Clinical Assessment of Gastrointestinal Involvement in Patients with Systemic Sclerosis

Anti-mitochondrial antibodies in systemic sclerosis target enteric neurons and are associated with GI dysmotility

Background

Most patients with systemic sclerosis (SSc) experience gastrointestinal (GI) dysmotility. The enteric nervous system (ENS) regulates GI motility, and its dysfunction causes dysmotility. A subset of SSc patients harbor autoantibodies against the M2 mitochondrial antigen (AM2A). Here, we investigate whether M2 is expressed by specific ENS cells, and if AM2A associate with GI dysmotility in SSc patients.

Methods

Sera from 154 well-characterized patients with SSc were screened for AM2A by ELISA. Clinical features and GI transit data were compared between AM2A-positive and negative patients. HepG2 cells were cultured with these sera and co-stained with AM2A.

Results

Nineteen of 147 patients (12.9%) were AM2A positive. AM2A positivity was significantly associated with slower transit in the esophagus (β -14.4, 95%CI -26.2, -2.6) and stomach (β -7.9, 95% CI -14.1, -1.6). Immunostaining demonstrated pan-mitochondrial antigens TOM-20 and M2 enrichment in human ENS neurons, specifically in mesoderm-derived enteric neurons (MENS). HepG2 cells cultured with SSc sera showed that SSc autoantibodies penetrate live cells and that AM2A and other SSc autoantibodies are localized to subcellular compartments containing target antigens.

Conclusion

AM2A in SSc patients associate with slower GI transit. MENs are enriched in mitochondria, suggesting enhanced susceptibility to mitochondrial dysfunction and associated GI dysmotility in SSc. Our finding that SSc autoantibodies penetrate live cells in vitro suggests that SSc-AM2A may penetrate MENs in vivo, driving ENS and GI dysfunction. Further studies are warranted to understand whether AM2As contribute to mitochondrial dysfunction, and whether mitochondrial dysfunction contributes to GI dysmotility in SSc.

Managing gastrointestinal manifestations in systemic sclerosis, a mechanistic approach

INTRODUCTION

Systemic sclerosis (SSc) is a connective tissue disease with heterogeneous presentation. Gastrointestinal (GI) complications of SSc are characterized by esophageal reflux, abnormal motility, and microbiome dysbiosis, which impact patient quality of life and mortality. Preventative therapeutics are lacking, with management primarily aimed at symptomatic control.

AREAS COVERED

A broad literature review was conducted through electronic databases and references from key articles. We summarize the physiology of gastric acid production and GI motility to provide context for existing therapies, detail the current understanding of SSc-GI disease, and review GI medications studied in SSc. Finally, we explore new therapeutic options. We propose a management strategy that integrates data on drug efficacy with knowledge of disease pathophysiology, aiming to optimize future therapeutic targets.

EXPERT OPINION

SSc-GI complications remain a challenge for patients, clinicians, and investigators alike. Management presently focuses on treating symptoms and minimizing mucosal damage. Little evidence exists to suggest immunosuppressive therapy halts progression of GI involvement or reverses damage, leaving many unanswered questions about the optimal clinical approach. Further research focused on identifying patients at risk for GI progression, and the underlying mechanism(s) that drive disease will provide opportunities to prevent long-term damage, and significantly improve patient quality of life.

Particularly severe form of refractory gastrointestinal involvement in systemic sclerosis

A woman with systemic sclerosis presents with a severe and rapidly progressive form of gastrointestinal involvement, mainly marked by recurrent refractory episodes of pseudo-obstruction, culminating in severe malnutrition and dependence of parenteral nutrition. The impact on her quality of life was extremely significant. As a last resort, she started intravenous immunoglobulin with progressive improvement of her symptoms, allowing for the reinstitution of oral diet and removal of parenteral nutrition. After more than 1 year, she maintains clinical stability. Systemic sclerosis has a heterogeneous phenotype, but gastrointestinal involvement is one of the most frequent. Severe manifestations are rare, but can lead to severe malnutrition and are associated with high morbidity and mortality rates. Their management is challenging, as the available treatments are still very limited. A better understanding of its pathophysiology, which seems to be unique, is essential to provide more effective treatments and improving quality of life.

Systemic sclerosis gastrointestinal dysmotility: risk factors, pathophysiology, diagnosis and management

Nearly all patients with systemic sclerosis (SSc) are negatively affected by dysfunction in the gastrointestinal tract, and the severity of gastrointestinal disease in SSc correlates with high mortality. The clinical complications of this dysfunction are heterogeneous and include gastro-oesophageal reflux disease, gastroparesis, small intestinal bacterial overgrowth, intestinal pseudo-obstruction, malabsorption and the requirement for total parenteral nutrition. The abnormal gastrointestinal physiology that promotes the clinical manifestations of SSc gastrointestinal disease throughout the gastrointestinal tract are diverse and present a range of therapeutic targets. Furthermore, the armamentarium of medications and non-pharmacological interventions that can benefit affected patients has substantially expanded in the past 10 years, and research is increasingly focused in this area. Here, we review the details of the gastrointestinal complications in SSc, tie physiological abnormalities to clinical manifestations, detail the roles of standard and novel therapies and lay a foundation for future investigative work.

Gastrointestinal involvement in systemic sclerosis: pathogenesis, assessment and treatment

PURPOSE OF REVIEW

The majority of patients with systemic sclerosis (SSc) will experience involvement of their gastrointestinal over the course of their disease. Despite the high prevalence of gastrointestinal involvement in SSc, the strategies pertaining to the assessment and treatment for this clinical dimension of SSc have historically been limited. However, the present review highlights recent research contributions that enhance our understanding of SSc-GI patient subsets and provides updates on pathogenic mechanisms of disease, assessment and symptom-directed management.

RECENT FINDINGS

In the past few years, several studies have identified risk factors for more severe gastrointestinal disease in SSc and have provided insight to optimize diagnosis and management of SSc-GI symptoms. This article also provides a review of currently available investigations and therapies for individual SSc-GI disease manifestations and reflects on actively evolving areas of research, including our understanding the role of the gut microbiome in SSc.

SUMMARY

Here, we provide important updates pertaining to the risk stratification, assessment, diagnosis and management of SSc patients with gastrointestinal symptoms. These findings provide opportunities to enhance patient care and highlight exciting opportunities for future research.