Serum N-terminal pro-brain natriuretic peptide, a marker of skin thickness in systemic sclerosis?

Large-Scale Characterization of Systemic Sclerosis Serum Protein Profile: Comparison to Peripheral Blood Cell Transcriptome and Correlations With Skin/Lung Fibrosis

OBJECTIVE

To provide a large-scale assessment of serum protein dysregulation in diffuse cutaneous systemic sclerosis (dcSSc) and to investigate serum protein correlates of SSc fibrotic features.

METHODS

We investigated serum protein profiles of 66 participants with dcSSc at baseline who were enrolled in the Scleroderma: Cyclophosphamide or Transplant Trial and 66 age- and sex-matched healthy control subjects. A panel of 230 proteins, including several cytokines and chemokines, was investigated. Whole blood gene expression profiling in concomitantly collected samples was performed.

RESULTS

Among the participants with dcSSc, the mean disease duration was 2.3 years. All had interstitial lung disease (ILD), and none were being treated with immunosuppressive agents at baseline. Ninety proteins were differentially expressed in participants with dcSSc compared to healthy control subjects. Similar to previous global skin transcript results, hepatic fibrosis, granulocyte and agranulocyte adhesion, and diapedesis were the top overrepresented pathways. Eighteen proteins correlated with the modified Rodnan skin thickness score (MRSS). Soluble epidermal growth factor receptor was significantly down-regulated in dcSSc and showed the strongest negative correlation with the MRSS, being predictive of the score's course over time, whereas α₁ -antichymotrypsin was significantly up-regulated in dcSSc and showed the strongest positive correlation with the MRSS. Furthermore, higher levels of cancer antigen 15-3 correlated with more severe ILD, based on findings of reduced forced vital capacity and higher scores of disease activity on high-resolution computed tomography. Only 14 genes showed significant differential expression in the same direction in serum protein and whole blood RNA gene expression analyses.

CONCLUSION

Diffuse cutaneous SSc has a distinct serum protein profile with prominent dysregulation of proteins related to fibrosis and immune cell adhesion/diapedesis. The differential expression for most serum proteins in SSc is likely to originate outside the peripheral blood cells.

N-TproBNP as biomarker in systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disorder characterized by tissue fibrosis affecting the skin and internal organs, fibroproliferative vasculopathy, and autoimmune activation. SSc still heralds a poor prognosis with significant morbidity and mortality. Early detection of organ involvement is critical as currently available treatments are most effective when started early. Many candidate biomarkers have been investigated in the past two decades. However, despite the enormous efforts, no accurate tool to predict the pattern of organ involvement and to assess disease activity has been yet identified. The N-terminal fragment of probrain natriuretic peptide (N-TproBNP) is a neurohormone released by ventricular myocytes in response to pressure overload. N-TproBNP is highly relevant for diagnosis, prognosis, and prediction of pulmonary arterial hypertension in SSc. Moreover, several studies support its potential benefit for cardiac assessment of scleroderma patients. Conversely, the role of N-TproBNP as surrogate marker of pulmonary fibrosis and skin involvement is much less clear. We provide an extensive review of the studies that have previously investigated the role of N-TproBNP as candidate biomarker in scleroderma manifestations, presenting also the findings of a recent study we conducted in a cohort of 87 SSc patients.

B-type natriuretic peptide in rheumatic diseases: a cardiac biomarker or a sophisticated acute phase reactant?

Natriuretic peptides (NP) are secreted by cardiomyocytes and are reliable markers of cardiac dysfunction and cardiovascular risk by reflecting myocardial stress due to various etiologies. Clinical and occult heart involvement is frequently observed in patients with rheumatic diseases and is associated with increased morbidity and mortality. Cardiac disease in autoimmune disorders encompasses different pathophysiological mechanisms including inflammation and involving either the myocardium or the coronary/pulmonary vessels. Although the major trigger for the synthesis and release of NP is myocardial strain, there is also some support for the concept that inflammation stimulates the neurohormonal system of the heart leading to increased production of NP. Recent studies have focused on the association of NP and inflammation in the context of rheumatic diseases, suggesting that up-regulation of neurohormonal axis in these conditions is linked with inflammation. Additionally the NP have a well-documented role in the diagnostic work-up of patients with connective tissue disease who are at increased risk of developing pulmonary hypertension, as the right ventricular overload results in increased NP synthesis and release. However the precise role of NP in the assessment and the management of cardiovascular risk in patients with rheumatic diseases is yet to be established. In the current article we discuss the pathophysiologic mechanisms involved in enhanced NP expression in patients with rheumatic disorders and their potential clinical implication in daily practice.

Systemic sclerosis and the heart: current diagnosis and management

PURPOSE OF REVIEW

When present clinically, cardiac involvement in systemic sclerosis (SSc) is a major risk factor for death. It is therefore vitally important to understand the epidemiology, screening, diagnosis, and treatment of the cardiac manifestations of SSc.

RECENT FINDINGS

The epidemiology of cardiac involvement in SSc has been the subject of several recent studies. Most importantly, the prevalence of overt left ventricular (LV) systolic dysfunction and its associated risk factors have been defined, and patients with diffuse cutaneous SSc appear to be most susceptible to direct cardiac involvement. From a diagnostic and screening standpoint, tissue Doppler echocardiography and natriuretic peptides have provided fresh insight into subclinical cardiac dysfunction in SSc. Newer techniques, such as speckle-tracking echocardiography, diffuse myocardial fibrosis imaging, and absolute myocardial perfusion imaging, are poised to further advance our knowledge. Lastly, there is now consistent observational data to suggest a central role for calcium channel blockers in the treatment of microvascular ischemia and prevention of overt LV systolic dysfunction, although randomized controlled trials are lacking.

SUMMARY

Recent studies have improved our understanding of cardiac involvement in SSc. Nevertheless, key questions regarding screening, diagnosis, and treatment remain. Novel diagnostic techniques and multicenter studies should yield important new data, which will hopefully ultimately result in improved outcomes.