Ecologic analysis of some immune-related disorders, including type 1 diabetes, in Australia: latitude, regional ultraviolet radiation, and disease prevalence.

Abstract

The apparent immune-suppressive effect of ultraviolet radiation (UVR) has suggested that this environmental exposure may influence the development of immune-related disorders. Self-reported prevalence rates of type 1 diabetes mellitus, rheumatoid arthritis (RA), eczema/dermatitis, and asthma, from the 1995 Australian National Health Survey, were therefore examined by latitude and ambient level of UVR. A positive association of type 1 diabetes mellitus prevalence was found with both increasing southern latitude of residence (r = 0.77; p = 0.026) and decreasing regional annual ambient UVR (r = -0.80; p = 0.018); a 3-fold increase in prevalence from the northernmost region to the southernmost region was evident. In contrast, asthma correlated negatively with latitude (r = -0.72; p = 0.046), although the change in asthma prevalence from the north to the south of Australia was only 0.7-fold. For both RA and eczema/dermatitis, there were no statistically significant associations between latitude/UVR and disease prevalence. These ecologic data provide some support for a previously proposed beneficial effect of UVR on T-helper 1-mediated autoimmune disorders such as type 1 diabetes. The inverse association of type 1 diabetes prevalence with UVR is consistent with that previously reported for another autoimmune disease, multiple sclerosis, in Australia, and also with type 1 diabetes latitudinal gradients in the Northern Hemisphere. The finding also accords with photoimmunologic evidence of UVR-induced immunosuppression and may suggest a beneficial effect of UVR in reducing the incidence of such autoimmune conditions. In light of this study, analytic epidemiologic studies investigating risk of immune disorders in relation to personal UVR exposure in humans are required.

Autoimmune disorders and risk of non-Hodgkin lymphoma subtypes: a pooled analysis within the InterLymph Consortium

“…A comparison of our control prevalences with population prevalence data from different countries showed good concordance, [49][50][51][52] except for ulcerative colitis, where the study control prevalences were higher than published prevalence estimates, 53 and in hemolytic anemia and sarcoidosis, where no published rates could be identified. Based on these comparisons, we think that misclassification of self-reports may have been less frequent for most of the autoimmune disorders studied than for RA.…”

The association between ultraviolet B irradiance, vitamin D status and incidence rates of type 1 diabetes in 51 regions worldwide

“…Previous research [3,[6][7][8][9][10][11][12][13] and the results of the present study suggest that many cases of type 1 diabetes might be prevented by raising the serum 25(OH)D levels of infants and children living at high latitudes to levels that are present in the tropics. Such levels are in the range of 125-150 nmol/l (50-60 ng/ml) [26].…”

“…Such antibodies are associated with the development of type 1 diabetes [12]. Another study reported lower incidence rates of type 1 diabetes in association with higher ultraviolet radiation in Australia [13].…”

Is the current public health message on UV exposure correct?

“…This link may explain the well established, although not ubiquitous, positive latitudinal gradient in incidence of both multiple sclerosis and of type 1 diabetes. 46,47 More specifically, obserr r vational epidemiological studies have shown a protective effect for the develr r opment of type 1 diabetes, 48 rheumatoid arthritis 49 and multiple sclerosis 50 with oral vitamin D supplementation. In adr r dition, low circulating serum levels of vitamin D show a positive correlation with measures of type 2 diabetes such as insulin resistance and pancreatic betar cell dysfunction.…”