Search

Introduction: Progressive loss of regulatory T cell (Treg)-mediated control over autoreactive effector T cells contributes to the development of systemic lupus erythematosus (SLE). Accordingly, we hypothesized that Treg may also have the capacity to suppress the activation of autoreactive CD4 + T cells that are considered to drive autoimmunity., Methods: To investigate whether Treg are involved in the control of autoreactive CD4 + T cells, we depleted CD25 + Treg cells either in vivo or in vitro , or combined both approaches before antigen-specific stimulation with the SLE-associated autoantigen SmD1(83-119) in the NZB/W F1 mouse model either after immunization against SmD1(83-119) or during spontaneous disease development. Frequencies of autoantigen-specific CD4 + T cells were determined by flow cytometry using the activation marker CD154., Results: Both in vitro and in vivo depletion of CD25 + Treg, respectively, increased the frequencies of detectable autoantigen-specific CD4 + T cells by approximately 50%. Notably, the combined in vivo and in vitro depletion of CD25 + Treg led almost to a doubling in their frequencies. Frequencies of autoantigen-specific CD4 + T cells were found to be lower in immunized haploidentical non-autoimmune strains and increased frequencies were detectable in unmanipulated NZB/W F1 mice with active disease. In vitro re-addition of CD25 + Treg after Treg depletion restored suppression of autoantigen-specific CD4 + T cell activation., Discussion: These results suggest that the activation and expansion of autoantigen-specific CD4 + T cells are partly controlled by Treg in murine lupus. Depletion of Treg therefore can be a useful approach to increase the detectability of autoantigen-specific CD4 + T cells allowing their detailed characterization including lineage determination and epitope mapping and their sufficient ex vivo isolation for cell culture., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Rosenberger, Undeutsch, Akbarzadeh, Ohmes, Enghard, Riemekasten and Humrich.)

Introduction: Vasculopathy, inflammatory fibrosis and functional autoantibodies (Abs) are major manifestations of systemic sclerosis (SSc). Abs directed against the angiotensin II type 1 receptor (AT₁R) and endothelin-1 type A receptor (ETAR) are associated with characteristic disease features including vascular, inflammatory, and fibrotic complications indicating their role in SSc pathogenesis. Therefore, the impact of anti-AT₁R and anti-ETAR Abs on initiation of inflammation and fibrosis was analyzed., Methods: Anti-AT₁R and anti-ETAR Ab-positive immunoglobulin G (IgG) from SSc patients (SSc-IgG) was used for experiments. Healthy donor IgG served as a normal control, and AT₁R and ETAR activation was inhibited by antagonists. Protein expression was measured with ELISA, mRNA expression with real time-PCR, endothelial repair with a scratch assay, and collagen expression with immunocytochemistry. Transendothelial neutrophil migration was measured with a culture insert system, and neutrophil ROS activation with immunofluorescence. Neutrophils in bronchoalveolar lavage fluids (BALFs) were analyzed microscopically after passive transfer of SSc-IgG or NC-IgG into naïve C57BL/6J mice. KC plasma levels were quantified by a suspension array system. Histologic analyses were performed by using light microscopy., Results: Anti-AT₁R and anti-ETAR Ab-positive SSc-IgG induced activation of human microvascular endothelial cells (HMEC-1). Elevated protein and mRNA levels of the proinflammatory chemokine interleukin-8 (IL-8, CXCL8) and elevated mRNA levels of the vascular cell adhesion molecule-1 (VCAM-1) were induced in HMEC-1. Furthermore, activation of HMEC-1 with SSc-IgG increased neutrophil migration through an endothelial cell layer and activation of reactive oxygen species (ROS). SSc-IgG decreased HMEC-1 wound repair and induced type I collagen production in healthy donor skin fibroblasts. Effects of migration, wound repair, and collagen expression were dependent on the Ab-levels. Passive transfer of anti-AT1R and anti-ETAR Ab-positive SSc-IgG into naïve C57BL/6J mice increased neutrophil BALF counts. In parallel, increased levels of the murine functional IL-8 homologue, chemokine KC, were found in the plasma of SSc-IgG-treated mice as well as structural alterations of the lungs., Conclusions: We conclude that angiotensin and endothelin-receptor activation via anti-AT₁R and anti-ETAR Abs mediate pathogenic effects, indicating their contribution to pathogenesis of SSc. Therefore, anti-AT₁R and anti-ETAR Abs could provide novel targets for therapeutic intervention in the treatment of SSc.

Objectives: Proliferative lupus nephritis (LN) is one of the major concerns in the treatment of systemic lupus erythematosus (SLE). Here we evaluate urinary CD4 T cells as a biomarker of active LN and indicator of treatment response., Methods: Urinary CD3CD4 T cells were quantified using flow cytometry in 186 urine samples from 147 patients with SLE. Fourteen patients were monitored as follow-up. Thirty-one patients with other nephropathies and 20 healthy volunteers were included as controls., Results: In SLE, urinary CD4 T cell counts ≥800/100 ml were observed exclusively in patients with active LN. Receiver operator characteristic analysis documented clear separation of SLE patients with active and non-active LN (area under the curve 0.9969). All patients with up-to-date kidney biopsy results showing proliferative LN had high urinary CD4 T cell numbers. In patients monitored under therapy, normalisation of urinary CD4 T cell counts indicated lower disease activity and better renal function. In contrast, patients with persistence of, or increase in, urinary T cells displayed worse outcomes., Conclusions: Urinary CD4 T cells are a highly sensitive and specific marker for detecting proliferative LN in patients with SLE. Furthermore, monitoring urinary CD4 T cells may help to identify treatment responders and treatment failure and enable patient-tailored therapy in the future.

Introduction: The ability to ameliorate murine lupus renders regulatory T cells (Treg) a promising tool for the treatment of systemic lupus erythematosus (SLE). In consideration to the clinical translation of a Treg-based immunotherapy of SLE, we explored the potential of CD4+Foxp3+ Treg to maintain disease remission after induction of remission with an established cyclophosphamide (CTX) regimen in lupus-prone (NZBxNZW) F1 mice. As a prerequisite for this combined therapy, we also investigated the impact of CTX on the biology of endogenous Treg and conventional CD4+ T cells (Tcon)., Methods: Remission of disease was induced in diseased (NZBxNZW) F1 mice with an established CTX regimen consisting of a single dose of glucocorticosteroids followed by five day course with daily injections of CTX. Five days after the last CTX injection, differing amounts of purified CD4+Foxp3+CD25+ Treg were adoptively transferred and clinical parameters, autoantibody titers, the survival and changes in peripheral blood lymphocyte subsets were determined at different time points during the study. The influence of CTX on the numbers, frequencies and proliferation of endogenous Treg and Tcon was analyzed in lymphoid organs by flow cytometry., Results: Apart from abrogating the proliferation of Tcon, we found that treatment with CTX induced also a significant inhibition of Treg proliferation and a decline in Treg numbers in lymphoid organs. Additional adoptive transfer of 1.5×10⁶ purified Treg after the CTX regimen significantly increased the survival and prolonged the interval of remission by approximately five weeks compared to mice that received only the CTX regimen. The additional clinical amelioration was associated with an increase in the Treg frequency in the peripheral blood indicating a compensation of CTX-induced Treg deficiency by the Treg transfer., Conclusions: Treg were capable to prolong the interval of remission induced by conventional cytostatic drugs. This study provides valuable information and a first proof-of-concept for the feasibility of a Treg-based immunotherapy in the maintenance of disease remission in SLE.

The origins and consequences of a regulatory T cell (Treg) disorder in systemic lupus erythematosus (SLE) are poorly understood. In the (NZBxNZW) F(1) mouse model of lupus, we found that CD4(+)Foxp3(+) Treg failed to maintain a competitive pool size in the peripheral lymphoid organs resulting in a progressive homeostatic imbalance of CD4(+)Foxp3(+) Treg and CD4(+)Foxp3(-) conventional T cells (Tcon). In addition, Treg acquired phenotypic changes that are reminiscent of IL-2 deficiency concomitantly to a progressive decline in IL-2-producing Tcon and an increase in activated, IFN-gamma-producing effector Tcon. Nonetheless, Treg from lupus-prone mice were functionally intact and capable to influence the course of disease. Systemic reduction of IL-2 levels early in disease promoted Tcon hyperactivity, induced the imbalance of Treg and effector Tcon, and strongly accelerated disease progression. In contrast, administration of IL-2 partially restored the balance of Treg and effector Tcon by promoting the homeostatic proliferation of endogenous Treg and impeded the progression of established disease. Thus, an acquired and self-amplifying disruption of the Treg-IL-2 axis contributed essentially to Tcon hyperactivity and the development of murine lupus. The reversibility of this homeostatic Treg disorder provides promising approaches for the treatment of SLE.

The SmD1(83-119) peptide is a main target of autoantibodies and T cells in human and murine lupus, but its role in autoimmunity induction remains elusive. Therefore, female Balb/c mice and (NZW x Balb/c)F1 [CWF1] mice with identical MHC haplotype as lupus prone NZB/W mice were immunized with SmD1(83-119). Immunizations of CWF1 mice with SmD1(83-119), but not with the controls (irrelevant peptide, HEL peptide, or saline), induced anti-SmD1(83-119) and anti-dsDNA antibodies and proteinuria not present in Balb/c mice. DsDNA-specific plasma cell induction after SmD1(83-119) immunizations was confirmed by ELISPOT assays showing that the generation of dsDNA-specific antibody forming cells (AFC) was mainly driven by increased T-cell help. T-cell help for the generation of dsDNA-specific AFC was also present in saline-treated CWF1 mice but was controlled on the levels of B cells preventing autoimmunity.

T cells that recognize nucleoproteins are required for the production of anti-dsDNA Abs involved in lupus development. SmD1 83-119 (a D1 protein of the Smith (Sm) proteins, part of small nuclear ribonucleoprotein) was recently shown to provide T cell help to anti-dsDNA Abs in the NZB/NZW model of lupus. Using this model in the present study, we showed that high dose tolerance to SmD1 (600-1000 microg i.v. of SmD1(83-119) peptide/mo) delays the production of autoantibodies, postpones the onset of lupus nephritis as confirmed by histology, and prolongs survival. Tolerance to SmD1 83-119 was adoptively transferred by CD90+ T cells, which also reduce T cell help for autoreactive B cells in vitro. One week after SmD1 83-119 tolerance induction in prenephritic mice, we detected cytokine changes in cultures of CD90+ T and B220+ B cells with decreased IFN-gamma and IL-4 expression and an increase in TGFbeta. Increased frequencies of regulatory IFN-gamma+ and IL10+ CD4+ T cells were later detected. Such regulatory IL-10+/IFN-gamma+ type 1 regulatory T cells prevented autoantibody generation and anti-CD3-induced proliferation of naive T cells. In conclusion, these results indicate that SmD1 83-119 peptide may play a dominant role in the activation of helper and regulatory T cells that influence autoantibody generation and murine lupus.