Molecular blocking of CD23 supports its role in the pathogenesis of arthritis

Fc receptors gone wrong: A comprehensive review of their roles in autoimmune and inflammatory diseases

Systemic autoimmune and inflammatory diseases have a complex and only partially known pathophysiology with various abnormalities involving all the components of the immune system. Among these components, antibodies, and especially autoantibodies are key elements contributing to autoimmunity. The interaction of antibody fragment crystallisable (Fc) and several distinct receptors, namely Fc receptors (FcRs), have gained much attention during the recent years, with possible major therapeutic perspectives for the future. The aim of this review is to comprehensively describe the known roles for FcRs (activating and inhibitory FcγRs, neonatal FcR [FcRn], FcαRI, FcεRs, Ro52/tripartite motif containing 21 [Ro52/TRIM21], FcδR, and the novel Fc receptor-like [FcRL] family) in systemic autoimmune and inflammatory disorders, namely rheumatoid arthritis, Sjögren's syndrome, systemic lupus erythematosus, systemic sclerosis, idiopathic inflammatory myopathies, mixed connective tissue disease, Crohn's disease, ulcerative colitis, immunoglobulin (Ig) A vasculitis, Behçet's disease, Kawasaki disease, IgG4-related disease, immune thrombocytopenia, autoimmune hemolytic anemia, antiphospholipid syndrome and heparin-induced thrombocytopenia.

Fungi, host immune response, and tumorigenesis

Advances in -omics analyses have tremendously enhanced our understanding of the role of the microbiome in human health and disease. Most research is focused on the bacteriome, but scientists have now realized the significance of the virome and microbial dysbiosis as well, particularly in noninfectious diseases such as cancer. In this review, we summarize the role of mycobiome in tumorigenesis, with a dismal prognosis, and attention to pancreatic ductal adenocarcinoma (PDAC). We also discuss bacterial and mycobial interactions to the host's immune response that is prevalently responsible for resistance to cancer therapy, including immunotherapy. We reported that the Malassezia species associated with scalp and skin infections, colonize in human PDAC tumors and accelerate tumorigenesis via activating the C3 complement-mannose-binding lectin (MBL) pathway. PDAC tumors thrive in an immunosuppressive microenvironment with desmoplastic stroma and a dysbiotic microbiome. Host-microbiome interactions in the tumor milieu pose a significant threat in driving the indolent immune behavior of the tumor. Microbial intervention in multimodal cancer therapy is a promising novel approach to modify an immunotolerant ("cold") tumor microenvironment to an immunocompetent ("hot") milieu that is effective in eliminating tumorigenesis.

Novel Approaches and Challenges of Discovery of Exosite Modulators of a Disintegrin and Metalloprotease 10

A disintegrin and metaproteinase 10 is an important target for multiple therapeutic areas, however, despite drug discovery efforts by both industry and academia no compounds have reached the clinic so far. The lack of enzyme and substrate selectivity of developmental drugs is believed to be a main obstacle to the success. In this review, we will focus on novel approaches and associated challenges in discovery of ADAM10 selective modulators that can overcome shortcomings of previous generations of compounds and be translated into the clinic.

Epstein-Barr Virus- (EBV-) Immortalized Lymphoblastoid Cell Lines (LCLs) Express High Level of CD23 but Low CD27 to Support Their Growth

Epstein-Barr virus (EBV) is one of the common human herpesvirus types in the world. EBV is known to infect more than 95% of adults in the world. The virus mainly infects B lymphocytes and could immortalize and transform the cells into EBV-bearing lymphoblastoid cell lines (LCLs). Limited studies have been focused on characterizing the surface marker expression of the immortalized LCLs. This study demonstrates the generation of 15 LCLs from sixteen rheumatoid arthritis (RA) patients and a healthy volunteer using B95-8 marmoset-derived EBV. The success rate of LCL generation was 88.23%. All CD19+ LCLs expressed CD23 (16.94-58.9%) and CD27 (15.74-80.89%) on cell surface. Our data demonstrated two distinct categories of LCLs (fast- and slow-growing) (p<0.05) based on their doubling time. The slow-growing LCLs showed lower CD23 level (35.28%) compared to fast-growing LCLs (42.39%). In contrast, the slow-growing LCLs showed higher percentage in both CD27 alone and CD23+CD27+ in combination. Overall, these findings may suggest the correlations of cellular CD23 and CD27 expression with the proliferation rate of the generated LCLs. Increase expression of CD23 may play a role in EBV immortalization of B-cells and the growth and maintenance of the EBV-transformed LCLs while CD27 expression might have inhibitory effects on LCL proliferation. Further investigations are warranted to these speculations.

Phase IIa trial in Duchenne muscular dystrophy shows vamorolone is a first-in-class dissociative steroidal anti-inflammatory drug

We report a first-in-patient study of vamorolone, a first-in-class dissociative steroidal anti-inflammatory drug, in Duchenne muscular dystrophy. This 2-week, open-label Phase IIa multiple ascending dose study (0.25, 0.75, 2.0, and 6.0 mg/kg/day) enrolled 48 boys with Duchenne muscular dystrophy (4 to <7 years), with outcomes including clinical safety, pharmacokinetics and pharmacodynamic biomarkers. The study design included pharmacodynamic biomarkers in three contexts of use: 1. Secondary outcomes for pharmacodynamic safety (insulin resistance, adrenal suppression, bone turnover); 2. Exploratory outcomes for drug mechanism of action; 3. Exploratory outcomes for expanded pharmacodynamic safety. Vamorolone was safe and well-tolerated through the highest dose tested (6.0 mg/kg/day) and pharmacokinetics of vamorolone were similar to prednisolone. Using pharmacodynamic biomarkers, the study demonstrated improved safety of vamorolone versus glucocorticoids as shown by reduction of insulin resistance, beneficial changes in bone turnover (loss of increased bone resorption and decreased bone formation only at the highest dose level), and a reduction in adrenal suppression. Exploratory biomarkers of pharmacodynamic efficacy showed an anti-inflammatory mechanism of action and a beneficial effect on plasma membrane stability, as demonstrated by a dose-responsive decrease in serum creatine kinase activity. With an array of pre-selected biomarkers in multiple contexts of use, we demonstrate the development of the first dissociative steroid that preserves anti-inflammatory efficacy and decreases steroid-associated safety concerns. Ongoing extension studies offer the potential to bridge exploratory efficacy biomarkers to clinical outcomes.

JNK1 negatively controls antifungal innate immunity by suppressing CD23 expression

Opportunistic fungal infections are a leading cause of death among immune-compromised patients, and there is a pressing need to develop new antifungal therapeutic agents because of toxicity and resistance to the antifungal drugs currently in use. Although C-type lectin receptor- and Toll-like receptor-induced signaling pathways are key activators of host antifungal immunity, little is known about the mechanisms that negatively regulate host immune responses to a fungal infection. Here we found that JNK1 activation suppresses antifungal immunity in mice. We showed that JNK1-deficient mice had a significantly higher survival rate than wild-type control mice in response to Candida albicans infection, and the expression of JNK1 in hematopoietic innate immune cells was critical for this effect. JNK1 deficiency leads to significantly higher induction of CD23, a novel C-type lectin receptor, through NFATc1-mediated regulation of the CD23 gene promoter. Blocking either CD23 upregulation or CD23-dependent nitric oxide production eliminated the enhanced antifungal response found in JNK1-deficient mice. Notably, JNK inhibitors exerted potent antifungal therapeutic effects in both mouse and human cells infected with C. albicans, indicating that JNK1 may be a therapeutic target for treating fungal infection.

Grape polyphenols and propolis mixture inhibits inflammatory mediator release from human leukocytes and reduces clinical scores in experimental arthritis

Polyphenols from red fruits and bee-derived propolis (PR) are bioactive natural products in various in vitro and in vivo models. The present study shows that hematotoxicity-free doses of grape polyphenols (GPE) and PR differentially decreased the secretion of pro-inflammatory cytokines from activated human peripheral blood leucocytes. While GPE inhibited the monocytes/macrophage response, propolis decreased both monokines and interferon γ (IFNγ) production. When used together, their distinct effects lead to the attenuation of all inflammatory mediators, as supported by a significant modulation of the transcriptomic profile of pro-inflammatory genes in human leukocytes. To enforce in vitro data, GPE+PR were tested for their ability to improve clinical scores and cachexia in chronic rat adjuvant-induced arthritis (AA). Extracts significantly reduced arthritis scores and cachexia, and this effect was more significant in animals receiving continuous low doses compared to those receiving five different high doses. Animals treated daily had significantly better clinical scores than corticoid-treated rats. Together, these findings indicate that the GPE+PR combination induces potent anti-inflammatory activity due to their complementary immune cell modulation.

Malvidin-3-O-β glucoside, major grape anthocyanin, inhibits human macrophage-derived inflammatory mediators and decreases clinical scores in arthritic rats

Polyphenolic anthocyanins are major colorful compounds in red fruits, known to prevent cardiovascular and other diseases. Grape polyphenols are a mixture of various molecules and their exact contribution to above bioactivities remains to be clarified. In the present study, we first analyzed the effect of purified grape-derived compounds on human peripheral blood mononuclear cell (PBMC) survival, proliferation, as well as for their ability to inhibit the activation of human normal macrophages. Data indicated that malvidin-3-O-β glucoside (Malβg), the major grape anthocyanin, is bioactive with no toxicity on human PBMC. Malβg decreased the transcription of genes encoding inflammatory mediators, confirmed by the inhibition of TNFα, IL1, IL-6 and iNOS-derived nitric oxide (NO) secretion from activated macrophages. As Malβg also inhibited inflammatory response of rat macrophages, we investigated the anti-inflammatory potential of Malβg in chronic rat adjuvant-induced arthritis (AIA). Malβg significantly diminished inflammatory cachexia and arthritic paw scores in AIA rats at both therapeutic and preventive levels. In vivo effects of Malβg correlated with down-regulation of NO generation from AIA rats' peritoneal macrophages ex vivo. These data indicate that Malβg, major grape anthocyanin, is a potent anti-inflammatory agent in vitro and in vivo, without detectable toxic effect.

Impact of different mesenchymal stromal cell types on T-cell activation, proliferation and migration

Mesenchymal stromal cells (MSCs) isolated from different tissue sources may present distinct immunomodulatory profiles. As lymphocyte responses are a combination of several distinct steps, we evaluated and compared the impact of MSCs from different sources on the activation, proliferation and migration of T-cells. We demonstrated that tissue-derived MSCs have important immunomodulatory effects. AT-MSCs induced potent anti-proliferative and anti-inflammatory (IFN-γ downregulation) effects and differentially modulated several T-cell activation markers (CD23, CD26, CD45, and CD69). Among all the MSC types tested, only AT-MSCs induced significant downregulation of CD26 and CD45 expression. Of importance, AT-MSCs maintained a sustained expression of CD69. AT-MSCs, particularly following exposure to an inflammatory environment, promoted the migration of lymphocytes into their surrounding environment. The AT-MSCs may increase recruitment of T lymphocytes by upregulation of IL-8 and CCL5 secretion. Following their migration, T-cells interact with MSCs, which can impair lymphocyte proliferation and activation depending on their origin. Inflammatory T-cells appeared to be progressively suppressed, which may lead to a population of lymphocytes with a regulatory phenotype. These findings are relevant, as they increase our understanding of the different immunomodulatory effect of MSCs as well as their behavior in an inflammatory environment.

Differential regulation of monocyte cytokine release by αV and β(2) integrins that bind CD23

The human soluble CD23 (sCD23) protein displays highly pleiotropic cytokine-like activity. Monocytic cells express the sCD23-binding integrins αVβ(3), αVβ(5), αMβ(2) and αXβ(2), but it is unclear which of these four integrins most acutely regulates sCD23-driven cytokine release. The hypothesis that ligation of different sCD23-binding integrins promoted release of distinct subsets of cytokines was tested. Lipopolysaccharide (LPS) and sCD23 promoted release of distinct groups of cytokines from the THP-1 model cell line. The sCD23-driven cytokine release signature was characterized by elevated amounts of RANTES (CCL5) and a striking increase in interleukin-8 (IL-8; CXCL8) secretion, but little release of macrophage inflammatory protein 1β (MIP-1β; CCL4). Antibodies to αVβ(3) or αXβ(2) both promoted IL-8 release, consistent with the sCD23-driven pattern, but both also evoked strong MIP-1β secretion; simultaneous ligation of these two integrins further increased cytokine secretion but did not alter the pattern of cytokine output. In both model cell lines and primary tissue, integrin-mediated cytokine release was more pronounced in immature monocyte cells than in mature cells. The capacity of anti-integrin monoclonal antibodies to elicit a cytokine release response is epitope-dependent and also reflects the differentiation state of the cell. Although a pattern of cytokine release identical to that provoked by sCD23 could not be elicited with any individual anti-integrin monoclonal antibody, αXβ(2) and αVβ(3) appear to regulate IL-8 release, a hallmark feature of sCD23-driven cytokine secretion, more acutely than αMβ(2) or αVβ(5).

IgE mediates killing of intracellular Toxoplasma gondii by human macrophages through CD23-dependent, interleukin-10 sensitive pathway

Background

In addition to helminthic infections, elevated serum IgE levels were observed in many protozoal infections, while their contribution during immune response to these pathogens remained unclear. As IgE/antigen immune complexes (IgE-IC) bind to human cells through FcεRI or FcεRII/CD23 surface molecules, the present study aimed to identify which functional receptor may be involved in IgE-IC interaction with human macrophages, the major effector cell during parasite infection.

Methodology/Principal Findings

Human monocyte-derived macrophages were infected with Toxoplasma gondii before being incubated with IgE-IC. IgE receptors were then identified using appropriate blocking antibodies. The activation of cells and parasiticidal activity were evaluated by mediator quantification and direct counting of infected macrophages. RNAs were extracted and cell supernatants were also collected for their content in tumor necrosis factor (TNF)-α, interleukin-10 (IL-10) and nitrites. Sera from symptomatic infected patients were also tested for their content of IgE, IL-10 and nitrites, and compared to values found in healthy donors. Results showed that IgE-IC induced intracellular elimination of parasites by human macrophages. IgE-mediated effect was FcεRI-independent, but required cross-linking of surface FcεRII/CD23, cell activation and the generation of nitric oxide (NO). Although TNF-α was shown to be produced during cell activation, this cytokine had minor contribution in this phenomenon while endogenous and exogenous IL-10 down-regulated parasite killing. Inverse relationship was found between IL-10 and NO expression by infected human macrophages at both mRNA and mediator levels. The relationship between these in vitro data and in vivo levels of various factors in T. gondii infected patients supports the involvement of CD23 antigen and IL-10 expression in disease control.

Conclusion

Thus, IgE may be considered as immune mediator during antiprotozoal activity of human macrophages through its ability to trigger CD23 signaling. Increased cell activation by IgE-IC may also account for chronic inflammatory diseases observed in some patients.

Phage display: selecting straws instead of a needle from a haystack

An increasing number of peptides with specific binding affinity to various protein and even non-protein targets are being discovered from phage display libraries. The power of this method lies in its ability to efficiently and rapidly identify ligands with a desired target property from a large population of phage clones displaying diverse surface peptides. However, the search for the needle in the haystack does not always end successfully. False positive results may appear. Thus instead of specific binders phage with no actual affinity toward the target are recovered due to their propagation advantages or binding to other components of the screening system, such as the solid phase, capturing reagents, contaminants in the target sample or blocking agents, rather than the target. Biopanning experiments on different targets performed in our laboratory revealed some previously identified and many new target-unrelated peptide sequences, which have already been frequently described and published, but not yet recognized as target-unrelated. Distinguishing true binders from false positives is an important step toward phage display selections of greater integrity. This article thoroughly reviews and discusses already identified and new target-unrelated peptides and suggests strategies to avoid their isolation.

CD23/FcεRII: molecular multi-tasking

CD23 is the low-affinity receptor for immunoglobulin (Ig)E and plays important roles in the regulation of IgE responses. CD23 can be cleaved from cell surfaces to yield a range of soluble CD23 (sCD23) proteins that have pleiotropic cytokine-like activities. The regions of CD23 responsible for interaction with many of its known ligands, including IgE, CD21, major histocompatibility complex (MHC) class II and integrins, have been identified and help to explain the structure-function relationships within the CD23 protein. Translational studies of CD23 underline its credibility as a target for therapeutic intervention strategies and illustrate its involvement in mediating therapeutic effects of antibodies directed at other targets.

Circulating levels of the innate and humoral immune regulators CD14 and CD23 are associated with adult glioma

Allergy history has been consistently inversely associated with glioma risk. Two serologic markers, soluble CD23 (sCD23) and soluble CD14 (sCD14), are part of the innate and adaptive humoral immune systems and modulate allergic responses in opposite directions, with sCD23 enhancing and sCD14 blunting inflammatory responses. We measured sCD23 and sCD14 in serum from blood that was drawn at a single time point from 1,079 glioma patients postdiagnosis and 736 healthy controls. Glioma was strongly associated with high sCD14 [highest versus lowest quartile odds ratio (OR), 3.94; 95% confidence interval (95% CI), 2.98-5.21] and low sCD23 (lowest versus highest quartile OR, 2.5; 95% CI, 1.89-3.23). Results were consistent across glioma histologic types and grades, but were strongest for glioblastoma. Whereas temozolomide treatment was not associated with either sCD14 or sCD23 levels among cases, those taking dexamethasone had somewhat lower sCD23 levels than those not taking dexamethasone. However, sCD23 was associated with case status regardless of dexamethasone treatment. These results augment the long-observed association between allergies and glioma and support a role for the innate and adaptive humoral functions of the immune system, in particular immunoregulatory proteins, in gliomagenesis.

Increases in levels of schistosome-specific immunoglobulin E and CD23(+) B cells in a cohort of Kenyan children undergoing repeated treatment and reinfection with Schistosoma mansoni

BACKGROUND

Age prevalence curves for areas in which schistosomiasis is endemic suggest that humans develop partial immunity to reinfection beginning in early adolescence. We conducted a 2-year longitudinal study to determine whether children infected with Schistosoma mansoni develop protection-related immune responses after treatment with praziquantel and whether the development of these immune responses is accelerated by frequent treatment after reinfection.

METHODS

Children (8-10 years old) were tested for S. mansoni every 4 months and treated with praziquantel when positive (arm A; n=68) or were tested and treated at the end of the 2-year follow-up period (arm B; n=49).

RESULTS

Children in arm A who remained free of infection during follow-up had significantly higher baseline levels of schistosome-specific immunoglobulin E (IgE) than did children with > or =2 repeat diagnoses of S. mansoni infection. Children with > or =2 repeat diagnoses of S. mansoni infection had significantly increased levels of anti-schistosome IgE and CD23(+) B cells after receiving > or =3 praziquantel treatments over the course of follow-up. No increase in either parameter was seen in children who received only the baseline praziquantel treatment.

CONCLUSIONS

B cell activation and anti-schistosome IgE are associated with resistance to S. mansoni in children, and these immunological parameters can be increased by multiple rounds of infections and praziquantel-induced cures.

CD23 mediates antimycobacterial activity of human macrophages

Engagement of surface receptors contributes to the antimicrobial activity of human immune cells. We show here that infection of human monocyte-derived macrophages (MDM) with live Mycobacterium avium induced the expression of CD23 on their membrane. Subsequent cross-linking of surface CD23 by appropriate ligands induced a dose-dependent antibacterial activity of MDM and the elimination of most infected cells. The stimulation of inducible nitric oxide synthase-dependent generation of NO from MDM after CD23 activation played a major role during their anti-M. avium activity. CD23 activation also induced tumor necrosis factor alpha (TNF-alpha) production from MDM. Mycobacteria reduction was partially inhibited by the addition of neutralizing anti-TNF-alpha antibody to cell cultures without affecting NO levels, which suggested the role of this cytokine for optimal antimicrobial activity. Finally, interleukin-10, a Th2 cytokine known to downregulate CD23 pathway, is shown to decrease NO generation and mycobacteria elimination by macrophages. Therefore, (i) infection with M. avium promotes functional surface CD23 expression on human macrophages and (ii) subsequent signaling of this molecule contributes to the antimicrobial activity of these cells through an NO- and TNF-alpha-dependent pathway. This study reveals a new human immune response mechanism to counter mycobacterial infection involving CD23 and its related ligands.