HLA-DR15-specific inhibition attenuates autoreactivity to the Goodpasture antigen
Introduction
Anti-glomerular basement membrane (GBM) disease, also known as Goodpasture's disease, results from autoimmunity against the non-collagenous domain of the α3 chain of type IV collagen, α3(IV)NC1, present in the GBM [1]. This disease manifests as rapidly progressive glomerulonephritis, with glomerular crescent formation and linear staining of glomerular antibody deposits [2]. Patients also develop pulmonary haemorrhage. Both humoral and cell mediated effectors contribute to the disease pathogenesis, with pathogenic anti- α3(IV)NC1 antibodies and autoreactive CD4+ T cells found in patients with anti-GBM disease and in experimental animal models of disease [[3], [4], [5], [6], [7], [8]]. Anti-GBM disease is strongly associated with the MHC class II allele HLA-DRB1*15:01 (HLA-DR15, previously known as HLA-DR2b), with an average odds ratio of 8.5 [9]. CD4+ T cells reactive to the immunodominant CD4+ T cell epitope, α3135-145 (135GWISLWKGFSF145), are expanded in HLA-DR15+ humans and induce disease in HLA-DR15 transgenic mice (HLA-DR15+, lacking mouse MHC class II), demonstrating the important contribution of HLA-DR15-mediated CD4+ T cell responses in this disease [10].
Treatments for autoimmune disease have remained largely unchanged for many years, with few advances that provide better options for patients. Current treatment for anti-GBM disease involves high dose corticosteroids, cyclophosphamide, and acute plasmapheresis to remove autoantibodies [2]. These toxic immunosuppressants often have severe side effects, including those that compromise protective immune function, risking life-threatening infections. There is a need for better treatments, in this and in other autoimmune kidney diseases.
Most autoimmune diseases have genetic associations with HLA alleles, although their mechanistic contribution to autoimmunity is unclear [11]. In anti-GBM disease, however, a mechanism by which HLA polymorphisms influence disease risk has been defined. HLA-DR15 increases disease susceptibility by presenting α3135-145 in a conformation that activates pro-inflammatory T cells; in contrast, the negatively associated HLA-DR1 confers protection by presenting α3135-145 in a conformation that activates regulatory T cells [8]. Thus, blocking the ability of HLA-DR15 to present α3135-145 could specifically inhibit pro-inflammatory α3135-145-specific responses while allowing protective immunity to be effected by the other unaffected HLA class II allomorphs found in each human (HLA-DQ, HLA-DP, and if not homozygous for DR15, the other HLA-DR). PV-267 is one such HLA-DR15-specific inhibitor, a small molecule that binds with high affinity and specificity to HLA-DR15 [12]. Thus, we hypothesize that HLA-DR15 inhibition with PV-267 will block the activation of α3135-145-specific T cells and attenuate experimental autoimmune anti-GBM disease. We tested these hypotheses using humanised HLA-DR15 transgenic mice.
Section snippets
Peptides and PV-267
The α3135-145 peptide (GWISLWKGFSF) and OVA323-339 peptide (ISQAVHAAHAEINEAGR) were synthesised to at least 95% purity (Mimotopes, Clayton, Australia). The PV-267 peptide [Ac–V(Chg)R (Tic)F–NH2] was designed and synthesised by Provid Pharmaceuticals (Monmouth Junction, NJ, USA). PV-267 was dissolved in 0.1 M sodium phosphate buffer (pH 7.4, with 0.02% Tween 80).
Mice
HLA-DR15 transgenic mice (mouse MHC class II−/, HLA-DRA1*01:01 transgenic, HLA-DRB1*15:01 transgenic, Fcgr2b+/+ or Fcgr2b−/-) were
Blocking HLA-DR15 inhibits α3135-145-specific immune responses
To determine whether PV-267 could limit the activation of α3135-145-specific T cells, HLA-DR15 transgenic (DR15+Fcgr2b+/+) mice were administered either vehicle or PV-267 (30 mg/kg, intraperitoneally) daily from one day prior to α3135-145 immunization (Fig. 1A). Ten days after α3135-145 immunization, α3135-145-specific responses were measured on cells from draining lymph nodes by proliferation using [3H]-thymidine incorporation, and IFN-γ and IL-17A ELISPOTs after ex vivo stimulation with α3
Discussion
Specifically inhibiting HLA allomorphs in autoimmune renal disease may offer a more targeted approach than current broadly immunosuppressive treatments. In the current studies, we explored the possibility of using a small molecule inhibitor, PV-267, to block HLA-DR15 mediated antigen presentation in an HLA transgenic mouse model of autoimmune anti-GBM glomerulonephritis. PV-267 effectively suppressed inflammatory responses to α3135-145 (Fig. 1) and protecteding mice from developing disease (
Conclusion
This study has shown that specific HLA-DR15 inhibition by PV-267 can attenuate renal injury, demonstrating antigen-specific therapeutic potential. If used as an adjunct treatment for anti-GBM disease, PV-267 may be able to provide a less toxic alternative and reduce adverse outcomes, for example by allowing lower doses of current therapies to be used. Furthermore, these results support the use of selective HLA class II inhibition in other autoimmune diseases, where specific HLA allomorphs
Author contributions
M.H., G.L.O., N.B.R., C.R.S., Y.S., S.R.H., A.R.K. and J.D.O. designed the experiments; M.H., P.E. and J.D.O. performed the experiments and collected the data; M.H., A.R.K. and J.D.O. drafted and revised the paper; all authors approved the final version of the paper.
Acknowledgments and disclosures
This work was supported by NHMRC Project grants (APP1084869 and APP1145105). J.D.O. is supported by an Al and Val Rosenstrauss Fellowship by the Rebecca Cooper Medical Research Foundation. G.L.O. is the chief executive officer of Provid; N.B.R., C.R.S. and Y.S. are employees of Provid.
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Cited by (6)
Autoimmunity in Anti–Glomerular Basement Membrane Disease: A Review of Mechanisms and Prospects for Immunotherapy
2023, American Journal of Kidney DiseasesCitation Excerpt :Unraveling the mechanism of HLA-mediated autoimmunity might lead to more immunotherapies tailored to patients with anti-GBM disease.7 Huynh et al78 demonstrated the potency of HLA-DR15 inhibition to alleviate α3136-146–immunized anti-GBM GN by administering HLA-DR15 transgenic mice with PV-267 (an HLA-DR15–specific inhibitor). PV-267 administration limited α3136-146–specific proinflammatory responses and attenuated kidney injury in animal models.
HLA-DR15 Molecules Jointly Shape an Autoreactive T Cell Repertoire in Multiple Sclerosis
2020, CellCitation Excerpt :Another small molecule (PV-267) that fills the binding pocket of DR2b inhibits cytokine production and proliferation of DR2b-restricted, MBP-specific T cells and allows prevention and treatment in a DR2b-transgenic EAE model (Ji et al., 2013). The same inhibitor attenuates anti-glomerular basement membrane activity in a Goodpasture model (Huynh et al., 2019). In both studies, DR2a was not considered, and one may speculate that single small molecules blocking both alleles or combining blockers for DR2a and DR2b could be explored as immunotherapy for MS. Future studies should address whether our observations hold for other MS autoantigens, such as myelin peptides and the recently discovered non-myelin protein guanosine diphosphate (GDP) L-fucose synthase, which is recognized by brain-infiltrating T cells and has similarities to GDP L-fucose synthase homologs of certain gut microbiota, most notably Akkermansia (Planas et al., 2018).
Autoimmunity in 2019
2020, Clinical Reviews in Allergy and Immunology
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