The Progression of Experimental Autoimmune Orchitis Coincidences with Increased Levels of Testicular IL-1 Family Members. Academic Article uri icon

abstract

  • Orchitis is characterized by inflammatory infiltrates in the testicular interstitium and is associated with focal or total impairment of spermatogenesis eventually leading to male infertility. Cytokines are considered to play a major role in the maintenance of normal testicular function. Under normal conditions, members of the Interleukin-1 (IL-1) family are expressed at basal levels in different types of testicular cells. During inflammation several cytokines are increased in the testis potentially leading to disturbed testicular function. IL-1Receptor antagonist knock out (IL-1Ra K/O) mice show elevation of IL-1alpha and IL-1beta levels in testicular tissue and impaired male fertility. The aim of this study is to investigate the expression levels of IL-1 family members (IL-1alpha, IL-1beta and IL-1Ra) in the testis during the progression of experimental autoimmune orchitis (EAO) in mice and to localize their production. A model for murine EAO was established. In brief, testes of adult wild type (WT) BALB/c mice (12 weeks old) were homogenized, mixed with complete Freund's adjuvant and injected subcutaneously in tail, neck and foot pad of Balb/c wildtype mice. Pertussis toxin (20µg/ml) was used as a co-adjuvant. In adjuvant control group testis homogenate was replaced with saline. Sham-treated animals were injected with saline only. At day 0 (untreated group), 20, 30, 40, 50 and 70 days after the first immunization mice were sacrificed, testes were weighted and either fixed in Bouin solution for histology assessment or homogenized for cytokine measurements. A scoring system reflecting the severity of EAO was developed based on examinations of hematoxylin-eosin stained paraffin sections. IL-1alpha, IL-1beta and IL-1Ra levels in the testes were measured using specific ELISA for each cytokine. The cellular localization of IL-1 in the testis of the EAO and control groups was determined by immunofluorescence staining. In the EAO model, testicular weight of the WT-EAO-mice was significantly decreased after 50 days compared to control group (p<0.001). Testes showed severe morphological changes such as germ cell sloughing, disruption of spermatogenesis and Sertoli-cell-only-syndrome as well as massive interstitial cell infiltration. Based on the histoscore, the disease progression was subdivided into five stages and the animals were grouped accordingly. ELISA measurements revealed higher levels of IL-1alpha, IL-1beta and IL-1Ra in EAO mice starting with gradual increase from day 30 after the first immunization compared to control groups. At day 70 differences between EAO and adjuvant control culminated and EAO mice displayed ca. 3-fold higher levels of the respective cytokines. EAO histology scores tended to coincide with the increased cytokines levels. Compared to the adjuvant control groups, testis sections of EAO-mice showed increased expression levels of IL-1alpha, IL-1beta, IL-1Ra and IL-1 receptor 1 (IL-1 R1) using immunofluorescence, which was particularly evident in the interstitial area. Increased staining of IL-1 R1 was also detected in the seminiferous epithelium. Members of IL-1 family are involved in the development of experimental autoimmune orchitis and may play a crucial role in the onset and progression of the disease. (poster)

publication date

  • January 1, 2010