Successful use of sirolimus in a patient with cardiac microangiopathy in primary antiphospholipid syndrome

Interaction of antiphospholipid antibodies with endothelial cells in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease with arteriovenous thrombosis and recurrent miscarriages as the main clinical manifestations. Due to the complexity of its mechanisms and the diversity of its manifestations, its diagnosis and treatment remain challenging issues. Antiphospholipid antibodies (aPL) not only serve as crucial "biomarkers" in diagnosing APS but also act as the "culprits" of the disease. Endothelial cells (ECs), as one of the core target cells of aPL, bridge the gap between the molecular level of these antibodies and the tissue and organ level of pathological changes. A more in-depth exploration of the relationship between ECs and the pathogenesis of APS holds the potential for significant advancements in the precise diagnosis, classification, and therapy of APS. Many researchers have highlighted the vital involvement of ECs in APS and the underlying mechanisms governing their functionality. Through extensive in vitro and in vivo experiments, they have identified multiple aPL receptors on the EC membrane and various intracellular pathways. This article furnishes a comprehensive overview and summary of these receptors and signaling pathways, offering prospective targets for APS therapy.

The mTOR pathway in the antiphospholipid syndrome

This perspective discussed the available evidence on the involvement of mTOR pathway in antiphospholipid syndrome (APS), from the aspects of endothelial cells, platelets, monocytes and anti-phospholipid antibodies (PLs), which may lead to future therapeutic applications of mTOR inhibition in APS.

Sirolimus Monotherapy for Thrombocytopenia in Primary Antiphospholipid Syndrome: A Pilot Study From a Tertiary Referral Center

Background

Thrombocytopenia (TP) is considered as a warning sign of high-risk antiphospholipid syndrome (APS) and sometimes a paradoxical sign of anti-thrombosis treatment. Currently, there is an extreme paucity of effective and safe drugs for long-term management of TP in primary APS patients; therefore, we explored the efficacy and safety of sirolimus monotherapy.

Methods

In this real-world study, we included 7 consecutive patients with primary APS who received sirolimus monotherapy for TP. Oral sirolimus was initiated at a dose of 1–2 mg once daily and then adjusted primarily based on clinical efficacy and tolerance, with consideration of the sirolimus trough concentration of ≤15 ng/ml.

Results

Of included patients, the median age was 58 years with a median disease course of 1.5 years and 4 patients were treatment-naïve. All patients completed 6 months of sirolimus therapy with a median follow-up of 6 months (range: 6–15). All patients received sirolimus monotherapy for TP during the entire follow-up, without any additional agents. Overall, the platelet count exhibited a substantially increasing trend after sirolimus administration during the first 6 months (p < 0.001) and stability later. Specifically, the median platelet count was significantly increased from 59 × 10⁹/l before sirolimus to 90 × 10⁹/l at month 1 (p = 0.028), 131 × 10⁹/l at 3 months (p = 0.028), and 178 × 10⁹/l at 6 months (p = 0.018). Overall and complete responses were respectively achieved in 6 (85.7%) and 5 (71.4%) patients at month 6. Importantly, overall response was achieved in all 4 treatment-naïve patients. Additionally, there were different extents of decline in the titers of antiphospholipid antibodies after sirolimus treatment. Regarding safety, only one patient experienced an elevated cholesterol level with recovery after atorvastatin treatment.

Conclusion

Sirolimus monotherapy confers good efficacy and tolerance for TP in primary APS patients and therefore may be considered as a first-line therapy.

Systemic sclerosis myocarditis has unique clinical, histological and prognostic features: a comparative histological analysis

OBJECTIVE

To outline the clinical, histological and prognostic features of systemic sclerosis (SSc) endomyocardial biopsy-proven myocarditis with respect to those of diverse endomyocardial biopsy-proven virus-negative myocarditis (VNM).

METHODS

We retrospectively analysed data from three cohorts of endomyocardial biopsy-proven myocarditis: SSc-related VNM (SSc-VNM); isolated VNM (i-VNM); and VNM related to other systemic autoimmune diseases (a-VNM). The degree of myocardial fibrosis was expressed as relative percentage and fibrotic score (0-3). Clinical data, cardiac enzymes, echocardiogram, 24 h ECG Holter and cardiac magnetic resonance were obtained at baseline and during follow-up. Non-parametric tests were used.

RESULTS

We enrolled 12 SSc-VNM [11 females, mean age 49.3 (14.2) years; seven diffuse-SSc, five early-SSc], 12 i-VNM [12 females, mean age 47.7 (10.8) years] and 10 a-VNM [four females, mean age 48.4 (16.3) years] patients. SSc patients had higher degrees of myocardial fibrosis as assessed by both percentage [SSc-VNM: 44.8 (18.8)%; a-VNM: 28.6 (16.5)%; i-VNM: 24.9 (10.3)%; P = 0.019] and score [SSc-VNM: 2.3 (0.8); a-VNM: 1.4 (1.1); i-VNM: 1.2 (0.7); P = 0.002]. Myocardial fibrosis directly correlated with skin score (r = 0.625, P = 0.03) and number of ventricular ectopic beats on 24 h ECG Holter in SSc patients (r = 0.756, P = 0.01). Dyspnoea class was higher at presentation in SSc-VNM patients (P = 0.041) and we found heart failure only in SSc patients (25%) (P = 0.05). At cardiac magnetic resonance, myocardial oedema was nearly undetectable in SSc-VNM patients compared with others (P = 0.02). All patients received immunosuppressive treatment. The number of patients who died during follow-up due to cardiac complications was significantly higher in SSc-VNM patients (50%), as compared with a-VNM (0%) and i-VNM (8.3%) patients (P = 0.006). Patients who died during follow-up had higher degrees of myocardial fibrosis [52.2 (11.6)% vs 27.5 (12.9)%, P = 0.024; fibrotic score: 2.83 (0.41) vs 1.4 (0.9), P < 0.001].

CONCLUSION

SSc has unique clinical and histological features, as it tends to present more frequently with heart failure and a higher dyspnoea class and to show higher degrees of myocardial fibrosis. These specific features are paralleled by a worse cardiac prognosis.

Treatment of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is the most common acquired thrombophilia. The clinical manifestations of APS are mainly vascular thrombosis (venous and/or arterial) and/or recurrent pregnancy morbidity with the concomitant persistent presence of antiphospholipid antibodies (aPL). Therefore, the goals of the treatment of patients with APS are reducing the pregnancy morbidity and/or the prevention of thrombotic events during the follow-up. Optimal treatment of APS has long been discussed, due to the heterogeneity of the clinical manifestations and the consequent plurality in the medical specialties involved in managing this condition. This review summarizes the available evidence on primary thromboprophylaxis in aPL-positive individuals with no prior thrombotic events, secondary prophylaxis in patients with positive history for thrombotic events, the management of refractory or difficult cases and the current strategies for the management of APS during pregnancy.