A novel monoclonal antibody against human CD80 and its immune protection in a mouse lupus-like disease

Acazicolcept (ALPN-101), a dual ICOS/CD28 antagonist, demonstrates efficacy in systemic sclerosis preclinical mouse models

Background

Uncontrolled immune response with T cell activation has a key role in the pathogenesis of systemic sclerosis (SSc), a disorder that is characterized by generalized fibrosis affecting particularly the lungs and skin. Costimulatory molecules are key players during immune activation, and recent evidence supports a role of CD28 and ICOS in the development of fibrosis. We herein investigated the efficacy of acazicolcept (ALPN-101), a dual ICOS/CD28 antagonist, in two complementary SSc-related mouse models recapitulating skin fibrosis, interstitial lung disease, and pulmonary hypertension.

Methods

Expression of circulating soluble ICOS and skin-expressed ICOS was investigated in SSc patients. Thereafter, acazicolcept was evaluated in the hypochlorous acid (HOCL)-induced dermal fibrosis mouse model and in the Fra-2 transgenic (Tg) mouse model. In each model, mice received 400 μg of acazicolcept or a molar-matched dose of an Fc control protein twice a week for 6 weeks. After 6 weeks, skin and lung were evaluated.

Results

ICOS was significantly increased in the sera from SSc patients and in SSc skin biopsies as compared to samples from healthy controls. Similar body weight changes were observed between Fc control and acazicolcept groups in both HOCL and Fra-2 Tg mice suggesting a good tolerance of acazicolcept treatment. In mice challenged with HOCL, acazicolcept induced a significant decrease in dermal thickness, collagen content, myofibroblast number, and inflammatory infiltrates characterized by B cells, T cells, neutrophils, and macrophages. In the Fra-2 Tg mouse model, acazicolcept treatment reduced lung collagen content, fibrillar collagen, histological fibrosis score, and right ventricular systolic pressure (RVSP). A reduction in frequency of CD4+ and T effector memory cells and an increase in the percentage of CD4+ T naïve cells in spleen and lung of acazicolcept-treated Fra-2 Tg mice was observed as compared to Fc control-treated Fra-2 Tg mice. Moreover, acazicolcept reduced CD69 and PD-1 expression on CD4+ T cells from the spleen and the lung. Target engagement by acazicolcept was demonstrated by blockade of CD28 and ICOS detection by flow cytometry in treated mice.

Conclusions

Our results confirm the importance of costimulatory molecules in inflammatory-driven fibrosis. Our data highlight a key role of ICOS and CD28 in SSc. Using complementary models, we demonstrated that dual ICOS/CD28 blockade by acazicolcept decreased dermal and pulmonary fibrosis and alleviated pulmonary hypertension. These results pave the way for subsequent research on ICOS/CD28-targeted therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02709-2.

CD80 Insights as Therapeutic Target in the Current and Future Treatment Options of Frequent-Relapse Minimal Change Disease

Minimal change disease (MCD) is the most common cause of idiopathic nephrotic syndrome in children, and it is well known for its multifactorial causes which are the manifestation of the disease. Proteinuria is an early consequence of podocyte injury and a typical sign of kidney disease. Steroid-sensitive patients react well with glucocorticoids, but there is a high chance of multiple relapses. CD80, also known as B7-1, is generally expressed on antigen-presenting cells (APCs) in steroid-sensitive MCD patients. Various glomerular disease models associated with proteinuria demonstrated that the detection of CD80 with the increase of urinary CD80 was strongly associated closely with frequent-relapse MCD patients. The role of CD80 in MCD became controversial because one contradicts finding. This review covers the treatment alternatives for MCD with the insight of CD80 as a potential therapeutic target. The promising effectiveness of CD20 (rituximab) antibody and CD80 inhibitor (abatacept) encourages further investigation of CD80 as a therapeutic target in frequent-relapse MCD patients. Therapeutic-based antibody towards CD80 (galiximab) had never been investigated in MCD or any kidney-related disease; hence, the role of CD80 is still undetermined. A new therapeutic approach towards MCD is essential to provide broader effective treatment options besides the general immunosuppressive agents with gruesome adverse effects.

A novel monoclonal antibody against human B7-1 protects against chronic graft-vs.-host disease in a murine lupus nephritis model

Lupus nephritis (LN) is the most common complication that causes mortality in patients with systemic lupus erythematosus. The B7-1/B7-2 and CD28/cytotoxic T-lymphocyte associated protein 4 co-stimulatory pathway serves a key role in autoimmune disease and organ transplantation. The aim of the present study was to generate and characterize a monoclonal antibody (mAb; clone 4E5) against human B7-1 and to investigate its potential use for the treatment of LN. The results demonstrated that the 4E5 mAb was successfully generated and able to recognize both human and mouse B7-1. After injection of this mAb into a mouse model with chronic graft-vs.-host disease (cGVHD)-induced lupus-like disease, the expression of CD21, CD23, CD80 and CD86 on B220⁺ B-cells in the spleen, and the concentrations of serum autoantibodies and urine protein, were decreased. Direct immunofluorescence analysis of the kidneys revealed that immunofluorescence of immune complex deposits was weaker in the 4E5-treated mice and electron microscopy analyses of renal tissues indicated that pathological injury of the kidneys of 4E5-treated mice was decreased compared with that in the model control mice. The results of the present study demonstrated that inhibition of the B7-1/CD28 co-stimulatory signaling pathway with the 4E5 mAb may represent a promising strategy to decelerate the progression of LN that is induced by cGVHD with potential for use in the treatment of other autoimmune diseases.

Therapeutic Targeting of Follicular T Cells with Chimeric Antigen Receptor-Expressing Natural Killer Cells

Follicular helper T cells (T_FH) are critical for vaccine and infection elicitation of long-lived humoral immunity, but exaggerated T_FH responses can promote autoimmunity and other pathologies. It is unfortunate that no clinical interventions exist for the selective depletion of follicular T cells to alleviate these diseases. We engineered a chimeric antigen receptor (CAR) facilitating the specific targeting of cells with high expression levels of human programmed cell death protein 1 (PD-1), a cardinal feature of follicular T cells. CAR-expressing human natural killer (NK) cells robustly and discriminately eliminated PD-1^high follicular human T cells in vitro and in a humanized mouse model of lupus-like disease while sparing B cells and other PD-1^low T cell subsets, including regulatory T cells. These results establish a strategy for specific targeting of PD-1^high T cells that can be advanced as a clinical tool for the selective depletion of pathogenic follicular T cells or other PD-1^high target cells in certain disease states.

T_FH exhibit high expression levels of PD-1

PD-L1 CAR-expressing NK cells selectively kill T_FH but not Treg or memory T cells

Killing of T_FH by CAR NK inhibits B cell proliferation and antibody production

The PD-L1 CAR represents a novel therapeutic tool in T_FH-driven diseases

An update on lupus animal models

PURPOSE OF REVIEW

The complexity and heterogeneity of the clinical presentation in systemic lupus of erythematosus (SLE), combined to the inherent limitations of clinical research, have made it difficult to investigate the cause of this disease directly in patients. Various mouse models have been developed to dissect the cellular and genetic mechanisms of SLE, as well as to identify therapeutic targets and to screen treatments. The purpose of this review is to summarize the major spontaneous and induced mouse models of SLE and to provide an update on the major advances they have contributed to the field.

RECENT FINDINGS

Mouse models of SLE have continued to contribute to understand the cellular, signaling and metabolic mechanisms contributing to the disease and how targeting these pathways can provide therapeutic targets. Whenever possible, we discuss the advantage of using one model over the others to test a specific hypothesis.

SUMMARY

Spontaneous and induced models of lupus models are useful tools for the study of the cause of the disease, identify therapeutic targets and screen treatments in preclinical studies. Each model shares specific subsets of attributes with the disease observed in humans, which provides investigators a tool to tailor to their specific needs.

A monoclonal antibody against CD86 and its protection in a murine lupus nephritis model of chronic graft-versus-host disease

CONTEXT

Lupus nephritis is the most common complication that causes the death of systemic lupus erythematosus patients. CD28/CTLA4 and their ligands CD80 or CD86 costimulatory pathway play a pivotal role in autoimmune disease and organ transplantation.

OBJECTIVES

We generated a monoclonal antibody (clone 1D1) against human CD86 (1D1) that could recognize both human and mouse CD86, and blocked the CD86/CD28 costimulatory pathway with our mAb on a murine lupus nephritis model induced with chronic graft-versus-host disease (cGVHD).

MATERIALS AND METHODS

Experimental lupus nephritis mice were induced with cGVHD, and splenocyte population were analyzed by flow cytometry. Autoantibodies and proteinuria were detected to evaluate the severity of lupus nephritis. The change of histopathology was observed by microscopy, fluorescence microscopy and electron microscopy.

RESULTS

we successfully generated a monoclonal antibody against human CD86(1D1). 1D1 mAb could recognize not only human CD86, but also mouse CD86. 1D1 was applied to the cGVHD-induced experimental lupus nephritis model, and our study found the production of ANA and anti-dsDNA in the 1D1-treated group was lower than those in IgG-treated group after four weeks. The pathological injure of kidney in the 1D1-treated group was lighten than that in IgG-treated group.

DISCUSSION AND CONCLUSIONS

Our data showed that blockade of CD86/CD28 with 1D1 induced a significant remission of proteinuria, production of autoantibodies, immune complex deposition and renal parenchyma lesions in experimental mice. Anti-CD86 Abs might be a potential method for immune therapy in autoimmune diseases and transplantation.

Btk inhibition treats TLR7/IFN driven murine lupus

Bruton's tyrosine kinase (Btk) is expressed in a variety of immune cells and previous work has demonstrated that blocking Btk is a promising strategy for treating autoimmune diseases. Herein, we utilized a tool Btk inhibitor, M7583, to determine the therapeutic efficacy of Btk inhibition in two mouse lupus models driven by TLR7 activation and type I interferon. In BXSB-Yaa lupus mice, Btk inhibition reduced autoantibodies, nephritis, and mortality. In the pristane-induced DBA/1 lupus model, Btk inhibition suppressed arthritis, but autoantibodies and the IFN gene signature were not significantly affected; suggesting efficacy was mediated through inhibition of Fc receptors. In vitro studies using primary human macrophages revealed that Btk inhibition can block activation by immune complexes and TLR7 which contributes to tissue damage in SLE. Overall, our results provide translational insight into how Btk inhibition may provide benefit to a variety of SLE patients by affecting both BCR and FcR signaling.

Reducing progression of experimental lupus nephritis via inhibition of the B7/CD28 signaling pathway

The aim of the present study was to evaluate the effects of the B7/cluster of differentiation (CD)28 signaling pathway on experimental lupus nephritis and examine the molecular mechanism involved by inhibiting the B7/CD28 signaling pathway. A lupus nephritis model in C57BL/6 J mice was induced via intraperitoneal injection of pristane. A recombinant B7-1 short hairpin RNA (shRNA) lentivirus vector was constructed by synthesis and splicing. A neutralizing mouse anti-human B7-1 antibody termed 4E5 was also prepared. The mouse model of lupus nephritis was treated with B7-1 shRNA and 4E5 via injection through the tail vein. The silencing effects of B7-1 shRNA lentiviral infection on target molecules were evaluated using immunofluorescence and flow cytometry. The levels of protein in the urine were detected using Albustix test paper each month over 10 months. The concentration of interleukin (IL)-4 and interferon-γ in the serum was determined using an ELISA. The immune complex (IC) deposits in the kidney were analyzed using direct immunofluorescence. The results demonstrated that the C57BL/6 J mouse lupus nephritis model was successfully constructed with immune cells activated in the spleen of the mice, increases in the concentration of anti-nuclear antibody (ANA) and anti-double stranded DNA antibodies as well as positive IC formation. Following B7-1 shRNA lentivirus or 4E5 treatment, CD11b⁺B7-1⁺, CD11c⁺B7-1⁺ and CD21⁺B7-1⁺ cells in the spleen of the mice were significantly reduced. The concentration of ANA and IL-4 in the serum was also decreased. The concentration of urine protein was reduced and it was at its lowest level in the 4E5 early intervention group. It was also revealed that the immunofluorescence intensity of the IC deposits was weak in the 4E5 early intervention group. In conclusion, inhibiting the B7-1/CD28 signaling pathway is able to alleviate experimental lupus nephritis and provides an experimental basis for the therapeutic use of blocking the B7-1/CD28 signaling pathway in human lupus nephritis and other autoimmune disorders.

Characterization and clinical relevance of circulating CD4+CD28- T cells in Graves' disease

During autoimmune disease the fraction of CD4+CD28- T cells in the peripheral blood of has been found to be elevated. In the present study, peripheral blood was collected from 61 patients with Graves' disease (GD) and 30 healthy control participants. Serum concentrations of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4) and thyrotropin receptor autoantibody (TRAb) were measured and peripheral blood mononuclear cell (PBMC) surface expression of CD4 and CD28 molecules was detected by flow cytometry. CD4+CD28- cells were sorted from six patients undergoing subtotal thyroidectomy and cultured ex vivo. The influence of TSH pretreated thyroid follicular cells on CD4+CD28- cell proliferation was evaluated using the agonist CD40 mAb 5C11, the blocking CD40L mAb 4F1 or B7-1 mAb 4E5 in 3H-TdR assays. Our data showed that the fraction of CD4+CD28- T cells was higher in GD patients than healthy donors (10.21%±8.56% vs. 2.33%±1.94%; P<0.001), and further elevated in 24 of 61 patients with Graves' ophthalmopathy (GO) (7.00±6.57% vs. 15.21±8.96%; P<0.001). A higher proportion of CD4+CD28- cells was detected in patients with degree II or III goiter than those with degree I goiter (11.53±9.18% vs. 6.11±3.97%; P<0.05 and 14.50±10.41% vs. 6.11±3.97%; P<0.01). The percentage of CD4+CD28- T cells correlated positively with serum levels of FT3 (r=0.354, P<0.01) and TRAb (r=0.304, P<0.05), but did not correlate with serum FT4 or TSH. Ex vivo, 5C11 enhanced proliferation of CD4+CD28+ cells (P<0.05), but did not influence the proliferation of CD4+CD28- cells. 4F1 inhibited the proliferation of both CD4+CD28+ (P<0.05) and CD4+CD28- (P<0.01) cells, and 4E5 inhibited proliferation of CD4+CD28+ cells (P<0.05). The elevation in circulating CD4+CD28- cells in GD patients correlates with disease severity and maybe plays an important role in the pathogenesis of GD.

Comparative effects of n-3, n-6 and n-9 unsaturated fatty acid-rich diet consumption on lupus nephritis, autoantibody production and CD4+ T cell-related gene responses in the autoimmune NZBWF1 mouse

Mortality from systemic lupus erythematosus (SLE), a prototypical autoimmune disease, correlates with the onset and severity of kidney glomerulonephritis. There are both preclinical and clinical evidence that SLE patients may benefit from consumption of n-3 polyunsaturated fatty acids (PUFA) found in fish oil, but the mechanisms remain unclear. Here we employed the NZBWF1 SLE mouse model to compare the effects of dietary lipids on the onset and severity of autoimmune glomerulonephritis after consuming: 1) n-3 PUFA-rich diet containing docosahexaenoic acid-enriched fish oil (DFO), 2) n-6 PUFA-rich Western-type diet containing corn oil (CRN) or 3) n-9 monounsaturated fatty acid (MUFA)-rich Mediterranean-type diet containing high oleic safflower oil (HOS). Elevated plasma autoantibodies, proteinuria and glomerulonephritis were evident in mice fed either the n-6 PUFA or n-9 MUFA diets, however, all three endpoints were markedly attenuated in mice that consumed the n-3 PUFA diet until 34 wk of age. A focused PCR array was used to relate these findings to the expression of 84 genes associated with CD4+ T cell function in the spleen and kidney both prior to and after the onset of the autoimmune nephritis. n-3 PUFA suppression of autoimmunity in NZBWF1 mice was found to co-occur with a generalized downregulation of CD4+ T cell-related genes in kidney and/or spleen at wk 34. These genes were associated with the inflammatory response, antigen presentation, T cell activation, B cell activation/differentiation and leukocyte recruitment. Quantitative RT-PCR of representative affected genes confirmed that n-3 PUFA consumption was associated with reduced expression of CD80, CTLA-4, IL-10, IL-18, CCL-5, CXCR3, IL-6, TNF-α and osteopontin mRNAs in kidney and/or spleens as compared to mice fed n-6 PUFA or n-9 MUFA diets. Remarkably, many of the genes identified in this study are currently under consideration as biomarkers and/or biotherapeutic targets for SLE and other autoimmune diseases.

Immune checkpoint receptors in regulating immune reactivity in rheumatic disease

Immune checkpoint regulators are critical modulators of the immune system, allowing the initiation of a productive immune response and preventing the onset of autoimmunity. Co-inhibitory and co-stimulatory immune checkpoint receptors are required for full T-cell activation and effector functions such as the production of cytokines. In autoimmune rheumatic diseases, impaired tolerance leads to the development of diseases such as rheumatoid arthritis, systemic lupus erythematosus, and Sjogren's syndrome. Targeting the pathways of the inhibitory immune checkpoint molecules CD152 (cytotoxic T lymphocyte antigen-4) and CD279 (programmed death-1) in cancer shows robust anti-tumor responses and tumor regression. This observation suggests that, in autoimmune diseases, the converse strategy of engaging these molecules may alleviate inflammation owing to the success of abatacept (CD152-Ig) in rheumatoid arthritis patients. We review the preclinical and clinical developments in targeting immune checkpoint regulators in rheumatic disease.

Costimulatory pathways: physiology and potential therapeutic manipulation in systemic lupus erythematosus

System lupus erythematosus (SLE) is an immune-complex-mediated autoimmune condition with protean immunological and clinical manifestation. While SLE has classically been advocated as a B-cell or T-cell disease, it is unlikely that a particular cell type is more pathologically predominant than the others. Indeed, SLE is characterized by an orchestrated interplay amongst different types of immunopathologically important cells participating in both innate and adaptive immunity including the dendritic cells, macrophages, neutrophils and lymphocytes, as well as traditional nonimmune cells such as endothelial, epithelial, and renal tubular cells. Amongst the antigen-presenting cells and lymphocytes, and between lymphocytes, the costimulatory pathways which involve mutual exchange of information and signalling play an essential role in initiating, perpetuating, and, eventually, attenuating the proinflammatory immune response. In this review, advances in the knowledge of established costimulatory pathways such as CD28/CTLA-4-CD80/86, ICOS-B7RP1, CD70-CD27, OX40-OX40L, and CD137-CD137L as well as their potential roles involved in the pathophysiology of SLE will be discussed. Attempts to target these costimulatory pathways therapeutically will pave more potential treatment avenues for patients with SLE. Preliminary laboratory and clinical evidence of the potential therapeutic value of manipulating these costimulatory pathways in SLE will also be discussed in this review.

IL-36 Receptor Antagonist with Special Emphasis on IL-38

IL-36 is another family member of IL-1 and induces the production of proinflammatory cytokines and activates MAPK and NFκB pathways. IL-36 is a common mediator of innate and adaptive immune response and is inhibited by IL-36 receptor antagonist (RA). IL-36RA acts on IL-36 receptor ligand which exerts proinflammatory effect in vivo and in vitro. IL-38 binds to IL-36 receptor as does IL-36RA and has similar biological effects on immune cells. IL-38 is also a member of IL-1 cytokine and shares some characteristics of IL-1RA, binding the same IL-1 receptor type I. IL-38 plays a role in the pathogenesis of inflammatory diseases, exerting protective effect in some autoimmune diseases. Both IL-38 and IL-36RA have an anti-inflammatory biological effect, however in some cases have contrary effects.

Impact of IL-33 on PGD2 Generation by Activated Human Cord Blood-Derived Mast Cell: Lack of Effect on Tryptase Release

Mast cells are important not only in allergic reactions, but also in inflammation and are involved in a variety of responses including the immediate release of potent inflammatory mediators after activation by cross-linking of FcεRI molecules. Prostaglandin D2 (PGD2) is a major cyclooxygenase metabolite of arachidonic acid produced by mast cells and it is released following allergen challenge in allergic diseases. IL-33 is an iflammatory cytokine which is critically involved in the regulation of in vitro and in vivo cyclooxygenase production, providing a potential therapeutic target for inflammatory disorders. In this study, using human derived umbelical cord blood mast cells, we show that IL-33 (50 ng/ml), and calcium ionophore A 23187 (0.5 μg/ml), compound 48/80 (10−5 M) or anti-IgE (10 μg/ml), enhaced the production of PGD2 and this effect was inhibited by indomethacin. However, IL-33 was unable to induce tryptase release in these cells. These effects confirm the inflammatory property of IL-33 by stimulating PGD2 but not tryptase in human mast cells. The inhibitory effect of this new cytokine may have a potential therapeutic response in allergic and inflammatory diseases.

Endothelial cells, cholesterol, cytokines, and aging

It has been reported that high levels of cholesterol and triglycerides are associated with increased risk of developing atherosclerosis and shorter life. In fact, vascular endothelial dysfunction occurs during the human aging process. Accumulation of lipids in vascular endothelium activates leukocytes to produce cytokines and chemokines which recruit macrophages. On the other hand, macrophages augment inflammatory response and secrete vascular endothelial growth factor, a key cytokine that mediates angiogenesis and inflammatory response. In addition, hyperlipidaemia is one of the main risk factors for aging, hypertension and diabetes. Here, we review the interrelationship between endothelial cells, high level of cholesterol, and aging.