Appearance of 'natural' antisperm autoantibodies after sexual maturation of normal Lewis rats

Mononuclear phagocytes rapidly clear apoptotic epithelial cells in the proximal epididymis

We have shown previously that a network of mononuclear phagocytes (MPs) expressing macrophage and dendritic cell markers such as CD11c, F4/80 and CX3CR1, lines the base of the epididymal tubule. However, in the initial segment (IS) and only in that particular segment, epididymal MPs establish extremely close interactions with the epithelium by projecting slender dendrites between most epithelial cells. We undertook the present study to determine how epididymal phagocytes respond to the transient wave of apoptosis initiated by unilateral efferent duct ligation (EDL) in the epididymal epithelium. We show profound morphological and phenotypical changes restricted to the MPs populating the proximal epididymis following EDL. Within 48 h, a large subset of IS epithelial cells had entered an apoptotic state, visualized by the terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay and CD11c(+) and CX3CR1(+) MPs readily engulfed TUNEL-positive cells and other debris. Despite the high levels of apoptosis and the rapid clearance of apoptotic cells occurring after EDL, the epithelium preserved its overall architecture and maintained tight junctions of the blood-epididymis barrier (BEB). The discovery of a functional population of MPs in the epididymal epithelium responsible for maintaining the integrity of the BEB raises further questions regarding the role of these cells in clearing defective epithelial cells in the steady-state epididymis, as well as pathogens and abnormal spermatozoa in the lumen.

Epithelial basal cells are distinct from dendritic cells and macrophages in the mouse epididymis

The epithelium that lines the epididymal duct establishes the optimal milieu in which spermatozoa mature, acquire motility, and are stored. This finely tuned environment also protects antigenic sperm against pathogens and autoimmunity, which are potential causes of transient or permanent infertility. The epididymal epithelium is pseudostratified and contains basal cells (BCs) that are located beneath other epithelial cells. Previous studies showed that in the mouse epididymis, BCs possess macrophage-like characteristics. However, we previously identified a dense population of cells belonging to the mononuclear phagocyte (MP) system (comprised of macrophages and dendritic cells) in the basal compartment of the mouse epididymis and showed that a subset of MPs express the macrophage marker F4/80. In the present study, we evaluate the distribution of BCs and MPs in the epididymis of transgenic CD11c-EYFP mice, in which EYFP is expressed exclusively in MPs, using antibodies against the BC marker keratin 5 (KRT5) and the macrophage marker F4/80. Immunofluorescence labeling for laminin, a basement membrane marker, showed that BCs and most MPs are located in the basal region of the epithelium. Confocal microscopy showed that in the initial segment, both BCs and MPs project intraepithelial extensions and establish a very intricate network. Flow cytometry experiments demonstrated that epididymal MPs and BCs are phenotypically distinct. BCs do not express F4/80, and MPs do not express KRT5. Therefore, despite their proximity and some morphological similarities with peritubular macrophages and dendritic cells, BCs do not belong to the MP system.

Effect of P/E-selectin blockage on antisperm antibody development and histopathological alterations in experimental orchitis

AIM

This study aimed to evaluate the effect of P/E-selectin blockage on antisperm antibody (ASA) development and histopathological alterations in experimental orchitis.

MATERIALS AND METHODS

Thirty-six Wistar albino-type male rats weighing 100-150 g were included in the study. Rats were allocated into six groups (n = 6) including control (CG), sham (SG), orchitis (OG), antimicrobial treatment (AG), P/E-selectin blockage (PESG), and both antimicrobial and P/E-selectin treatment (TG) groups. In CG, serum samples were taken from the tail vein prior to the procedure and followed by extraction of both testes. In SG, 1 ml of saline solution was injected in testicular parenchyma. OG was obtained by injecting 0.1 ml 106 cfu/ml Escherichia coli (0:6 strain) and 1 ml saline solution into the right testes. AG received ciprofloxacin (50 mg/kg/day) twice a day through gastrogavage 24 hours after generating orchitis. In PESG, P/E-selectin antibody (100 μg) was administered intravenously via the tail vein 24 hours after the induction of orchitis. Finally, both ciprofloxacin and P/E-selectin antibody were administered in TG 24 hours after the induction of orchitis for 14 days. At the end of treatment, 1 ml of serum sample was obtained to evaluate the ASA, P-selectin and E-selectin levels. In order to evaluate spermatogenesis (Johnsen score) and testicular injury (Cosentino score), both testes were extracted at the end of the 14th day.

RESULTS

In orchitis-induced groups (OG, ATG, PSEG, TG), ASA levels were significantly increased at the 14th day when compared to SG (p < 0.05). In TG, ASA levels were decreased when compared to AG. However, similar alteration in ASA levels was not detected in PSEG (p > 0.05). In OG and AG, P-selectin levels were decreased at the 14th day when compared to levels observed on 0 day (p < 0.05). E-selectin levels on 0 day showed that each group had higher levels of E-selectin when compared to CG (p > 0.05). There was no significant difference regarding E-selectin when compared to CG (p > 0.05). No significant differences regarding E-selectin levels were detected on the 0th and 14th days between AG and CG (p > 0.05). When the Cosentino and Johnsen scores were compared among groups, TG and PSEG has decreased scores of Cosentino than OG on the right testicle (p < 0.05). In contrast, an increased Johnsen score was detected in TG and PSEG when compared to OG (p < 0/05). No significant difference was detected for both Cosentino and Johnsen scores on the left testicle (p > 0.05). There was no difference with regard to the right and left testicular injury in TG. In P/E-blocked groups, decreased histopathological alterations were observed in the contralateral testis.

CONCLUSION

P/E-selectin blockage may reduce ASA production after orchitis when combined with antimicrobial treatment. P/E-selectin blockage not only has a protective effect on blood-testis barrier but also decreases the histopathological alterations in both the affected and contralateral testis. Histopathological parameters of spermatogenesis may also be prevented by P/E-selectin blockage in experimental orchitis.

Alzheimer's disease, brain immune privilege and memory: a hypothesis

The most distinctive feature of Alzheimer's disease (AD) is the specific degeneration of the neurons involved in memory consolidation, storage, and retrieval. Patients suffering from AD forget basic information about their past, loose linguistic and calculative abilities and communication skills. Thus, understanding the etiology of AD may provide insights into the mechanisms of memory and vice versa. The brain is an immunologically privileged site protected from the organism's immune reactions by the blood-brain barrier (BBB). All risk factors for AD (both cardiovascular and genetic) lead to destruction of the BBB. Evidence emerging from recent literature indicates that AD may have an autoimmune nature associated with BBB impairments. This hypothesis suggests that the process of memory consolidation involves the synthesis of novel macromolecules recognized by the immune system as "non-self" antigens. The objective of this paper is to stimulate new approaches to studies of neural mechanisms underpinning memory consolidation and its breakdown during AD. If the hypothesis on the autoimmune nature of AD is correct, the identification of the putative antigenic macromolecules might be critical to understanding the etiology and prevention of AD, as well as for elucidating cellular mechanisms of learning and memory.

The age-related changes in the incidence of 'natural' anti-sperm antibodies suggest they are not auto-/isoantibodies

PROBLEM

Establishing the age-dependent patterns of sperm antibody levels among normal humans.

METHODS OF STUDY

Sera samples from 498 healthy subjects aged 0-97 years - 246 males and 252 females - were tested by the gelatin agglutination test of Kibrick, tray agglutination test of Friberg, sperm immobilization test of Isojima and enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found a significant increase in the level of sperm agglutinins after 40 years, which decreased after 88 years. The antibodies detected by ELISA were the highest among prepubertal subjects and also declined with aging. No age-dependent changes were established for the sperm immobilizins. With few exceptions, there were no significant differences between male and female sera, as well as between sera of newborn and their mothers.

CONCLUSIONS

These data are similar to those established for the age-dependent changes of antibodies towards exogenous antigens, suggesting that the 'naturally occurring' antibodies against human spermatozoa are not auto-/isoantibodies.

Absence of antisperm surface antibodies in prepubertal boys with cryptorchidism and other anomalies of the inguinoscrotal region before and after surgery

PURPOSE

Although the prepubertal immune system cannot recognize postmeiotic germ cell antigens, an overall 21 to 28% incidence of antisperm antibodies directed at these antigens has been reported preoperatively in prepubertal children with cryptorchidism and other inguinoscrotal anomalies. We investigated the prevalence of antisperm antibodies in these prepubertal patients before and after surgery.

MATERIALS AND METHODS

We examined 82 prepubertal boys 0.6 to 13.2 years old, including 33 with unilateral cryptorchidism, 21 with inguinoscrotal anomalies and 28 who were normal. IgG, IgM and IgA antisperm antibodies were determined by the indirect Immunobead test. Serum testing was repeated 1 and 2 years postoperatively and annually for 2 more years in the normal children. Also sera from 183 infertile men 21 to 47 years old with a history of cryptorchidism and/or inguinal hernia operated on in childhood were similarly studied.

RESULTS

Of the adults 70 (39%) tested IgG positive, including 12 (7%) who were also IgA positive, and all tested IgM negative. Repeat measurements were negative for all IgG, IgA and IgM isotypes in all children, patients and controls.

CONCLUSIONS

We conclude that there are no antibodies to sperm surface antigens in prepubertal children with cryptorchidism and inguinoscrotal anomalies before and within 2 years after surgery. Autoimmunity against postmeiotic sperm membrane antigens is apparent in adults only.

Degeneration of the seminiferous epithelium following epididymal obstruction in prepubertal rats

The development of the testes was studied in rats following prepubertal obstruction of the epididymis. Male rats received bilateral ligation of the corpus epididymidis or a sham operation at 10 days of age, and temporal changes in testicular morphology and weights of reproductive organs were determined at intervals spanning sexual maturation. Development of the testes was normal through 35 days of age. The initial histological changes in the testes of ligated animals, observed at 56 days, included an increased diameter of the seminiferous tubule lumen, depletion of spermatids, and the presence of multinucleate spermatids. Subsequently, germ cells were greatly depleted in the testes of 91- and 128-day-old rats with ligated epididymides. After puberty, testicular weight and volume declined relative to corresponding sham-operated animals. On the other hand, the weights of the epididymides in ligated animals prior to puberty significantly exceeded those of sham-operated rats but weighed significantly less than those of rats in the sham group after sexual maturation. Testicular alterations occurred after increases in the weights of the epididymides. Testicular changes may have contributed to rather than resulted from an autoimmune response to spermatozoa because testicular alterations preceded increases in antisperm autoantibodies.