A retrospective study on the relationship between annual airborne pollen levels during four decades of 1975–2014 and annual occurrence of ulcerative colitis, Crohn's disease, primary biliary cirrhosis, fulminant hepatitis, severe acute pancreatitis, interstitial pneumonia, amyloidosis, based on the national registry database of specific intractable diseases in Japan

Background: Systemic vasculitis such as Kawasaki Disease (KD) and collagen diseases have been suggested to be related to pollen exposure (PE).Objective: To elucidate effects of PE on outbreaks of gastrointestinal diseases including inflammatory bowel diseases(IBDs) and associated diseases. Methods:We analyzed national database on annual occurrence of ulcerative colitis(UC), Crohn's disease(CD), as well as primary biliary cirrhosis(PBC), fulminant hepatitis(FH), severe acute pancreatitis(SAP), interstitial pneumonia(IP), amyloidosis(AMY), idiopathic thrombocytopenic purpura and aplastic anemia.Results: Increase in pollen scatter started during 1977-1987 in Japan, characterized by three upward peaks (1978-79, 1982, and 1984-86), with which triphasic outbreaks of KD coincided.During 1975-2014, the 1984-86 peak of pollen scatter was the earliest peak with which simultaneous increase in occurrence of UC, CD, and FH coincided.Furthermore, simultaneous outbreaks of UC, CD and FH coincided with subsequent four peaks of pollen scatter in 1997-98, 2000-03, 2008-09 and 2011.Our results showed statistically significant correlations for UC, CD, and IP between the annual number of newly registered patients in the patient-registry year and annual pollen levels in the same patient-registry year.Significant correlations were also shown between the number of newly registered patients in the patient-registry year and annual pollen levels measured 6 years (UC, CD, PBC, SAP), 9 years (UC, CD, IP), 11 years (UC, CD), 14 years (IP) and 16years (CD, PBC, SAP, AMY) before the patient-registry year. Conclusion:We assume that cumulative effects of PE during a decade or more before the diagnosis of IBDs might possibly trigger onset of IBDs when cumulative effects of PE as environmental stress overwhelmed immunoreactive threshold.