Interleukin­6 signalling as a valuable cornerstone for molecular medicine (Review).

ABSTRACT

The biological abilities of interleukin­6 (IL­6) have been under investigation for nearly 40 years. IL­6 works through an interaction with the complex peptide IL­6 receptor (IL­6R). IL­6 is built with four α­chain nanostructures, while two different chains, IL­6Rα (gp80) and gp130/IL6ß (gp130), are included in IL­6R. The three­dimensional shapes of the six chains composing the IL­6/IL­6R complex are the basis for the nanomolecular roles of IL­6 signalling. Genes, pseudogenes and competitive endogenous RNAs of IL­6 have been identified. In the present review, the roles played by miRNA in the post­transcriptional regulation of IL­6 expression are evaluated. mRNAs are absorbed via the 'sponge' effect to dynamically balance mRNA levels and this has been assessed with regard to IL­6 transcription efficiency. According to current knowledge on molecular and nanomolecular structures involved in active IL­6 signalling, two different IL­6 models have been proposed. IL­6 mainly has functions in inflammatory processes, as well as in cognitive activities. Furthermore, the abnormal production of IL­6 has been found in patients with severe acute respiratory syndrome coronavirus 2 (SARS­CoV­2; also known as COVID­19). In the present review, both inflammatory and cognitive IL­6 models were analysed by evaluating the cytological and histological locations of IL­6 signalling. The goal of this review was to illustrate the roles of the classic and trans­signalling IL­6 pathways in endocrine glands such as the thyroid and in the central nervous system. Specifically, autoimmune thyroid diseases, disorders of cognitive processes and SARS­CoV­2 virus infection have been examined to determine the contribution of IL­6 to these disease states.