Sphingosine-1-phosphate is a possible fibrogenic factor in gluteal muscle fibrosis

Role of sphingosine 1-phosphate signalling in tissue fibrosis

Fibrosis is characterized by the excessive accumulation of extracellular matrix components, leading to loss of tissue function in affected organs. Although the majority of fibrotic diseases have different origins, they have in common a persistent inflammatory stimulus and lymphocyte-monocyte interactions that determine the production of numerous fibrogenic cytokines. Treatment to contrast fibrosis is urgently needed, since some fibrotic diseases lead to systemic fibrosis and represent a major cause of death. In this article, the role of the bioactive sphingolipid sphingosine 1-phosphate (S1P) and its signalling pathway in the fibrosis of different tissue contexts is extensively reviewed, highlighting that it may represent an innovative and promising pharmacological therapeutic target for treating this devastating multifaceted disease. In multiple tissues S1P influences different aspects of fibrosis modulating the recruitment of inflammatory cells, as well as cell proliferation, migration and transdifferentiation into myofibroblasts, the cell type mainly involved in fibrosis development. Moreover, at the level of fibrotic lesions, S1P metabolism is profoundly influenced by multiple cross-talk with profibrotic mediators, such as transforming growth factor β, thus finely regulating the development of fibrosis. This article is part of a Special Issue entitled "Physiological and pathological roles of bioactive sphingolipids".

Gluteal Fibrosis and Its Surgical Treatment

BACKGROUND

The objective of this study was to analyze the literature regarding the diagnosis, pathogenesis, and prevalence of gluteal fibrosis (GF) and the outcomes of treatment.

METHODS

We searched PubMed, Embase, and Cochrane literature databases, from database inception to December 15, 2016. We used the following search terms including variants: "contracture," "fibrosis," "injections," "injections, adverse reactions,' "gluteal," and "hip." All titles and abstracts of potentially relevant studies were scanned to determine whether the subject matter was potentially related to GF, using predefined inclusion and exclusion criteria. If the abstract had subject matter involving GF, the paper was selected for review if full text was available. Only papers including ≥10 subjects who underwent surgical treatment were included in the systematic analysis. Data abstracted included the number of patients, patient age and sex, the type of surgical treatment, the method of outcome measurement, and outcomes and complications.

RESULTS

The literature search yielded 2,512 titles. Of these, 82 had a focus on GF, with 50 papers meeting the inclusion criteria. Of the 50 papers reviewed, 18 addressed surgical outcomes. The surgical techniques in these papers included open, minimally invasive, and arthroscopic release and radiofrequency ablation. Of 3,733 operatively treated patients in 6 reports who were evaluated on the basis of the criteria of Liu et al., 83% were found to have excellent results. Few papers focused on the incidence, prevalence, and natural history of GF, precluding quantitative synthesis of the evidence in these domains.

CONCLUSIONS

This study provided a systematic review of surgical outcomes and a summary of what has been reported on the prevalence, diagnosis, prognosis, and pathogenesis of GF. Although GF has been reported throughout the world, it requires further study to determine the exact etiology, pathogenesis, and appropriate treatment. Surgical outcomes appear satisfactory.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The Role of S1P and the Related Signaling Pathway in the Development of Tissue Fibrosis

Tissue fibrosis, including pulmonary fibrosis, hepatic fibrosis, and cardiac fibrosis, is an important stage in the development of many diseases. It can lead to structural damage and dysfunction and even severe carcinogenesis or death. There is currently no effective method for the treatment of fibrosis. At present, the molecular mechanism of tissue fibrosis has not yet been fully elucidated, but many studies have demonstrated that it is involved in conveying the complex messages between fibroblasts and various cytokines. Sphingosine 1-phosphate (S1P) is a naturally bioactive sphingolipid. S1P and the related signaling pathways are important intracellular metabolic pathways involved in many life activities, including cell proliferation, differentiation, apoptosis, and cellular signal transduction. Increasing evidence suggests that S1P and its signaling pathways play an important role in the development of tissue fibrosis; however, the mechanisms of these effects have not yet been fully elucidated, and even the role of S1P and its signaling pathways are still controversial. This article focuses on the role of S1P and the related signaling pathways in the development of fibrosis of lung, liver, heart, and other tissues, with emphasis on the application of inhibitors of some of molecules in the pathway in clinical treatment of fibrosis diseases.

Comparison of the clinical effects of arthroscopic surgery vs. open surgery for grade II gluteal muscle contracture in adults

The aim of the present study was to compare the clinical effects of arthroscopic surgery with open surgery for grade II gluteal muscle contracture (GMC) in adults and to discuss the indication and technique for arthroscopic GMC release. The clinical data of 113 adult patients with grade II GMC between 2011 and 2016 was retrospectively collected. Among these patients, 72 patients received open surgery and 41 received arthroscopic surgeryy. The 2 groups were compared in terms of surgical duration, incision size, blood loss, hospital stay, analgesic dose and ranking of postoperative functions and effects. Mean surgical duration was significantly greater in the arthroscopic surgery group (P<0.001). Mean incision size, blood loss, hospital stay and analgesic dose were significantly lower in the arthroscopic surgery group compared with the open surgery group (P<0.001). There was no significant difference observed regarding the ranking of functions and effects between the two groups. These results suggest that existing untreated patients with GMC having low-severity (grade II) contractures of limited area are suitable for arthroscopic surgery. The advantages of arthroscopic GMC release include limited surgical trauma, a small incision, low blood loss and fewer surgical complications.

The role of sphingosine 1-phosphate receptor 2 in bile-acid-induced cholangiocyte proliferation and cholestasis-induced liver injury in mice

Bile duct obstruction is a potent stimulus for cholangiocyte proliferation, especially for large cholangiocytes. Our previous studies reported that conjugated bile acids (CBAs) activate the protein kinase B (AKT) and extracellular signal-regulated kinase 1 and 2 (ERK1/2) signaling pathways through sphingosine 1-phosphate receptor (S1PR) 2 in hepatocytes and cholangiocarcinoma cells. It also has been reported that taurocholate (TCA) promotes large cholangiocyte proliferation and protects cholangiocytes from bile duct ligation (BDL)-induced apoptosis. However, the role of S1PR2 in bile-acid-mediated cholangiocyte proliferation and cholestatic liver injury has not been elucidated. Here, we report that S1PR2 is the predominant S1PR expressed in cholangiocytes. Both TCA- and sphingosine-1-phosphate (S1P)-induced activation of ERK1/2 and AKT were inhibited by JTE-013, a specific antagonist of S1PR2, in cholangiocytes. In addition, TCA- and S1P-induced cell proliferation and migration were inhibited by JTE-013 and a specific short hairpin RNA of S1PR2, as well as chemical inhibitors of ERK1/2 and AKT in mouse cholangiocytes. In BDL mice, expression of S1PR2 was up-regulated in whole liver and cholangiocytes. S1PR2 deficiency significantly reduced BDL-induced cholangiocyte proliferation and cholestatic injury, as indicated by significant reductions in inflammation and liver fibrosis in S1PR2 knockout mice. Treatment of BDL mice with JTE-013 significantly reduced total bile acid levels in serum and cholestatic liver injury.

CONCLUSION

This study suggests that CBA-induced activation of S1PR2-mediated signaling pathways plays a critical role in obstructive cholestasis and may represent a novel therapeutic target for cholestatic liver diseases. (Hepatology 2017;65:2005-2018).

Roles of TGF-β/Smad signaling pathway in pathogenesis and development of gluteal muscle contracture

PURPOSE OF THE STUDY

Gluteal muscle contracture (GMC) is a chronic fibrotic disease of gluteal muscles which is characterized by excessive deposition of collagen in the extracellular matrix. Transforming growth factor (TGF)-βs have been shown to play an important role in the progression of GMC. However, the underlying mechanisms are not entirely clear. We sought to explore the expression of TGF-β/Smad pathway proteins and their downstream targets in gluteal muscle contracture disease.

MATERIALS AND METHODS

The expression levels of collagens type I/III, TGF-β1, Smad2/3/4/7 and PAI-1 (plasminogen activator inhibitor type 1) in gluteal muscle contraction (GMC) patients were measured using immunohistochemistry, reverse transcription and polymerase chain reaction (RT-PCR) and western blot assays.

RESULTS

The expressions of collagens type I/III and TGF-β1 were significantly increased in the contraction band compared with unaffected muscle. In addition, R-Smad phosphorylation and Smad4 protein expression in the contraction band were also elevated, while the expression of Smad7 was significantly decreased in the fibrotic muscle of the GMC patients compared to the unaffected adjacent muscle. The protein and mRNA levels of PAI-1 were also remarkably increased in the contraction band compared with adjacent muscle. Immunohistochemical analysis also demonstrated that the expression levels of TGF-β1 and PAI-1 were higher in contraction band than those in the adjacent muscle.

CONCLUSION

Our data confirm the stimulating effects of the TGF-β/Smad pathway in gluteal muscle contracture disease and reveal the internal changes of TGF-β/Smad pathway proteins and their corresponding targets in gluteal muscle contracture patients.