N‐acetilcisteína oral no tratamento do fenômeno de Raynaud secundário à esclerose sistêmica: ensaio clínico randomizado, placebo‐controlado e duplo‐cego

Systematic literature review to inform the Portuguese recommendations for the management of Raynaud's phenomenon and digital ulcers in systemic sclerosis and other connective tissue diseases

OBJECTIVE

To perform a systematic literature review (SLR) aimed at evaluating the efficacy and safety of pharmacological and non-pharmacological treatments for Raynaud's phenomenon (RP) and digital ulcers (DU) in patients with systemic sclerosis (SSc) and other connective tissue diseases (CTD), in order to inform the Portuguese recommendations for managing RP and DU in these patients.

METHODS

A SLR was conducted until May 2022 to identify studies assessing the efficacy and safety of pharmacological and non-pharmacological interventions for RP and DU in SSc and other CTD. Eligible study designs included randomized controlled trials (RCTs), controlled clinical trials, and their extensions for assessing efficacy and safety of interventions. Observational studies with a comparator were included for evaluating the efficacy and safety of non-pharmacological interventions and safety of pharmacological interventions. The risk of bias of each study was assessed using standard tools.

RESULTS

Out of 71 publications meeting the inclusion criteria, 59 evaluated pharmacological and 12 non-pharmacological interventions. We found moderate quality evidence supporting the efficacy of calcium channel blockers, phosphodiesterase-5 inhibitors, and intravenous prostacyclin analogues in reducing RP frequency, severity, and duration. Intravenous iloprost had a small to moderate effect size in improving DU healing. Phosphodiesterase-5 inhibitors were effective in reducing total DU count, new DU occurrence, and enhancing DU healing. Bosentan effectively prevented new DU in SSc patients. No new safety concerns were associated with these treatments. The studies on non-pharmacological interventions were, in general, of low quality, and had a small sample size. Warming measures decreased frequency and duration of RP attacks; laser therapy improved RP-related outcomes; local oxygen-ozone therapy improved RP outcomes as an add-on therapy; bone marrow mononuclear cell implantation improved DU-associated pain; periarterial sympathectomy and vascular bypass reduced DU number and finger amputation risk.

CONCLUSION

The available evidence supports the efficacy and safety of pharmacological interventions, namely nifedipine, sildenafil, iloprost, and bosentan in treating RP and DU in patients with SSc and other CTD. Scarce and low-quality evidence does support the use of some non-pharmacological interventions but with only a modest effect size. This SLR underscores the limited availability of high-quality evidence for determining the optimal treatment.

N-Acetylcysteine and Atherosclerosis: Promises and Challenges

Atherosclerosis remains a leading cause of cardiovascular diseases. Although the mechanism for atherosclerosis is complex and has not been fully understood, inflammation and oxidative stress play a critical role in the development and progression of atherosclerosis. N-acetylcysteine (NAC) has been used as a mucolytic agent and an antidote for acetaminophen overdose with a well-established safety profile. NAC has antioxidant and anti-inflammatory effects through multiple mechanisms, including an increase in the intracellular glutathione level and an attenuation of the nuclear factor kappa-B mediated production of inflammatory cytokines like tumor necrosis factor-alpha and interleukins. Numerous animal studies have demonstrated that NAC significantly decreases the development and progression of atherosclerosis. However, the data on the outcomes of clinical studies in patients with atherosclerosis have been limited and inconsistent. The purpose of this review is to summarize the data on the effect of NAC on atherosclerosis from both pre-clinical and clinical studies and discuss the potential mechanisms of action of NAC on atherosclerosis, as well as challenges in the field.

Effects of N-acetylcysteine on Pulmonary Functions in Patients with Systemic Sclerosis: A Randomized Double Blind, Placebo Controlled Study

BACKGROUND

Systemic sclerosis (SSc) is a systematic and rare autoimmune disease that affects many organs. N-acetylcysteine (NAC), thiol-containing compound, can act both as the precursor of reduced glutathione and direct scavenger of reactive oxygen species.

OBJECTIVE

We assessed the clinical effect of NAC on the pulmonary function test of patients with diffuse scleroderma.

METHODS

This study is a randomized double-blind clinical trial that was done on 25 patients with diffuse SSc without lung involvement on primary chest high-resolution computed tomography. Placebo was administered for 13 patients and 1200 milligram NAC for 12 patients. Body plethysmography parameters were assessed at the beginning of the study and after 24 weeks.

RESULTS

Patients in the two groups were matched in the basic demographic data like age, duration of disease, and modified Rodnan skin score. The analysis showed no significant differences in parameters of plethysmography between the two groups. After importing the data of 2 patients in the placebo-treated group, who developed interstitial lung disease, DLCO in the placebo-treated group was 90.69 ± 21.29 milliliter at the end of the study, which significantly decreased compared with the beginning of the study (102.30 ± 13.83 ml). Also, changes of DLCO between the two groups were significantly different.

CONCLUSION

In this trial, the sensitivity of DLCO as the first marker in the evaluation of pulmonary function in patients with SSc was confirmed. On the other hand, NAC had no effect versus placebo in a period of 24 weeks.

Comparative efficacy and safety of treatments for secondary Raynaud's phenomenon: a systematic review and network meta-analysis of randomised trials

BACKGROUND

Several pharmacological treatments are available for secondary Raynaud's phenomenon, but there is uncertainty regarding the best options. We aimed to assess and compare the benefits and harms of treatments available for secondary Raynaud's phenomenon.

METHOD

We did a systematic review and network meta-analysis of randomised controlled trials (RCTs) of pharmacological treatments. We searched for systematic reviews published in MEDLINE and the Cochrane Database of Systematic Reviews up to Jan 31, 2017, and for RCTs published from inception to Sept 24, 2019 in MEDLINE, Embase, and ClinicalTrials.gov. We included double-blind RCTs (parallel or crossover) that compared two or more pharmacological treatments or placebo in patients with secondary Raynaud's phenomenon. Individual patient data were obtained for one unpublished RCT. Three researchers independently screened the texts and extracted the data. Efficacy outcomes included severity (on a ten-point scale), daily frequency, and mean duration of Raynaud's phenomenon attacks. We also examined tolerability and acceptability. Pairwise meta-analyses and Bayesian random-effects network meta-analyses were used to synthesise data. This study is registered with PROSPERO (CRD42017057518).

FINDINGS

We included 58 RCTs in the analysis, comprising 3867 patients (3540 [91·5%] with secondary Raynaud's phenomenon) and 15 classes of drugs. Phosphodiesterase 5 (PDE5) inhibitors were more effective than placebo for frequency (mean difference -0·36 [95% credibility interval -0·69 to -0·04]), severity (-0·34 [-0·66 to -0·03]), and duration (-3·42 [-6·62 to -0·29]) of attacks (low to moderate level of evidence). Calcium channel blockers (CCBs) were superior to placebo for frequency (-0·35 [-0·67 to -0·02]) and severity (-0·84 [-1·25 to -0·45]) of attacks (low level of evidence). For severity of attacks, selective serotonin-reuptake inhibitors (-1·54 [-2·68 to -0·41]; very low level of evidence) and oral prostacyclin receptor agonists (-0·48 [-0·80 to -0·16]; low level of evidence) were superior to placebo. No other drug classes were significantly superior to placebo with regard to efficacy outcomes. Compared with placebo, tolerability was lower for PDE5 inhibitors (incidence rate ratio for serious adverse events or early study exit due to adverse events 3·30 [95% CrI 1·49 to 7·55]) and CCBs (3·13 [1·33 to 7·04]). For all outcomes, global heterogeneity and between-study variance ranged from low (I2=0% and τ2=0·0 for attack severity and duration) to moderate (I2=41% and τ2=0·2 for tolerability). The overall risk of bias was judged to be low in 22 (38%), high in ten (17%), and unclear in 26 (45%) RCTs.

INTERPRETATION

PDE5 inhibitors and CCBs are the most effective pharmacological options, albeit with moderate efficacy and a low level of evidence. Current evidence does not support the use of any other drug in secondary Raynaud's phenomenon.

FUNDING

None.

Implication of oxidative stress in the pathogenesis of systemic sclerosis via inflammation, autoimmunity and fibrosis

Systemic sclerosis is an autoimmune disorder characterized by inflammation and a progressive fibrosis affecting the skin and visceral organs. Over the last two decades, it became clear that oxidative stress plays a key role in its pathogenesis. In this review, we highlighted the role of ROS in the various pathological components of systemic sclerosis, namely the inflammatory, the autoimmune and the fibrotic processes. We also discussed how these pathological processes can induce ROS overproduction, thus maintaining a vicious circle. Finally, we summarized the therapeutic approaches targeting oxidative stress tested in systemic sclerosis, in cells, animal models and patients.

Oxidative/nitrative stress in the pathogenesis of systemic sclerosis: are antioxidants beneficial?

Systemic sclerosis (SSc) is a multisystem autoimmune disease: characterised from the clinical side by progressive vasculopathy and fibrosis of the skin and different organs and from the biochemical side by fibroblast deregulation with excessive production of collagen and increased expression of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4). The latter contributes to an overproduction of reactive oxygen species that through an autocrine loop maintains NOX4 in a state of activation. Reactive oxygen and nitrogen species are implicated in the origin and perpetuation of several clinical manifestations of SSc having vascular damage in common; attempts to dampen oxidative and nitrative stress through different agents with antioxidant properties have not translated into a sustained clinical benefit. Objective of this narrative review is to describe the origin and clinical implications of oxidative and nitrative stress in SSc, with particular focus on the central role of NOX4 and its interactions, to re-evaluate the antioxidant approaches so far used to limit disease progression, to appraise the complexity of antioxidant treatment and to touch on novel pathways elements of which may represent specific treatment targets in the not so distant future.

The Role of Oxidative Stress in the Development of Systemic Sclerosis Related Vasculopathy

Systemic sclerosis (SSc) is a rare connective tissue disease characterized by autoimmunity, vasculopathy, and progressive fibrosis typically affecting multiple organs including the skin. SSc often is a lethal disorder, because effective disease-modifying treatment still remains unavailable. Vasculopathy with endothelial dysfunction, perivascular infiltration of mononuclear cells, vascular wall remodeling and rarefaction of capillaries is the hallmark of the disease. Most patients present with vasospastic attacks of the digital arteries referred to as 'Raynaud's phenomenon,' which is often an indication of an underlying widespread vasculopathy. Although autoimmune responses and inflammation are both found to play an important role in the pathogenesis of this vasculopathy, no definite initiating factors have been identified. Recently, several studies have underlined the potential role of oxidative stress in the pathogenesis of SSc vasculopathy thereby proposing a new aspect in the pathogenesis of this disease. For instance, circulating levels of reactive oxygen species (ROS) related markers have been found to correlate with SSc vasculopathy, the formation of fibrosis and the production of autoantibodies. Excess ROS formation is well-known to lead to endothelial cell (EC) injury and vascular complications. Collectively, these findings suggest a potential role of ROS in the initiation and progression of SSc vasculopathy. In this review, we present the background of oxidative stress related processes (e.g., EC injury, autoimmunity, inflammation, and vascular wall remodeling) that may contribute to SSc vasculopathy. Finally, we describe the use of oxidative stress related read-outs as clinical biomarkers of disease activity and evaluate potential anti-oxidative strategies in SSc.

Systemic sclerosis: Current concepts of skin and systemic manifestations

Systemic sclerosis is an uncommon autoimmune connective tissue disease with multiorgan system involvement and significant associated morbidity and mortality. Cutaneous signs and clinical manifestations are of particular importance, as they may be recognized before systemic manifestations, allowing earlier risk stratification into the limited and diffuse cutaneous subtypes, as well as earlier initiation of treatment. Important cutaneous manifestations include Raynaud's phenomenon, digital ulcers, cutaneous sclerosis, calcinosis cutis, telangiectasias, pruritus, and dyspigmentation. Despite investigation of a wide variety of treatments, no FDA-approved pharmacologic therapies exist for systemic sclerosis, and data from high-quality studies are limited. In the following review, we will discuss skin-directed therapies. Although there is evidence to support specific treatments for Raynaud's phenomenon, digital ulcers, and cutaneous sclerosis, there are limited rigorous studies evaluating the treatment of other cutaneous signs and clinical manifestations. Additional randomized-controlled trials and large observational studies are necessary to develop future evidence-based treatment options.

Raynaud's phenomenon

Raynaud's phenomenon (RP) is a major cause of pain and disability in patients with autoimmune connective tissue diseases (CTDs), particularly systemic sclerosis (SSc). The clinician must perform a comprehensive clinical assessment in patients with RP to differentiate between primary (idiopathic) and secondary RP, in particular (for rheumatologists), secondary to an autoimmune CTD, as both the prognosis and treatment may differ significantly. Key investigations are nailfold capillaroscopy and testing for autoantibodies (in particular, those associated with SSc). Patients with RP and either abnormal nailfold capillaroscopy or an SSc-specific antibody (and especially with both) have a high risk of transitioning to an autoimmune CTD. Both nailfold capillaroscopy and autoantibody specificity may help the clinician in predicting organ-based complications. The management of CTD-associated RP requires a multifaceted approach to treatment, including patient education and conservative ('non-drug') measures. Patients with CTD-associated RP often require pharmacological treatment, which in the first instance is usually a calcium channel blocker, although other agents can be used. There is an increasing tendency to use phosphodiesterase type 5 inhibitors early in the treatment of CTD-associated RP. Oral therapies are commonly associated with side effects (often due to systemic vasodilation) that may result in failure of dose escalation and/or permanent discontinuation. Intravenous prostanoid therapy and surgery (e.g., botulinum toxin injection and digital sympathectomy) can be considered in severe RP. Patients with CTD-associated RP can develop a number of ischaemic digital complications (primarily ulcers and critical ischaemia), which may be associated with significant tissue loss. Future research is required to increase the understanding of the pathogenesis and natural history of RP (to drive therapeutic advances), and to explore/develop drug therapies, including those that target the mechanisms mediating cold-induced vasoconstriction, and locally acting therapies free of systemic side effects.