Evaluation of TNF-α and IL-6 in saliva among diabetic retinopathy patients in East Coast Malaysia.

OBJECTIVE: To compare tumour necrosis factor-alpha (TNF) and interleukin (IL)-6 levels in saliva between different stages of diabetic retinopathy (DR). METHODS: This comparative cross-sectional study was conducted between January 2018 and November 2020. This study included diabetes mellitus (DM) patients with no DR, non-proliferative DR (NPDR), and proliferative DR (PDR). None of the patients with DM were included in the control group. Unstimulated saliva samples were then collected. TNF-α and IL-6 levels were measured. RESULTS: Altogether, 120 patients were included in the study (DM without DR, 33 patients; DM with NPDR, 30 patients; DM with PDR, 32 patients; non-DM, 25 patients). The mean IL-6 level in saliva was significantly higher in the DM group (0.033 ± 0.005 pg/ml) than in the non-DM group (0.027 ± 0.001 pg/ml) (p < 0.001 after adjusting for covariates). There was no significant difference in the mean salivary TNF-α between patients with DM and those without DM after adjusting for covariates. The mean IL-6 in saliva was significantly higher in the NPDR (0.036 ± 0.003 pg/ml) and PDR (0.093 ± 0.023 pg/ml) groups than in the no DR group (0.027 ± 0.001 pg/ml) (p < 0.001 and p < 0.001, respectively). Mean TNF-α in saliva was significantly higher in the NPDR (0.086 ± 0.022 pg/ml) and PDR (0.093 ± 0.023 pg/ml) groups than in the no DR group (0.049 ± 0.011 pg/ml) (p = 0.015 and p = 0.003, respectively). CONCLUSION: There is an association between inflammatory biomarkers in saliva (IL-6 and TNF-α) and severity of DR among patients with DM, suggesting that these salivary biomarkers are potential biomarkers for screening, monitoring, and predicting the progression of DR.

MicroRNA and Their Potential Role in Conjunctival Disorders.

MicroRNAs (miRNAs) are the small noncoding RNA molecules which regulate target gene expression posttranscriptionally. They are known to regulate key cellular processes like inflammation, cell differentiation, cell proliferation, and cell apoptosis across various ocular diseases. Due to their easier access, recent focus has been laid on the investigation of miRNA expression and their involvement in several conjunctival diseases. The aim of this narrative review is to provide understanding of the miRNAs and describe the current role of miRNAs as the mediators of the various conjunctival diseases. A literature search was made using PubMed, Scopus, and Web of Science databases for studies involving miRNAs in the conjunctival pathological conditions. Original articles in the last 10 years involving both human and animal models were included. Literature search retrieved 27 studies matching our criteria. Pertaining to the numerous literatures, there is a strong correlation between miRNA and the various pathological conditions that occur in the conjunctiva. miRNAs are involved in various physiological processes such as cell differentiation, proliferation, apoptosis, development, and inflammation by regulating various signaling pathways, genes, proteins, and mediators. Pterygium was the most studied conjunctival disease for miRNA involvement, whereas miRNA research in allergic conjunctivitis is still in its early stages. Our review provides deep insights into the various miRNAs playing an important role in the various conjunctival diseases. miRNAs do have the potential to serve as noninvasive biomarkers with diagnostic, prognostic, and therapeutic implications. However, multitudinous studies are required to validate miRNAs as the reliable biomarkers in conjunctival pathologies and its targeted therapy.