Stroke-induced immunosuppression is a process that leads to peripheral suppression of the immune system after a stroke and belongs to the central nervous system injury-induced immunosuppressive syndrome. Stroke-induced immunosuppression leads to increased susceptibility to post-stroke infections, such as urinary tract infections and stroke-associated pneumonia, worsening prognosis. Molecular chaperones are a large class of proteins that are able to maintain proteostasis by directing the folding of nascent polypeptide chains, refolding misfolded proteins, and targeting misfolded proteins for degradation. Various molecular chaperones have been shown to play roles in stroke-induced immunosuppression by modulating the activity of other molecular chaperones, cochaperones, and their associated pathways. This review summarizes the role of molecular chaperones in stroke-induced immunosuppression and discusses new approaches to restore host immune defense after stroke.

Heat shock protein 90 (HSP90) family is a class of proteins known as molecular chaperones that promote client protein folding and translocation in unstressed cells and regulate cellular homeostasis in the stress response. Noncoding RNAs (ncRNAs) are defined as RNAs that do not encode proteins. Previous studies have shown that ncRNAs are key regulators of multiple fundamental cellular processes, such as development, differentiation, proliferation, transcription, post-transcriptional modifications, apoptosis, and cell metabolism. It is known that ncRNAs do not act alone but function via the interactions with other molecules, including co-chaperones, RNAs, DNAs, and so on. As a kind of molecular chaperone, HSP90 is also involved in many biological procedures of ncRNAs. In this review, we systematically analyze the impact of HSP90 on various kinds of ncRNAs, including their synthesis and function, and how ncRNAs influence HSP90 directly and indirectly.