Post-covid medical complaints following infection with SARS-CoV-2 Omicron vs Delta variants

The SARS-CoV-2 Omicron (B.1.1.529) variant has been associated with less severe acute disease, however, concerns remain as to whether long-term complaints persist to a similar extent as for earlier variants. Studying 1 323 145 persons aged 18-70 years living in Norway with and without SARS-CoV-2 infection in a prospective cohort study, we found that individuals infected with Omicron had a similar risk of post-covid complaints (fatigue, cough, heart palpitations, shortness of breath and anxiety/depression) as individuals infected with Delta (B.1.617.2), from 14 to up to 126 days after testing positive, both in the acute (14 to 29 days), sub-acute (30 to 89 days) and chronic post-covid (≥90 days) phases. However, at ≥90 days after testing positive, individuals infected with Omicron had a lower risk of having any complaint (43 (95%CI = 14 to 72) fewer per 10,000), as well as a lower risk of musculoskeletal pain (23 (95%CI = 2-43) fewer per 10,000) than individuals infected with Delta. Our findings suggest that the acute and sub-acute burden of post-covid complaints on health services is similar for Omicron and Delta. The chronic burden may be lower for Omicron vs Delta when considering musculoskeletal pain, but not when considering other typical post-covid complaints.

Lupus or not? SLE Risk Probability Index (SLERPI): a simple, clinician-friendly machine learning-based model to assist the diagnosis of systemic lupus erythematosus

OBJECTIVES

Diagnostic reasoning in systemic lupus erythematosus (SLE) is a complex process reflecting the probability of disease at a given timepoint against competing diagnoses. We applied machine learning in well-characterised patient data sets to develop an algorithm that can aid SLE diagnosis.

METHODS

From a discovery cohort of randomly selected 802 adults with SLE or control rheumatologic diseases, clinically selected panels of deconvoluted classification criteria and non-criteria features were analysed. Feature selection and model construction were done with Random Forests and Least Absolute Shrinkage and Selection Operator-logistic regression (LASSO-LR). The best model in 10-fold cross-validation was tested in a validation cohort (512 SLE, 143 disease controls).

RESULTS

A novel LASSO-LR model had the best performance and included 14 variably weighed features with thrombocytopenia/haemolytic anaemia, malar/maculopapular rash, proteinuria, low C3 and C4, antinuclear antibodies (ANA) and immunologic disorder being the strongest SLE predictors. Our model produced SLE risk probabilities (depending on the combination of features) correlating positively with disease severity and organ damage, and allowing the unbiased classification of a validation cohort into diagnostic certainty levels (unlikely, possible, likely, definitive SLE) based on the likelihood of SLE against other diagnoses. Operating the model as binary (lupus/not-lupus), we noted excellent accuracy (94.8%) for identifying SLE, and high sensitivity for early disease (93.8%), nephritis (97.9%), neuropsychiatric (91.8%) and severe lupus requiring immunosuppressives/biologics (96.4%). This was converted into a scoring system, whereby a score >7 has 94.2% accuracy.

CONCLUSIONS

We have developed and validated an accurate, clinician-friendly algorithm based on classical disease features for early SLE diagnosis and treatment to improve patient outcomes.

Transcriptome reprogramming and myeloid skewing in haematopoietic stem and progenitor cells in systemic lupus erythematosus

OBJECTIVES

Haematopoietic stem and progenitor cells (HSPCs) are multipotent cells giving rise to both myeloid and lymphoid cell lineages. We reasoned that the aberrancies of immune cells in systemic lupus erythematosus (SLE) could be traced back to HSPCs.

METHODS

A global gene expression map of bone marrow (BM)-derived HSPCs was completed by RNA sequencing followed by pathway and enrichment analysis. The cell cycle status and apoptosis status of HSPCs were assessed by flow cytometry, while DNA damage was assessed via immunofluorescence.

RESULTS

Transcriptomic analysis of Lin-Sca-1+c-Kit+ haematopoietic progenitors from diseased lupus mice demonstrated a strong myeloid signature with expanded frequencies of common myeloid progenitors (CMPs)-but not of common lymphoid progenitors-reminiscent of a 'trained immunity' signature. CMP profiling revealed an intense transcriptome reprogramming with suppression of granulocytic regulators indicative of a differentiation arrest with downregulation trend of major regulators such as Cebpe, Cebpd and Csf3r, and disturbed myelopoiesis. Despite the differentiation arrest, frequencies of BM neutrophils were markedly increased in diseased mice, suggesting an alternative granulopoiesis pathway. In patients with SLE with severe disease, haematopoietic progenitor cells (CD34+) demonstrated enhanced proliferation, cell differentiation and transcriptional activation of cytokines and chemokines that drive differentiation towards myelopoiesis, thus mirroring the murine data.

CONCLUSIONS

Aberrancies of immune cells in SLE can be traced back to the BM HSPCs. Priming of HSPCs and aberrant regulation of myelopoiesis may contribute to inflammation and risk of flare.

TRIAL REGISTRATION NUMBER

4948/19-07-2016.

Anterior uveitis in patients with spondyloarthritis treated with secukinumab or tumour necrosis factor inhibitors in routine care: does the choice of biological therapy matter?

BACKGROUND

The effect of interleukin 17-inhibitors on anterior uveitis (AU) in spondyloarthritis (SpA) is poorly understood. This study aimed to compare the risk of AU during treatment with secukinumab versus tumour necrosis factor inhibitors (TNFi).

METHODS

Patients with SpA starting secukinumab or a TNFi 2015 through 2018 were identified in the Swedish Rheumatology Quality Register. Occurrence of AU was identified based on diagnosis codes in outpatient ophthalmology care in the National Patient Register. The main outcomes were crude rates of AU-diagnoses per 100 patient-years, and adjusted HRs for AU, during treatment, in patients without AU during the year before treatment start (in order to reduce confounding by indication). HRs were adjusted for age, sex, history of AU and patient global assessment of disease activity.

RESULTS

Based on 4851 treatment starts (456 secukinumab; 4395 any TNFi), the rate of AU-diagnoses per 100 patient-years was 6.8 (95% CI 5.2 to 8.7) for secukinumab. Among the TNFi, the rate varied from 2.9 (95% CI 2.1 to 3.7) for infliximab and 4.0 (95% CI 3.3 to 4.9) for adalimumab to 7.5 (95% CI 6.7 to 8.4) for etanercept. The adjusted HRs for first AU (adalimumab as reference) were: secukinumab 2.32 (95% CI 1.16 to 4.63), infliximab 0.99 (95% CI 0.49 to 1.96), etanercept 1.82 (95% CI 1.13 to 2.93), golimumab 1.59 (95% CI 0.90 to 2.80) and certolizumab 1.12 (95% CI 0.44 to 2.83). Sensitivity analyses confirmed the pattern of higher AU rates with secukinumab and etanercept versus monoclonal TNFi.

CONCLUSION

As used in clinical practice in SpA, secukinumab appears to be associated with a higher risk of AU, compared with the monoclonal TNFi and a similar risk compared with etanercept.

TLR8 escapes X chromosome inactivation in human monocytes and CD4+ T cells

BACKGROUND

Human endosomal Toll-like receptors TLR7 and TLR8 recognize self and non-self RNA ligands, and are important mediators of innate immunity and autoimmune pathogenesis. TLR7 and TLR8 are, respectively, encoded by adjacent X-linked genes. We previously established that TLR7 evades X chromosome inactivation (XCI) in female immune cells. Whether TLR8 also evades XCI, however, has not yet been explored.

METHOD

In the current study, we used RNA fluorescence in situ hybridization (RNA FISH) to directly visualize, on a single-cell basis, primary transcripts of TLR7 and TLR8 relative to X chromosome territories in CD14+ monocytes and CD4+ T lymphocytes from women, Klinefelter syndrome (KS) men, and euploid men. To assign X chromosome territories in cells lacking robust expression of a XIST compartment, we designed probes specific for X-linked genes that do not escape XCI and therefore robustly label the active X chromosome. We also assessed whether XCI escape of TLR8 was associated with sexual dimorphism in TLR8 protein expression by western blot and flow cytometry.

RESULTS

Using RNA FISH, we show that TLR8, like TLR7, evades XCI in immune cells, and that cells harboring simultaneously TLR7 and TLR8 transcript foci are more frequent in women and KS men than in euploid men, resulting in a sevenfold difference in frequency. This transcriptional bias was again observable when comparing the single X of XY males with the active X of cells from females or KS males. Interestingly, TLR8 protein expression was significantly higher in female mononuclear blood cells, including all monocyte subsets, than in male cells.

CONCLUSIONS

TLR8, mirroring TLR7, escapes XCI in human monocytes and CD4+ T cells. Co-dependent transcription from the active X chromosome and escape from XCI could both contribute to higher TLR8 protein abundance in female cells, which may have implications for the response to viruses and bacteria, and the risk of developing inflammatory and autoimmune diseases.

Calcium calmodulin kinase II activity is required for cartilage homeostasis in osteoarthritis

WNT ligands can activate several signalling cascades of pivotal importance during development and regenerative processes. Their de-regulation has been associated with the onset of different diseases. Here we investigated the role of the WNT/Calcium Calmodulin Kinase II (CaMKII) pathway in osteoarthritis. We identified Heme Oxygenase I (HMOX1) and Sox-9 as specific markers of the WNT/CaMKII signalling in articular chondrocytes through a microarray analysis. We showed that the expression of the activated form of CaMKII, phospho-CaMKII, was increased in human and murine osteoarthritis and the expression of HMOX1 was accordingly reduced, demonstrating the activation of the pathway during disease progression. To elucidate its function, we administered the CaMKII inhibitor KN93 to mice in which osteoarthritis was induced by resection of the anterior horn of the medial meniscus and of the medial collateral ligament in the knee joint. Pharmacological blockade of CaMKII exacerbated cartilage damage and bone remodelling. Finally, we showed that CaMKII inhibition in articular chondrocytes upregulated the expression of matrix remodelling enzymes alone and in combination with Interleukin 1. These results suggest an important homeostatic role of the WNT/CaMKII signalling in osteoarthritis which could be exploited in the future for therapeutic purposes.

Mechanisms of action of therapeutic exercise for knee and hip OA remain a black box phenomenon: an individual patient data mediation study with the OA Trial Bank

OBJECTIVES

To evaluate mediating factors for the effect of therapeutic exercise on pain and physical function in people with knee/hip osteoarthritis (OA).

METHODS

For Subgrouping and TargetEd Exercise pRogrammes for knee and hip OsteoArthritis (STEER OA), individual participant data (IPD) were sought from all published randomised controlled trials (RCTs) comparing therapeutic exercise to non-exercise controls in people with knee/hip OA. Using the Counterfactual framework, the effect of the exercise intervention and the percentage mediated through each potential mediator (muscle strength, proprioception and range of motion (ROM)) for knee OA and muscle strength for hip OA were determined.

RESULTS

Data from 12 of 31 RCTs of STEER OA (1407 participants) were available. Within the IPD data sets, there were generally statistically significant effects from therapeutic exercise for pain and physical function in comparison to non-exercise controls. Of all potential mediators, only the change in knee extension strength was statistically and significantly associated with the change in pain in knee OA (β -0.03 (95% CI -0.05 to -0.01), 2.3% mediated) and with physical function in knee OA (β -0.02 (95% CI -0.04 to -0.00), 2.0% mediated) and hip OA (β -0.03 (95% CI -0.07 to -0.00), no mediation).

CONCLUSIONS

This first IPD mediation analysis of this scale revealed that in people with knee OA, knee extension strength only mediated ±2% of the effect of therapeutic exercise on pain and physical function. ROM and proprioception did not mediate changes in outcomes, nor did knee extension strength in people with hip OA. As 98% of the effectiveness of therapeutic exercise compared with non-exercise controls remains unexplained, more needs to be done to understand the underlying mechanisms of actions.

Comorbidity in incident osteoarthritis cases and matched controls using electronic health record data

BACKGROUND

Comorbidities are common in patients with osteoarthritis (OA). This study aimed to determine the association of a wide range of previously diagnosed comorbidities in adults with newly diagnosed OA compared with matched controls without OA.

METHODS

A case-control study was conducted. The data were derived from an electronic health record database that contains the medical records of patients from general practices throughout the Netherlands. Incident OA cases were defined as patients with one or more diagnostic codes recorded in their medical records that correspond to knee, hip, or other/peripheral OA. Additionally, the first OA code had to be recorded between January 1, 2006, and December 31, 2019. The date of cases' first OA diagnosis was defined as the index date. Cases were matched (by age, sex, and general practice) to up to 4 controls without a recorded OA diagnosis. Odds ratios were derived for each 58 comorbidities separately by dividing the comorbidity prevalence of cases by that of their matched controls at the index date.

RESULTS

80,099 incident OA patients were identified of whom 79,937 (99.8%) were successfully matched with 318,206 controls. OA cases had higher odds for 42 of the 58 studied comorbidities compared with matched controls. Musculoskeletal diseases and obesity showed large associations with incident OA.

CONCLUSIONS

Most of the comorbidities under study had higher odds in patients with incident OA at the index date. While previously known associations were confirmed in this study, some associations were not described earlier.

Tregs protect against invariant NKT cell-mediated autoimmune colitis and hepatitis

Immunomodulatory T cells play a pivotal role in protection against (auto)immune-mediated diseases that open perspectives for therapeutic modulation. However, how immune regulatory networks operate in vivo is less understood. To this end, we focused on FOXP3+CD4+CD25+ regulatory T cells (Tregs) and invariant natural killer T (iNKT) cells, two lymphocyte populations that independently regulate adaptive and innate immune responses. In vitro, a functional interplay between Tregs and iNKT cells has been described, but whether Tregs modulate the function and phenotype of iNKT cell subsets in vivo and whether this controls iNKT-mediated autoimmunity is unclear. Taking advantage of the conditional depletion of Tregs, we examined the in vivo interplay between iNKT and Treg cells in steady state and in preclinical models of liver and gut autoimmunity. Under non-inflamed conditions, Treg depletion enhanced glycolipid-mediated iNKT cell responses, with a general impact on Type 1, 2 and 17 iNKT subsets. Moreover, in vivo iNKT activation in the absence of Tregs suppressed the induction of iNKT anergy, consistent with a reduction in programmed cell death receptor 1 (PD-1) expression. Importantly, we unveiled a clear role for an in vivo Treg-iNKT crosstalk both in concanavalin A-induced acute hepatitis and oxazolone-induced colitis. Here, the absence of Tregs led to a markedly enhanced liver and gut pathology, which was not observed in iNKT-deficient mice. Taken together, these results provide evidence for a functional interplay between regulatory T cell subsets critical in controlling the onset of autoimmune disease.

Association of child neurodevelopmental or behavioural problems with maternal unemployment in a population-based birth cohort

PURPOSE

To estimate associations between suspected or diagnosed neurodevelopmental or behavioural problems in 7-year-old children and maternal unemployment at child age 7 and 10, in a Portuguese birth cohort.

METHODS

We evaluated 5754 mothers and their children of the population-based birth cohort Generation XXI in Porto, Portugal. Data on suspected and diagnosed child neurodevelopmental and behavioural problems (exposures)-learning, attention and language problems, externalising behaviours, developmental delay, autism spectrum disorders, and other neurodevelopmental problems-were retrieved at 7 years of age by interviewing caregivers. Maternal employment status (outcome) was collected at the 7- and 10-year follow-up waves. Robust Poisson regression models were used to estimate associations.

RESULTS

After adjustment for maternal and household characteristics, women were more likely to be unemployed at child age 10 if the child had, up to age 7, any of the following suspected problems: an autism spectrum disorder (PR = 1.73; 95% CI 1.07, 2.79), developmental delay (PR = 1.58; 95% CI 1.20, 2.06), externalising behaviours (PR = 1.29; 95% CI 1.11, 1.50) or learning problems (PR = 1.26; 95% CI 1.07, 1.48). When the exposure was restricted to clinically diagnosed disorders, the magnitude of associations remained similar but estimates were less precise. Associations with unemployment were stronger at child age 10 (prospective analyses), than at child age 7 (cross-sectional).

CONCLUSION

Having a child with learning, developmental or behavioural problems, or an autism spectrum disorder up to age 7 was associated with maternal unemployment three years later, even in a less affluent European economy where the dual-earner family structure is often necessary to make ends meet.

Safety of Fertility Treatments in Women With Systemic Lupus Erythematosus: Data From a Prospective Population-Based Study

OBJECTIVE

To assess safety of fertility treatments in women with systemic lupus erythematosus (SLE).

DESIGN

Data from the multicentre French observational GR2 (Groupe de Recherche sur la Grossesse et les Maladies Rares) study (2014-ongoing).

SETTING

Seventy-six centres in France.

POPULATION

All pregnancies in women with SLE enrolled in the GR2 study, conceived before 1 August 2022, with available end-of-pregnancy data and known conception type, were included; that is, 577 spontaneous and 53 assisted pregnancies.

METHODS

A comparative analysis of spontaneous and assisted pregnancies was conducted. Logistic regression was used to determine if fertility treatments were independently associated with live birth prognosis, adjusting for confounders (e.g., maternal age). Kaplan-Meier analysis compared cumulative incidences of disease flares and adverse pregnancy outcomes (APOs), with confounding factors adjusted using a Cox regression model.

MAIN OUTCOME MEASURES

Live birth, disease flares, and APOs.

RESULTS

The mean age was older (35.8 vs. 32.3 years, p < 1 × 10-4), and twins were more frequent in assisted pregnancies (5/50, 10.0% vs. 20/554, 3.6%; p = 0.047). Lupus disease was clinically inactive at baseline in 51 (96.2%) assisted pregnancies (vs. n = 511, 89.6%; p = 0.15), with 35 of 45 (77.8%) having no chronic damage (vs. 448/513, 87.3%; p = 0.07). The live birth rate was similar between assisted and spontaneous pregnancies (n = 46, 86.8% vs. n = 505, 87.5%; p = 0.83), with no statistical difference in the incidence of lupus flares and APOs. These results remained consistent after adjusting for confounding factors.

CONCLUSIONS

Fertility treatments in women with mostly well-controlled SLE did not appear to increase risks of maternal and neonatal complications, supporting current recommendations. Trial Registration ClinicalTrials.gov identifier: NCT02450396.

Clinical indications associated with new opioid use for pain management in the United Kingdom: using national primary care data

ABSTRACT

Prescription opioids for noncancer pain in the United Kingdom have increased over the past 2 decades, alongside associated harms. Policies addressing opioid prescribing must be tailored to individual patient needs with specific disease systems. The aim of this study was to evaluate clinical conditions associated with new opioid initiation in noncancer pain using nationally representative UK data. Primary care electronic health records from January 1, 2006, to September 31, 2021, were used from the Clinical Research Practice Datalink to identify incident opioid prescriptions. Patient histories were reviewed using code lists for opioid-related conditions with a 5-year look-back for chronic conditions and a 1-year look-back for surgical indications before opioid initiation. In total, 3,030,077 new opioid use episodes in 2,027,402 patients were identified, with 61% being women, 77% aged 45 years and older, and 48% from the highest deprivation quintile. Ten systems associated with opioid initiation were identified, which were not mutually exclusive, as patients could have opioids prescribed for multiple indications. The most common were musculoskeletal (80.8%), respiratory (57.6%), infections (30.4%), trauma/injury (20.4%), neurology (19.9%), and postsurgical indications (5.5%). Osteoarthritis (60.7%) and low back pain (41.0%) were the most frequent musculoskeletal conditions. Orthopedic surgeries accounted for 41.2% of all postsurgical indications. This is the first study in the United Kingdom evaluating large-scale national data to assess indications associated with opioid initiation. Nearly 3 quarters of new opioid prescriptions for noncancer pain were in patients with musculoskeletal conditions, often for conditions with limited evidence for opioid efficacy. These findings could inform targeted interventions and future policies to support nonpharmacological interventions in the most common conditions where opioid harms outweigh benefits.

CD163+ macrophages monitor enhanced permeability at the blood-dorsal root ganglion barrier

In dorsal root ganglia (DRG), macrophages reside close to sensory neurons and have largely been explored in the context of pain, nerve injury, and repair. However, we discovered that most DRG macrophages interact with and monitor the vasculature by sampling macromolecules from the blood. Characterization of the DRG vasculature revealed a specialized endothelial bed that transformed in molecular, structural, and permeability properties along the arteriovenous axis and was covered by macrophage-interacting pericytes and fibroblasts. Macrophage phagocytosis spatially aligned with peak endothelial permeability, a process regulated by enhanced caveolar transcytosis in endothelial cells. Profiling the DRG immune landscape revealed two subsets of perivascular macrophages with distinct transcriptome, turnover, and function. CD163+ macrophages self-maintained locally, specifically participated in vasculature monitoring, displayed distinct responses during peripheral inflammation, and were conserved in mouse and man. Our work provides a molecular explanation for the permeability of the blood-DRG barrier and identifies an unappreciated role of macrophages as integral components of the DRG-neurovascular unit.

Increased prevalence of malignancies in patients with IgG4-related disease: implications for clinical care

OBJECTIVES

The association between cancer and IgG4-related disease (IgG4-RD) is evolving. The primary aim of this study was to investigate the prevalence of malignancies in IgG4-RD. The secondary aim was to describe the epidemiological and clinical characteristics of IgG4-RD patients with a history of cancer.

METHODS

Two hundred and ten patients with IgG4-RD were included in this retrospective study. IgG4-RD phenotypes, clinical and serological variables were analysed. The prevalence of cancer in IgG4-RD was compared with that in the Italian population using the registry of the Global Cancer Observatory (GCO) of the World Health Organization. The Standardized Incidence Ratio (SIR) for cancer in IgG4-RD was obtained based on the 5-year Limited Duration Prevalence (2015-2020) of tumours in the Italian population.

RESULTS

Thirty-seven/210 patients (18%) developed cancer before or after the diagnosis of IgG4-RD. Solid and haematologic tumours were more frequently observed in pancreato-biliary IgG4-RD. The SIR for malignancy in IgG4-RD patients was 2.54 higher than the general Italian population (P = 0.007). The SIR was 2.78 higher for males (P = 0.005) and 1.15 higher for females (P > 0.05). Thirty-two malignancies were diagnosed before and 16 after IgG4-RD diagnosis. Interval 'from IgG4-RD to cancer' was shorter than that 'from cancer to IgG4-RD'. Most tumours occurring after IgG4-RD developed within 36 months from diagnosis of IgG4-RD.

CONCLUSIONS

The prevalence of cancer in patients with IgG4-RD is increased compared with the Italian population and mechanistically suggests a possible paraneoplastic association. Close surveillance is warranted for the first 36 months after IgG4-RD diagnosis.

Polyarticular juvenile idiopathic arthritis has a distinct co-inhibitor receptor profile

OBJECTIVES

JIA is the most common rheumatic disease of childhood; the pathogenesis is associated with T-cell activation. T-cell activation can be counterbalanced by signals generated by inhibitory receptors (IRs) such as CTLA-4, PD-1, LAG-3 and TIM-3. Here, we identify the role of IRs in the pathogenesis of different JIA subtypes.

METHODS

In total, we included 67 oligoarticular JIA, 12 IgM-RF negative polyarticular JIA, 17 enthesitis-related arthritis, 11 systemic JIA patients and 10 healthy controls. We collected plasma (and SF) samples from the patients either at the onset or during a flare of their disease. We measured the soluble levels of co-IRs (IL-2Rα, 4-1BB, CD86, TGF-β1, CTLA-4, PD-L1, PD-1, TIM-3, LAG- 3, Galectin-9) by cytometric bead array kits and their cellular expression (PD-1, CTLA-4, TIM-3, LAG-3) by flow cytometry. We compared the plasma levels and cellular expressions of different co-IRs within different JIA subgroups.

RESULTS

The polyarticular JIA group was different from the three other examined JIA subgroups, having higher levels of plasma sCTLA-4 (P < 0.001), sPD-1 (P < 0.05) and s4-1BB (P < 0.05) when compared with the other JIA subgroups and healthy controls. We analysed the cellular surface expression of different co-IRs on the peripheral blood mononuclear cells of different JIA subtypes. Similar to plasma levels, both the percentage (P < 0.05) and the mean fluorescence intensity (P < 0.01) of CTLA4 expression were higher in the polyarticular JIA subgroup.

CONCLUSION

This is the first report studying the expression profile of different co-IRs in different subtypes of JIA. Polyarticular JIA patients had a different co-IR profile, having more CTLA-4, PD-1 and 4-1BB in their plasma than the other subtypes of JIA.

Altered X-chromosome inactivation predisposes to autoimmunity

In mammals, males and females show marked differences in immune responses. Males are globally more sensitive to infectious diseases, while females are more susceptible to systemic autoimmunity. X-chromosome inactivation (XCI), the epigenetic mechanism ensuring the silencing of one X in females, may participate in these sex biases. We perturbed the expression of the trigger of XCI, the noncoding RNA Xist, in female mice. This resulted in reactivation of genes on the inactive X, including members of the Toll-like receptor 7 (TLR7) signaling pathway, in monocyte/macrophages and dendritic and B cells. Consequently, female mice spontaneously developed inflammatory signs typical of lupus, including anti-nucleic acid autoantibodies, increased frequencies of age-associated and germinal center B cells, and expansion of monocyte/macrophages and dendritic cells. Mechanistically, TLR7 signaling is dysregulated in macrophages, leading to sustained expression of target genes upon stimulation. These findings provide a direct link between maintenance of XCI and female-biased autoimmune manifestations and highlight altered XCI as a cause of autoimmunity.

The Expression of Toll-like Receptors in Cartilage Endplate Cells: A Role of Toll-like Receptor 2 in Pro-Inflammatory and Pro-Catabolic Gene Expression

INTRODUCTION

The vertebral cartilage endplate (CEP), crucial for intervertebral disc health, is prone to degeneration linked to chronic low back pain, disc degeneration, and Modic changes (MC). While it is known that disc cells express toll-like receptors (TLRs) that recognize pathogen- and damage-associated molecular patterns (PAMPs and DAMPs), it is unclear if CEP cells (CEPCs) share this trait. The CEP has a higher cell density than the disc, making CEPCs an important contributor. This study aimed to identify TLRs on CEPCs and their role in pro-inflammatory and catabolic gene expression.

METHODS

Gene expression of TLR1-10 was measured in human CEPs and expanded CEPCs using quantitative polymerase chain reaction. Additionally, surface TLR expression was measured in CEPs grouped into non-MC and MC. CEPCs were stimulated with tumor necrosis factor alpha, interleukin 1 beta, small-molecule TLR agonists, or the 30 kDa N-terminal fibronectin fragment. TLR2 signaling was inhibited with TL2-C29, and TLR2 protein expression was measured with flow cytometry.

RESULTS

Ex vivo analysis found all 10 TLRs expressed, while cultured CEPCs lost TLR8 and TLR9 expression. TLR2 expression was significantly increased in MC1 CEPCs, and its expression increased significantly after pro-inflammatory stimulation. Stimulation of the TLR2/6 heterodimer upregulated TLR2 protein expression. The TLR2/1 and TLR2/6 ligands upregulated pro-inflammatory genes and matrix metalloproteases (MMP1, MMP3, and MMP13), and TLR2 inhibition inhibited their upregulation. Endplate resorptive capacity of TLR2 activation was confirmed in a CEP explant model.

CONCLUSIONS

The expression of TLR1-10 in CEPCs suggests that the CEP is susceptible to PAMP and DAMP stimulation. Enhanced TLR2 expression in MC1, and generally in CEPCs under inflammatory conditions, has pro-inflammatory and pro-catabolic effects, suggesting a potential role in disc degeneration and MC.

Classification of patients with osteoarthritis through clusters of comorbidities using 633 330 individuals from Spain

OBJECTIVES

To explore clustering of comorbidities among patients with a new diagnosis of OA and estimate the 10-year mortality risk for each identified cluster.

METHODS

This is a population-based cohort study of individuals with first incident diagnosis of OA of the hip, knee, ankle/foot, wrist/hand or 'unspecified' site between 2006 and 2020, using SIDIAP (a primary care database representative of Catalonia, Spain). At the time of OA diagnosis, conditions associated with OA in the literature that were found in ≥1% of the individuals (n = 35) were fitted into two cluster algorithms, k-means and latent class analysis. Models were assessed using a range of internal and external evaluation procedures. Mortality risk of the obtained clusters was assessed by survival analysis using Cox proportional hazards.

RESULTS

We identified 633 330 patients with a diagnosis of OA. Our proposed best solution used latent class analysis to identify four clusters: 'low-morbidity' (relatively low number of comorbidities), 'back/neck pain plus mental health', 'metabolic syndrome' and 'multimorbidity' (higher prevalence of all studied comorbidities). Compared with the 'low-morbidity' cluster, the 'multimorbidity' cluster had the highest risk of 10-year mortality (adjusted hazard ratio [HR]: 2.19 [95% CI: 2.15, 2.23]), followed by the 'metabolic syndrome' cluster (adjusted HR: 1.24 [95% CI: 1.22, 1.27]) and the 'back/neck pain plus mental health' cluster (adjusted HR: 1.12 [95% CI: 1.09, 1.15]).

CONCLUSION

Patients with a new diagnosis of OA can be clustered into groups based on their comorbidity profile, with significant differences in 10-year mortality risk. Further research is required to understand the interplay between OA and particular comorbidity groups, and the clinical significance of such results.

Identification and quantification of degradome components in human synovial fluid reveals an increased proteolytic activity in knee osteoarthritis patients vs controls

Synovial fluid (SF) may contain cleavage products of proteolytic activities. Our aim was to characterize the degradome through analysis of proteolytic activity and differential abundance of these components in a peptidomic analysis of SF in knee osteoarthritis (OA) patients versus controls (n = 23). SF samples from end-stage knee osteoarthritis patients undergoing total knee replacement surgery and controls, that is, deceased donors without known knee disease were previously run using liquid chromatography mass spectrometry (LC-MS). This data was used to perform new database searches generating results for non-tryptic and semi-tryptic peptides for studies of degradomics in OA. We used linear mixed models to estimate differences in peptide-level expression between the two groups. Known proteolytic events (from the MEROPS peptidase database) were mapped to the dataset, allowing the identification of potential proteases and which substrates they cleave. We also developed a peptide-centric R tool, proteasy, which facilitates analyses that involve retrieval and mapping of proteolytic events. We identified 429 differentially abundant peptides. We found that the increased abundance of cleaved APOA1 peptides is likely a consequence of enzymatic degradation by metalloproteinases and chymase. We identified metalloproteinase, chymase, and cathepsins as the main proteolytic actors. The analysis indicated increased activity of these proteases irrespective of their abundance.

Stability of symptom-based subtypes in Sjogren's disease

OBJECTIVES

The Newcastle Sjogren's Stratification Tool (NSST) stratifies Sjogren's disease patients into four subtypes. Understanding the stability of the subtypes is vital if symptom-based stratification is to be more broadly adopted. In this study, we stratify patients longitudinally to understand how symptom-based subtypes vary over time and factors influencing subtype change.

METHODS

274 patients from the United Kingdom Primary Sjögren's Syndrome Registry (UKPSSR) with data permitting NSST subtype assignment from two study visits were included. The French Assessment of Systemic Signs and Evolution of Sjogren's Syndrome (ASSESS) cohort (n=237) acted as an independent comparator. Group analyses of significant differences were performed, with logistic regression models used to assess covariates of subtype stability.

RESULTS

UKPSSR and ASSESS cohorts showed a broadly similar proportion of subjects in each subtype and similar baseline clinical characteristics except body mass index (BMI). Several baseline characteristics differ significantly between the subtypes, most notably anti-Ro status and BMI. Subtype membership was reasonably stable in both cohorts with 60% and 57% retaining subtype. The high-symptom burden subtype was the most stable over time with 70% and 67% retaining subtype. Higher baseline probability score was the greatest predictor of subtype stability with higher C4 levels, antidepressant use, and a higher CCI score also predicting increased stability.

CONCLUSION

NSST subtype membership remains stable over time in a large proportion of patients. When subtype transition is associated with factors at baseline, it is most strongly associated with an uncertain subtype allocation. Our findings support the hypothesis that symptom-based subtypes reflect genuine pathobiological endotypes and therefore maybe important to consider in trial design and clinical management.