Immunomodulation is on the cusp of being an important therapy for treating many diseases, due to the significant role of the immune system in defending the human body. Although the immune system is an essential defense system, overactivity can result in diverse sicknesses such as inflammation and autoimmune disease. Exosomes are emerging as a state-of-the-art therapeutic strategy for treating an overactive immune system. Thus, in this review, we will thoroughly review therapeutic applications of exosomes in various inflammatory and autoimmune diseases. Finally, issues for an outlook to the future of exosomal therapy will be introduced.

Purpose of reviewDementia is a syndrome with several possible pathologies. To date, definitive methods for diagnosis and treatment of sub-types of dementia have not been established. Emerging evidence suggests that exosomes can provide important information for the diagnosis and treatment of several subtypes of dementia. This article reviews recent studies on the application of exosomes in dementia.Recent findingsExosomes are involved in the pathogenesis of Alzheimer's disease (AD) and Parkinson's disease (PD) through transporting toxic proteins such as amyloid beta (Aβ), tau, and α-synuclein. Exosomal microRNAs (miR) and proteins reflect the disease state, and therefore, exosomes can be used as diagnostic markers for diseases such as AD, PD, Huntington's disease (HD), vascular dementia (VaD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). Mesenchymal stem cell (MSC)-derived exosomes have been shown to ameliorate disease pathology, and improve cognitive function in AD, PD, and VAD.SummaryRecent studies have shown that exosomes could be novel diagnostic agents for dementia because they contain molecules that could be potential biomarker candidates indicative of the type and stage of dementia. Therapeutic application of exosomes in dementia has revealed that exosomes only, or exosomes loaded with an active pharmaceutical ingredient (API), ameliorate disease phenotype of dementia. Further work is needed to exploit this potential.