Inhibition of complement alternative pathway suppresses experimental autoimmune anterior uveitis by modulating T cell responses

Alternative Complement Pathway Signature Determines Immunosuppression and Resistance to Immunotherapy Plus Tyrosine Kinase Inhibitor Combinations in Renal Cell Carcinoma

BACKGROUND

Latest guidelines recommended immunotherapy (IO) plus tyrosine kinase inhibitor (TKI) combination as standard first-line therapy in renal cell carcinoma (RCC), with no predictive biomarker being applied. Complement system shapes tumor microenvironment, which may influence TKI+IO benefit.

METHODS

Two cohorts from our institute and 2 external cohorts were enrolled. RNA-sequencing was performed for each sample, and alternative complement pathway signature (ACPS) was defined by single sample gene set enrichment analysis. Immune infiltration and function were assessed by immunohistochemistry and flow cytometry.

RESULTS

Under TKI+IO therapy, ACPS was elevated in non-responders (P<0.01), and high-ACPS predicted lower response rate and shorter progression-free survival (P=0.040). Moreover, TKI+IO, rather than TKI monotherapy, may benefit patients of low-ACPS combined with SETD2-wild type (HR=0.55, P<0.001). In RCC, ACPS was associated with increased tumor-infiltrating T cells (Spearman's ρ=0.50, P=0.001). However, in high-ACPS samples, CD8+ T cells revealed an exhausted phenotype with decreased GZMB (P<0.001) and increased PD1 (P=0.008) expression. Elevated PD1 expression in high-ACPS samples was confirmed by immunohistochemistry (P=0.046). Besides, macrophage infiltration was increased in high-ACPS samples (P=0.045), along with suppressive cytokines.

CONCLUSIONS

Under TKI+IO, high-ACPS was linked to immunosuppression and treatment resistance. ACPS might be used as a biomarker for better treatment strategy between TKI+IO or TKI monotherapy.

Targeting the Complement Alternative Pathway Permits Graft Versus Leukemia Activity while Preventing Graft Versus Host Disease

PURPOSE

Application of allogeneic hematopoietic cell transplantation (allo-HCT) for patients with hematologic disorders is limited by the development of GVHD. Separation of GVHD and graft-versus-leukemia (GVL) remains a great challenge in the field. We investigated the contribution of individual pathways involved in the complement cascade in GVH and GVL responses to identify specific targets by which to separate these two processes.

EXPERIMENTAL DESIGN

We used multiple preclinical murine and human-to-mouse xenograft models involving allo-HCT recipients lacking components of the alternative pathway (AP) or classical pathway (CP)/lectin pathway (LP) to dissect the role of each individual pathway in GVHD pathogenesis and the GVL effect. For translational purposes, we used the AP-specific complement inhibitor, CR2-fH, which localizes in injured target organs to allow specific blockade of complement activation at sites of inflammation.

RESULTS

Complement deposition was evident in intestines of mice and patients with GVHD. In a preclinical setting, ablation of the AP, but not the CP/LP, significantly improved GVHD outcomes. Complement activation through the AP in host hematopoietic cells, and specifically dendritic cells (DC), was required for GVHD progression. AP deficiency in recipients decreased donor T-cell migration and Th1/Th2 differentiation, while increasing the generation of regulatory T cells. This was because of decreased activation and stimulatory activity of recipient DCs in GVHD target organs. Treatment with CR2-fH effectively prevented GVHD while preserving GVL activity.

CONCLUSIONS

This study highlights the AP as a new therapeutic target to prevent GVHD and tumor relapse after allo-HCT. Targeting the AP by CR2-fH represents a promising therapeutic approach for GVHD treatment.

Sarcoidosis Related Novel Candidate Genes Identified by Multi-Omics Integrative Analyses

Sarcoidosis is a multifactorial systemic disease characterized by granulomatous inflammation and greatly impacting on global public health. The etiology and mechanisms of sarcoidosis are not fully understood. Recent high-throughput biological research has generated vast amounts of multi-omics big data on sarcoidosis, but their significance remains to be determined. We sought to identify novel candidate regions, and genes consistently altered in heterogeneous omics studies so as to reveal the underlying molecular mechanisms. We conducted a comprehensive integrative literature analysis on global data on sarcoidosis, including genomic, transcriptomic, proteomic, and phenomic studies. We performed positional integration analysis of 38 eligible datasets originating from 17 different biological layers. Using the integration interval length of 50 kb, we identified 54 regions reaching significance value p ≤ 0.0001 and 15 regions with significance value p ≤ 0.00001, when applying more stringent criteria. Secondary literature analysis of the top 20 regions, with the most significant accumulation of signals, revealed several novel candidate genes for which associations with sarcoidosis have not yet been established, but have considerable support for their involvement based on omic data. These new plausible candidate genes include NELFE, CFB, EGFL7, AGPAT2, FKBPL, NRC3, and NEU1. Furthermore, annotated data were prepared to enable custom visualization and browsing of these sarcoidosis related omics evidence in the University of California Santa Cruz (UCSC) Genome Browser. Further multi-omics approaches are called for sarcoidosis biomarkers and diagnostic and therapeutic innovation. Our approach for harnessing multi-omics data and the findings presented herein reflect important steps toward understanding the etiology and underlying pathological mechanisms of sarcoidosis.

Complement Component C4 Regulates the Development of Experimental Autoimmune Uveitis through a T Cell-Intrinsic Mechanism

In addition to its conventional roles in the innate immune system, complement has been found to directly regulate T cells in the adaptive immune system. Complement components, including C3, C5, and factor D, are important in regulating T cell responses. However, whether complement component C4 is involved in regulating T cell responses remains unclear. In this study, we used a T cell-dependent model of autoimmunity, experimental autoimmune uveitis (EAU) to address this issue. We compared disease severity in wild-type (WT) and C4 knockout (KO) mice using indirect ophthalmoscopy, scanning laser ophthalmoscopy, spectral-domain optical coherence tomography, and histopathological analysis. We also explored the underlying mechanism by examining T cell responses in ex vivo antigen-specific recall assays and in in vitro T cell priming assays using bone marrow-derived dendritic cells, splenic dendritic cells, and T cells from WT or C4 KO mice. We found that C4 KO mice develop less severe retinal inflammation than WT mice in EAU and show reduced autoreactive T cell responses and decreased retinal T cell infiltration. We also found that T cells, but not dendritic cells, from C4 KO mice have impaired function. These results demonstrate a previously unknown role of C4 in regulating T cell responses, which affects the development of T cell-mediated autoimmunity, as exemplified by EAU. Our data could shed light on the pathogenesis of autoimmune uveitis in humans.

Association of the C2-CFB locus with non-infectious uveitis, specifically predisposed to Vogt-Koyanagi-Harada disease

Complement component 2 (C2) and factor B (CFB) are regulators of complement system and involved in the alternative pathway, which have been identified to be associated with multiple immune-related diseases. This study aimed to investigate the association of these genes with non-infectious intermediate and posterior uveitis. A total of 260 Chinese non-infectious uveitis patients were recruited, including 97 patients with Vogt-Koyanagi-Harada disease (VKH), 70 patients with intermediate uveitis (IU) and 93 patients with Behçet's disease (BD). Two hundred and ninety-three normal control subjects were also recruited. Five SNPs across the C2/CFB region were selected and genotyped using TaqMan SNP Genotyping Assays. Association analysis was adjusted for gender and stratified by different subtypes. The CFB SNP rs1048709 was significantly associated with non-infectious uveitis [P corr = 0.01, OR 1.49 (allele model) and P corr = 0.04, OR 1.58 (dominant model), respectively], and similar association was also detected between rs1048709 and female uveitis patients (P corr = 0.01, OR 1.70 and P corr = 0.049, OR 184, respectively). Moreover, subgroup analyses showed that CFB-rs1048709 was specifically associated with VKH, where significantly higher frequencies of A allele and AA homozygosity were observed in VKH patients compared with controls (P corr = 0.025 and P corr = 0.035, respectively), whereas none of these five SNPs was associated with IU or BD. In addition, a haplotype block across CFB (GTG) was significantly predisposed to uveitis with protective effect (OR 0.66, P corr = 0.048). Our results revealed a significant association of CFB with non-infectious uveitis, particularly predisposed to VKH disease. Genetic differences for uveitis could be gender-specific.

Genotype-Phenotype Association Study Reveals CFI-Rs13104777 to be a Protective Genetic Marker Against Acute Anterior Uveitis

PURPOSE

To investigate the roles of CFI, genotype-phenotype associations were identified in AAU.

METHODS

A case-control study was conducted in a total of 575 subjects consisting of 279 AAU patients and 296 healthy controls. Genotypic analyses were performed using Sequenom MassARRAY technology. Analyses were stratified to a series of clinical ophthalmic confounding factors.

RESULTS

A lower frequency of the CFI-rs13104777 C allele was found in the AAU cohort compared with the controls, and, thus, was significantly associated with AAU pathogenesis (p = 0.041, OR = 0.712, 95% CI: 0.513-0.987). Stratified analysis also demonstrated the associations may differ depending on the HLA-B27 status and laterality status.

CONCLUSIONS

This study has revealed a significant genetic role for CFI-rs13104777 in AAU. This influence may be dependent on human leukocyte antigen (HLA)-B27 and disease laterality. Overall, the results provide evidence for a pathogenic role for CFI in AAU and expand our knowledge on the genetic basis of AAU.

CFI-rs7356506 polymorphisms associated with Vogt-Koyanagi-Harada syndrome

PURPOSE

Complement factor I (CFI) plays an important role in complement activation pathways and is known to affect the development of uveitis. The present study was performed to investigate the existence of an association between CFI genetic polymorphisms and Vogt-Koyanagi-Harada (VKH) syndrome.

METHODS

A total of 100 patients diagnosed with VKH syndrome and 300 healthy controls were recruited for the study. Two milliliters of peripheral blood were collected in a sterile anticoagulative tube. CFI-rs7356506 polymorphisms were genotyped using Sequenom MassARRAY technology. Allele and genotype frequencies were compared between patients and controls using a χ(2) test. The analyses were stratified for recurrent status, complicated cataract status, and steroid-sensitive status.

RESULTS

No significant association was found between CFI-rs7356506 polymorphisms and VKH syndrome. However, patients with recurrent VKH syndrome had lower frequencies of the G allele and GG homozygosity in CFI-rs7356506 when compared to the controls (p=0.016, odds ratio [OR]=0.429, 95% confidence interval [CI]=0.212-0.871; p=0.014, OR=0.364, 95% CI=0.158-0.837, respectively). Furthermore, there were significant decreases in the frequencies of the G allele and GG homozygosity in CFI-rs7356506 in patients with VKH syndrome with complicated cataract compared to the controls (p<0.001, OR=0.357, 95% CI=0.197-0.648; p<0.001, OR=0.273, 95% CI=0.135-0.551, respectively). Nevertheless, no significant association with patients with VKH syndrome in steroid-sensitive statuses was detected for CFI-rs7356506 polymorphisms.

CONCLUSIONS

Our results indicate that CFI polymorphisms are not significantly associated with VKH syndrome; nevertheless, we identified a trend for the association of CFI-7356506 with VKH syndrome that depends on the recurrent status and the complicated cataract status but not on the steroid-sensitive status.

Genetic of uveitis

Immune-mediated uveitis may be associated with a systemic disease or may be localized to the eye. T-cell-dependent immunological events are increasingly being regarded as extremely important in the pathogenesis of uveitis. Several studies have also shown that macrophages are major effectors of tissue damage in uveitis. Uveitis phenotypes can differ substantially, and most uveitis diseases are considered polygenic with complex inheritance patterns. This review attempts to present the current state of knowledge from in vitro and in vivo research on the role of genetics in the development and clinical course of uveitis. A review of the literature in the PubMed, MEDLINE, and Cochrane databases was conducted to identify clinical trials, comparative studies, case series, and case reports describing host genetic factors as well as immune imbalance which contribute to the development of uveitis. The search was limited to primary reports published in English with human subjects from 1990 to the present, yielding 3590 manuscripts. In addition, referenced articles from the initial searches were hand searched to identify additional relevant reports. After title and abstract selection, duplicate elimination, and manual search, 55 papers were selected for analysis and reviewed by the authors for inclusion in this review. Studies have demonstrated associations between various genetic factors and the development and clinical course of intraocular inflammatory conditions. Genes involved included genes expressing interleukins, chemokines, chemokine receptors, and tumor necrosis factor and genes involved in complement system. When considering the genetics of uveitis, common threads can be identified. Genome-wide scans and other genetic methods are becoming increasingly successful in identifying genetic loci and candidate genes in many inflammatory disorders that have a uveitic component. It will be important to test these findings as uveitis-specific genetic factors. Therefore, the burgeoning understanding of the human genome promises to result in new insight into the pathogenesis of uveitis.

Complement anaphylatoxin receptors C3aR and C5aR are required in the pathogenesis of experimental autoimmune uveitis

Recent studies have suggested that reagents inhibiting complement activation could be effective in treating T cell mediated autoimmune diseases such as autoimmune uveitis. However, the precise role of the complement anaphylatoxin receptors (C3a and C5a receptors) in the pathogenesis of autoimmune uveitis remains elusive and controversial. We induced experimental autoimmune uveitis in mice deficient or sufficient in both C3a and C5a receptors and rigorously compared their retinal phenotype using various imaging techniques, including indirect ophthalmoscopy, confocal scanning laser ophthalmoscopy, spectral domain optical coherence tomography, topical endoscopic fundus imaging, and histopathological analysis. We also assessed retinal function using electroretinography. Moreover, we performed Ag-specific T cell recall assays and T cell adoptive transfer experiments to compare pathogenic T cell activity between wild-type and knockout mice with experimental autoimmune uveitis. These experiments showed that C3a receptor/C5a receptor-deficient mice developed much less severe uveitis than did control mice using all retinal examination methods and that these mice had reduced pathogenic T cell responses. Our data demonstrate that both complement anaphylatoxin receptors are important for the development of experimental autoimmune uveitis, suggesting that targeting these receptors could be a valid approach for treating patients with autoimmune uveitis.

Autoimmune uveitis: clinical, pathogenetic, and therapeutic features

Autoimmune uveitis (AU), an inflammatory non-infectious process of the vascular layer of the eye, can lead to visual impairment and, in the absence of a timely diagnosis and suitable therapy, can even result in total blindness. The majority of AU cases are idiopathic, whereas fewer than 20 % are associated with systemic diseases. The clinical severity of AU depends on whether the anterior, intermediate, or posterior part of the uvea is involved and may range from almost asymptomatic to rapidly sight-threatening forms. Race, genetic background, and environmental factors can also influence the clinical picture. The pathogenetic mechanism of AU is still poorly defined, given its remarkable heterogeneity and the many discrepancies between experimental and human uveitis. Even so, the onset of AU is thought to be related to an aberrant T cell-mediated immune response, triggered by inflammation and directed against retinal or cross-reactive antigens. B cells may also play a role in uveal antigen presentation and in the subsequent activation of T cells. The management of AU remains a challenge for clinicians, especially because of the paucity of randomized clinical trials that have systematically evaluated the effectiveness of different drugs. In addition to topical treatment, several different therapeutic options are available, although a standardized regimen is thus far lacking. Current guidelines recommend corticosteroids as the first-line therapy for patients with active AU. Immunosuppressive drugs may be subsequently required to treat steroid-resistant AU and for steroid-sparing purposes. The recent introduction of biological agents, such as those targeting tumor necrosis factor-α, is expected to remarkably increase the percentages of responders and to prevent irreversible sight impairment. This paper reviews the clinical features of AU and its crucial pathogenetic targets in relation to the current therapeutic perspectives. Also, the largest clinical trials conducted in the last 12 years for the treatment of AU are summarized and critically discussed.

Chitosan oligosaccharides attenuate ocular inflammation in rats with experimental autoimmune anterior uveitis

We investigated the protective effects and mechanisms of chitosan oligosaccharides (COS) on experimental autoimmune anterior uveitis (EAAU) in rats. EAAU was induced in Lewis rats by footpad and intraperitoneal injections of melanin-associated antigen. The rats received intraperitoneal injections of low-dose (5 mg/kg) or high-dose (10 mg/kg) COS or PBS daily after the immunization. The effects of COS were evaluated by determining the clinical scores and the morphology of the iris/ciliary body (ICB). The expression of inflammatory mediators was evaluated using western blot, immunofluorescence, and ELISA. Treatment with COS significantly attenuated the clinical scores and the leukocyte infiltration in the ICB in a dose-dependent manner. COS effectively reduced the expression of inflammatory mediators (TNF-α, iNOS, MCP-1, RANTES, fractalkine, and ICAM-1). Moreover, COS decreased the IκB degradation and p65 presence in the ICB, which resulted in the inhibition of NF-κB/DNA binding activity. In an in vitro study, sensitized spleen-derived lymphocytes of the COS-treated group showed less chemotaxis toward their aqueous humor and decreased secretion of the above inflammatory mediators in the culture media. COS treated EAAU by inhibiting the activation of NF-κB and reducing the expression of inflammatory mediators. COS might be a potential treatment for acute anterior uveitis.

Influence of molecular genetics in Vogt-Koyanagi-Harada disease

Vogt-Koyanagi-Harada (VKH) disease is a systemic autoimmune disorder against melanocytes. Recent studies have identified multiple genetic factors that might be associated with the pathogenesis of VKH disease. We performed an electronic database search of PubMed, MEDLINE, and EMBASE, and all relevant papers published up to 13 June 2014 were reviewed. A total of 1,031 publications including articles relevant to the genetics of VKH disease and the references of these articles were reviewed. The review identified a number of genetic factors which might be involved in the pathogenesis of VKH disease, some of which may alter the clinical course of VKH disease. Genes which might be involved in the pathogenesis of VKH disease included genes expressing HLA, complement factor H, interleukins, cytotoxic T-lymphocyte antigen 4 (CTLA-4), killer cell immunoglobulin-like receptors (KIR), programmed cell death 1 (PDCD1), protein tyrosine phosphatase non-receptor 22 (PTPN22), osteopontin, tumor necrosis factor alpha-induced protein 3 (TNFAIP3), macrophage migration inhibitory factor (MIF), and other immune response genes. Further studies to explore the correlation among different genotypes and phenotypes of VKH disease will be useful to shed light on the pathogenesis of uveitis in VKH disease and may facilitate the development of new treatment modalities of uveitis in VKH disease.