Long Noncoding RNAs in Urine Are Detectable and May Enable Early Detection of Acute T Cell-Mediated Rejection of Renal Allografts

Advances in diagnostics for transplant rejection

INTRODUCTION

Identification of allograft injury, including acute clinical and subclinical injury, is vital in increasing the longevity of the transplanted organ. Acute rejection, which occurs as a result of a variety of immune and non-immune factors including the infiltration of immune cells and antibodies to the donor specific epitopes, poses a significant risk to the organ. Recent years have marked an increase in the discovery of new genomic, transcriptomic, and proteomic biomarkers in molecular diagnostics, which offer better potential for personalized management of the transplanted organ by providing earlier detection of rejection episodes. Areas covered: This review was compiled from key word searches of full-text publications relevant to the field. Expert commentary: Many of the recent advancements in the molecular diagnostics of allograft injury show much promise, but before they can be fully realized further validation in larger sample sets must be conducted. Additionally, for better informed therapeutic decisions, more work must be completed to differentiate between different causes of injury. Moreover, the diagnostics field is looking at methodologies that allow for multiplexing, the ability to identify multiple targets simultaneously, in order to provide more robust biomarkers and better understanding.

Mitochondrial long noncoding RNAs as blood based biomarkers for cardiac remodeling in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a hereditary heart disease with a high risk for sudden cardiac death in young people. As a subtype, hypertrophic obstructive cardiomyopathy (HOCM) additionally has a left ventricular outflow gradient, showing stronger symptoms and requires a different treatment compared with hypertrophic nonobstructive cardiomyopathy (HNCM). In this study our aim was to investigate the regulation of mitochondrial and cardiac remodeling associated long noncoding RNAs (lncRNAs) in blood of patients affected with HOCM and HNCM. We included 28 HNCM, 57 HOCM, and 26 control inviduals. Already known mitochondrial and cardiac remodeling associated lncRNAs uc004cos.4, uc004coz.1, uc004cov.4, uc011mfi.2, uc022bqw.1, uc022bqs.1, and uc022bqu.1 were amplified in serum of these patients and correlated with clinical parameters. Long noncoding RNAs uc004cov.4 and uc022bqu.1 were significantly increased in patients with HOCM but not in patients with HNCM. With the use of receiver operator characteristic (ROC) curve analysis, lncRNAs uc004cov.4 and uc022bqu.1 were able to identify HOCM patients. In our study we evidenced that the specific mitochondrial long noncoding RNAs uc004cov.4 and uc022bqu.1 were upregulated in patients with HOCM and they were also able to identify HOCM and could be developed as useful clinical biomarkers in the future.

Long noncoding RNAs in kidney and cardiovascular diseases

Transcription of a large part of the human genome results in RNA transcripts that have limited or no protein-coding potential. These include long noncoding RNAs (lncRNAs), which are defined as being ≥200 nucleotides long. Unlike microRNAs, which have been extensively studied, little is known about the functional role of lncRNAs. However, studies over the past 5 years have shown that lncRNAs interfere with tissue homeostasis and have a role in pathological processes, including in the kidney and heart. The developmental expression of the microRNA sponge H19, for example, is altered in the kidneys of embryos carried by hyperglycaemic mothers, and the lncRNA Malat1 regulates hyperglycaemia-induced inflammation in endothelial cells. Putative roles for other lncRNAs have been identified in conditions such as heart failure, cardiac autophagy, hypertension, acute kidney injury, glomerular diseases, acute allograft rejection and renal cell carcinoma. This Review outlines our current understanding of the role and function of lncRNAs in kidney and cardiovascular disease as novel important regulators and potential therapeutic entry points of disease progression.