Role of the circulatory interleukin-6 in the pathogenesis of gliomas: A systematic review

Figure 1 Physiology of interleukin (IL)-6. IL-6 has regulatory role in various physiological processes such as inflammation, immunity and reproduction. IL-6 is induced by viruses and UV, etc., and is released by macrophages, monocytes and stromal cells under normal physiological conditions, and under pathophysiological conditions, it is induced by nuclear factor-κB, prostaglandin E2, hypoxia and released by tumor-infiltrating immune cells and tumor cells, etc. IL-6 can activate the STAT3 signaling pathway either by the classical pathway or trans-signaling pathway. Activation of STAT3 can upregulate a variety of genes and may have an important role in tumor formation.

Figure 2 Electronic search. This review was based on a search of electronic databases using the keywords shown. The resulting 953 articles were screened and assessed by language and three were excluded. The remaining 950 articles were again screened by title and 865 were excluded. The 85 studies were critically reviewed and 10 were duplicates, systematic reviews or meta-analyses and these were excluded. The resultant 75 studies were further divided into two: five studies were included in this mini literature review on the basis of inclusion criteria, and 70 studies based on in vivo and/or in vitro and/or genetic and/or immunohistochemistry methods were chosen as supporting articles.