Treatment with a CD40 Antagonist Antibody Reverses Severe Proteinuria and Loss of Saliva Production and Restores Glomerular Morphology in Murine Systemic Lupus Erythematosus

Clinical and Biomarker Responses to BI 655064, an Antagonistic Anti-CD40 Antibody, in Patients With Active Lupus Nephritis: A Randomized, Double-Blind, Placebo-Controlled, Phase II Trial

OBJECTIVE

To characterize its dose-response relationship, BI 655064 (an anti-CD40 monoclonal antibody) was tested as an add-on to mycophenolate and glucocorticoids in patients with active lupus nephritis (LN).

METHODS

A total of 121 patients were randomized (2:1:1:2) to receive placebo or BI 655064 120, 180, or 240 mg and received a weekly loading dose for 3 weeks followed by dosing every 2 weeks for the 120 and 180 mg groups, and 120 mg weekly for the 240 mg group. The primary endpoint was complete renal response (CRR) at week 52. Secondary endpoints included CRR at week 26.

RESULTS

A dose-response relationship with CRR at week 52 was not shown (BI 655064 120 mg, 38.3%; 180 mg, 45.0%; 240 mg, 44.6%; placebo, 48.3%). At week 26, 28.6% (120 mg), 50.0% (180 mg), 35.0% (240 mg), and 37.5% (placebo) achieved CRR. The unexpected high placebo response prompted a post hoc analysis evaluating confirmed CRR (cCRR, at weeks 46 and 52). cCRR was achieved in 22.5% (120 mg), 44.3% (180 mg), 38.2% (240 mg), and 29.1% (placebo) of patients. Most patients reported ≥1 adverse event (BI 655064, 85.7-95.0%; placebo, 97.5%), most frequently infections and infestations (BI 655064 61.9-75.0%; placebo 60%). Compared with other groups, higher rates of serious (20% vs. 7.5-10%) and severe infections (10% vs. 4.8-5.0%) were reported with 240 mg BI 655064.

CONCLUSION

The trial failed to demonstrate a dose-response relationship for the primary CRR endpoint. Post hoc analyses suggest a potential benefit of BI 655064 180 mg in patients with active LN.

B Cell Tolerance and Targeted Therapies in SLE

Systemic Lupus Erythematosus (SLE) is a chronic systemic autoimmune disease of high clinical and molecular heterogeneity, and a relapsing-remitting pattern. The disease is currently without cure and more prevalent in women. B cell tolerance and production of autoantibodies are critical mechanisms that drive SLE pathophysiology. However, how the balance of the immune system is broken and how the innate and adaptive immune systems are interacting during lupus-specific autoimmune responses are still largely unknown. Here, we review the latest knowledge on B cell development, maturation, and central versus peripheral tolerance in connection to SLE and treatment options. We also discuss the regulation of B cells by conventional T cells, granulocytes, and unconventional T cells, and how effector B cells exert their functions in SLE. We also discuss mechanisms of action of B cell-targeted therapies, as well as possible future directions based on current knowledge of B cell biology.

Role of CD40(L)-TRAF signaling in inflammation and resolution—a double-edged sword

Cardiovascular diseases (CVD) and cardiovascular risk factors are the leading cause of death in the world today. According to the Global Burden of Disease Study, hypertension together with ischemic heart and cerebrovascular diseases is responsible for approximately 40% of all deaths worldwide. The major pathomechanism underlying almost all CVD is atherosclerosis, an inflammatory disorder of the vascular system. Recent large-scale clinical trials demonstrated that inflammation itself is an independent cardiovascular risk factor. Specific anti-inflammatory therapy could decrease cardiovascular mortality in patients with atherosclerosis (increased markers of inflammation). Inflammation, however, can also be beneficial by conferring so-called resolution, a process that contributes to clearing damaged tissue from cell debris upon cell death and thereby represents an essential step for recovery from, e.g., ischemia/reperfusion damage. Based on these considerations, the present review highlights features of the detrimental inflammatory reactions as well as of the beneficial process of immune cell-triggered resolution. In this context, we discuss the polarization of macrophages to either M1 or M2 phenotype and critically assess the role of the CD40L-CD40-TRAF signaling cascade in atherosclerosis and its potential link to resolution. As CD40L can bind to different cellular receptors, it can initiate a broad range of inflammatory processes that may be detrimental or beneficial. Likewise, the signaling of CD40L downstream of CD40 is mainly determined by activation of TRAF1-6 pathways that again can be detrimental or beneficial. Accordingly, CD40(L)-based therapies may be Janus-faced and require sophisticated fine-tuning in order to promote cardioprotection.

Association of Immune-Related Genetic and Epigenetic Alterations with Lupus Nephritis

BACKGROUND

The familial clustering phenomenon together with environmental influences indicates the presence of a genetic and epigenetic predisposition to systematic lupus erythematosus (SLE). Interestingly, regarding lupus nephritis (LN), the worst complication of SLE, mortality, and morbidity were not consistent with SLE in relation to sexuality and ethnicity.

SUMMARY

Genetic and epigenetic alterations in LN include genes and noncoding RNAs that are involved in antigen-presenting, complements, immune cell infiltration, interferon pathways, and so on. Once genetic or epigenetic change occurs alone or simultaneously, they will promote the formation of immune complexes with autoantibodies that target various autoantigens, which results in inflammatory cytokines and autoreactive immune cells colonizing renal tissues and contributing to LN.

KEY MESSAGES

Making additional checks for immunopathology-related heredity and epigenetic factors may lead to a more holistic perspective of LN.

3-hydroxy butyrate dehydrogenase 2 deficiency aggravates systemic lupus erythematosus progression in a mouse model by promoting CD40 ligand demethylation

The implications of the CD40-CD40 ligand (CD40L) signaling pathway in systemic lupus erythematosus (SLE) were well documented, due to its important role among immune cells. Previous research found that 3-hydroxy butyrate dehydrogenase 2 (BDH2), a modulator of intracellular iron homeostasis and iron transportation promoted the pathogenic process of SLE by regulating the demethylation of cd70, cd11a, and cd40l genes among CD4 + T cells. The purpose of this study was to explore the role of BDH2 in oxidative damage-induced SLE. First, CD4 + T cells treated with H₂O₂ were injected into the tail vein of mice to establish a lupus model. CD40L knockdown significantly decreased CD40L expression on CD4 + T cells in the spleen of SLE mice. Compared with SLE model mice, the levels of serum anti-dsDNA antibody and urinary protein in the CD40L interference group were significantly decreased. CD40L knockdown alleviated the immune complex glomerulonephritis in syngeneic SLE mice. Moreover, the levels of IFN-γ and IL-2 were decreased. However, IL-4 and IL-10 levels were significantly upregulated in the serum of CD40L knockdown SLE mice, compared with SLE model mice. Accordingly, CD40L knockdown reduced Th1/Th2 percentage in SLE mice. Inhibiting the expression of BDH2 of CD4 + T cells promoted the demethylation of CD40L, while it inhibited cell proliferation, elevated oxidative stress through increased expression of CD40L, and thus, promoted the progress of SLE. Our results demonstrate that BDH2 aggravates the pathologic progression of SLE in mice, by increasing the demethylation level of CD40L among CD4 + T cells.

Differentiating between UCTD and early-stage SLE: from definitions to clinical approach

Systemic lupus erythematosus (SLE) is an autoimmune disease with heterogeneous clinical manifestations that can potentially affect every organ and system. SLE is usually identified on the basis of clinical or serological manifestations; however, some individuals can present with signs and symptoms that are consistent with SLE but are not sufficient for a definite diagnosis. Disease in these individuals can either progress over time to definite SLE or remain stable, in which case their disease is often described as intermediate, possible or probable SLE. Alternatively, such individuals might have undifferentiated connective tissue disease (UCTD). Being able to differentiate between those with stable UCTD and those with SLE at an early stage is important to avoid irreversible target-organ damage from occurring. This Review provides insight into existing and evolving perceptions of the early stages of SLE, including clinical and mechanistic considerations, as well as potential paths towards early identification and intervention. Further research into the earliest phases of SLE will be important for the development of targeted diagnostic approaches and biomarkers for the identification of individuals with early disease who are likely to progress to definite SLE.

Anti-CD40 Antibodies Fused to CD40 Ligand Have Superagonist Properties

CD40 is a potent activating receptor within the TNFR family expressed on APCs of the immune system, and it regulates many aspects of B and T cell immunity via interaction with CD40 ligand (CD40L; CD154) expressed on the surface of activated T cells. Soluble CD40L and agonistic mAbs directed to CD40 are being explored as adjuvants in therapeutic or vaccination settings. Some anti-CD40 Abs can synergize with soluble monomeric CD40L. We show that direct fusion of CD40L to certain agonistic anti-CD40 Abs confers superagonist properties, reducing the dose required for efficacy, notably greatly increasing total cytokine secretion by human dendritic cells. The tetravalent configuration of anti-CD40-CD40L Abs promotes CD40 cell surface clustering and internalization and is the likely mechanism of increased receptor activation. CD40L fused to either the L or H chain C termini, with or without flexible linkers, were all superagonists with greater potency than CD40L trimer. The increased anti-CD40-CD40L Ab potency was independent of higher order aggregation. Moreover, the anti-CD40-CD40L Ab showed higher potency in vivo in human CD40 transgenic mice compared with the parental anti-CD40 Ab. To broaden the concept of fusing agonistic Ab to natural ligand, we fused OX40L to an agonistic OX40 Ab, and this resulted in dramatically increased efficacy for proliferation and cytokine production of activated human CD4⁺ T cells as well as releasing the Ab from dependency on cross-linking. This work shows that directly fusing antireceptor Abs to ligand is a useful strategy to dramatically increase agonist potency.

Anti-Monomeric C-Reactive Protein Antibody Ameliorates Arthritis and Nephritis in Mice

Conformation-specific Ags are ideal targets for mAb-based immunotherapy. Here, we demonstrate that the monomeric form of C-reactive protein (mCRP) is a specific therapeutic target for arthritis and nephritis in a murine model. Screening of >1800 anti-mCRP mAb clones identified 3C as a clone recognizing the monomeric, but not polymeric, form of CRP. The anti-mCRP mAb suppressed leukocyte infiltration in thioglycollate-induced peritonitis, attenuated rheumatoid arthritis symptoms in collagen Ab-induced arthritis model mice, and attenuated lupus nephritis symptoms in MRL/Mp-lpr/lpr lupus-prone model mice. These data suggest that the anti-mCRP mAb 3C has therapeutic potential against rheumatoid arthritis and lupus nephritis.

Association of CD40 Gene Polymorphisms With Systemic Lupus Erythematosus and Rheumatoid Arthritis in a Chinese Han Population

Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are complex autoimmune diseases. CD40 participates in inflammatory response, and promotes fibroblast proliferation, leading to occurrence and progression of SLE, RA. This study explores CD40 gene polymorphisms in SLE and RA patients from a Chinese Han population. Two hundred SLE patients, 340 RA patients, and 900 healthy controls were enrolled. Genomic DNA was extracted from peripheral blood, and six polymorphisms of CD40 gene (rs3765456, rs1569723, rs73115010, rs13040307, rs1883832, and rs4810485) were detected by KASP method. Frequencies of rs1569723 genotypes AA, AC, AA+AC were significantly higher in RA patients as compared to those in healthy controls (P = 0.049, P = 0.024, P = 0.022). Frequencies of genotypes CT, CC+CT of rs1883832, and GT, GG+GT of rs4810485 were significantly higher in RA patients as compared to those in healthy controls (P = 0.012, P = 0.018, P = 0.009, P = 0.015). RA patients carrying rs13040307 C allele and rs73115010 T allele showed increased number of swollen joints. Moreover, frequency of allele T of rs13040307 was lower in SLE patients with positive anti-dsDNA and hematuria as compared to that in patients without these parameters (P = 0.038, P = 0.045). There were increased frequencies of genotype TT, allele T for rs13040307 and lower frequencies of genotype TT, allele T for rs73115010 in lupus patients with myositis (all P<0.05). Interestingly, frequencies of rs1569723 A allele, rs4810485 T allele were higher in SLE patients with myositis, and frequencies of rs3765456 A allele, rs1883832 T allele were lower in SLE patients with myositis (All P<0.05). In conclusion, CD40 gene polymorphisms may associate with susceptibility to SLE and RA.

Investigation of the effect of Huaiqihuang granules via adjuvant treatment in children with relapsed systemic lupus erythematosus

OBJECTIVE

To investigate the therapeutic effect of Huaiqihuang granules in children with relapsed systemic lupus erythematosus (SLE), and analyze its impact on the regulation of inflammatory factors, immune function, and recurrence rate.

METHODS

Seventy-six children with relapsed SLE were evenly divided into two groups, the control group with conventional SLE treatment and the observation group which was treated with Huaiqihuang granules on the basis of the conventional treatment. After 8 weeks of treatment, the positive rate of antinuclear antibody (ANA) titer, 24-hour urine protein (24 h Upro), serum inflammatory factors, monocyte chemoattractant protein 1 (MCP-1), receptor for advanced glycation end products (RAGE) level and systemic lupus erythematosus disease activity index (SLEDAI) score were compared. The recurrence rate of SLE between the two groups was also analyzed at the 6-month follow-up.

RESULTS

Compared with before treatment, the positive rate of ANA titer, 24 h Upro, and serum interleukin-10 (IL-10) and tumor necrosis factor family B cell activating factor (BAFF) levels in the two groups of children were decreased after treatment; in addition, levels of these parameters in the observation group were significantly lower than those of the control group. The interleukin-2 (IL-2) level of both groups was significantly increased after treatment, and the observation group showed a significantly higher level of IL-2 than that of the control group (all P<0.05). After treatment, serum MCP-1 and RAGE levels of the two groups were considerably lower compared with that before treatment, which were significantly lower in the observation group than those of the control group (all P<0.05). SLEDAI scores of the two groups were significantly decreased after treatment, which were notably lower in the observation group than those of the control group (all P<0.05). The six-month follow-up demonstrated that the recurrence rate of SLE in the observation group was remarkably lower than that of the control group (P<0.05).

CONCLUSION

The adjuvant treatment by Huaiqihuang granules can effectively reduce the inflammatory response, decrease the disease activity of SLE, and lower the recurrence rate in children with SLE relapse, which is worthy of clinical application.

Dendritic Cell Regulation of T Helper Cells

As the professional antigen-presenting cells of the immune system, dendritic cells (DCs) sense the microenvironment and shape the ensuing adaptive immune response. DCs can induce both immune activation and immune tolerance according to the peripheral cues. Recent work has established that DCs comprise several phenotypically and functionally heterogeneous subsets that differentially regulate T lymphocyte differentiation. This review summarizes both mouse and human DC subset phenotypes, development, diversification, and function. We focus on advances in our understanding of how different DC subsets regulate distinct CD4⁺ T helper (Th) cell differentiation outcomes, including Th1, Th2, Th17, T follicular helper, and T regulatory cells. We review DC subset intrinsic properties, local tissue microenvironments, and other immune cells that together determine Th cell differentiation during homeostasis and inflammation.

Anti-CD40 antibody KPL-404 inhibits T cell-mediated activation of B cells from healthy donors and autoimmune patients

BACKGROUND

CD40-CD40L is a key co-stimulatory pathway for B cell activation. As such, its blockade can inhibit pathogenic B cell responses in autoimmune diseases, such as Sjogren's syndrome (SjS) and systemic lupus erythematosus (SLE). In this study, we examined the in vitro effects of KPL-404, a humanized anti-CD40 monoclonal antibody (Ab), on primary human B cells derived from either healthy donors (HD) or autoimmune patients and compared them to the effects of G28-5, a partially antagonistic anti-CD40 antibody.

METHODS

PBMCs from HD or SjS and SLE patients were cultured in high-density cell cultures in the presence of IgG4 isotype control or anti-CD40 Abs KPL-404 or G28-5. Cells were stimulated with anti-CD3/CD28 cross-linking reagent ImmunoCult (IC) to induce CD40L-CD40-mediated B cell responses. B cell proliferation and activation, measured by dilution of proliferation tracker dye and the upregulation of CD69 and CD86, respectively, were assessed by flow cytometry. Anti-CD40 Ab cell-internalization was examined by imaging flow cytometry. Cytokine release in the PBMC cultures was quantified by bead-based multiplex assay.

RESULTS

KPL-404 binds to CD40 expressed on different subsets of B cells without inducing cell depletion, or B cell proliferation and activation in in vitro culture. Under the same conditions, G28-5 promoted proliferation of and increased CD69 expression on otherwise unstimulated B cells. KPL-404 efficiently blocked the CD40L-CD40-mediated activation of B cells from HD at concentrations between 1 and 10 μg/ml. Treatment with KPL-404 alone did not promote cytokine production and blocked the production of IFNβ in healthy PBMC cultures. KPL-404 efficiently blocked CD40L-CD40-mediated activation of B cells from patients with SjS and SLE, without affecting their anti-IgM responses or affecting their cytokine production. Consistent with the differences of their effects on B cell responses, KPL-404 was not internalized by cells, whereas G28-5 showed partial internalization upon CD40 binding.

CONCLUSIONS

Anti-CD40 mAb KPL-404 showed purely antagonistic effects on B cells and total PBMCs. KPL-404 inhibited CD40L-CD40-mediated B cell activation in PBMC cultures from both healthy controls and autoimmune patients. These data support the therapeutic potential of CD40 targeting by KPL-404 Ab for inhibiting B cell responses in SjS and SLE.

FcγRIIA expression accelerates nephritis and increases platelet activation in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease characterized by deposits of immune complexes (ICs) in organs and tissues. The expression of FcγRIIA by human platelets, which is their unique receptor for immunoglobulin G antibodies, positions them to ideally respond to circulating ICs. Whereas chronic platelet activation and thrombosis are well-recognized features of human SLE, the exact mechanisms underlying platelet activation in SLE remain unknown. Here, we evaluated the involvement of FcγRIIA in the course of SLE and platelet activation. In patients with SLE, levels of ICs are associated with platelet activation. Because FcγRIIA is absent in mice, and murine platelets do not respond to ICs in any existing mouse model of SLE, we introduced the FcγRIIA (FCGR2A) transgene into the NZB/NZWF1 mouse model of SLE. In mice, FcγRIIA expression by bone marrow cells severely aggravated lupus nephritis and accelerated death. Lupus onset initiated major changes to the platelet transcriptome, both in FcγRIIA-expressing and nonexpressing mice, but enrichment for type I interferon response gene changes was specifically observed in the FcγRIIA mice. Moreover, circulating platelets were degranulated and were found to interact with neutrophils in FcγRIIA-expressing lupus mice. FcγRIIA expression in lupus mice also led to thrombosis in lungs and kidneys. The model recapitulates hallmarks of human SLE and can be used to identify contributions of different cellular lineages in the manifestations of SLE. The study further reveals a role for FcγRIIA in nephritis and in platelet activation in SLE.

Safety, pharmacokinetics and pharmacodynamics of BI 655064 in phase 1 clinical trials in healthy Chinese and Japanese subjects

Aims

To evaluate the safety, pharmacokinetics and pharmacodynamics of BI 655064 in healthy Chinese and Japanese subjects after administration of single doses of 80‐240 mg and multiple dosing of 240 mg once weekly over 4 weeks.

Methods

Two phase 1, double‐blind, placebo‐controlled studies were conducted (single‐rising doses of BI 655064 in Chinese/Japanese male subjects [n = 12 per BI 655064 dose group] or repeated 240 mg BI 655064 in Chinese male subjects [n = 9]). Plasma samples were collected to investigate BI 655064 pharmacokinetics, pharmacodynamics (CD40 receptor occupancy [RO]) and immunogenicity, along with the safety and tolerability of BI 655064.

Results

BI 655064 showed good overall tolerability following single‐dose administration of 80‐240 mg and repeated administration of 240 mg BI 655064 over 4 weeks. More Chinese subjects reported adverse events compared with Japanese subjects following single‐dose administration (59.4% vs 3.1%). BI 655064 exhibited nonlinear, saturable kinetics, with higher doses resulting in slower apparent clearance (0.514‐0.713 mL min⁻¹), and disproportionately higher total exposure (AUC_0‐inf; 5610‐7780 μg·h mL⁻¹) and maximum plasma concentration (15 700‐21 300 ng mL⁻¹) with 240 mg BI 655064. Ninety percent inhibition of CD40 RO was achieved with doses ≥120 mg, and a direct relationship between BI 655064 plasma concentration and inhibition of CD40 RO was observed. Most subjects had a positive treatment‐emergent antidrug antibody response.

Conclusions

BI 655064 pharmacokinetic and safety profiles in East Asian male subjects were consistent with those observed in a Western population. No adjustments in the BI 655064 dosing recommendations are warranted for future clinical trials.

CD40/CD40L Signaling as a Promising Therapeutic Target for the Treatment of Renal Disease

The cluster of differentiation 40 (CD40) is activated by the CD40 ligand (CD40L) in a variety of diverse cells types and regulates important processes associated with kidney disease. The CD40/CD40L signaling cascade has been comprehensively studied for its roles in immune functions, whereas the signaling axis involved in local kidney injury has only drawn attention in recent years. Clinical studies have revealed that circulating levels of soluble CD40L (sCD40L) are associated with renal function in the setting of kidney disease. Levels of the circulating CD40 receptor (sCD40), sCD40L, and local CD40 expression are tightly related to renal injury in different types of kidney disease. Additionally, various kidney cell types have been identified as non-professional antigen-presenting cells (APCs) that express CD40 on the cell membrane, which contributes to the interactions between immune cells and local kidney cells during the development of kidney injury. Although the potential for adverse CD40 signaling in kidney cells has been reported in several studies, a summary of those studies focusing on the role of CD40 signaling in the development of kidney disease is lacking. In this review, we describe the outcomes of recent studies and summarize the potential therapeutic methods for kidney disease which target CD40.

CD40/CD40L and Related Signaling Pathways in Cardiovascular Health and Disease-The Pros and Cons for Cardioprotection

The CD40–CD40 ligand (CD40L) dyad represents a scientific and clinical field that has raised many controversies in the past and cannot be clearly defined as being an either beneficial or harmful pathway. Being crucially involved in physiological immunological processes as well as pathological inflammatory reactions, the signaling pathway has been recognized as a key player in the development of both autoimmune and cardiovascular disease. Even though the possibilities of a therapeutic approach to the dyad were recognized decades ago, due to unfortunate events, detailed in this review, pharmacological treatment targeting the dyad, especially in patients suffering from atherosclerosis, is not available. Despite the recent advances in the treatment of classical cardiovascular risk factors, such as arterial hypertension and diabetes mellitus, the treatment of the associated low-grade inflammation that accounts for the progression of atherosclerosis is still challenging. Low-grade inflammation can be detected in a significant portion of patients that suffer from cardiovascular disease and it is therefore imperative to develop new therapeutic strategies in order to combat this driver of atherosclerosis. Of note, established cardiovascular drugs such as angiotensin-converting enzyme inhibitors or statins have proven beneficial cardiovascular effects that are also related to their pleiotropic immunomodulatory properties. In this review, we will discuss the setbacks encountered as well as new avenues discovered on the path to a different, inflammation-centered approach for the treatment of cardiovascular disease with the CD40–CD40L axis as a central therapeutic target.

The NZB/W F1 mouse model for Sjögren's syndrome: A historical perspective and lessons learned

Sjögren's syndrome (SS) is a chronic rheumatic autoimmune disorder affecting multiple organ systems. The clinical findings in SS patients show considerable heterogeneity and overlap with other autoimmune diseases. In addition, the autoimmune response in SS initiates several years before the appearance of clinical symptoms. Thus, understanding the pathogenic mechanisms involved in the disease process have been a challenge. Several animal model systems of SS-like disease have been developed to overcome these issues. The New Zealand Black (NZB) x New Zealand White (NZW) F1 (NZB/W F1) mouse represents the first spontaneous mouse model of SS. In this review, we provide a historical perspective and detailed description of this mouse model focusing on exocrine gland histopathology, autoantibody populations, and glandular dysfunction. Considering that NZB/W F1 mice also develop a systemic lupus erythematosus (SLE)-like disease, this mouse model mimics the clinical presentation of polyautoimmunity seen in a sizable subset of SS patients. It is plausible that such patients will require distinct therapeutic interventions necessary to treat both SLE and SS. Therefore, the NZB/W F1 mouse is a powerful tool to decipher pathogenic mechanisms involved in SS related polyautoimmunity and develop appropriate therapeutic strategies.

IKZF1 polymorphisms are associated with susceptibility, cytokine levels, and clinical features in systemic lupus erythematosus

Ikaros family zinc finger 1(IKZF1) encodes a lymphoid-restricted zinc finger transcription factor named Ikaros that regulates lymphocyte differentiation and proliferation as well as self-tolerance. Increasing evidence indicates that IKZF1 could contribute to the pathogenesis of autoimmune diseases. Recent research has provided evidence that IKZF1 might correlate with Systemic lupus erythematosus (SLE), but no clear definition has been made yet. In this study, we focus on the relationship between IKZF1 polymorphisms and SLE susceptibility, cytokine levels, and clinical characteristics in the Chinese Han population.One thousand seventy-six subjects, including 400 SLE patients and 676 healthy controls, were included in this study. Three single nucleotide polymorphisms within IKZF1 containing rs4917014, rs11980379, and rs4132601 were genotyped in all subjects by an improved multiplex ligation detection reaction technique. 143 subjects from SLE patients were randomly selected for testing the levels of serum cytokines. The clinical characteristics of SLE patients were gathered and collated from medical records. The data were analyzed mainly using SPSS20.0 (SPSS lnc., Chicago, IL).Significant relationships were observed between rs4132601 and SLE susceptibility, CD40 ligand, and malar rash (P < .001, P = .04, and P = .01, respectively). In addition, significant relationships were observed between rs4917014 and susceptibility, granzyme B level, and hematological disorder in SLE (P = .005, P = .03 and P = .005, respectively).The results further support that IKZF1 may have an important role in the development and pathogenesis of SLE. Allele G of rs4132601 and rs4917014 is related to a decreased risk of SLE occurrence and associated with clinical features in SLE patients, including CD40 ligand level, granzyme B level, malar rash, and hematological disorder, which play important roles in disease progression.

Phoenix from the flames: Rediscovering the role of the CD40-CD40L pathway in systemic lupus erythematosus and lupus nephritis

Lupus nephritis (LN) is a significant complication of systemic lupus erythematosus (SLE), increasing its morbidity and mortality. Although the current standard of care helps suppress disease activity, it is associated with toxicity and ultimately does not cure SLE. At present, there are no therapies specifically indicated for the treatment of LN and there is an unmet need in this disease where treatment remains a challenge. The CD40-CD40L pathway is central to SLE pathogenesis and the generation of autoantibodies and their deposition in the kidneys, resulting in renal injury in patients with LN. CD40 is expressed on immune cells (including B cells, monocytes and dendritic cells) and also non-haematopoietic cells. Interactions between CD40L on T cells and CD40 on B cells in the renal interstitium are critical for the local expansion of naive B cells and autoantibody-producing B cells in LN. CD40L-mediated activation of myeloid cells and resident kidney cells, including endothelial cells, proximal tubular epithelial cells, podocytes and mesangial cells, further amplifies the inflammatory milieu in the interstitium and the glomeruli. Several studies have highlighted the upregulated expression of CD40 in LN kidney biopsies, and preclinical data have demonstrated the importance of the CD40-CD40L pathway in murine SLE and LN. Blocking this pathway is expected to ameliorate inflammation driven by infiltrating immune cells and resident kidney cells. Initial experimental therapeutic interventions targeting the CD40-CD40L pathway, based on CD40L antibodies, were associated with an increased incidence of thrombosis. However, this safety issue has not been observed with second-generation CD40/CD40L antibodies that have been engineered to prevent platelet activation. With these advancements, together with recent preclinical and clinical findings, it is anticipated that selective blockade of the CD40-CD40L pathway may address the unmet treatment needs in SLE, LN and other autoimmune diseases.

CD154 inhibits death of T cells via a Cis interaction with the α5β1 integrin

CD154 plays a major role in the pathogenesis of several autoimmune and inflammatory diseases. In addition to CD40, soluble CD154 (sCD154) binds to other receptors namely αIIbβ3, αMβ2, α5β1 and αvβ3 integrins. We have previously reported that binding of sCD154 to α5β1 integrin expressed on several human T cell lines is capable of inhibiting Fas-induced cell death. In the current study, we show that such effect of the sCD154/α5β1 interaction is not restricted to the cell death response induced by Fas but could also be exhibited toward other death signals such as TRAIL and TNF- α. We also demonstrate that sCD154 is capable of inhibiting Fas-mediated death of human activated T cells, more importantly of CD4⁺ than CD8⁺ T ones. Our data also show that membrane-bound CD154 and α5β1 integrin expressed on the surface of distinct cells failed to influence cell death responses. However, when membrane-bound CD154 and α5β1 are expressed on the surface of same cell, their interaction was capable of down regulating cell death. CD154 was shown to co-localize with the α5β1 integrin on the surface of these cells. These data strongly suggest a cis-type of interaction between CD154 and α5β1 when both are expressed on the same cell surface, rather than a trans-interaction which usually implicates the ligand and its receptor each expressed on the surface of a distinct cell. Taken together, these findings add to the list of roles through which CD154 is contributing to the pathogenesis of autoimmune-inflammatory diseases, i.e. by protecting T cells from death and enhancing their survival.

Protecting the kidney in systemic lupus erythematosus: from diagnosis to therapy

Lupus nephritis (LN) is a common manifestation of systemic lupus erythematosus that can lead to irreversible renal impairment. Although the prognosis of LN has improved substantially over the past 50 years, outcomes have plateaued in the USA in the past 20 years as immunosuppressive therapies have failed to reverse disease in more than half of treated patients. This failure might reflect disease complexity and heterogeneity, as well as social and economic barriers to health-care access that can delay intervention until after damage has already occurred. LN progression is still poorly understood and involves multiple cell types and both immune and non-immune mechanisms. Single-cell analysis of intrinsic renal cells and infiltrating cells from patients with LN is a new approach that will help to define the pathways of renal injury at a cellular level. Although many new immune-modulating therapies are being tested in the clinic, the development of therapies to improve regeneration of the injured kidney and to prevent fibrosis requires a better understanding of the mechanisms of LN progression. This mechanistic understanding, together with the development of clinical measures to evaluate risk and detect early disease and better access to expert health-care providers, should improve outcomes for patients with LN.

Targeting the CD40-CD154 Signaling Pathway for Treatment of Autoimmune Arthritis

Full activation of T lymphocytes requires signals from both T cell receptors and costimulatory molecules. In addition to CD28, several T cell molecules could deliver costimulatory signals, including CD154, which primarily interacts with CD40 on B-cells. CD40 is a critical molecule regulating several B-cell functions, such as antibody production, germinal center formation and cellular proliferation. Upregulated expression of CD40 and CD154 occurs in immune effector cells and non-immune cells in different autoimmune diseases. In addition, therapeutic benefits have been observed by blocking the CD40-CD154 interaction in animals with collagen-induced arthritis. Given the therapeutic success of the biologics abatacept, which blocks CD28 costimulation, and rituximab, which deletes B cells in the treatment of autoimmune arthritis, the inhibition of the CD40-CD154 axis has two advantages, namely, attenuating CD154-mediated T cell costimulation and suppressing CD40-mediated B-cell stimulation. Furthermore, blockade of the CD40-CD154 interaction drives the conversion of CD4+ T cells to regulatory T cells that mediate immunosuppression. Currently, several biological products targeting the CD40-CD154 axis have been developed and are undergoing early phase clinical trials with encouraging success in several autoimmune disorders, including autoimmune arthritis. This review addresses the roles of the CD40-CD154 axis in the pathogenesis of autoimmune arthritis and its potential as a therapeutic target.