Defining inflammatory cell states in rheumatoid arthritis joint synovial tissues by integrating single-cell transcriptomics and mass cytometry.

To define the cell populations that drive joint inflammation in rheumatoid arthritis (RA), we applied single-cell RNA sequencing (scRNA-seq), mass cytometry, bulk RNA sequencing (RNA-seq) and flow cytometry to T cells, B cells, monocytes, and fibroblasts from 51 samples of synovial tissue from patients with RA or osteoarthritis (OA). Utilizing an integrated strategy based on canonical correlation analysis of 5,265 scRNA-seq profiles, we identified 18 unique cell populations. Combining mass cytometry and transcriptomics revealed cell states expanded in RA synovia: THY1(CD90)+HLA-DRAhi sublining fibroblasts, IL1B+ pro-inflammatory monocytes, ITGAX+TBX21+ autoimmune-associated B cells and PDCD1+ peripheral helper T (TPH) cells and follicular helper T (TFH) cells. We defined distinct subsets of CD8+ T cells characterized by GZMK+, GZMB+, and GNLY+ phenotypes. We mapped inflammatory mediators to their source cell populations; for example, we attributed IL6 expression to THY1+HLA-DRAhi fibroblasts and IL1B production to pro-inflammatory monocytes. These populations are potentially key mediators of RA pathogenesis.

Deconstruction of rheumatoid arthritis synovium defines inflammatory subtypes.

Rheumatoid arthritis is a prototypical autoimmune disease that causes joint inflammation and destruction1. There is currently no cure for rheumatoid arthritis, and the effectiveness of treatments varies across patients, suggesting an undefined pathogenic diversity1,2. Here, to deconstruct the cell states and pathways that characterize this pathogenic heterogeneity, we profiled the full spectrum of cells in inflamed synovium from patients with rheumatoid arthritis. We used multi-modal single-cell RNA-sequencing and surface protein data coupled with histology of synovial tissue from 79 donors to build single-cell atlas of rheumatoid arthritis synovial tissue that includes more than 314,000 cells. We stratified tissues into six groups, referred to as cell-type abundance phenotypes (CTAPs), each characterized by selectively enriched cell states. These CTAPs demonstrate the diversity of synovial inflammation in rheumatoid arthritis, ranging from samples enriched for T and B cells to those largely lacking lymphocytes. Disease-relevant cell states, cytokines, risk genes, histology and serology metrics are associated with particular CTAPs. CTAPs are dynamic and can predict treatment response, highlighting the clinical utility of classifying rheumatoid arthritis synovial phenotypes. This comprehensive atlas and molecular, tissue-based stratification of rheumatoid arthritis synovial tissue reveal new insights into rheumatoid arthritis pathology and heterogeneity that could inform novel targeted treatments.

Precision Medicine in Rheumatology: The Promise of Ultrasound-Guided Synovial Biopsy, Barriers to Its Implementation in the United States, and Proposed Solutions.

PURPOSE OF REVIEW: In the clinical evaluation of inflammatory arthritis and the research into its pathogenesis, there is a growing role for the direct analysis of synovial tissue. Over the years, various biopsy techniques have been used to obtain human synovial tissue samples, and there have been progressive improvements in the safety, tolerability, and utility of the procedure. RECENT FINDINGS: The latest advancement in synovial tissue biopsy techniques is the use of ultrasound imaging to guide the biopsy device, along with evolution in the characteristics of the device itself. While ultrasound guided synovial biopsy (UGSB) has taken a strong foothold in Europe, the procedure is still relatively new to the United States of America (USA). In this paper, we describe the expansion of UGSB in the USA, elucidate the challenges faced by rheumatologists developing UGSB programs in the USA, and describe several strategies for overcoming these challenges.

From the Medical Board of the National Psoriasis Foundation: Treatment targets for plaque psoriasis.

BACKGROUND: An urgent need exists in the United States to establish treatment goals in psoriasis. OBJECTIVE: We aim to establish defined treatment targets toward which clinicians and patients with psoriasis can strive to inform treatment decisions, reduce disease burden, and improve outcomes in practice. METHODS: The National Psoriasis Foundation conducted a consensus-building study among psoriasis experts using the Delphi method. The process consisted of: (1) literature review, (2) pre-Delphi question selection and input from general dermatologists and patients, and (3) 4 Delphi rounds. RESULTS: A total of 25 psoriasis experts participated in the Delphi process. The most preferred instrument was body surface area (BSA). The most preferred time for evaluating patient response after starting new therapies was at 3 months. The acceptable response at 3 months postinitiation was either BSA 3% or less or BSA improvement 75% or more from baseline. The target response at 3 months postinitiation was BSA 1% or less. During the maintenance period, evaluation every 6 months was most preferred. The target response at every 6 months maintenance evaluation is BSA 1% or less. LIMITATIONS: Although BSA is feasible in practice, it does not encompass health-related quality of life, costs, and risks of side effects. CONCLUSION: With defined treatment targets, clinicians and patients can regularly evaluate treatment responses and perform benefit-risk assessments of therapeutic options individualized to the patient.

TLR5, a novel and unidentified inflammatory mediator in rheumatoid arthritis that correlates with disease activity score and joint TNF-α levels.

The innate immune system plays an important role in rheumatoid arthritis (RA) pathogenesis. Previous studies support the role of TLR2 and 4 in RA and experimental arthritis models; however, the regulation and pathogenic effect of TLR5 is undefined in RA. In this study, we show that TLR5 is elevated in RA and osteoarthritis ST lining and sublining macrophages and endothelial cells compared with normal individuals. Furthermore, expression of TLR5 is elevated in RA synovial fluid macrophages and RA peripheral blood monocytes compared with RA and normal peripheral blood in vitro-differentiated macrophages. We also found that TLR5 on RA monocytes is an important modulator of TNF-α in RA synovial fluid and that TLR5 expression on these cells strongly correlates with RA disease activity and TNF-α levels. Interestingly, TNF-α has a feedback regulation with TLR5 expression in RA monocytes, whereas expression of this receptor is regulated by IL-17 and IL-8 in RA macrophages and fibroblasts. We show that RA monocytes and macrophages are more responsive to TLR5 ligation compared with fibroblasts despite the proinflammatory response being mediated through the same signaling pathways in macrophages and fibroblasts. In conclusion, we document the potential role of TLR5 ligation in modulating transcription of TNF-α from RA synovial fluid and the strong correlation of TLR5 and TNF-α with each other and with disease activity score in RA monocytes. Our results suggest that expression of TLR5 may be a predictor for RA disease progression and that targeting TLR5 may suppress RA.

Ligation of TLR7 by rheumatoid arthritis synovial fluid single strand RNA induces transcription of TNFα in monocytes.

OBJECTIVE: The aim of the study was to characterise the expression, regulation and pathogenic role of toll-like receptor 7 (TLR7) and TLR8 in rheumatoid arthritis (RA). METHODS: Expression of TLR7 and TLR8 was demonstrated in RA, osteoarthritis (OA) and normal (NL) synovial tissues (STs) employing immunohistochemistry. The authors next examined the mechanism by which TLR7 and TLR8 ligation mediates proinflammatory response by Western blot analysis and ELISA. Expression of TLR7 and TLR8 in RA monocytes was correlated to disease activity score (DAS28) and tumour necrosis factor α (TNFα) levels. Further, the effect of TLR7 ligation in RA monocytes was determined on synovial fluid (SF)-mediated TNFα transcription. RESULTS: TLR7/8 are predominately expressed in RA ST lining and sublining macrophages. The authors show that NF-κB and/or PI3K pathways are essential for TLR7/8 induction of proinflammatory factors in RA peripheral blood (PB)-differentiated macrophages. Expression of TLR7 in RA monocytes shows a strong correlation with DAS28 and TNFα levels. By contrast, expression of TLR8 in these cells does not correlate with DAS28, TLR7 or TNFα levels. The authors further demonstrate that RNA from RA SF, but not RA or NL plasma, could modulate TNFα transcription from RA monocytes that can be downregulated by antagonising TLR7 ligation or degradation of single stand (ss) RNA. Thus, ssRNA present in RA SF may function as a potential endogenous ligand for TLR7. CONCLUSIONS: These results suggest that expression of TLR7, but not TLR8, may be a predictor for RA disease activity and anti-TNFα responsiveness, and targeting TLR7 may suppress chronic progression of RA.

Role of the CCL21 and CCR7 pathways in rheumatoid arthritis angiogenesis.

OBJECTIVE: To determine the role of CCL21 and its receptor CCR7 in the pathogenesis of rheumatoid arthritis (RA). METHODS: Histologic studies were performed to compare the expression of CCR7 and CCL21 in RA synovial tissue. Next, the role of CCL21 and/or CCR7 in angiogenesis was examined using in vitro chemotaxis, tube formation, and in vivo Matrigel plug assays. Finally, the mechanism by which CCL21 mediates angiogenesis was determined by Western blot analysis and endothelial cell chemotaxis and tube formation assays. RESULTS: CCL21, but not CCL19, at concentrations present in the RA joint, induced human microvascular endothelial cell (HMVEC) migration that was mediated through CCR7 ligation. Suppression of the phosphatidylinositol 3-kinase pathway markedly reduced CCL21-induced HMVEC chemotaxis and tube formation; however, suppression of the ERK and JNK pathways had no effect on these processes. Neutralization of either CCL21 in RA synovial fluid or CCR7 in HMVECs significantly reduced the induction of HMVEC migration and/or tube formation by RA synovial fluid. We further demonstrated that CCL21 is angiogenic, by showing its ability to promote blood vessel growth in Matrigel plugs in vivo at concentrations that are present in RA joints. CONCLUSION: Angiogenesis is dependent on endothelial cell activation, migration, and proliferation, and inhibition of angiogenesis may provide a novel therapeutic approach in RA. This study identified a novel function of CCL21 as a mediator of RA angiogenesis, supporting CCL21/CCR7 as a therapeutic target in RA.

Best practices for ultrasound-guided synovial biopsy in the United States.

The target organ in many forms of inflammatory arthritis is the synovium. However, synovial tissue has historically been perceived as either difficult to obtain or of little practical value. Ultrasound-guided synovial biopsy [UGSB] is a safe and well-tolerated bedside procedure that is established in Europe and rapidly growing in popularity in the United States. The technique can be mastered by rheumatologists who are already experienced in ultrasound-guided procedures such as joint aspirations. The USGB procedure allows the proceduralist to access small, medium, and large joints and is inexpensive and less invasive compared to surgical alternatives. The relative ease of obtaining this tissue, along with recent research suggesting that synovium may have more clinical and investigational utility than previously thought, has led clinicians and researchers to a new appreciation of the role of synovial biopsy in both the clinical and research setting. In this manuscript, the authors present recommendations on best practices for ultrasound-guided synovial biopsy in the United States, based on our initial training with well-established experts overseas and our own subsequent collective experience in performing numerous synovial biopsies in the United States over the past 7 years for both clinical and research indications. We envision a future where UGSB is more frequently incorporated in the standard diagnostic workup of arthritis and drives novel research initiatives.

Integrating PROMIS Measures in a Treat-to-Target Approach to Standardize Patient-Centered Treatment of Rheumatoid Arthritis.

OBJECTIVE: To evaluate the effect of a patient-centered rheumatoid arthritis (RA) treat-to-target (T2T) disease management approach on patient outcomes and patient satisfaction with care. METHODS: In this longitudinal, observational pilot study, rheumatologists implemented a modified T2T approach that integrated Patient Reported Outcomes Measurement Information System (PROMIS) measures for depression, fatigue, pain interference, physical function, and social function into RA care. Study participants selected 1 PROMIS domain to target treatment and completed quarterly follow-up assessments. Participants were classified as improved if their Clinical Disease Activity Index (CDAI) changed by > 5 points. Change in PROMIS t scores was examined for the group with improved CDAI, and then compared to those with unchanged or worsened CDAI. Satisfaction with care was assessed using multiple measures, including the Functional Assessment of Chronic Illness Therapy-Treatment Satisfaction-Patient Satisfaction Scale. RESULTS: The analytical sample (n = 119, median age 57 years, 90.8% female) was split between those with CDAI > 10 (n = 63) and CDAI ≤ 10 (n = 53). At 1 year, there was improvement in CDAI by > 5 points in 66% and 13% of individuals with baseline CDAI > 10 and baseline CDAI ≤ 10, respectively. Across all participants, improvement in CDAI by > 5 points correlated with improvements in the 5 PROMIS domains. Satisfaction with RA treatment also increased. CONCLUSION: The integration of PROMIS measures into the T2T approach for RA care was associated with improvements in disease activity, and improvement in disease activity was associated with improvements in PROMIS measures.

Management of Enthesitis in Patients With Psoriatic Arthritis: An Updated Literature Review Informing the 2021 GRAPPA Treatment Recommendations.

OBJECTIVE: Enthesitis is a key pathological and clinical feature of psoriatic arthritis (PsA) in children and adults. Enthesitis is typically assessed clinically using several validated enthesitis scoring systems that have been used in clinical trials. Enthesitis treatment response has been reported as change in the total enthesitis score or the proportion of patients who achieved complete resolution. The majority of trials in PsA did not require patients to have enthesitis at study entry since enthesitis was evaluated only as a secondary outcome. Despite the inherent limitations of the clinical assessment of enthesitis, imaging of the entheses using ultrasound or magnetic resonance imaging has rarely been used in clinical trials to assess response to treatment of enthesitis. This systematic review summarizes existing evidence regarding pharmaceutical and nonpharmaceutical interventions for enthesitis in patients with PsA to facilitate an evidence-based update of the Group for Research and Assessment in Psoriasis and Psoriatic Arthritis (GRAPPA) treatment recommendations for PsA. METHODS: We performed a systematic literature review to identify 41 randomized clinical trials that reported enthesitis treatment response in patients with PsA. For each intervention, the response effect size was summarized and the quality of evidence was graded. Recommendations were then formulated for the various pharmacological and nonpharmacological therapies. RESULTS: We included 41 randomized clinical trials in our review and graded each intervention. CONCLUSION: Several classes of systemic conventional and advanced therapies and local measures were recommended for active enthesitis in patients with PsA.

Tissue-resident, extravascular Ly6c- monocytes are critical for inflammation in the synovium.

Monocytes are abundant immune cells that infiltrate inflamed organs. However, the majority of monocyte studies focus on circulating cells, rather than those in tissue. Here, we identify and characterize an intravascular synovial monocyte population resembling circulating non-classical monocytes and an extravascular tissue-resident monocyte-lineage cell (TR-MC) population distinct in surface marker and transcriptional profile from circulating monocytes, dendritic cells, and tissue macrophages that are conserved in rheumatoid arthritis (RA) patients. TR-MCs are independent of NR4A1 and CCR2, long lived, and embryonically derived. TR-MCs undergo increased proliferation and reverse diapedesis dependent on LFA1 in response to arthrogenic stimuli and are required for the development of RA-like disease. Moreover, pathways that are activated in TR-MCs at the peak of arthritis overlap with those that are downregulated in LFA1-/- TR-MCs. These findings show a facet of mononuclear cell biology that could be imperative to understanding tissue-resident myeloid cell function in RA.

Characterization of interleukin-7 and interleukin-7 receptor in the pathogenesis of rheumatoid arthritis.

OBJECTIVE: To characterize the expression of interleukin-7 (IL-7) and IL-7 receptor (IL-7R) in rheumatoid arthritis (RA) synovial tissue and to examine their regulation and pathogenic role in macrophages, endothelial cells, and synovial tissue fibroblasts in RA. METHODS: Expression of IL-7 and IL-7R in RA and normal synovial tissue was demonstrated by immunohistochemistry. Expression and regulation of IL-7 and IL-7R in RA peripheral blood in vitro-differentiated macrophages, RA synovial tissue fibroblasts, and human microvascular endothelial cells (HMVECs) were determined by real-time reverse transcription-polymerase chain reaction and/or flow cytometry. Enzyme-linked immunosorbent assay was used to examine production of proangiogenic factors by IL-7-activated macrophages, RA fibroblasts, and endothelial cells. RESULTS: IL-7 and IL-7R were coexpressed on RA synovial tissue lining and sublining macrophages and endothelial cells. Expression of IL-7 and its receptor was significantly elevated in RA synovial fluid and peripheral blood macrophages as well as RA fibroblasts, compared to normal cells. Toll-like receptor 4 ligation (with lipopolysaccharide) and tumor necrosis factor α (TNFα) stimulation modulated expression of IL-7 and IL-7R on RA macrophages and HMVECs. However, in RA fibroblasts, lipopolysaccharide and TNFα activation increased expression of IL-7R only. IL-7 also mediated RA pathogenesis by inducing production of potent proangiogenic factors from macrophages and endothelial cells. CONCLUSION: We have identified, for the first time, regulators of IL-7 and IL-7R expression in RA fibroblasts, RA peripheral blood in vitro-differentiated macrophages, and endothelial cells. Our results document a novel role of IL-7 in RA angiogenesis.

Local expression of interleukin-27 ameliorates collagen-induced arthritis.

OBJECTIVE: To determine the mechanism of action of interleukin-27 (IL-27) against rheumatoid arthritis (RA). METHODS: Adenovirus containing IL-27 transcript was constructed and was locally delivered into the ankles of mice with collagen-induced arthritis (CIA). Progression of arthritis was determined in treated and untreated mice by measuring ankle circumference and through histologic analysis. IL-17 and its downstream targets as well as cytokines promoting Th17 cell differentiation were quantified by enzyme-linked immunosorbent assay in CIA mouse ankles locally expressing adenoviral IL-27 as well as in control-treated mouse ankles. Ankles from both treatment groups were immunostained for neutrophil and monocyte migration (macrophages in the tissue). Finally, vascularization was quantified by histology and by determining ankle hemoglobin levels. RESULTS: Ectopic expression of IL-27 in CIA mice ameliorated inflammation, lining hypertrophy, and bone erosion as compared with control-treated CIA mice. Serum and joint levels of IL-17 were significantly reduced in the IL-27-treated group compared with the control-treated group. Two of the main cytokines that induce Th17 cell differentiation and IL-17 downstream target molecules were greatly down-regulated in CIA mouse ankles receiving forced expression of IL-27. The control mice had higher levels of vascularization and monocyte trafficking than did mice ectopically expressing IL-27. CONCLUSION: Our results suggest that increased levels of IL-27 relieve arthritis in CIA mouse ankles. This amelioration of arthritis involves a reduction in CIA mouse serum and joint levels of IL-17 and results in decreased IL-17-mediated monocyte recruitment and angiogenesis. Hence, the use of IL-27 may be a strategy for treatment of patients with RA.

Characterization of CCL19 and CCL21 in rheumatoid arthritis.

OBJECTIVE: To characterize the expression of CCL19 and CCL21 in rheumatoid arthritis (RA) synovial tissue (ST) and to examine their regulation and pathogenetic role in macrophages and RA ST fibroblasts. METHODS: Expression of CCL19 and CCL21 in RA and normal ST was demonstrated by immunohistochemistry analysis. CCL19 and CCL21 levels in synovial fluid (SF) from patients with osteoarthritis (OA), juvenile idiopathic arthritis, psoriatic arthritis (PsA), and RA were quantified by enzyme-linked immunosorbent assay (ELISA). Regulation of CCL19 and CCL21 expression in in vitro-differentiated RA peripheral blood macrophages as well as RA ST fibroblasts was determined by real-time reverse transcription-polymerase chain reaction. Proangiogenic factor production in CCL19- and CCL21-activated in vitro-differentiated peripheral blood macrophages and RA ST fibroblasts was examined by ELISA. RESULTS: CCL19 and CCL21 were elevated in RA ST compared to tissue from normal controls. Levels of CCL19 and CCL21 were greatly increased in RA and PsA SF versus OA SF. In RA macrophages and fibroblasts, expression of CCL19 was increased by stimulation with lipopolysaccharide, tumor necrosis factor α (TNFα), and interleukin-1ß (IL-1ß). However, CCL21 expression was modulated only by IL-1ß in RA fibroblasts, and by TNFα and RA SF in RA macrophages. CCL19 and CCL21 activation induced vascular endothelial growth factor and angiotensin I (Ang I) production in RA ST fibroblasts and secretion of IL-8 and Ang I from macrophages. CONCLUSION: The findings of the present study identify, for the first time, regulators of CCL19 and CCL21 in RA fibroblasts and in vitro-differentiated RA peripheral blood macrophages and demonstrate a novel role of CCL19/CCL21 in angiogenesis in RA.

IL-17-mediated monocyte migration occurs partially through CC chemokine ligand 2/monocyte chemoattractant protein-1 induction.

Rheumatoid arthritis (RA) is a chronic inflammatory disease that is mediated, in part, by proinflammatory factors produced by RA synovial tissue (ST) fibroblasts and macrophages, resulting in monocyte migration from the blood to the ST. To characterize the potential role of IL-17 in monocyte migration, RA synovial fibroblasts and macrophages were activated with IL-17 and examined for the expression of monocyte chemokines. The two potentially important monocyte chemoattractants identified were CCL20/MIP-3alpha and CCL2/MCP-1, which were significantly induced in RA synovial fibroblasts and macrophages. However, in vivo, only CCL2/MCP-1 was detectable following adenovirus IL-17 injection. We found that IL-17 induction of CCL2/MCP-1 was mediated by the PI3K, ERK, and JNK pathways in RA ST fibroblasts and by the PI3K and ERK pathways in macrophages. Further, we show that neutralization of CCL2/MCP-1 significantly reduced IL-17-mediated monocyte recruitment into the peritoneal cavity. We demonstrate that local expression of IL-17 in ankle joints was associated with significantly increased monocyte migration and CCL2/MCP-1 levels. Interestingly, we show that RA synovial fluids immunoneutralized for IL-17 and CCL2/MCP-1 have similar monocyte chemotaxis activity as those immunoneutralized for each factor alone. In short, CCL2/MCP-1 produced from cell types present in the RA joint, as well as in experimental arthritis, may be responsible, in part, for IL-17-induced monocyte migration; hence, these results suggest that CCL2/MCP-1 is a downstream target of IL-17 that may be important in RA.

IL-17 contributes to angiogenesis in rheumatoid arthritis.

Angiogenesis is an early and a critical event in the pathogenesis of rheumatoid arthritis (RA). Neovascularization is dependent on endothelial cell activation, migration and proliferation, and inhibition of angiogenesis may provide a novel therapeutic approach in RA. In this study, we document a novel role of IL-17 in mediating angiogenesis. Local expression of IL-17 in mouse ankles increases vascularity. We further demonstrate that IL-17 is angiogenic by showing its ability to promote blood vessel growth in Matrigel plugs in vivo. Additionally, IL-17, in concentrations present in the RA joint, induces human lung microvascular endothelial cell (HMVEC) migration mediated through the PI3K/AKT1 pathway. Furthermore, suppression of the PI3K pathway markedly reduces IL-17-induced tube formation. We also show that both IL-17-induced HMVEC chemotaxis and tube formation are mediated primarily through IL-17 receptor C. Neutralization of either IL-17 in RA synovial fluids or IL-17 receptor C on HMVECs significantly reduces the induction of HMVEC migration by RA synovial fluid. Finally, RA synovial fluid immunoneutralized with anti-IL-17 and antivascular endothelial growth factor does not reduce HMVEC migration beyond the effect detected by immunodepleting each factor alone. These observations identify a novel function for IL-17 as an angiogenic mediator in RA, supporting IL-17 as a therapeutic target in RA.

Anti-CXCL5 therapy ameliorates IL-17-induced arthritis by decreasing joint vascularization.

IL-17-induced joint inflammation is associated with increased angiogenesis. However, the mechanism by which IL-17 mediates angiogenesis is undefined. Therefore, the pathologic role of CXCL1 and CXCL5 was investigated in arthritis mediated by local expression of IL-17, employing a neutralizing antibody to each chemokine. Next, endothelial chemotaxis was utilized to examine whether endothelial migration was differentially mediated by CXCL1 and CXCL5. Our results demonstrate that IL-17-mediated disease activity was not affected by anti-CXCL1 treatment alone. In contrast, mice receiving anti-CXCL5 demonstrated significantly reduced clinical signs of arthritis, compared to the mice treated with IgG control. Consistently, while inflammation, synovial lining thickness, bone erosion and vascularization were markedly reduced in both the anti-CXCL5 and combination anti-CXCL1 and 5 treatment groups, mice receiving anti-CXCL1 antibody had clinical scores similar to the control group. In contrast to joint FGF2 and VEGF levels, TNF-α was significantly reduced in mice receiving anti-CXCL5 or combination of anti-CXCL1 and 5 therapies compared to the control group. We found that, like IL-17, CXCL1-induced endothelial migration is mediated through activation of PI3K. In contrast, activation of NF-κB pathway was essential for endothelial chemotaxis induced by CXCL5. Although CXCL1 and CXCL5 can differentially mediate endothelial trafficking, blockade of CXCR2 can inhibit endothelial chemotaxis mediated by either of these chemokines. These results suggest that blockade of CXCL5 can modulate IL-17-induced inflammation in part by reducing joint blood vessel formation through a non-overlapping IL-17 mechanism.

Heat shock protein 96 is elevated in rheumatoid arthritis and activates macrophages primarily via TLR2 signaling.

Macrophages are important mediators of chronic inflammation and are prominent in the synovial lining and sublining of patients with rheumatoid arthritis (RA). Recently, we demonstrated increased TLR2 and TLR4 expression and increased response to microbial TLR2 and TLR4 ligands in macrophages from the joints of RA. The current study characterized the expression of the 96-kDa heat shock glycoprotein (gp96) in the joints of RA and its role as an endogenous TLR ligand to promote innate immunity in RA. gp96 was increased in RA compared with osteoarthritis and arthritis-free control synovial tissues. The expression of gp96 strongly correlated with inflammation and synovial lining thickness. gp96 was increased in synovial fluid from the joints of RA compared with disease controls. Recombinant gp96 was a potent activator of macrophages and the activation was mediated primarily through TLR2 signaling. The cellular response to gp96 was significantly stronger with RA synovial macrophages compared with peripheral blood monocytes from RA or healthy controls. The transcription of TLR2, TNF-alpha, and IL-8, but not TLR4, was significantly induced by gp96, and the induction was significantly greater in purified RA synovial macrophages. The expression of TLR2, but not TLR4, on synovial fluid macrophages strongly correlated with the level of gp96 in the synovial fluid. The present study documents the potential role of gp96 as an endogenous TLR2 ligand in RA and provides insight into the mechanism by which gp96 promotes the chronic inflammation of RA, identifying gp96 as a potential new therapeutic target.

Dietary Recommendations for Adults With Psoriasis or Psoriatic Arthritis From the Medical Board of the National Psoriasis Foundation: A Systematic Review.

Importance: Psoriasis is a chronic, inflammatory skin disease and has significant associated morbidity and effect on quality of life. It is important to determine whether dietary interventions help reduce disease severity in patients with psoriatic diseases. Objective: To make evidence-based dietary recommendations for adults with psoriasis and/or psoriatic arthritis from the Medical Board of the National Psoriasis Foundation. Evidence Review: We used literature from prior systematic reviews as well as additional primary literature from the MEDLINE database from January 1, 2014, to August 31, 2017, that evaluated the impact of diet on psoriasis. We included observational and interventional studies of patients with psoriasis or psoriatic arthritis. The quality of included studies was assessed using the Newcastle-Ottawa scale for observational studies and the Cochrane Risk of Bias Tool for interventional studies. We made evidence-based dietary recommendations, which were voted on by the National Psoriasis Foundation Medical Board. Findings: We identified 55 studies meeting the inclusion criteria for this review. These studies represent 77 557 unique participants of which 4534 have psoriasis. Based on the literature, we strongly recommend dietary weight reduction with a hypocaloric diet in overweight and obese patients with psoriasis. We weakly recommend a gluten-free diet only in patients who test positive for serologic markers of gluten sensitivity. Based on low-quality data, select foods, nutrients, and dietary patterns may affect psoriasis. For patients with psoriatic arthritis, we weakly recommend vitamin D supplementation and dietary weight reduction with a hypocaloric diet in overweight and obese patients. Dietary interventions should always be used in conjunction with standard medical therapies for psoriasis and psoriatic arthritis. Conclusions and Relevance: Adults with psoriasis and/or psoriatic arthritis can supplement their standard medical therapies with dietary interventions to reduce disease severity. These dietary recommendations from the National Psoriasis Foundation Medical Board will help guide clinicians regarding the utility of dietary interventions in adults with psoriatic diseases.

Transcriptional Profiling of Synovial Macrophages Using Minimally Invasive Ultrasound-Guided Synovial Biopsies in Rheumatoid Arthritis.

OBJECTIVE: Currently, there are no reliable biomarkers for predicting therapeutic response in patients with rheumatoid arthritis (RA). The synovium may unlock critical information for determining efficacy, since a reduction in the numbers of sublining synovial macrophages remains the most reproducible biomarker. Thus, a clinically actionable method for the collection of synovial tissue, which can be analyzed using high-throughput strategies, must become a reality. This study was undertaken to assess the feasibility of utilizing synovial biopsies as a precision medicine-based approach for patients with RA. METHODS: Rheumatologists at 6 US academic sites were trained in minimally invasive ultrasound-guided synovial tissue biopsy. Biopsy specimens obtained from patients with RA and synovial tissue from patients with osteoarthritis (OA) were subjected to histologic analysis, fluorescence-activated cell sorting, and RNA sequencing (RNA-seq). An optimized protocol for digesting synovial tissue was developed to generate high-quality RNA-seq libraries from isolated macrophage populations. Associations were determined between macrophage transcriptional profiles and clinical parameters in RA patients. RESULTS: Patients with RA reported minimal adverse effects in response to synovial biopsy. Comparable RNA quality was observed from synovial tissue and isolated macrophages between patients with RA and patients with OA. Whole tissue samples from patients with RA demonstrated a high degree of transcriptional heterogeneity. In contrast, the transcriptional profile of isolated RA synovial macrophages highlighted different subpopulations of patients and identified 6 novel transcriptional modules that were associated with disease activity and therapy. CONCLUSION: Performance of synovial tissue biopsies by rheumatologists in the US is feasible and generates high-quality samples for research. Through the use of cutting-edge technologies to analyze synovial biopsy specimens in conjunction with corresponding clinical information, a precision medicine-based approach for patients with RA is attainable.