Part II: The treatment of primary and secondary Raynaud's phenomenon

Raynaud phenomenon (RP) presents with either primary or secondary disease, and both have the potential to negatively impact patient quality of life. First-line management of RP should include lifestyle modifications in all patients. Some patients with primary RP and most with secondary RP require pharmacologic therapies, which may include calcium channel blockers, topical nitrates, phosphodiesterase 5 inhibitors, or endothelin antagonists. Additional approaches to treatment for those with signs of critical ischemia or those who fail pharmacologic therapy include botulinum toxin injection and digital sympathectomy. Herein, we describe in detail the treatment options for patients with RP as well as provide treatment algorithms for each RP subtype.

Inhibiting Intracellular α2C-Adrenoceptor Surface Translocation Using Decoy Peptides: Identification of an Essential Role of the C-Terminus in Receptor Trafficking

The G protein-coupled α2-adrenoceptor subtype C (abbreviated α2C-AR) has been implicated in peripheral vascular conditions and diseases such as cold feet-hands, Raynaud's phenomenon, and scleroderma, contributing to morbidity and mortality. Microvascular α2C-adrenoceptors are expressed in specialized smooth muscle cells and mediate constriction under physiological conditions and the occlusion of blood supply involving vasospastic episodes and tissue damage under pathological conditions. A crucial step for receptor biological activity is the cell surface trafficking of intracellular receptors, triggered by cAMP-Epac-Rap1A GTPase signaling, which involves protein-protein association with the actin-binding protein filamin-2, mediated by critical amino acid residues in the last 14 amino acids of the receptor carboxyl (C)-terminus. This study assessed the role of the C-terminus in Rap1A GTPase coupled receptor trafficking by domain-swapping studies using recombinant tagged receptors in transient co-transfections and compared with wild-type receptors using immunofluorescence microscopy. We further tested the biological relevance of the α2C-AR C-terminus, when introduced as competitor peptides, to selectively inhibit intracellular α2C-AR surface translocation in transfected as well as in microvascular smooth muscle cells expressing endogenous receptors. These studies contribute to establishing proof of principle to target intracellular α2C-adrenoceptors to reduce biological activity, which in clinical conditions can be a target for therapy.

Treatable Traits in Systemic Sclerosis

Systemic sclerosis (SSc) is a chronic systemic disease within the spectrum of connective tissue diseases, specifically characterized by vascular abnormalities and inflammatory and fibrotic involvement of the skin and internal organs resulting in high morbidity and mortality. The clinical phenotype of SSc is heterogeneous, and serum autoantibodies together with the extent of skin involvement have a predictive value in the risk stratification. Current recommendations include an organ-based management according to the predominant involvement with only limited individual factors included in the treatment algorithm. Similar to what has been proposed for other chronic diseases, we hypothesize that a "treatable trait" approach based on relevant phenotypes and endotypes could address the unmet needs in SSc stratification and treatment to maximize the outcomes. We provide herein a comprehensive review and a critical discussion of the literature regarding potential treatable traits in SSc, focusing on established and candidate biomarkers, with the purpose of setting the bases for a precision medicine-based approach. The discussion, structured based on the organ involvement, allows to conjugate the pathogenetic mechanisms of tissue injury with the proposed predictors, particularly autoantibodies and other serum biomarkers. Ultimately, we are convinced that precision medicine is the ideal guide to manage a complex condition such as SSc for which available treatments are largely unsatisfactory.

Complementary therapies for patients with systemic sclerosis

Patients with systemic sclerosis often seek information regarding complementary and nutrition-based therapy. Some study results have shown that vitamins D and E, probiotics, turmeric, l-arginine, essential fatty acids, broccoli, biofeedback, and acupuncture may be beneficial in systemic sclerosis care. However, large randomized clinical trials have not been conducted. This review summarizes current data regarding various complementary therapies in systemic sclerosis and concludes with recommendations.

The clinical effects of l-arginine and asymmetric dimethylarginine: implications for treatment in secondary Raynaud's phenomenon

Secondary Raynaud's phenomenon (RP) is often the sentinel clinical finding in systemic sclerosis and may precede systemic disease by several years. Altered nitric oxide metabolism plays a critical role in both fibrosis and severe secondary RP phenotypes in these patients. Increased flux through inducible nitric oxide synthase (iNOS) drives cutaneous fibrosis. Failure of flux through endothelial nitric oxide synthase (eNOS) contributes to increased vasoconstriction and decreased vasorelaxation. The underproduction of nitric oxide by eNOS is in part due to increased levels of asymmetric dimethylarginine (ADMA), an endogenous competitive inhibitor of nitric oxide synthase. The inhibitory effects of increased ADMA levels may be counteracted increasing serum l‐arginine, which is often an effective treatment strategy in these patients. As such, l‐arginine‐based therapies should be considered in managing secondary RP, particularly given their favourable safety and tolerability profile. While there is no established dosing regimen, studies of oral l‐arginine in secondary RP suggest that divided dosing may begin at 1–2 g/day and may be titrated up to 10 g/day. Conversely, primary RP is not associated with increased ADMA production which likely accounts for the failure of l‐arginine trials to show benefit in primary RP.

L-Arginine in pregnant scleroderma patients

Systemic sclerosis (SSc) pregnant women show a high frequency of premature births and occurrence of renal crisis. Some evidences showed the role of L-arginine in the prevention and treatment of preeclampsia. Here, we report our experience on the effect of L-arginine treatment in four consecutive SSc pregnant women. Two patients, who have planned the pregnancy, were treated with oral L-arginine; both delivered healthy babies without any prenatal complications. The other two, with high risk of pregnancy complications because of severe lung involvement and type 1 diabetes, respectively, underwent i.v. L-arginine: patient 3 had a premature delivery of a 2-kg healthy baby, while patient 4 developed preeclampsia and, at the 28th week, delivered a 1,050-g girl. The neonate had severe respiratory distress syndrome complicated by severe infection and died at day 28. Although limited, our pilot study suggests that L-arginine may be a useful therapeutic agent in pregnant SSc women.

Raynaud phenomenon and the vascular disease in scleroderma

PURPOSE OF REVIEW

Raynaud phenomenon is the earliest and most common clinical manifestations of scleroderma (systemic sclerosis). Therefore, Raynaud phenomenon offers the best window into the investigation of the early steps in the pathogenesis of systemic sclerosis. This review focuses on the differential diagnosis of Raynaud phenomenon, the transition of Raynaud phenomenon to systemic sclerosis, mechanisms and consequences of vascular injury and dysfunction in systemic sclerosis, and therapeutic options.

RECENT FINDINGS

Careful clinical evaluation using a simple definition of Raynaud phenomenon is the most reliable and reproducible method in the diagnosis. Although the assessment of vascular function by noninvasive methods is still not sensitive enough for the evaluation and follow-up of individual patients, it helps in the differential diagnosis and in population studies. Progressive deficiency in vasodilatory capacity of the vessels is proposed as a mechanism of Raynaud phenomenon, particularly in systemic sclerosis. In addition, decreased fibrinolysis and enhanced coagulation pathways undoubtedly contribute to vascular dysfunction. The mechanism of endothelial injury is still elusive, yet endothelial apoptosis mediated by antiendothelial antibodies is the most attractive hypothesis now. Therapies directed at the vascular disease continue to focus on the alleviation of vascular spasm. However, immunosuppressive therapy may influence the levels of vascular injury markers and thus may have an effect on the vascular disease itself.

SUMMARY

Continued progress in the investigation of the vascular aspects of scleroderma is described in this review. Immune involvement in the early stages of the disease and mechanism of vascular repair in advance cases are some of the highlights of last year's progress.