Translational Immunology, Volume 3: Autoimmune Disease Associated with Different Clinical Features by Nima Rezaei

Author:Nima Rezaei [Rezaei, Nima]
Language: eng
Format: epub
ISBN: 9780323854153
Publisher: Elsevier
Published: 2022-03-30T00:00:00+00:00

3.2: Epididymitis

The epididymis is a tube located at the back of the testicles that stores and carries sperm. Similar to the testis, epididymis has a blood-epididymis barrier composed of 3 components to prevent autoimmune responses against antigenic post-pubertal germ cells, which includes (1) anatomical barrier, which is tight junctions formed from the principal cells’ basolateral and apical membranes; (2) physiological barrier, which is made up of transporters and channels; and (3) immunological barrier, which is characterized by a lower number of immune cells and the higher expression of immunoregulatory molecules such as indoleamine 2,3-dioxygenase (IDO), defensins, transforming growth factor-beta (TGF-β) and interleukin-10 (IL-10) to induce an immunotolerant circumstance [99]. As a result, these characteristics of the epididymis provide a suitable and immune-privileged environment for sperms to mature with motility and to achieve complete fertilizing capacity.

Since the blood-epididymis barrier is not as effective as the blood-testis barrier, there can still be possible direct interactions between intraepithelial immune cells and sperm antigens [100]. Therefore, the epididymis is more prone to autoimmune responses than the testis. The damage of the blood-epididymis barrier (caused by infection, inflammation, and trauma) can open access for the entry of immunological components, which can lead to autoimmunity against sperm antigens, finally leading to male infertility [101]. Studies on autoimmune epididymitis in humans are rare due to the difficulties in collecting the tissue and “silent” symptoms, which is also the reason why epidemiological data on autoimmune orchitis and epididymitis are scarce. Animal models of experimental autoimmune epididymitis provide important information regarding this condition [102]. It has been reported that epithelial damage, immune cell infiltrates and fibrosis were noteworthy in cauda, but minimal in caput, to cause dysfunction of sperm [103]. This observation suggested that cauda is more susceptible to inflammatory damage following an autoimmune challenge, and caput can provide a more tolerogenic environment to protect the autoantigenic sperm when released from the testis [103].

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