Reporting and Establishment of Reference Intervals for Antiphospholipid Antibody Immunoassays: A Survey of Participants in the College of American Pathologists Proficiency Testing Program

CONTEXT.—

Misdiagnosis of antiphospholipid syndrome can occur owing to the wide diversity of antiphospholipid (aPL) assays and a lack of international calibrators and harmonized reference intervals.

OBJECTIVE.—

To assess laboratory practices regarding reporting and establishing reference intervals for immunoglobulin (Ig) G/IgM anti-cardiolipin (aCL) and anti-beta-2 glycoprotein I (anti-β2GPI) assays.

DESIGN.—

Supplemental questions related to reporting and establishing reference ranges for aPL assays were sent as part of the Antiphospholipid Antibody (ACL)-B 2019 College of American Pathologists (CAP) proficiency testing survey. The response rate and methods assessment details were determined, as well as qualitative and quantitative results for 3 test samples.

RESULTS.—

The number of participants reporting results for IgG aCL (n = 489), IgM aCL (n = 476), IgG anti-β2GPI (n = 354), and IgM anti-β2GPI (n = 331) varied by antibody type. The enzyme-linked immunosorbent assay (ELISA) (up to 58.6%, 260 of 444) was the most used method; others included multiplex (from 18.9% to 23.9%), fluorescence enzyme immunoassay (14.4%-17.6%), and chemiluminescence immunoassay (6.5%-9.0%). More respondents reported quantitative than qualitative results, and manufacturer cutoff ranges were used by 92.9% and 94.2% of respondents for aCL and anti-β2GPI, respectively. Despite variation in the use of semiquantitative ranges, qualitative negative/positive reporting of the test samples achieved almost 100% consensus. Qualitative consensus was met in contrast to the wide range of quantitative results obtained for each analyte across different kits.

CONCLUSIONS.—

ELISA remains the most used method for detecting aPL antibodies, with most laboratories reporting quantitative results based on manufacturers' suggested reference ranges. The categorization of quantitative results as equivocal, weak positive, or positive for responders using kits from the same manufacturer was variable.

New molecular targets in the treatment of rheumatoid arthritis

PURPOSE OF REVIEW

This review will discuss selected emerging molecular targets and associated potential therapeutic agents for rheumatoid arthritis (RA)-directed treatment.

RECENT FINDINGS

Agents in active development for RA treatment include those targeted to CD40 and CD40 ligand, programmed death protein 1 (PD-1), and granulocyte-macrophage colony-stimulating factor (GM-CSF). Several other molecules with a strong theoretical role in RA pathogenesis and/or demonstrated efficacy in other autoimmune diseases are also being evaluated as potential drug targets in preclinical or translational studies in RA. These targets include interleukin 1 receptor associated kinases 1 and 4 (IRAK1, IRAK4), tyrosine kinase 2 (Tyk2), bradykinin receptor 1 (B1R), OX40 and OX40 ligand.

SUMMARY

Identification of molecular targets for RA treatment remains an active area of investigation, with multiple therapeutic agents in clinical and preclinical development.

CD6 triggers actomyosin cytoskeleton remodeling after binding to its receptor complex

The T cell marker CD6 regulates both T cells and target cells during inflammatory responses by interacting with its receptors. However, only a few receptors binding to the extracellular domains of CD6 have been identified, and cellular events induced by CD6 engagement with its receptors in target cells remain poorly understood. In this study, we identified CD44 as a novel CD6 receptor by proximity labeling and confirmed the new CD6-CD44 interaction by biochemical and biophysical approaches. CD44 and the other 2 known CD6 receptors, CD166 and CDCP1, were distributed diffusely on resting retinal pigment epithelium (RPE) cells but clustered together to form a receptor complex upon CD6 binding. CD6 stimulation induced dramatic remodeling of the actomyosin cytoskeleton in RPE cells mediated by activation of RhoA, and Rho-associated kinase signaling, resulting in increased myosin II phosphorylation. Such actomyosin activation triggered the disassembly of tight junctions responsible for RPE barrier integrity in a process that required all components of the tripartite CD6 receptor complex. These data provided new insights into the mechanisms by which CD6 mediates T cell-driven disruption of tissue barriers during inflammation.

Siponimod Attenuates Neuronal Cell Death Triggered by Neuroinflammation via NFκB and Mitochondrial Pathways

Multiple sclerosis (MS) is the most common autoimmune demyelinating disease of the central nervous system (CNS), consisting of heterogeneous clinical courses varying from relapsing-remitting MS (RRMS), in which disability is linked to bouts of inflammation, to progressive disease such as primary progressive MS (PPMS) and secondary progressive MS (SPMS), in which neurological disability is thought to be linked to neurodegeneration. As a result, successful therapeutics for progressive MS likely need to have both anti-inflammatory and direct neuroprotective properties. The modulation of sphingosine-1-phosphate (S1P) receptors has been implicated in neuroprotection in preclinical animal models. Siponimod/BAF312, the first oral treatment approved for SPMS, may have direct neuroprotective benefits mediated by its activity as a selective (S1P receptor 1) S1P1 and (S1P receptor 5) S1P5 modulator. We showed that S1P1 was mainly present in cortical neurons in lesioned areas of the MS brain. To gain a better understanding of the neuroprotective effects of siponimod in MS, we used both rat neurons and human-induced pluripotent stem cell (iPSC)-derived neurons treated with the neuroinflammatory cytokine tumor necrosis factor-alpha (TNF-α). Cell survival/apoptotic assays using flow cytometry and IncuCyte live cell analyses showed that siponimod decreased TNF-α induced neuronal cell apoptosis in both rat and human iPSCs. Importantly, a transcriptomic analysis revealed that mitochondrial oxidative phosphorylation, NFκB and cytokine signaling pathways contributed to siponimod's neuroprotective effects. Our data suggest that the neuroprotection of siponimod/BAF312 likely involves the relief of oxidative stress in neuronal cells. Further studies are needed to explore the molecular mechanisms of such interactions to determine the relationship between mitochondrial dysfunction and neuroinflammation/neurodegeneration.

Activation of cytotoxic lymphocytes through CD6 enhances killing of cancer cells

Immune checkpoint inhibitors (ICIs) have demonstrated efficacy and improved survival in a growing number of cancers. Despite their success, ICIs are associated with immune-related adverse events that can interfere with their use. Therefore, safer approaches are needed. CD6, expressed by T-lymphocytes and human NK cells, engages in cell-cell interactions by binding to its ligands CD166 (ALCAM) and CD318 (CDCP1). CD6 is a target protein for regulating immune responses and is required for the development of several mouse models of autoimmunity. Interestingly, CD6 is exclusively expressed on immune cells while CD318 is strongly expressed on most cancers. Here we demonstrate that disrupting the CD6-CD318 axis with UMCD6, an anti-CD6 monoclonal antibody, prolongs survival of mice in xenograft mouse models of human breast and prostate cancer, treated with infusions of human lymphocytes. Analysis of tumor-infiltrating immune cells showed that augmentation of lymphocyte cytotoxicity by UMCD6 is due to effects of this antibody on NK, NKT and CD8 + T cells. In particular, tumor-infiltrating cytotoxic lymphocytes from UMCD6-treated mice expressed higher levels of perforin and were found in higher proportions than those from IgG-treated mice. Moreover, RNA-seq analysis of human NK-92 cells treated with UMCD6 revealed that UMCD6 up-regulates the NKG2D-DAP10 receptor complex, important in NK cell activation, as well as its downstream target PI3K. Our results now describe the phenotypic changes that occur on immune cells upon treatment with UMCD6 and further confirm that the CD6-CD318 axis can regulate the activation state of cytotoxic lymphocytes and their positioning within the tumor microenvironment.

Challenges and promise of targeting miRNA in rheumatic diseases: a computational approach to identify miRNA association with cell types, cytokines, and disease mechanisms

MicroRNAs (miRNAs) are small non-coding RNAs that alter the expression of target genes at the post-transcriptional level, influencing diverse outcomes in metabolism, cell differentiation, proliferation, cell survival, and cell death. Dysregulated miRNA expression is implicated in various rheumatic conditions, including ankylosing spondylitis (AS), gout, juvenile idiopathic arthritis (JIA), osteoarthritis (OA), psoriatic arthritis, rheumatoid arthritis (RA), Sjogren's syndrome, systemic lupus erythematosus (SLE) and systemic sclerosis. For this review, we used an open-source programming language- PowerShell, to scan the massive number of existing primary research publications on PubMed on miRNAs in these nine diseases to identify and count unique co-occurrences of individual miRNAs and the disease name. These counts were used to rank the top seven most relevant immuno-miRs based on their research volume in each rheumatic disease. Individual miRNAs were also screened for publication with the names of immune cells, cytokines, and pathological processes involved in rheumatic diseases. These occurrences were tabulated into matrices to identify hotspots for research relevance. Based on this information, we summarize the basic and clinical findings for the top three miRNAs - miR-146, miR-155, and miR-21 - whose relevance spans across multiple rheumatic diseases. Furthermore, we highlight some unique miRNAs for each disease and why some rheumatic conditions lack research in this emerging epigenetics field. With the overwhelming number of publications on miRNAs in rheumatic diseases, this review serves as a 'relevance finder' to guide researchers in selecting miRNAs based on the compiled existing knowledge of their involvement in disease pathogenesis. This approach applies to other disease contexts with the end goal of developing miRNA-based therapeutics.

A CD6-targeted antibody-drug conjugate as a potential therapy for T cell-mediated disorders

The selective targeting of pathogenic T cells is a holy grail in the development of new therapeutics for T cell-mediated disorders, including many autoimmune diseases and graft versus host disease. We describe the development of a CD6-targeted antibody-drug conjugate (CD6-ADC) by conjugating an inactive form of monomethyl auristatin E (MMAE), a potent mitotic toxin, onto a mAb against CD6, an established T cell surface marker. Even though CD6 is present on all T cells, only the activated (pathogenic) T cells vigorously divide and thus are susceptible to the antimitotic MMAE-mediated killing via the CD6-ADC. We found CD6-ADC selectively killed activated proliferating human T cells and antigen-specific mouse T cells in vitro. Furthermore, in vivo, whereas the CD6-ADC had no significant detrimental effect on normal T cells in naive CD6-humanized mice, the same dose of CD6-ADC, but not the controls, efficiently treated 2 preclinical models of autoimmune uveitis and a model of graft versus host disease. These results provide evidence suggesting that CD6-ADC could be further developed as a potential therapeutic agent for the selective elimination of pathogenic T cells and treatment of many T cell-mediated disorders.

Herbal compound cepharanthine attenuates inflammatory arthritis by blocking macrophage M1 polarization

OBJECTIVE

Cepharanthine (CEP) is a drug candidate for tumor, viral infection, and some inflammatory diseases, but its effect on rheumatoid arthritis (RA) and the underlying mechanism are incompletely understood.

METHODS

CEP was administered intraperitoneally to a collagen-induced arthritis (CIA) model. Joints went radiological and histological examination and serum cytokines were examined with cytometry-based analysis. M1 macrophages were induced from THP-1 cells or mouse bone marrow-derived macrophages with LPS and IFN-γ. Bulk RNA-seq was performed on macrophage undergoing M1-polarizatioin. Western blotting was applied to determine pathways involved in monocyte chemotaxis and polarization. Glycolysis metabolites were measured by chemiluminescence while glycolytic enzymes were examined by quantitative PCR.

RESULTS

We found CEP significantly ameliorated synovial inflammation and joint destruction of CIA mice. It downregulated TNF-α levels in serum and in joints. The number of M1 macrophages were reduced in CEP-treated mice. In vitro, CEP inhibited monocyte chemotaxis to MCP-1 by downregulating CCR2 and reducing ERK1/2 signaling. Additionally, CEP suppressed M1 polarization of macrophages induced by LPS and IFN-γ. Genes involved in IFN-γ signaling, IL-6-JAK/STAT3 signaling, glycolysis, and oxidative phosphorylation process were downregulated by CEP. Several enzymes critically involved in glycolytic metabolism were suppressed by CEP, which resulted in reduced citrate in M1-polarizing macrophages. The inhibitory effect of CEP on macrophage polarization might be attributed to the blockage of TLRs-MyD88/IRAK4-IRF5 signaling pathway together with suppression of overactivated glycolytic metabolism in M1-polarizing macrophages.

CONCLUSION

CEP attenuated joint inflammation by suppressing monocyte chemotaxis and proinflammatory differentiation. It has the potential to be developed into a complementary or alternative therapy for RA.

Activation of Cytotoxic Lymphocytes Through CD6 Enhances Killing of Cancer Cells

Immune checkpoint inhibitors (ICIs) have demonstrated efficacy and improved survival in a growing number of cancers. Despite their success, ICIs are associated with immune-related adverse events that can interfere with their use. Therefore, safer approaches are needed. CD6, expressed by T-lymphocytes and human NK cells, engages in cell-cell interactions by binding to its ligands CD166 (ALCAM) and CD318 (CDCP1). CD6 is a target protein for regulating immune responses and is required for the development of several mouse models of autoimmunity. Interestingly, CD6 is exclusively expressed on immune cells while CD318 is strongly expressed on most cancers. Here we demonstrate that disrupting the CD6-CD318 axis with UMCD6, an anti-CD6 monoclonal antibody, prolongs survival of mice in xenograft models of human breast and prostate cancer, treated with infusions of human lymphocytes. Analysis of tumor-infiltrating immune cells showed that augmentation of lymphocyte cytotoxicity by UMCD6 is due to effects of this antibody on NK, NKT and CD8+ T cells. Tumor-infiltrating cytotoxic lymphocytes were found in higher proportions and were activated in UMCD6-treated mice compared to controls. Similar changes in gene expression were observed by RNA-seq analysis of NK cells treated with UMCD6. Particularly, UMCD6 up-regulated the NKG2D-DAP10 complex and activated PI3K. Thus, the CD6-CD318 axis can regulate the activation state of cytotoxic lymphocytes and their positioning within the tumor microenvironment.

Immunosuppression causes dynamic changes in expression QTLs in psoriatic skin

Psoriasis is a chronic, systemic inflammatory condition primarily affecting skin. While the role of the immune compartment (e.g., T cells) is well established, the changes in the skin compartment are more poorly understood. Using longitudinal skin biopsies (n = 375) from the "Psoriasis Treatment with Abatacept and Ustekinumab: A Study of Efficacy"(PAUSE) clinical trial (n = 101), we report 953 expression quantitative trait loci (eQTLs). Of those, 116 eQTLs have effect sizes that were modulated by local skin inflammation (eQTL interactions). By examining these eQTL genes (eGenes), we find that most are expressed in the skin tissue compartment, and a subset overlap with the NRF2 pathway. Indeed, the strongest eQTL interaction signal - rs1491377616-LCE3C - links a psoriasis risk locus with a gene specifically expressed in the epidermis. This eQTL study highlights the potential to use biospecimens from clinical trials to discover in vivo eQTL interactions with therapeutically relevant environmental variables.

CD6-targeted antibody-drug conjugate as a new therapeutic agent for T cell lymphoma

T cell lymphomas (TCL) are heterogeneous, aggressive, and have few available targeted therapeutics. In this study, we determined that CD6, an established T cell marker, was expressed at high levels on almost all examined TCL patient specimens, suggesting that CD6 could be a new therapeutic target for this life-threatening blood cancer. We prepared a CD6-targeted antibody-drug conjugate (CD6-ADC) by conjugating monomethyl auristatin E (MMAE), an FDA-approved mitotic toxin, to a high-affinity anti-human CD6 monoclonal antibody (mAb). In contrast to both the unconjugated anti-CD6 mAb, and the non-binding control ADC, CD6-ADC potently and selectively killed TCL cells in vitro in both time- and concentration-dependent manners. It also prevented the development of tumors in vivo in a preclinical model of TCL. More importantly, systemic or local administration of the CD6-ADC or its humanized version, but not the controls, significantly shrank established tumors in the preclinical mouse model of TCL. These results suggest that CD6 is a novel therapeutic target in TCLs and provide a strong rationale for the further development of CD6-ADC as a promising therapy for patients with these potentially fatal lymphoid neoplasms.

MOG-specific T cell response amplified in para- and post-SAR-CoV-2 infection in myelin oligodendrocyte glycoprotein antibody-associated disease

We describe clinical characteristics and deep immunophenotypes in two patients with myelin-oligodendrocyte-glycoprotein (MOG)-antibody-associated-disease after COVID-19. The para-COVID case was a 74-year-old man who developed optic neuritis two days after COVID-19. Immunological assays revealed reduced absolute CD8+ T- and B-cell counts with increased frequency of NK cells. Post-COVID case was a 63-year-old man with optic neuritis six months after COVID-19, a frequency of CD8+ T-cells was elevated with a relatively low fraction of naïve and a high fraction of effector memory CD8+ T-cells. There was increased frequency of CD8+CD38+HLA-DR+ T-cells in the para-COVID case; interestingly, CD4+CD38+HLA-DR+ T cell frequency was increased in the post-COVID case. Both had increased SARS-CoV-2-specific and MOG-specific T-cell responses.

Single-cell transcriptome analysis and protein profiling reveal broad immune system activation in IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic autoimmune disease with unclear pathogenesis. We performed single-cell RNA-seq and surface proteome analyses on 61,379 PBMCs from 9 treatment-naive IgG4-RD patients and 7 age- and sex-matched healthy controls. Integrative analyses were performed for altered gene expression in IgG4-RD, and flow cytometry and immunofluorescence were used for validation. We observed expansion of plasmablasts with enhanced protein processing and activation, which correlated with the number of involved organs in IgG4-RD. Increased proportions of CD4+ cytotoxic T lymphocytes (CTLs), CD8+ CTLs-GNLY (granulysin), and γδT cells with enhanced chemotaxis and cytotoxicity but with suppressed inhibitory receptors characterize IgG4-RD. Prominent infiltration of lymphocytes with distinct compositions were found in different organs of IgG4-RD patients. Transcription factors (TFs), including PRDM1/XBP1 and RUNX3, were upregulated in IgG4-RD, promoting the differentiation of plasmablasts and CTLs, respectively. Monocytes in IgG4-RD have stronger expression of genes related to cell adhesion and chemotaxis, which may give rise to profibrotic macrophages in lesions. The gene activation pattern in peripheral immune cells indicated activation of multiple interaction pathways between cell types, in part through chemokines or growth factors and their receptors. Specific upregulation of TFs and expansion of plasmablasts and CTLs may be involved in the pathogenesis of IgG4-RD, and each of these populations are candidate targets for therapeutic interventions in this disease.

A perspective on In vitro developmental neurotoxicity test assay results: An expert panel review

For decades, there has been increasing concern about the potential developmental neurotoxicity (DNT) associated with chemicals. Regulatory agencies have historically utilized standardized in vivo testing to evaluate DNT. Owing to considerations including higher-throughput screening for DNT, reduction in animal use, and potential cost efficiencies, the development of alternative new approach methods (NAMs) occurred; specifically, the advent of the DNT in vitro test battery (DNT IVB). SciPinion convened an expert panel to address specific questions related to the interpretation of in vitro DNT test data. The consensus of the expert panel was that the DNT IVB might be used during initial screening, but it is not presently a complete or surrogate approach to determine whether a chemical is a DNT in humans. By itself, the DNT IVB does not have the ability to capture nuances and complexity of the developing nervous system and associated outcomes including behavioral ontogeny, motor activity, sensory function, and learning/memory. Presently, such developmental landmarks cannot be adequately assessed in the DNT IVB or by other NAMs. The expert panel (all who serve as co-authors of this review) recommended that additional data generation and validation is required before the DNT IVB can be considered for application within global regulatory frameworks for decision-making.

An agonistic anti-signal regulatory protein α antibody for chronic inflammatory diseases

Signal regulatory protein (SIRPα) is an immune inhibitory receptor expressed by myeloid cells to inhibit immune cell phagocytosis, migration, and activation. Despite the progress of SIRPα and CD47 antagonist antibodies to promote anti-cancer immunity, it is not yet known whether SIRPα receptor agonism could restrain excessive autoimmune tissue inflammation. Here, we report that neutrophil- and monocyte-associated genes including SIRPA are increased in inflamed tissue biopsies from patients with rheumatoid arthritis and inflammatory bowel diseases, and elevated SIRPA is associated with treatment-refractory ulcerative colitis. We next identify an agonistic anti-SIRPα antibody that exhibits potent anti-inflammatory effects in reducing neutrophil and monocyte chemotaxis and tissue infiltration. In preclinical models of arthritis and colitis, anti-SIRPα agonistic antibody ameliorates autoimmune joint inflammation and inflammatory colitis by reducing neutrophils and monocytes in tissues. Our work provides a proof of concept for SIRPα receptor agonism for suppressing excessive innate immune activation and chronic inflammatory disease treatment.

Machine-learning classification identifies patients with early systemic sclerosis as abatacept responders via CD28 pathway modulation

Here, the efficacy of abatacept in patients with early diffuse systemic sclerosis (dcSSc) was analyzed to test the hypothesis that patients in the inflammatory intrinsic subset would show the most significant clinical improvement. Eighty-four participants with dcSSc were randomized to receive abatacept or placebo for 12 months. RNA-Seq was performed on 233 skin paired biopsies at baseline and at 3 and 6 months. Improvement was defined as a 5-point or more than 20% change in modified Rodnan skin score (mRSS) between baseline and 12 months. Samples were assigned to intrinsic gene expression subsets (inflammatory, fibroproliferative, or normal-like subsets). In the abatacept arm, change in mRSS was most pronounced for the inflammatory and normal-like subsets relative to the placebo subset. Gene expression for participants on placebo remained in the original molecular subset, whereas inflammatory participants treated with abatacept had gene expression that moved toward the normal-like subset. The Costimulation of the CD28 Family Reactome Pathway decreased in patients who improved on abatacept and was specific to the inflammatory subset. Patients in the inflammatory subset had elevation of the Costimulation of the CD28 Family pathway at baseline relative to that of participants in the fibroproliferative and normal-like subsets. There was a correlation between improved ΔmRSS and baseline expression of the Costimulation of the CD28 Family pathway. This study provides an example of precision medicine in systemic sclerosis clinical trials.

The dual role of CD6 as a therapeutic target in cancer and autoimmune disease

Autoimmune disease involves loss of tolerance to self-antigen, while progression of cancer reflects insufficient recognition and response of the immune system to malignant cells. Patients with immune compromised conditions tend to be more susceptible to cancer development. On the other hand, cancer treatments, especially checkpoint inhibitor therapies, can induce severe autoimmune syndromes. There is recent evidence that autoimmunity and cancer share molecular targets and pathways that may be dysregulated in both types of diseases. Therefore, there has been an increased focus on understanding these biological pathways that link cancer and its treatment with the appearance of autoimmunity. In this review, we hope to consolidate our understanding of current and emerging molecular targets used to treat both cancer and autoimmunity, with a special focus on Cluster of Differentiation (CD) 6.

Extracellular sulfatase-2 is overexpressed in rheumatoid arthritis and mediates the TNF-α-induced inflammatory activation of synovial fibroblasts

Extracellular sulfatase-2 (Sulf-2) influences receptor-ligand binding and subsequent signaling by chemokines and growth factors, yet Sulf-2 remains unexplored in inflammatory cytokine signaling in the context of rheumatoid arthritis (RA). In the present study, we characterized Sulf-2 expression in RA and investigated its potential role in TNF-α-induced synovial inflammation using primary human RA synovial fibroblasts (RASFs). Sulf-2 expression was significantly higher in serum and synovial tissues from patients with RA and in synovium and serum from hTNFtg mice. RNA sequencing analysis of TNF-α-stimulated RASFs showed that Sulf-2 siRNA modulated ~2500 genes compared to scrambled siRNA. Ingenuity Pathway Analysis of RNA sequencing data identified Sulf-2 as a primary target in fibroblasts and macrophages in RA. Western blot, ELISA, and qRT‒PCR analyses confirmed that Sulf-2 knockdown reduced the TNF-α-induced expression of ICAM1, VCAM1, CAD11, PDPN, CCL5, CX3CL1, CXCL10, and CXCL11. Signaling studies identified the protein kinase C-delta (PKCδ) and c-Jun N-terminal kinase (JNK) pathways as key in the TNF-α-mediated induction of proteins related to cellular adhesion and invasion. Knockdown of Sulf-2 abrogated TNF-α-induced RASF proliferation. Sulf-2 knockdown with siRNA and inhibition by OKN-007 suppressed the TNF-α-induced phosphorylation of PKCδ and JNK, thereby suppressing the nuclear translocation and DNA binding activity of the transcription factors AP-1 and NF-κBp65 in human RASFs. Interestingly, Sulf-2 expression positively correlated with the expression of TNF receptor 1, and coimmunoprecipitation assays demonstrated the binding of these two proteins, suggesting they exhibit crosstalk in TNF-α signaling. This study identified a novel role of Sulf-2 in TNF-α signaling and the activation of RA synoviocytes, providing the rationale for evaluating the therapeutic targeting of Sulf-2 in preclinical models of RA.

Case report: IgG4-related intracranial lesions mimicking multiple sclerosis in a 14-year-old girl

Objectives

IgG4-related disease (IgG4-RD) is distinguished by the infiltration of IgG4-positive plasma cells in a variety of tissues and organs. Even so, central nervous system lesions associated with IgG4-RD are scarce. We present a case of IgG4-related brain parenchymal lesions that mimics multiple sclerosis in a young girl.

Methods

The patient was followed by our neurology and rheumatology teams. Clinical information was recorded, and the brain was screened using magnetic resonance imaging (MRI). During follow-up, we examined serum IgE, IgG and IgG4 and lymph node biopsy.

Results

Here, we presented details of a 14-year-old Chinese girl suffering from diplopia, left eyelid ptosis, right facial numbness, and right lower limb weakness admitted to our institute. Brain MRI revealed multiple sclerosis-like lesions in the brain parenchyma and spinal cord. During the follow-up, she developed lymphadenopathy. Elevation of serum, IgG, IgG4 and IgE and lymph node biopsy favors a diagnosis of IgG4-RD. The patient had a good response to glucocorticoids and mycophenolate mofetil. The literature review summarized eight previously reported IgG4-RD involving brain parenchyma.

Discussion

Our case expands the known age spectrum of IgG4-RD. The intracranial IgG4-RD is rare and could mimic multiple sclerosis. Careful examination and dynamic review of disease history are crucial in the differential diagnosis.

CDCP1 regulates retinal pigmented epithelial barrier integrity for the development of experimental autoimmune uveitis

Cub domain-containing protein 1 (CDCP1) is a protein that is highly expressed on the surface of many cancer cells. However, its distribution in normal tissues and its potential roles in nontumor cells are poorly understood. We found that CDCP1 is present on both human and mouse retinal pigment epithelial (RPE) cells. CDCP1-KO mice developed attenuated retinal inflammation in a passive model of autoimmune uveitis, with disrupted tight junctions and infiltrating T cells detected in RPE flat mounts from WT but not CDCP1-KO mice during EAU development. Mechanistically, we discovered that CDCP1 on RPE cells was upregulated by IFN-γ in vitro and after EAU induction in vivo. CD6 stimulation induced increased RPE barrier permeability of WT but not CDCP1-knockdown (CDCP1-KD) RPE cells, and activated T cells migrated through WT RPE monolayers more efficiently than the CDCP1-KD RPE monolayers. In addition, CD6 stimulation of WT but not the CDCP1-KD RPE cells induced massive stress fiber formation and focal adhesion disruption to reduce cell barrier tight junctions. These data suggest that CDCP1 on RPE cells interacts with CD6 on T cells to induce RPE cytoskeleton remodeling and focal adhesion disruption, which open up the tight junctions to facilitate T cell infiltration for the development of uveitis.

Tofacitinib blocks IFN-regulated biomarker genes in skin fibroblasts and keratinocytes in a systemic sclerosis trial

BACKGROUNDSystemic sclerosis (SSc) is an autoimmune, connective tissue disease characterized by vasculopathy and fibrosis of the skin and internal organs.METHODSWe randomized 15 participants with early diffuse cutaneous SSc to tofacitinib 5 mg twice a day or matching placebo in a phase I/II double-blind, placebo-controlled trial. The primary outcome measure was safety and tolerability at or before week 24. To understand the changes in gene expression associated with tofacitinib treatment in each skin cell population, we compared single-cell gene expression in punch skin biopsies obtained at baseline and 6 weeks following the initiation of treatment.RESULTSTofacitinib was well tolerated; no participants experienced grade 3 or higher adverse events before or at week 24. Trends in efficacy outcome measures favored tofacitnib. Baseline gene expression in fibroblast and keratinocyte subpopulations indicated IFN-activated gene expression. Tofacitinib inhibited IFN-regulated gene expression in SFRP2/DPP4 fibroblasts (progenitors of myofibroblasts) and in MYOC/CCL19, representing adventitial fibroblasts (P < 0.05), as well as in the basal and keratinized layers of the epidermis. Gene expression in macrophages and DCs indicated inhibition of STAT3 by tofacitinib (P < 0.05). No clinically meaningful inhibition of T cells and endothelial cells in the skin tissue was observed.CONCLUSIONThese results indicate that mesenchymal and epithelial cells of a target organ in SSc, not the infiltrating lymphocytes, may be the primary focus for therapeutic effects of a Janus kinase inhibitor.TRIAL REGISTRATIONClinicalTrials.gov NCT03274076.FUNDINGPfizer, NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) R01 AR070470, NIH/NIAMS K24 AR063120, Taubman Medical Research Institute and NIH P30 AR075043, and NIH/NIAMS K01 AR072129.

Immunodeficiency and autoimmunity: companions not opposites

Autoimmunity has long been regarded as the polar opposite of immunodeficiency, but clinical and experimental evidence refute this notion. Indeed, numerous inborn or acquired immunodeficiency syndromes are characterized by the development of autoimmune complications in the setting of deficient immune defenses against microbial pathogens. Appreciation that much of the daily business of a healthy immune system is the avoidance of potentially harmful responses to innocuous environmental antigens or components of the host organism helps provide a context for these observations. In this issue of the JCI, Abt and colleagues report on purine nucleoside phosphorylase (PNP) deficiency, exploring the basis for the autoimmune complications that develop in this particular form of T cell immune deficiency and assigning a key role for overactivation of TLR7.

Soluble CD13 induces inflammatory arthritis by activating the bradykinin receptor B1

CD13, an ectoenzyme on myeloid and stromal cells, also circulates as a shed, soluble protein (sCD13) with powerful chemoattractant, angiogenic, and arthritogenic properties, which require engagement of a G protein-coupled receptor (GPCR). Here we identify the GPCR that mediates sCD13 arthritogenic actions as the bradykinin receptor B1 (B1R). Immunofluorescence and immunoblotting verified high expression of B1R in rheumatoid arthritis (RA) synovial tissue and fibroblast-like synoviocytes (FLSs), and demonstrated binding of sCD13 to B1R. Chemotaxis, and phosphorylation of Erk1/2, induced by sCD13, were inhibited by B1R antagonists. In ex vivo RA synovial tissue organ cultures, a B1R antagonist reduced secretion of inflammatory cytokines. Several mouse arthritis models, including serum transfer, antigen-induced, and local innate immune stimulation arthritis models, were attenuated in Cd13-/- and B1R-/- mice and were alleviated by B1R antagonism. These results establish a CD13/B1R axis in the pathogenesis of inflammatory arthritis and identify B1R as a compelling therapeutic target in RA and potentially other inflammatory diseases.

Inhibition of histone readers bromodomain extra-terminal proteins alleviates skin fibrosis in experimental models of scleroderma

Binding of the bromodomain and extraterminal domain proteins (BETs) to acetylated histone residues is critical for gene transcription. We sought to determine the antifibrotic efficacy and potential mechanisms of BET inhibition in systemic sclerosis (SSc). Blockade of BETs was done using a pan-BET inhibitor, JQ1; BRD2 inhibitor, BIC1; or BRD4 inhibitors AZD5153 or ARV825. BET inhibition, specifically BRD4 blockade, showed antifibrotic effects in an animal model of SSc and in patient-derived diffuse cutaneous SSc (dcSSc) fibroblasts. Transcriptome analysis of JQ1-treated dcSSc fibroblasts revealed differentially expressed genes related to extracellular matrix, cell cycle, and calcium (Ca²⁺) signaling. The antifibrotic effect of BRD4 inhibition was mediated at least in part by downregulation of Ca²⁺/calmodulin–dependent protein kinase II α and reduction of intracellular Ca²⁺ concentrations. On the basis of these results, we propose targeting Ca²⁺ pathways or BRD4 as potentially novel therapeutic approaches for progressive tissue fibrosis.