Interestingly, in our study, HSPA1A levels were significantly lower in RA than in OA or CPPA synovium and negatively correlated with the histological inflammatory score as well as with the 10 other aforementioned protein levels of the ER pathway suggesting a defective anti-inflammatory response in favor of a pro-inflammatory one under the control of ER proteins. Here, HSPA1A is linked to rheumatoid arthritis.