Effects on the Local Immunity in the Testis by Exposure to Di-(2-ethylhexyl) Phthalate (DEHP) in Mice

Abstract

Exposure to di-(2-ethylhexyl) phthalate (DEHP) has been reported to induce spermatogenic disturbance through oxidant stress and affect the immune system as an adjuvant. However, the effect of DEHP on the testicular immune microenvironment has not yet been investigated. In the present study, we examined the testicular immune microenvironment after exposure to doses of DEHP, previously identified as no-observed-adverse-effect levels. Adult male mice were administered food containing 0%, 0.01% or 0.1% DEHP and then testes were analyzed. The results showed that a slight but significant spermatogenic disturbance appeared in the 0.1% DEHP group but not in the 0.01% DEHP group at 8 weeks. It was also demonstrated that lymphocytes and F4/80- and MHC class II- positive cells were significantly increased with the elevation of IL-10 and IFN-γ mRNA expressions in the testes of not only the 0.1% DEHP group but also the 0.01% DEHP group at 8 weeks. Histochemical analyses involving horseradish peroxidase (HRP) as a tracer showed that a little blood-borne HRP had infiltrated into the lumen of a few seminiferous tubules beyond the blood-testis-barrier in both the 0.1% and 0.01% DEHP groups at 8 weeks. This indicates that a dose of DEHP that has little effects on spermatogenesis can change the testicular immune microenvironment with functional damage of the blood-testis barrier.

Low-dose exposure to di-(2-ethylhexyl) phthalate (DEHP) increases susceptibility to testicular autoimmunity in mice

“…After approval by the Tokyo Medical University Animal Committee (s-22020), all animal experiments were performed in accordance with the guidelines of the National Institute of Health. Previously, we showed that a significant spermatogenic disturbance was induced by 0.1% DEHP, but not by 0.01% DEHP treatment [20]. No significant differences in the consumption of food and water were observed between the experimental and control groups.…”

“…Previous studies have reported that exposure to MEHP leads to the appearance of small vacuoles in the cytoplasm of Sertoli cells and that associated disappearance of vimentin in Sertoli cells can cause morphological changes at the tight junctions of the BTB [17][18][19]. Recently, we demonstrated that a low dose of DEHP, which did not affect spermatogenesis, was able to change the testicular immune microenvironment in mice [20]. More specifically, exposure to low-dose of DEHP caused the formation of small vacuoles in the Sertoli cells, with some damage to the BTB.…”

“…No significant differences in the consumption of food and water were observed between the experimental and control groups. Also, body and testis weights between the control and DEHP-treated mice did not differ [20]. In the current study, we addressed the question how the low-dose DEHP treatment (0.01%; 11.3-13.3 mg/kg bwt/day), that does not induce a significant SD, affects susceptibility to murine EAO.…”

“…The sections were counterstained with methyl green (Vector Laboratories) and were analyzed at 200Â magnification by light microscopy. Because cytoplasmic volume rather than cell number is crucial for activation of macrophages, the F4/80-positive area, but not the number of positive cells per interstitium, was determined (National Institutes of Health ImageJ version 1.62 software) in each region [20]. An area of at least 1 mm 2 of the interstitium was examined in each testicular region in five sections from each testis.…”

“…More specifically, exposure to low-dose of DEHP caused the formation of small vacuoles in the Sertoli cells, with some damage to the BTB. Moreover, in the low-dose DEHP-treated testes, lymphocytic infiltration increased and interferon gamma (IFN-g) level rose [20] in comparison to controls.…”