BACKGROUND: Vascular fibrosis directly causes vascular thickening in Takayasu arteritis (TAK), in which sustained transforming growth factor beta (TGF-β) activation is critical. Understanding TGF-β activation regulation and blocking it might yield a therapeutic effect in TAK. Proprotein convertase subtilisin/kexin type 5 (PCSK5) rs6560480 (T/C) is associated with TAK development. In this study, we assessed the association between the PCSK5 rs6560480 genotype and PCSK5 expression in TAK and explored its molecular role in TGF-β activation and vascular fibrosis development.
METHODS: In TAK patients, PCSK5 and TGF-β expression in plasma and aortic tissue was examined by ELISA and immunohistochemical staining, and PCSK5 rs6560480 was genotyped. The correlation between PCSK5 and extracellular matrix (ECM) expression was examined by Western blotting (WB) and immunohistochemistry staining. Detection by co-immunoprecipitation was performed to detect the interaction between PCSK5 and TGF-β in adventitial fibroblasts (AAFs). Downstream signaling pathways were detected by WB and validated with appropriate inhibitors. Potential immunosuppressive agents to inhibit the effects of PCSK5 were explored in cell culture and TAK patients.
RESULTS: Patients with PCSK5 rs6560480 TT patients had significantly higher PCSK5 levels and more thickened vascular lesions than patients with PCSK5 rs6560480 CT. PCSK5 expression was significantly increased in alpha smooth muscle actin (α-SMA)-positive myofibroblasts in TAK vascular lesions. Overexpressing PCSK5 facilitated TGF-β and downstream SMAD2/3 activation and ECM expression in AAFs and aorta in in-vitro culture. The mechanistic study supported that PCSK5 activated precursor TGF-β (pro-TGF-β) to the mature form by binding the pro-TGF-β cleavage site. Leflunomide inhibited PCSK5 and pro-TGF-β binding, decreasing TGF-β activation and ECM expression, which was also partially validated in leflunomide-treated patients.
CONCLUSIONS: The findings revealed a novel pro-fibrotic mechanism of PCSK5 in TAK vascular fibrosis via TGF-β and downstream SMAD2/3 pathway activation. Leflunomide might be anti-fibrotic by disrupting PCSK5 and pro-TGF-β binding, presenting a new TAK treatment approach.

In this study, we wanted to investigate the effectiveness of combining disease-modifying anti-rheumatic drugs (DMARD) with hyperbaric oxygen therapy (HBOT) in reducing inflammation in a rheumatoid arthritis (RA) model using rats. We divided 56 male Sprague-Dawley rats into seven groups and induced RA using complete Freund\'s adjuvant. Some groups received HBOT, whereas others were given etanercept or leflunomide. We started the treatment on the 10th day after inducing RA and continued it for 18 days. To evaluate the effectiveness of the treatments, we measured paw swelling and used X-rays to examine the joints before and after the treatment. We also analysed the levels of two inflammatory markers, tumour necrosis factor (TNF)-α and interleukin (IL)-1β, using an enzyme-linked immunosorbent assay. Additionally, we conducted histological analysis and assessed the expressions of anti-IL-1β and anti-TNF-α antibodies. All the treatment groups showed a significant decrease in arthritis scores, paw swelling and levels of TNF-α and IL-1β. The X-ray images revealed improvements in joint structure, and the histopathological analysis showed reduced inflammation and collagen abnormalities. Combining DMARD with HBOT had similar effects to individual therapies, suggesting a cost-effective and potentially safer approach for improving outcomes in rats with RA.

UNASSIGNED: Among patients with rheumatoid arthritis (RA) who had an inadequate response to methotrexate, a treatment sequence initiated with biosimilar disease-modifying antirheumatic drugs (DMARDs) provides better clinical efficacy compared with conventional synthetic DMARDs recommended by current treatment guidelines; but its cost-effectiveness evidence remains unclear.
UNASSIGNED: To evaluate the cost-effectiveness of the treatment sequence initiated with biosimilar DMARDs after failure with methotrexate vs leflunomide and inform formulary listing decisions.
UNASSIGNED: This economic evaluation\'s cost-effectiveness analysis was performed at a Hong Kong public institution using the Markov disease transition model to simulate the lifetime disease progression and cost for patients with RA, using monetary value in 2022. Scenario and sensitivity analyses were performed to test the internal validity of the modeling conclusion. Participants included patients diagnosed with RA from 2000 to 2021 who were retrieved retrospectively from local electronic medical records to generate model input parameters. Statistical analysis was performed from January 2023 to March 2024.
UNASSIGNED: The model assesses 3 competing treatment sequences initiated with biosimilar infliximab (CT-P13), biosimilar adalimumab (ABP-501), and leflunomide; all used in combination with methotrexate.
UNASSIGNED: Lifetime health care cost and quality-adjusted life-years (QALYs) of the simulated cohort.
UNASSIGNED: In total, 25 099 patients with RA were identified (mean [SD] age, 56 [17] years; 19 469 [72.7%] women). In the base-case analysis, the lifetime health care cost and QALYs for the treatment sequence initiated with leflunomide were US $154 632 and 14.82 QALYs, respectively; for biosimilar infliximab, they were US $152 326 and 15.35 QALYs, respectively; and for biosimilar adalimumab, they were US $145 419 and 15.55 QALYs, respectively. Both biosimilar sequences presented lower costs and greater QALYs than the leflunomide sequence. In the deterministic sensitivity analysis, the incremental cost-effectiveness ratio (US$/QALY) comparing biosimilar infliximab sequence vs leflunomide sequence and biosimilar adalimumab sequence vs leflunomide sequence ranged from -15 797 to -8615 and -9088 to 10 238, respectively, all below the predefined willingness-to-pay threshold (US $48 555/QALY gain). In the probabilistic sensitivity analysis, the probability of treatment sequence initiated with leflunomide, biosimilar infliximab, and biosmilar adalimumab being cost-effective out of 10 000 iterations was 0%, 9%, and 91%, respectively.
UNASSIGNED: In this economic evaluation study, the treatment sequences initiated with biosimilar DMARDs were cost-effective compared with the treatment sequence initiated with leflunomide in managing patients with RA who experienced failure with the initial methotrexate treatment. These results suggest the need to update clinical treatment guidelines for initiating biosimilars immediately after the failure of methotrexate for patients with RA.

To develop the second evidence-based Brazilian Society of Rheumatology consensus for diagnosis and treatment of lupus nephritis (LN).
Two methodologists and 20 rheumatologists from Lupus Comittee of Brazilian Society of Rheumatology participate in the development of this guideline. Fourteen PICO questions were defined and a systematic review was performed. Eligible randomized controlled trials were analyzed regarding complete renal remission, partial renal remission, serum creatinine, proteinuria, serum creatinine doubling, progression to end-stage renal disease, renal relapse, and severe adverse events (infections and mortality). The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to develop these recommendations. Recommendations required ≥82% of agreement among the voting members and were classified as strongly in favor, weakly in favor, conditional, weakly against or strongly against a particular intervention. Other aspects of LN management (diagnosis, general principles of treatment, treatment of comorbidities and refractory cases) were evaluated through literature review and expert opinion.
All SLE patients should undergo creatinine and urinalysis tests to assess renal involvement. Kidney biopsy is considered the gold standard for diagnosing LN but, if it is not available or there is a contraindication to the procedure, therapeutic decisions should be based on clinical and laboratory parameters. Fourteen recommendations were developed. Target Renal response (TRR) was defined as improvement or maintenance of renal function (±10% at baseline of treatment) combined with a decrease in 24-h proteinuria or 24-h UPCR of 25% at 3 months, a decrease of 50% at 6 months, and proteinuria < 0.8 g/24 h at 12 months. Hydroxychloroquine should be prescribed to all SLE patients, except in cases of contraindication. Glucocorticoids should be used at the lowest dose and for the minimal necessary period. In class III or IV (±V), mycophenolate (MMF), cyclophosphamide, MMF plus tacrolimus (TAC), MMF plus belimumab or TAC can be used as induction therapy. For maintenance therapy, MMF or azathioprine (AZA) are the first choice and TAC or cyclosporin or leflunomide can be used in patients who cannot use MMF or AZA. Rituximab can be prescribed in cases of refractory disease. In cases of failure in achieving TRR, it is important to assess adherence, immunosuppressant dosage, adjuvant therapy, comorbidities, and consider biopsy/rebiopsy.
This consensus provides evidence-based data to guide LN diagnosis and treatment, supporting the development of public and supplementary health policies in Brazil.

Microscopic colitis (MC) is characterized by chronic watery diarrhea that requires histological examination for diagnosis. Here, we present a case of a 63-year-old female with rheumatoid arthritis who developed persistent diarrhea following leflunomide initiation. Despite a normal colonoscopy, random colonic biopsies confirmed MC. Discontinuation of leflunomide led to symptom resolution, implicating it as the causative agent. Leflunomide-induced MC is exceedingly rare, with limited documented cases. Understanding its variability in presentation and timely recognition is crucial. This case underscores the importance of thorough medication history assessment and consideration of drug-induced colitis in patients presenting with unexplained diarrhea, facilitating prompt management and resolution.

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This study examines the association of standard-of-care systemic lupus erythematosus (SLE) medications with key outcomes such as low disease activity attainment, flares, damage accrual, and steroid-sparing, for which there is current paucity of data.
The Asia Pacific Lupus Collaboration (APLC) prospectively collects data across numerous sites regarding demographic and disease characteristics, medication use, and lupus outcomes. Using propensity score methods and panel logistic regression models, we determined the association between lupus medications and outcomes.
Among 1707 patients followed over 12,689 visits for a median of 2.19 years, 1332 (78.03%) patients achieved the Lupus Low Disease Activity State (LLDAS), 976 (57.18%) experienced flares, and on most visits patients were taking an anti-malarial (69.86%) or immunosuppressive drug (76.37%). Prednisolone, hydroxychloroquine and azathioprine were utilised with similar frequency across all organ domains; methotrexate for musculoskeletal activity. There were differences in medication utilisation between countries, with hydroxychloroquine less frequently, and calcineurin inhibitors more frequently, used in Japan. More patients taking leflunomide, methotrexate, chloroquine/hydroxychloroquine, azathioprine, and mycophenolate mofetil/mycophenolic acid were taking ≤ 7.5 mg/day of prednisolone (compared to > 7.5 mg/day) suggesting a steroid-sparing effect. Patients taking tacrolimus were more likely (Odds Ratio [95% Confidence Interval] 13.58 [2.23-82.78], p = 0.005) to attain LLDAS. Patients taking azathioprine (OR 0.67 [0.53-0.86], p = 0.001) and methotrexate (OR 0.68 [0.47-0.98], p = 0.038) were less likely to attain LLDAS. Patients taking mycophenolate mofetil were less likely to experience a flare (OR 0.79 [0.64-0.97], p = 0.025). None of the drugs was associated with a reduction in damage accrual.
This study suggests a steroid-sparing benefit for most commonly used standard of care immunosuppressants used in SLE treatment, some of which were associated with an increased likelihood of attaining LLDAS, or reduced incidence of flares. It also highlights the unmet need for effective treatments in lupus.

OBJECTIVE: To retrospectively evaluate safety and tolerance of leflunomide for long-term treatment of canine idiopathic immune-mediated polyarthritis (IMPA).
METHODS: 27 dogs with clinical signs and synovial fluid cytology supportive of IMPA with ≥ 6 months\' follow-up after starting leflunomide.
METHODS: Medical records were reviewed to identify dogs prescribed leflunomide for treatment of IMPA from February 2012 to May 2022. Initial leflunomide doses of 2 to 4 mg/kg once daily were prescribed and were titrated to the lowest effective dose with concurrent anti-inflammatory therapy. Complete blood count, serum chemistry, and clinical signs were monitored throughout the course of treatment.
RESULTS: Adverse effects potentially attributable to leflunomide noted in 9 of 27 dogs (33%) included vomiting, diarrhea, lethargy, decreased or absent appetite, polyuria and polydipsia, and secondary antibiotic responsive infection and were self-limiting or resolved with outpatient therapy. Alkaline phosphatase (ALP) and alanine aminotransferase (ALT) elevation were documented in all dogs prescribed leflunomide plus prednisone, with persistent liver enzyme elevation in 6 of 9 dogs (67%) and normalization after antibiotic therapy in 3 of 9 dogs (33%). The majority of dogs prescribed leflunomide plus NSAID (11/17 [65%] dogs) did not experience liver enzyme elevation; 2 of 17 (12%) dogs developed transient antibiotic-responsive liver enzyme elevations, and 4 of 17 (23%) dogs had persistent liver enzyme elevation.
CONCLUSIONS: Leflunomide was well tolerated for long-term management of IMPA. A significant difference in liver enzyme elevation was identified between dogs prescribed prednisone versus NSAID in combination with leflunomide. Leflunomide with NSAID therapy resulted in less hepatotoxicity compared with leflunomide with prednisone.

Neonatal hypoxia-ischemia (HI) affects 2-3 per 1000 live births in developed countries and up to 26 per 1000 live births in developing countries. It is estimated that of the 750,000 infants experiencing a hypoxic-ischemic event during birth per year, more than 400,000 will be severely affected. As treatment options are limited, rapidly identifying new therapeutic avenues is critical, and repurposing drugs already in clinical use offers a fast-track route to clinic. One emerging avenue for therapeutic intervention in neonatal HI is to target mitochondrial dysfunction, which occurs early in the development of brain injury. Mitochondrial dynamics are particularly affected, with mitochondrial fragmentation occurring at the expense of the pro-fusion protein Optic Atrophy (OPA)1. OPA1, together with mitofusins (MFN)1/2, are required for membrane fusion, and therefore, protecting their function may also safeguard mitochondrial dynamics. Leflunomide, an FDA-approved immunosuppressant, was recently identified as an activator of MFN2 with partial effects on OPA1 expression. We, therefore, treated C17.2 cells with Leflunomide before or after oxygen-glucose deprivation, an in vitro mimic of HI, to determine its efficacy as a neuroprotection and inhibitor of mitochondrial dysfunction. Leflunomide increased baseline OPA1 but not MFN2 expression in C17.2 cells. However, Leflunomide was unable to promote cell survival following OGD. Equally, there was no obvious effect on mitochondrial morphology or bioenergetics. These data align with studies suggesting that the tissue and mitochondrial protein profile of the target cell/tissue are critical for taking advantage of the therapeutic actions of Leflunomide.

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by abnormal activation of CD4+ T cells and an imbalance of T helper 17 (Th17) and regulatory T (Treg) cells. Tolerogenic therapy via administration of self-antigens is a promising strategy for RA treatment, but delivery of autoantigens alone may exacerbate disease conditions. Current studies indicated that codelivery of autoantigens with immunomodulators can lead to a more tolerogenic immune response. Here, we constructed an autoantigen type II collagen peptide (CII250-270)- and immunomodulator leflunomide (LEF)-coloaded phosphatidylserine liposome vaccine (CII250-270-LEF-PSL) for RA treatment via induction of tolerant dendritic cells (tolDC) for further activation of Treg cells. The in vivo results showed that CII250-270-LEF-PSL can effectively induce tolDC, regulate the balance of Th1/Th2 and Th17/Treg, and reduce the secretion of pro-inflammatory cytokines (IFN-γ, IL-1β, and IL-17A) and IgG antibodies to inhibit synovial inflammation and bone erosion. Furthermore, our study also suggested that LEF regulated Th1 cell differentiation by inhibiting the activation of the JAK1/STAT1 signaling pathway, further alleviating RA. Overall, this work proved that the combination of autoantigenic peptides and immunomodulators was a promising modality for RA treatment by reestablishing antigen-specific immune tolerance, which also inspired additional insights into the development of combination therapies for the tolerability of RA.