points-week 0 (baseline), week 1 and week 4-in two patient groups-placebo and canakinumab. Two-way repeated-measures analysis of variance revealed a significant temporal effect on the concentrations of MRP 8/14, S100A12, IL-6 and IL-18 with a significant decrease at week 4 in the canakinumab group exclusively. Comparing responders with non-responders to canakinumab showed a significant decrease in MRP 8/14, IL-1RA, IL-18 and IL-6 in responders at week 4, while S100A12 levels decreased significantly in responders and non-responders. In summary, canakinumab showed a striking effect on the cytokine profile in patients with AOSD, exhibiting a clear association with clinical response.

Response to abatacept is associated with the inhibition of proteasome ß1i expression in T cells of patients with rheumatoid arthritis.

OBJECTIVE: Abatacept is a biological disease-modifying antirheumatic drug (DMARD) used for the treatment of rheumatoid arthritis (RA) and modulates the costimulatory signal by cluster of differentiation (CD)28:CD80/CD86 interaction required for T cell activation. Since CD28-mediated signalling regulates many T cell functions including cytokine production of, for example, interferons (IFNs), it is of interest to clarify, whether response to abatacept has an effect on the IFN inducible immunoproteasome, as a central regulator of the immune response. METHODS: Effects of abatacept on the proteasome were investigated in 39 patients with RA over a period of 24 weeks. Using real-time PCR, transcript levels of constitutive and corresponding immunoproteasome catalytic subunits were investigated at baseline (T0), week 16 (T16) and week 24 (T24) in sorted blood cells. Proteasomal activity and induction of apoptosis after proteasome inhibition were also evaluated. RESULTS: Abatacept achieved remission or low disease activity in 55% of patients at T16 and in 70% of patients at T24. By two-way analysis of variance (ANOVA), a significant reduction of proteasome immunosubunit ß1i was shown only in CD4+ and CD8+ T cells of sustained responders at both T16 and T24. One-way ANOVA analysis for each response group confirmed the results and showed a significant reduction at T24 in CD4+ and CD8+ T cells of the same group. Abatacept did not influence chymotrypsin-like activity of proteasome and had no effect on induction of apoptosis under exposure to a proteasome inhibitor in vitro. CONCLUSION: The reduction of proteasome immunosubunit ß1i in T cells of patients with RA with sustained response to abatacept suggests association of the immunoproteasome of T cells with RA disease activity.

Carbamylation of vimentin is inducible by smoking and represents an independent autoantigen in rheumatoid arthritis.

OBJECTIVES: Smoking has been connected to citrullination of antigens and formation of anti-citrullinated peptide antibodies (ACPAs) in rheumatoid arthritis (RA). Since smoking can modify proteins by carbamylation (formation of homocitrulline), this study was conducted to investigate these effects on vimentin in animal models and RA. METHODS: The efficiency of enzymatic carbamylation of vimentin was characterised. B-cell response was investigated after immunisation of rabbits with different vimentin isoforms. Effects of tobacco smoke exposure on carbamylation of vimentin and formation of autoantibodies were analysed in mice. The antibody responses against isoforms of vimentin were characterised with respect to disease duration and smoking status of patients with RA. RESULTS: Enzymatic carbamylation of vimentin was efficiently achieved. Subsequent citrullination of vimentin was not disturbed by homocitrullination. Sera from rabbits immunised with carbamylated vimentin (carbVim), in addition to carbVim also recognised human IgG-Fc showing rheumatoid factor-like reactivity. Smoke-exposed mice contained detectable amounts of carbVim and developed a broad immune response against carbamylated antigens. Although the prevalence of anti-carbamylated antibodies in smokers and non-smokers was similar, the titres of carbamylated antibodies were significantly increased in sera of smoking compared with non-smoking RA. CarbVim antibodies were observed independently of ACPAs in early phases of disease and double-positive patients for anti-mutated citrullinated vimentin (MCV) and anti-carbVim antibodies showed an extended epitope recognition pattern towards MCV. CONCLUSIONS: Carbamylation of vimentin is inducible by cigarette smoke exposure. The polyclonal immune response against modified antigens in patients with RA is not exclusively citrulline-specific and carbamylation of antigens could be involved in the pathogenesis of disease. TRIAL REGISTRATION NUMBER: ISRCTN36745608; EudraCT Number: 2006-003146-41.

The immunoproteasomes are key to regulate myokines and MHC class I expression in idiopathic inflammatory myopathies.

Idiopathic inflammatory myopathies (IIMs) are diseases with muscle weakness, morphologically characterized by inflammatory infiltration and increased expression of MHC class I molecule on myofibers. Immunoproteasome, as a proteolytic complex that shapes the repertoire of antigenic peptides, has been previously demonstrated to be over-expressed in IIMs at mRNA level. In this study, we investigated the expression and the function of the immunoproteasome in IIMs in more detail. As shown by immunofluorescence staining, expression of relevant players of the immunoproteasome was detectable in the inflamed skeletal muscle tissue from IIM patients. In fact, two subunits of the immunoproteasome, ß1i or ß5i were upregulated in sporadic inclusion body myositis, immune-mediated necrotizing myopathies and dermatomyositis muscle biopsies and co-localized with the MHC class I expressing myofibers. Double immunofluorescence revealed that both myofibers and muscle infiltrating cells, including CD8+ T-cells and CD68 + macrophages in IIMs expressed ß1i or ß5i. In addition, we have also investigated the role of the immunoproteasome in myoblasts during in vitro inflammatory conditions. Using human primary myoblasts cultures we found that pro-inflammatory cytokines, TNF-α or IFN-γ upregulate ß1i or ß5i. Selective inhibition or depletion of ß5i amplified the TNF-α or IFN-γ mediated expression of cytokines/chemokines (myokines) in myoblasts. Furthermore, we demonstrated that specific inhibitors of ß1i or ß5i reduced the cell surface expression of MHC class I in myoblasts induced by IFN-γ. Taken together, our data suggest that the immunoproteasome is involved in pathologic MHC class I expression and maintenance of myokine production in IIMs. Thus, induction of the immunoproteasome was identified as a pathomechanism underlying inflammation in IIMs.

Upregulation of immunoproteasome subunits in myositis indicates active inflammation with involvement of antigen presenting cells, CD8 T-cells and IFNΓ.

OBJECTIVE: In idiopathic inflammatory myopathies (IIM) infiltration of immune cells into muscle and upregulation of MHC-I expression implies increased antigen presentation and involvement of the proteasome system. To decipher the role of immunoproteasomes in myositis, we investigated individual cell types and muscle tissues and focused on possible immune triggers. METHODS: Expression of constitutive (PSMB5, -6, -7) and corresponding immunoproteasomal subunits (PSMB8, -9, -10) was analyzed by real-time RT-PCR in muscle biopsies and sorted peripheral blood cells of patients with IIM, non-inflammatory myopathies (NIM) and healthy donors (HD). Protein analysis in muscle biopsies was performed by western blot. Affymetrix HG-U133 platform derived transcriptome data from biopsies of different muscle diseases and from immune cell types as well as monocyte stimulation experiments were used for validation, coregulation and coexpression analyses. RESULTS: Real-time RT-PCR revealed significantly increased expression of immunoproteasomal subunits (PSMB8/-9/-10) in DC, monocytes and CD8+ T-cells in IIM. In muscle biopsies, the immunosubunits were elevated in IIM compared to NIM and exceeded levels of matched blood samples. Proteins of PSMB8 and -9 were found only in IIM but not NIM muscle biopsies. Reanalysis of 78 myositis and 20 healthy muscle transcriptomes confirmed these results and revealed involvement of the antigen processing and presentation pathway. Comparison with reference profiles of sorted immune cells and healthy muscle confirmed upregulation of PSMB8 and -9 in myositis biopsies beyond infiltration related changes. This upregulation correlated highest with STAT1, IRF1 and IFNγ expression. Elevation of T-cell specific transcripts in active IIM muscles was accompanied by increased expression of DC and monocyte marker genes and thus reflects the cell type specific involvement observed in peripheral blood. CONCLUSIONS: Immunoproteasomes seem to indicate IIM activity and suggest that dominant involvement of antigen processing and presentation may qualify these diseases exemplarily for the evolving therapeutic concepts of immunoproteasome specific inhibition.

Gene expression of catalytic proteasome subunits and resistance toward proteasome inhibition of B lymphocytes from patients with primary sjogren syndrome.

OBJECTIVE: Dysregulation of proteasome subunit ß1i expression has been shown in total blood mononuclear cells (PBMC) from patients with primary Sjögren syndrome (pSS), a B cell-driven systemic autoimmune disorder. METHODS: Proteasome activation was investigated in sorted blood cells from patients with pSS and controls by measuring transcript levels of constitutive (ß1/ß2/ß5) and corresponding immunoproteasome catalytic subunits (ß1i/ß2i/ß5i) using real-time PCR. At protein level, ß1i protein expression was analyzed by immunoblotting. Functional effects of proteasome inhibition on proteolytic activity and induction of apoptosis were also evaluated in cellular subsets. RESULTS: The proteasome was found to be activated in pSS, with upregulation of gene expression of catalytic proteasome subunits. Western blot analysis revealed decreased ß1i protein expression in pSS B lymphocytes, with decreased protein despite increased messenger RNA (mRNA) levels. After proteasome inhibition in vitro, proteolytic activity was less reduced and resistance to apoptosis was increased in B lymphocytes compared to other cells. CONCLUSION: In pSS, catalytic subunits of the proteasome are upregulated at the mRNA level, while dysregulation of subunit ß1i is attributed to B lymphocytes. B cell resistance after proteasome inhibition differs from the classical concept of increased susceptibility toward inhibition in activated cells, supporting the novel notion that susceptibility depends on cellular intrinsic factors and on proteasome activation.