Non-Invasive microRNA Profiling in Saliva can Serve as a Biomarker of Alcohol Exposure and Its Effects in Humans

Abstract

Alcohol Use Disorder (AUD) is one of the most prevalent mental disorders worldwide. Considering the widespread occurrence of AUD, a reliable, cheap, non-invasive biomarker of alcohol consumption is desired by healthcare providers, clinicians, researchers, public health and criminal justice officials. microRNAs could serve as such biomarkers. They are easily detectable in saliva, which can be sampled from individuals in a non-invasive manner. Moreover, microRNAs expression is dynamically regulated by environmental factors, including alcohol. Since excessive alcohol consumption is a hallmark of alcohol abuse, we have profiled microRNA expression in the saliva of chronic, heavy alcohol abusers using microRNA microarrays. We observed significant changes in salivary microRNA expression caused by excessive alcohol consumption. These changes fell into three categories: downregulated microRNAs, upregulated microRNAs, and microRNAs upregulated de novo. Analysis of these combinatorial changes in microRNA expression suggests dysregulation of specific biological pathways leading to impairment of the immune system and development of several types of epithelial cancer. Moreover, some of the altered microRNAs are also modulators of inflammation, suggesting their contribution to pro-inflammatory mechanisms of alcohol actions. Establishment of the cellular source of microRNAs in saliva corroborated these results. We determined that most of the microRNAs in saliva come from two types of cells: leukocytes involved in immune responses and inflammation, and buccal cells, involved in development of epithelial, oral cancers. In summary, we propose that microRNA profiling in saliva can be a useful, non-invasive biomarker allowing the monitoring of alcohol abuse, as well as alcohol-related inflammation and early detection of cancer.

RNA biomarkers for alcohol use disorder

“…Transcriptome studies in the alcohol research field have revealed that alcohol use affects the expression patterns of hundreds of mRNAs and ncRNAs in the brain tissue of humans and animal models, e.g., see reviews and primary research articles (Contet, 2012;Nunez and Mayfield, 2012;Mayfield, 2017;Warden and Mayfield, 2017;Ferguson et al, 2019;Brenner et al, 2020;Drake et al, 2020). In addition to brain tissue, some studies have explored alcohol's effects in peripheral tissues including blood and saliva (Beech et al, 2012(Beech et al, , 2014Hicks et al, 2012;Kupfer et al, 2013;McClintick et al, 2014McClintick et al, , 2019Ignacio et al, 2015;Barr et al, 2016;Sureshchandra et al, 2016Sureshchandra et al, , 201910.3389/fnmol.2022.1032362 Ten Berg et al, 2018;Rosato et al, 2019;Lewis et al, 2021;Liu et al, 2021;Mead et al, 2021;Ferguson et al, 2022;Gong et al, 2022). These studies will be detailed in the following sections.…”

“…Increasing evidence suggests that non-coding RNAs (ncRNAs) play a role in psychiatric disorders including AUD (Mayfield, 2017). The effects of alcohol on ncRNAs have been explored in both brain (Bohnsack et al, 2019;Drake et al, 2020) and peripheral tissues (Ignacio et al, 2015;Momen-Heravi et al, 2015;Barr et al, 2016;Sureshchandra et al, 2016Sureshchandra et al, , 2019Ten Berg et al, 2018;Rosato et al, 2019;Liu et al, 2021;Mead et al, 2021;Gong et al, 2022;Lewis et al, 2022). The studies identified in the literature search analyzed two types of ncRNAs in peripheral tissues: microRNAs and circRNAs.…”

“…Eight studies measured microRNA levels in peripheral tissues (Ignacio et al, 2015;Barr et al, 2016;Sureshchandra et al, 2016Sureshchandra et al, , 2019Ten Berg et al, 2018;Rosato et al, 2019;Mead et al, 2021;Lewis et al, 2022; Tables 2, 3). MicroRNAs are short RNAs (about 20-24 nucleotides long) that regulate mRNA expression at the post-transcriptional level by repressing the translation or cleaving the transcript (Lagos-Quintana et al, 2001;Bartel, 2004).…”

“…Three studies assessed the diagnostic discrimination of peripheral microRNA profiles for recreational alcohol drinking (Ten Berg et al, 2018), AUD (Rosato et al, 2019), and alcohol abuse (Mead et al, 2021; Table 2). The first study demonstrated that circulating microRNAs are dynamic and highly predictive of drinking even a modest amount of alcohol (Ten Berg et al, 2018).…”

Confounding Factors Impacting microRNA Expression in Human Saliva: Methodological and Biological Considerations

“…Notably, high powered cohort studies identify predictive miRNAs for of autism spectrum disorder [ 4 , 16 , 17 ], traumatic brain injury [ 18 , 19 , 20 , 21 ] endometriosis [ 22 ], and a variety of cancers [ 23 , 24 , 25 ]. Other recent studies include the prediction of alcohol use disorder [ 26 , 27 ], Parkinson’s Disease [ 28 , 29 ], and malignant pleural effusion [ 30 ]. Broad commonalities of these studies include saliva collection, saliva storage, miRNA extraction and isolation, and miRNA expression profiling.…”