Elsevier

Journal of Hepatology

Volume 64, Issue 6, June 2016, Pages 1265-1273
Journal of Hepatology

Assessment of response to beta-blockers by expression of βArr2 and RhoA/ROCK2 in antrum mucosa in cirrhotic patients

https://doi.org/10.1016/j.jhep.2016.01.022Get rights and content

Background & Aims

Non-selective beta-blockers (NSBB) are first choice for prevention of variceal bleeding. But possible deleterious effects in refractory ascites and frequent non-response are clinical drawbacks. Since levels of vasoactive proteins in antrum mucosa reflect vascular dysfunction in cirrhosis, these expression levels might also reflect hemodynamic response to NSBB.

Methods

Biopsies from the gastric and duodenal mucosa of 25 patients with cirrhosis were collected and the hepatic venous pressure gradient (HVPG) was measured before and after an acute propranolol challenge. Transcription and protein expression of Ras homolog family member A (RhoA), Rho-kinase (ROCK)2, beta-arrestin2 (βArr2), endothelial nitric oxide synthase (eNOS) and the phosphorylation of downstream effectors VASP and moesin were analyzed using PCR and Western blot. Further 21 patients on NSBB were evaluated on their follow up for events of variceal bleeding defined as non-response.

Results

Ten patients showed HVPG <10 mmHg, further seven patients showed significant hemodynamic response to NSBB, whereas eight patients were non-responders. The mucosal transcription of vasoactive proteins was higher in antrum mucosa compared to corpus and duodenum. The transcriptional levels of vasoactive proteins were higher in patients with HVPG >10 mmHg and HVPG >16 mmHg. Interestingly, mRNA levels of RhoA and ROCK2 were lower in patients with large varices at endoscopy. Moreover, RhoA and ROCK2 transcription correlated with the decrease of HVPG after acute NSBB challenge. Finally, acute and long-term non-responders showed lower expression of βArr2 in antrum mucosa.

Conclusion

This study shows for the first time that the expression of βArr2 in antrum mucosa biopsies might reflect the hemodynamic response to NSBB and their long-term protective effect. This finding might offer an easy approach at upper endoscopy to facilitate the decision to treat with NSBB if varices are present.

Graphical abstract

If varices are present, β-Arrestin2-expression in the gastric antrum mucosal might offer an easy and rapid biomarker to distinguish between responder and non-responder to non-selective beta-blockers (NSBB).

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Introduction

Morbidity and mortality of patients with liver cirrhosis and portal hypertension is mainly associated with inflammatory response and infections derived from refractory ascites and variceal bleeding [1], [2], [3]. Non-selective beta-blockers (NSBB), especially propranolol as the most studied one, are the standard of care in the primary and secondary prophylaxis of variceal bleeding [4]. Moreover, NSBB might decrease bacterial translocation in cirrhotic patients [5]. The risk of first bleeding or rebleeding is markedly reduced if the hepatic venous pressure gradient (HVPG) is reduced by ⩾20% or to values ⩽12 mmHg (hemodynamic response) or during acute betablockade using propranolol by >10% [6], [7], [8]. However, NSBB might influence the survival in patients with refractory ascites and therefore should be carefully evaluated in these patients [4], [9], [10]. Only 35–40% of patients are hemodynamic responders to NSBB, but although carvedilol might work in 50% of propranolol non-responders, the non-responders have a worse outcome compared to the responders [11], [12]. In addition, non-responders to NSBB seem to be better of with alternatives to NSBB [12]. Thus, the response to NSBB is a clinically important information, which to date can only be obtained invasively by two HVPG measurements [1]. Moreover, a recent study demonstrated that non-responders often bled before the second HVPG measurement to test the hemodynamic response of NSBB [13]. Therefore, the evaluation of NSBB response during or directly after the upper GI endoscopy, if varices are present, would be clinically helpful.

The mechanism by which NSBB decrease portal pressure and prevent complications, is the decrease in splanchnic hyperperfusion due to decreased cardiac output (CO) and increased splanchnic vascular resistance [14], [15]. It has been previously shown that vascular splanchnic dysfunction is crucially involved in splanchnic hyperperfusion and aggravates portal hypertension [16]. This dysfunction is, at least partly, a result of an imbalance in vasoconstricting and vasodilating pathways. The defective Ras homolog family member A (RhoA)/Rho-kinase (ROCK) pathway together with upregulated beta-arrestin2 (βArr2) blunts contraction [17], [18], [19], [20], [21]. Furthermore, a higher production of nitric oxide (NO) deriving from upregulation of endothelial nitric oxide synthase (eNOS) and iNOS induce exaggerated vasodilatation [22], [23], [24]. Both pathomechanisms lead to arterial hypocontractility and splanchnic hyperperfusion.

Interestingly, splanchnic vascular dysfunction was reflected in expression and activity of these pathways in the gastric antral mucosa of cirrhotic patients, which were partly corrected by transjugular intrahepatic portosystemic shunt (TIPS) after 6 months [25]. In the present study we studied the relation of the expression of specific vasoactive proteins and the response to NSBB treatment in patients with cirrhosis.

Section snippets

Patients and data collection

In this study we enrolled 25 patients with clinically diagnosed liver cirrhosis but without previous variceal bleeding in Hvidovre Hospital, University of Copenhagen, Denmark. All patients received a splanchnic and systemic hemodynamic investigation for evaluation of portal hypertension. Additionally, patients with clinically significant portal hypertension received repeated evaluation at the index catheterization after acute NSBB administration using 0.15 mg/kg bodyweight propranolol infusion

General characteristics of patients

Demographics of patients and controls are shown in Table 1, laboratory parameters in Table 2. Among a total number of 25 patients, etiology of liver cirrhosis was alcohol abuse (n = 19), NASH (n = 2), viral hepatitis (n = 3) and PBC (n = 1). Ten patients showed no CSPH defined as HVPG lower than 10 mmHg, and three patients without CSPH were under NSBB treatment already. Patients with CSPH received acute NSBB challenge. HVPG decreased in seven patients more than 10% after acute NSBB administration and

Discussion

The main findings of the present study are that 1. Mucosal transcription levels of vasoactive proteins are more increased in antrum mucosa than in the rest of the ventricle; 2. Higher transcriptional levels correlate with the degree of portal hypertension; 3. RhoA and ROCK2 transcriptions correlate with the portal pressure response to NSBB challenge, 4. Expression of βArr2, RhoA and ROCK2 are lower in acute non-NSBB responders, and 5. Expression of βArr2 is lower in patients bleeding under NSBB

Financial support

This study was supported by grants from the Deutsche Forschungsgemeinschaft (SFB TRR57 to P18), the H. J. & W. Hector Stiftung and the Capital Region of Denmark Foundation of Health Research and Hvidovre Hospital Foundation for Liver Diseases and the NovoNordisk Foundation, Ernst-Bertha-Grimmke-Stiftung (6/15) and European Union’s Horizon 2020 research and innovation programme (No 668031).

Conflict of interest

The authors who have taken part in this study declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.

Authors’ contributions

Jonel Trebicka: study concept and design, acquisition of data, analysis and interpretation of data, drafting of the manuscript, critical revision of the manuscript for important intellectual content, statistical analysis, obtained funding, administrative, technical, and material support, study supervision; Matthias von Heydebrand: acquisition of data, analysis and interpretation of data, drafting of the manuscript, statistical analysis; Jennifer Lehmann: acquisition of data, analysis and

Acknowledgements

The authors thank Gudrun Hack, Silke Bellinghausen, Gitte Fisker Søndergaard, and Katrine Lyngby for excellent technical assistance.

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