Background & Aims: Inflammation is a complex physiological and pathological process. Inflammation is usually an adaptive response caused by harmful stimuli and conditions (such as infection and tissue damage) to maintain body homeostasis. Inflammation can be divided into acute inflammation and chronic inflammation. Acute inflammation lasts only a short time and is usually beneficial to the host. When inflammation continues for a long time, it becomes chronic and can contribute to various chronic diseases such as obesity, diabetes, arthritis, pancreatitis, cardiovascular, neurodegenerative, metabolic, and certain types of cancer. Inflammatory mechanisms in various diseases such as arthritis, psoriasis, depression, and atherosclerotic disease processes have attracted the attention of researchers, and high levels of inflammatory mediators have been detected in lesion sites. Inflammation makes the disease more severe and creates a vicious cycle that poses challenges to the treatment. Therefore, it is clear that inflammation plays an important role in the occurrence and development of the disease, and compounds with anti-inflammatory effects are the first therapeutic strategy to reduce the complications of inflammatory diseases and the level of inflammation. The significant anti-inflammatory activity of curcumin has attracted the attention of many researchers and is known as one of the natural compounds with the greatest potential in the treatment of diseases. Curcumin has anti-inflammatory, antioxidant, anti-tumor ,and other biological activities. It can be said that the basis of various biological activities of curcumin is its anti-inflammatory properties and it plays an important role in the treatment of inflammatory diseases. Curcumin and curcuminoids, the active components of turmeric, have been effective in the treatment of inflammatory diseases for many years. In general, the anti-inflammatory effects of drugs can be mainly listed as follows: effect on receptors and signaling pathways, regulating the response of target tissues to inflammatory mediators ,and reversing the effect of the environment on the target tissue. Curcumin has anti-inflammatory effects by regulating inflammatory signaling pathways and inhibiting the production of inflammatory mediators. Curcumin has significant anti-inflammatory effects and a large number of pre-clinical or clinical studies have investigated its effect on inflammatory diseases such as inflammatory bowel disease, arthritis, psoriasis, depression, and arteriosclerosis. Current evidence shows that curcumin is effective in reducing the levels of inflammatory mediators and the anti-inflammatory properties of curcumin may have a beneficial effect on these diseases. There are several studies that confirm the link between curcumin and reduced levels of inflammatory disease. The findings of the studies conducted in the field of medicine and paramedicine show that there are very good anti-inflammatory properties in curcumin and curcumin regulates NF-kB, MAPK, AP-1, JAK/STAT, and other signaling pathways. Curcumin controls and inhibits the production of inflammatory mediators. Considering the importance of the issue of inflammatory diseases and the effect of curcumin on this type of disease and the explanations provided, the question that is raised here is, what are the results of various studies in the field of inflammatory diseases and the role of curcumin on this condition? What has been achieved and what requirements have been recommended regarding the reduction of inflammatory diseases through curcumin?
Methods: The current study is a review study that includes articles published in domestic and foreign journals available in SID, PubMed, Google Scholar, Magiran, Springer, Wiley, Web of Science (ISI), Scopus, Science Direct, ProQuest databases. The range of years 2020 to 2022 was used. Articles were searched using the keywords "curcumin, inflammatory diseases" and their English equivalents. As a result of the initial search of articles, there were 156 articles, of which 74 articles remained in the screening stage, and at the end, 12 articles were subjected to content analysis.
Results: This review study showed that curcumin is effective in reducing complications and improving the condition of inflammatory diseases, and curcumin, having anti-inflammatory properties, can play an effective role in improving the symptoms of these diseases.
Conclusion: In general, it can be concluded that to reduce the complications of inflammatory diseases, it is important to pay attention to curcumin and it is not far from the expectation that it is one of the drugs considered by researchers to treat inflammatory diseases. Administration of curcumin also reduces mRNA expression of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α through IL-1β/NF-κB signaling, and inhibits NLRP3 inflammasome activation. Curcumin ameliorates IL-1β-induced neuronal apoptosis by inhibiting the P38 pathway in chronic mild stress-induced rats. The anti-inflammatory effect of curcumin is one reason for its improvement in depression, but this is not conclusive. In addition to its anti-inflammatory properties, curcumin also prevents the release of monoamine oxidase, serotonin, and dopamine, and strengthens the pituitary axis of the adrenal gland, hypothalamus, nutritional factors, hippocampal neurogenesis, and neural flexibility. Curcumin may play an anti-inflammatory role by regulating inflammatory mediators and immune cells. Curcumin is found in traditional Chinese medicine, and is prescribed to control stress and mood disorders. Curcumin has anti-inflammatory, antioxidant, and neurotrophic properties, indicating a strong potential for depression relief. Chronically unpredictable mice exposed to mild stress exhibited depressive-like behaviors and elevated levels of depression-related cytokines, a classic model for studying depression. According to the results of relevant tests, such as social interaction test, sucrose preference test, forced swimming test, open field test, curcumin treatment succeeded in correcting depression-like behavior of stressed rats.