Oestrogen and autoimmune disease activity: A scoping review

IntroductionSymptoms of autoimmune disorders (ADs) have been observed to fluctuate around reproductive events, likely due to hormone changes during these timepoints. There is conflicting evidence for how changes in oestrogen levels may be related to a reduction of AD symptoms, and how this varies across specific ADs. MethodsA scoping review was conducted according to PRISMA guidelines, to harmonise the current evidence within this field. PubMed was searched and data extracted based on AD type (rheumatoid arthritis (RA), multiple sclerosis (MS) and type-one diabetes (T1D)), AD symptom measured, oestrogen hormone type, demographics (population location, age, gender, human/animal study), and summarised. ResultsA total of 68 studies were included; 35 measured RA, 25 for MS, 7 for T1D, and 1 for both RA and MS combined. Most studies used a female only sample (74%). Of the 68 included studies, 34 showed oestrogen hormones were associated with improvements in AD symptoms, 14 found no impact and 3 showed worsening of symptoms. Additionally, 12 studies only reported differences in hormone levels, and not the impact on AD symptoms. The symptoms measured varied between studies, reflecting disease-specific focus areas. DiscussionThis scoping review had broadly summarised the existing literature investigating the impact of oestrogen on three common ADs, suggesting that oestrogen may be anti-inflammatory within the context of ADs. Future research should investigate the combined influence of multiple hormones, across genders and assess their impact at repeated timepoints on ADs.