New use for an old treatment: Hydroxychloroquine as a potential treatment for systemic vasculitis

Evaluation of early retinal changes in patients on long-term hydroxychloroquine using optical coherence tomography angiography

Background

Connective tissue diseases (CTD), including systemic lupus erythematosus and rheumatoid arthritis (RA), have long been treated with hydroxychloroquine (HCQ). However, prolonged HCQ use poses a risk of adverse effects, particularly retinopathy.

Objective

To detect early retinal changes assessed by optical coherence tomography angiography (OCTA) in CTD patients with long-term HCQ treatment and to explore the relationship between OCTA parameters and the concentrations of HCQ and its metabolites.

Design

A cross-sectional study conducted from March 2020 to October 2021 at the First Affiliated Hospital of Anhui Medical University.

Methods

The area and perimeter of the foveal avascular zone (FAZ), the thickness of the fovea and parafovea, and the vascular density of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) in each area of the macula were measured by OCTA in 43 CTD patients treated with HCQ for over 6 months. Meantime, blood concentrations of HCQ and its metabolites were determined by high-performance liquid chromatography-tandem mass spectrometry, and the clinical documents of all 43 involved patients were collected.

Results

There is no significant correlation between OCTA outcomes and the patient's age, disease duration, and weight-dependent dose. HCQ cumulative duration positively correlated with FAZ area and perimeter (r = 0.419, p = 0.005 and r = 0.407, p = 0.007, respectively) and negatively correlated with the foveal vessel density in DCP (r = -0.378, p = 0.012). HCQ cumulative dose had a positive correlation with FAZ area and perimeter (r = 0.445, p = 0.003 and r = 0.434, p = 0.004, respectively) and had a negative correlation with foveal vessel density in SCP and DCP (r = -0.383, p = 0.011 and r = -0.424, p = 0.005, respectively). OCTA outcomes did not correlate with HCQ and its metabolite concentrations.

Conclusion

OCTA could be used to detect microvascular changes in the macula of CTD patients with long-term HCQ therapy. It was not found the concentrations of HCQ and its metabolites were associated with retinal vascular changes.

A narrative review of potential drug treatments for nephritis in children with IgA vasculitis (HSP)

Immunoglobulin A (IgA) vasculitis (IgAV, also known as Henoch-Schoenlein purpura, HSP) is the most common vasculitis of childhood. It usually presents with a simple, self-limiting disease course; however, a small subset of patients may develop kidney involvement (IgAV-N) which occurs 4-12 weeks after disease onset and is the biggest contributor to long-term morbidity. Treatment currently targets patients with established kidney involvement; however; there is a desire to work towards early prevention of inflammation during the window of opportunity between disease presentation and onset of significant nephritis. There are no clinical trials evaluating drugs which may prevent or halt the progression of nephritis in children with IgAV apart from the early use of corticosteroids which have no benefit. This article summarises the latest scientific evidence and clinical trials that support potential therapeutic targets for IgAV-N that are currently being developed based on the evolving understanding of the pathophysiology of IgAV-N. These span the mucosal immunity, B-cell and T-cell modulation, RAAS inhibition, and regulation of complement pathways, amongst others. Novel drugs that may be considered for use in early nephritis include TRF-budesonide; B-cell inhibiting agents including belimumab, telitacicept, blisibimod, VIS649, and BION-1301; B-cell depleting agents such as rituximab, ofatumumab, and bortezomib; sparsentan; angiotensin converting enzyme inhibitors (ACE-Is); and complement pathway inhibitors including avacopan, iptacopan, and narsoplimab. Further clinical trials, as well as pre-clinical scientific studies, are needed to identify mechanistic pathways as there may be an opportunity to prevent nephritis in this condition. Key Points • Kidney involvement is the main cause of long-term morbidity and mortality in IgA vasculitis despite the current treatment recommendations. • The evolving understanding of the pathophysiology of IgA vasculitis is allowing exploration of novel treatment options which target underlying immune pathways. • Novel treatments currently being trialled in IgA nephropathy may have benefit in IgA vasculitis due to the similarities in the underlying pathophysiology, such as TRF-budesonide, B-cell modulators, and complement inhibitors. • Further studies, including clinical trials of novel drugs, are urgently needed to improve the long-term outcomes for children with IgA vasculitis nephritis.

A case series on recurrent and persisting IgA vasculitis (Henoch Schonlein purpura) in children

BACKGROUND

IgA vasculitis (IgAV) is a small vessel vasculitis that is more common in childhood. Very limited evidence exists on patients who experience an atypical disease course. The aim of this study was to describe a cohort of children diagnosed with recurrent or persisting IgAV to identify any themes associated with their disease course and areas of unmet needs.

METHODS

A single centre retrospective study of children diagnosed with recurrent or persisting IgAV at Alder Hey Children's Hospital (Liverpool, UK). Clinical data, including features at presentation and during follow up, potential triggers, abnormal laboratory and histology results, treatment and outcome at last clinical review were retrospectively collected. Key themes were identified.

RESULTS

A total of 13 children met the inclusion criteria (recurrent disease, n = 4; persisting disease, n = 9). Median age at first presentation was 10.2 years [2.6-15.5], female:male ratio 1.2:1. Children in the atypical cohort were significantly older than a larger cohort of children who followed a non-complicated disease course (median age 5.5 years (range [0.6-16.7], p = 0.003)). All children re-presented with a purpuric rash (either recurring or persisting), accompanied by joint involvement in 92% of patients (12/13). Disease-modifying anti-rheumatic drugs (DMARDs) were used in 8/13 (62%) children. The median time from first presentation to diagnosis of atypical disease was 18.4 months [5.3-150.8] and the time from first presentation to treatment was 24.1 months [1.8-95.4]. Use of corticosteroids was significantly higher in children with renal involvement (p = 0.026). During follow up, 8/13 (62%) children were admitted at least once, whilst 10/13 (77%) had re-presented at least once to the emergency department. Five (38%) children were referred to psychology services and 7 (54%) children reported feelings of frustration.

CONCLUSIONS

This series describes some characteristics of a small cohort of children with atypical IgAV. It also identifies unmet needs in children with atypical IgAV, which includes delays in diagnosis and lengthy waits for treatment, lack of high-quality evidence regarding treatment choices and a high unrecognised disease burden. Further research is needed to study this subgroup of children as evidence is lacking.

Predictors of Prolonged Euthyroidism After Radioactive Iodine Treatment for Graves' Disease: A Pilot Study

OBJECTIVE

Patients with Graves' disease who remain hyperthyroid under the treatment of antithyroid drugs (ATD) or cannot tolerate ATD usually receive radioactive iodine (RAI) to control disease activity. This pilot study aimed to identify predictors of prolonged euthyroidism > 12 months after receiving RAI.

METHODS

Demographic, clinical, and laboratory data from 117 patients receiving RAI were retrospectively collected, including age, gender, body surface area, smoking status, free thyroxine, thyrotropin, thyrotropin binding inhibiting immunoglobulin, microsomal antibody, thyroglobulin antibody, medication history, and thyroid volume. Only 85 patients without missing values were included in statistical analysis. The calculated RAI dose was the estimated thyroid volume × 0.4. The difference and ratio between the actual and calculated RAI doses were examined. A stepwise logistic regression analysis was conducted to identify important predictors of prolonged euthyroidism > 12 months. The cut-off values for discretizing continuous covariates were estimated by fitting generalized additive models.

RESULTS

Among the 85 patients on RAI, 18 (21.2%) achieved prolonged euthyroidism > 12 months, 38 (44.7%) remained hyperthyroid with decreased ATD doses, but 29 (34.1%) suffered permanent hypothyroidism and needed long-term levothyroxine. Logistic regression analysis revealed that patients with age > 66 years, 33 < age ≤ 66 years, quitting smoking vs nonsmoking or current smoking, 600 < micorsomal antibody ≤ 1729 IU/mL, 47% < thyrotropin binding inhibiting immunoglobulin ≤ 81%, 7 < thyroglobulin antibody ≤ 162 IU/mL, 0.63 < ratio between actual and calculated RAI doses ≤ 1.96, or taking hydroxychloroquine would have a higher chance of reaching prolonged euthyroidism > 12 months after receiving RAI. Its area under the Receiver Operating Characteristic (ROC) curve was 0.932.

CONCLUSION

Patients with Graves' disease who received an actual RAI dose close to the calculated RAI dose achieved prolonged euthyroidism > 12 months if they also took hydroxychloroquine during RAI treatment.

Hydroxychloroquine Alleviates EAU by Inhibiting Uveitogenic T Cells and Ameliorating Retinal Vascular Endothelial Cells Dysfunction

Purpose

Inflammation triggers the activation of CD4⁺T cells and the breakdown of blood–retinal barrier, thus contributing to the pathology of experimental autoimmune uveitis (EAU). We explored the anti-inflammatory effect of hydroxychloroquine (HCQ) on EAU and the potential mechanisms active in T cells and retinal vascular endothelial cells (RVECs).

Methods

C57BL/6J mice were immunized with interphotoreceptor retinoid binding protein 1-20 (IRBP_1–20) to induce EAU and then treated with the vehicle or HCQ (100 mg/kg/day). On day 7, 14, 21, 30 and 60 after immunization, clinical scores were evaluated. On day 14, histopathological scores were assessed, and retinas, spleens, and lymph nodes were collected for quantitative polymerase chain reaction or flow cytometry analysis. RVEC dysfunction was induced by tumor necrosis factor α (TNF-α) stimulation. The expression of cytokines, chemokines, adhesion molecules, and lectin-like oxidized LDL receptor-1 (LOX-1)/nuclear factor κB (NF-κB) was measured in RVECs with or without HCQ.

Results

HCQ treatment protected mice from uveitis, evidenced by reduced expression of inflammatory factors, chemokines, and adhesion molecules in the retina. In systemic immune response, HCQ inhibited the activation of naïve CD4⁺T cells and frequencies of T effector cells, and promoted T regulatory cells. HCQ decreased IRBP_1-20–specific T cell responses and proliferation of CD4⁺T cells in vitro. Further studies established that TNF-α induced RVECs to express inflammatory cytokines, chemokines, and adhesion molecules, whereas HCQ alleviated the alterations via the LOX-1/NF-κB pathways.

Conclusions

HCQ alleviates EAU by regulating the Teff/Treg balance and ameliorating RVECs dysfunction via the LOX-1/NF-κB axis. HCQ may be a promising therapeutic candidate for uveitis.

CMTM6-Deficient Monocytes in ANCA-Associated Vasculitis Fail to Present the Immune Checkpoint PD-L1

Objectives

ANCA-associated vasculitides (AAV) affect small- and medium-sized blood vessels. In active disease, vessel wall infiltrates are mainly composed of monocytes and macrophages. Immune checkpoint molecules are crucial for the maintenance of self-tolerance and the prevention of autoimmune diseases. After checkpoint inhibitor therapy, the development of autoimmune vasculitis has been observed. However, defects of immune checkpoint molecules in AAV patients have not been identified yet.

Methods

Monocytes and monocyte-derived macrophages from AAV patients and healthy age-matched controls were tested for surface expression of immunoinhibitory checkpoint programmed cell death ligand-1 (PD-L1). Using in vitro co-culture approaches, the effect of monocyte PD-L1 expression on CD4⁺ T cell activation and proliferation was tested.

Results

Monocytes from AAV patients displayed lower PD-L1 expression and a defective PD-L1 presentation upon activation, an effect that was correlated with disease activity. Lower PD-L1 expression was due to increased lysosomal degradation of PD-L1 in AAV monocytes. We identified a reduced expression of CMTM6, a protein protecting PD-L1 from lysosomal breakdown, as the underlying molecular defect. PD-L1^low AAV monocytes showed increased stimulatory capacity and induced T cell activation and proliferation. Inhibiting lysosomal function corrected this phenotype by increasing PD-L1, thus normalizing the pro-stimulatory behavior of AAV monocytes.

Conclusions

This study identifies a defect of the immunoinhibitory checkpoint PD-L1 in monocytes from patients with AAV. Low expression of CMTM6 results in enhanced lysosomal degradation of PD-L1, thus providing insufficient negative signaling to T cells. Correcting this defect by targeting lysosomal function may represent a novel strategy to treat AAV.

Comorbidities in rheumatic diseases need special consideration during the COVID-19 pandemic

Comorbidities in rheumatic and musculoskeletal diseases (RMDs) not only increase morbidity and mortality but also confound disease activity, limit drug usage and increase chances of severe infections or drug-associated adverse effects. Most RMDs lead to accelerated atherosclerosis and variable manifestations of the metabolic syndrome. Literature on COVID-19 in patients with RMDs, and the effects of various comorbidities on COVID-19 was reviewed. The initial data of COVID-19 infections in RMDs have not shown an increased risk for severe disease or the use of different immunosuppression. However, there are some emerging data that patients with RMDs and comorbidities may fare worse. Various meta-analyses have reiterated that pre-existing hypertension, cardiovascular disease, stroke, diabetes, chronic kidney disease, heart failure, lung disease or obesity predispose to increased COVID-19 mortality. All these comorbidities are commonly encountered in the various RMDs. Presence of comorbidities in RMDs pose a greater risk than the RMDs themselves. A risk score based on comorbidities in RMDs should be developed to predict severe COVID-19 and death. Additionally, there should be active management of such comorbidities to mitigate these risks. The pandemic must draw our attention towards, and not away from, comorbidities.

Formulation and stability study of hydroxychloroquine sulfate oral suspensions

Hydroxychloroquine is an antimalarial drug indicated in the treatment of acute attacks of malaria due to Plasmodium vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum. It is also used for the treatment of rheumatoid arthritis, discoid and systemic lupus erythematosus, and more recently proposed in COVID-19 therapy. Hydroxychloroquine is only available in tablets which are not easy to administer for pediatric and geriatric patients, and patients unable to swallow such as patients found in intensive care units. The aim of this work was to develop and optimize a ready to use liquid hydroxychloroquine formulation and to carry out the corresponding chemical and microbiological stability studies. The formulation was evaluated for ease of preparation, physical properties, and palatability. Its stability was performed at ambient temperature and under refrigeration. After 6 months of stability testing, the results showed no pH change, no drug loss, no microbial development, and no visual change. The formulation, employing excipients in a range that EMA has recommended, showed chemical and microbiological stability for at least 6 months even in the worst storage conditions.

Prevalence of hydroxychloroquine retinopathy using 2018 Royal College of Ophthalmologists diagnostic criteria

INTRODUCTION

To measure the prevalence of hydroxychloroquine retinopathy in patients attending a hydroxychloroquine monitoring service using 2018 Royal College of Ophthalmologists diagnostic criteria.

METHODS

A service evaluation audit of a hydroxychloroquine retinopathy monitoring service was undertaken. Results of Humphrey 10-2 field tests, spectral-domain optical coherence tomography and fundus autofluorescence were collected with data on dose, weight, duration of treatment, estimated glomerular filtration rate, and concurrent tamoxifen therapy. Visual field tests were assessed as reliable or unreliable, and classified as normal, hydroxychloroquine-like, poor test or related to other pathology. Cases of definite and possible retinopathy were identified using the 2018 RCOphth criteria.

RESULTS

There were 1976 attendances over two years of 1597 patients. Seven hundred and twenty-eight patients had taken hydroxychloroquine for less than 5 years and 869 had taken hydroxychloroquine for 5 years or more. Fourteen patients were identified with definite hydroxychloroquine retinopathy (1.6%), and 41 patients with possible retinopathy (4.7%). Sixty-seven per cent of 861 visual fields were performed reliably, with 66.9% classified as normal, 24.9% as poor test, 5.2% hydroxychloroquine-like and 3.0% abnormal due to other pathology.

CONCLUSIONS

The 1.6% prevalence of hydroxychloroquine retinopathy is lower than the previously reported prevalence of 7.5% as reported by Melles and Marmor JAMA Ophthalmol 132: 1453-60 (2014). This is because of a difference in the diagnostic criteria. Both definite and possible retinopathy would meet the diagnostic criteria of the Melles and Marmor study; 6.3% in our data, compared with 7.5%, a much smaller difference and likely to be explained by differences in the risk characteristics of the two groups.

Immunotherapy for ANCA-associated vasculitis during the COVID-19 pandemic

Since the first description of infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in China in December 2019, it has evolved into a pandemic and emerged as an unprecedented worldwide crisis overwhelming healthcare systems globally. Analysis of the available literature to date suggests that, in addition to older age, patients with underlying co-morbidities including hypertension, diabetes, heart disease are at higher risk for severe disease with increased mortality. Practitioners around the world also have become increasingly concerned that immunosuppressed patients including those with autoimmune diseases may be at increased risk for developing Coronavirus Disease 2019 (COVID-19) with serious complications. Very little is known about how anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis modifies the susceptibility, clinical presentation and disease course of COVID-19. In this review, we discuss the mechanism of action and challenges of the current therapeutic armamentarium of ANCA-associated vasculitis and outline approaches to management of ANCA-associated vasculitis during the COVID-19 pandemic.

Review on the Clinical Pharmacology of Hydroxychloroquine Sulfate for the Treatment of COVID-19

BACKGROUND

As the number of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infected people is greatly increasing worldwide, the international medical situation becomes very serious. Potential therapeutic drugs, vaccine and stem cell replacement methods are emerging, so it is urgent to find specific therapeutic drugs and the best treatment regimens. After the publications on hydroxychloroquine (HCQ) with anti- SARS-COV-2 activity in vitro, a small, non-randomized, open-label clinical trial showed that HCQ treatment was significantly associated with reduced viral load in patients with coronavirus disease-19 (COVID-19). Meanwhile, a large prophylaxis study of HCQ sulfate for COVID-19 has been initiated in the United States. HCQ offered a promising efficacy in the treatment of COVID-19, but the optimal administration is still being explored.

METHODS

We used the keyword "hydroxychloroquine" to conduct a literature search in PubMed to collect relevant literature on the mechanism of action of HCQ, its clinical efficacy and safety, pharmacokinetic characteristics, precautions for clinical use and drug interactions to extract and organize information.

RESULTS

This paper reviews the mechanism, clinical efficacy and safety, pharmacokinetic characteristics, exposureresponse relationship and precautions and drug interactions of HCQ, and summarizes dosage recommendations for HCQ sulfate.

CONCLUSION

It has been proved that HCQ, which has an established safety profile, is effective against SARS-CoV-2 with sufficient pre-clinical rationale and evidence. Data from high-quality clinical trials are urgently needed worldwide.

Ocular flare-up in patients with systemic lupus erythematosus following discontinuation of hydroxychloroquine

In this report, we describe two patients with systemic lupus erythematosus (SLE) who manifested with posterior segment flare-up approximately three months after cessation of hydroxychloroquine (HCQ). They were stable systemically with no history of hypertension or nephropathy at the time of referral. Our first patient presented with bilateral retinal vein occlusion, while evidence of choroidal involvement such as vascular leakage and wedge-shaped filling delay was present in indocyanine green angiography of both patients. HCQ is well known to have a role in the treatment of SLE for its immunomodulatory and antithrombotic effects. Although reports of systemic flare-up of SLE following HCQ cessation exist in the literature, this is the first report of ocular flare-up in such settings.

Clinical associations of renal involvement in ANCA-associated vasculitis

OBJECTIVE

Renal involvement in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis is associated with significant morbidity and higher mortality rates. This study examined clinical manifestations associated with renal involvement in ANCA-associated vasculitis within a large, international cross-sectional cohort.

METHODS

Univariate and multivariate analyses were performed to identify clinical factors associated with renal disease, which was defined as i) a serum-creatinine >30% above normal and a fall in creatinine-clearance >25%; or ii) haematuria attributable to active vasculitis.

RESULTS

The study cohort include 1230 patients from 31 countries; 723 (58.8%) presented with renal involvement: microscopic polyangiitis (82.2%), granulomatosis with polyangiitis (58.6%), and eosinophilic granulomatosis with polyangiitis (26.4%). The following clinical and laboratory factors were more common among patients with renal disease: age (OR 1.01, 95% CI 1.01-1.02), fever (OR 1.97, 95% CI 1.35-2.88), fatigue (OR 1.55, 95% CI 1.14-2.10), weight loss (OR 1.62, 95% CI 1.23-2.12), polyarthritis (OR 1.39, 95% CI 1.02-1.89), petechiae/purpura (OR 1.47, 95% CI 1.06-2.05), pulmonary haemorrhage (OR 5.23, 95% CI 1.39-19.63), gastrointestinal symptoms (OR 2.19, 95% CI 1.34-3.58), seizures (OR 3.42, 95% CI 1.26-9.30), lower serum albumin (OR 2.42, 95% CI 1.64-3.57), higher CRP (OR 2.06, 95% CI 1.04-4.06), low serum C3 at baseline (OR 3.86, 95% CI 1.30-11.53), myeloperoxidase- (OR 7.97, 95% CI 2.74-23.20) and proteinase 3-ANCA (OR 3.40, 95% CI 1.22-9.50). The following clinical factors were less common among patients with renal disease: mononeuritis multiplex (OR 0.63, 95% CI 0.41-0.98), proptosis/exophthalmos (OR 0.19, 95% CI 0.06-0.59), nasal polyps (OR 0.32, 95% CI 0.19-0.55), septal defect/perforation (OR 0.29, 95% CI 0.14-0.60), respiratory distress/pulmonary fibrosis/asthma (OR 0.08, 95% CI 0.04-0.19), and wheeze/obstructive airway disease (OR 0.29, 95% CI 0.16-0.52).

CONCLUSION

In this large international study, several clinical and laboratory factors were identified as associated with renal involvement in ANCA-associated vasculitis.

Hydroxychloroquine is a novel therapeutic approach for rosacea

Rosacea is a chronic inflammatory disease in face. Hydroxychloroquine (HCQ), an anti-malaria drug, was reported to have anti-inflammation activities. However, the role of HCQ on rosacea remains unclear. In this study, we revealed the potential molecular mechanism by which HCQ improved rosacea in rosacea-like mice and mast cells (MCs). Moreover, the effects of HCQ treatment for rosacea patients were investigated. In this study, we found HCQ ameliorated the rosacea-like phenotype and MCs infiltration. The elevated pro-inflammatory factors and mast cell protease were significantly inhibited by HCQ treatment in rosacea-like mice. In vitro, HCQ suppresses LL37-induced MCs activation in vitro, including the release of inflammatory factors, chemotaxis, degranulation and calcium influx. Moreover, HCQ attenuated LL37-mediated MCs activation partly via inhibiting KCa3.1-mediated calcium signaling. Thus, these evidences suggest HCQ ameliorated rosacea-like dermatitis may be by regulating immune response of MCs. Finally, the 8-week HCQ treatment exerted satisfactory therapeutic effects on erythema and inflammatory lesions of rosacea patients, indicating that it is a promising drug for rosacea in clinical treatment.

Recurrent Henoch Schönlein purpura without renal involvement successfully treated with methotrexate

Introduction

Henoch Schönlein purpura is characterised by palpable purpura, abdominal pain, arthritis/arthralgia, often with a self-limiting course. Herein, we report a patient with recurrent Henoch Schönlein purpura and severe gastrointestinal involvement, successfully treated with methotrexate.

Case presentation

A 12-year-old boy was admitted to our department with palpable purpura, abdominal pain and arthralgia. Since gastrointestinal complaints were severe, systemic steroids were administered, with tapering of dosage. Henoch Schönlein purpura recurred several times with severe abdominal pain, maelena and purpura during next two months. Colchicine and hydroxychloroquine were initiated. After four months, we also introduced methotrexate, which enabled discontinuation of previous medications including corticosteroids. Methotrexate was ceased four months later, and remission was sustained without any medications for 24 months.

Conclusion

Besides the conflicting data regarding the use of methotrexate in recurrent Henoch Schönlein purpura, our case introduces successful methotrexate experience in a child with Henoch Schönlein purpura and recurrent severe gastrointestinal involvement.

Hydroxychloroquine partially prevents endothelial dysfunction induced by anti-beta-2-GPI antibodies in an in vivo mouse model of antiphospholipid syndrome

Background

Antiphospholipid syndrome is associated with endothelial dysfunction, which leads to thrombosis and early atheroma. Given that hydroxychloroquine has anti-thrombotic properties in lupus, we hypothesized that it could reduce endothelial dysfunction in an animal model of antiphospholipid syndrome. We evaluated the effect of hydroxychloroquine in preventing endothelial dysfunction in a mouse model of antiphospholipid syndrome.

Methods

Antiphospholipid syndrome was induced by an injection of monoclonal anti-beta-2-GPI antibodies. Vascular reactivity was evaluated in mesenteric resistance arteries isolated from mice 3 weeks (APL3W) after receiving a single injection of anti-beta-2-GPI antibodies and after 3 weeks of daily oral hydroxychloroquine treatment (HCQ3W) compared to control mice (CT3W). We evaluated endothelial dysfunction by measuring acetylcholine-mediated vasodilation. A pharmacological approach was used to evaluate NO synthase uncoupling (tetrahydrobiopterin) and the generation of reactive oxygen species (Tempol).

Results

Impaired acetylcholine-mediated dilation was evidenced in mice 3 weeks after anti-beta-2-GPI antibodies injection compared to CT3W, by reduced maximal dilation (p<0.0001) and sensitivity (pKd) (p = 0.01) to acetylcholine. Hydroxychloroquine improved acetylcholine-dependent dilation, on pKd (p = 0.02) but not maximal capacity compared to untreated mice. The addition of tetrahydrobiopterin (p = 0.02) and/or Tempol (p = 0.0008) improved acetylcholine-mediated dilation in APL3W but not in HCQ3W.

Conclusions

We demonstrated that endothelial dysfunction in mouse resistance arteries persisted at 3 weeks after a single injection of monoclonal anti-beta-2-GPI antibodies, and that hydroxychloroquine improved endothelium-dependent dilation at 3 weeks, through improvement of NO synthase coupling and oxidative stress reduction.