Seminal vesicle amyloid: the first example of exocrine cell origin of an amyloid fibril precursor

Seminal Tract Amyloidosis: Synchronous Amyloidosis of the Seminal Vesicles, Deferent Ducts and Ejaculatory Ducts

Senile Seminal Vesicle Amyloidosis (SSVA) increases with age. Involvement of the whole seminal tract, i.e. the seminal vesicles, ejaculatory and deferent ducts was first reported by us in the International Symposium on Amyloidosis 1998. Since then we encountered four more cases of SSVA. In all these cases the ejaculatory and deferent ducts were also involved by amyloid. The amyloid was located mostly sub-epithelially, stained positively with Congo red, gave green birefringence under polarized light and was permanganate sensitive, slightly positive for lactoferrin immunostaining and negative for all known amyloid types. In recent years the amyloid was found to be derived from Semenogelin I, a major constituent of the seminal fluid which is present in the epithelial cells of the seminal vesicle and vas deference. This would explain the deposition of amyloid not only in the seminal vesicles but also in the deferent an ejaculatory ducts which transport the seminal fluid. In a review of the literature we found three more articles on SSVA in which the amyloid was not limited to the seminal vesicles alone. We propose to designate this type of amyloid as "Senile seminal Tract Amyloidosis" (SSTA) instead of "Senile Seminal Vesicle Amyloidosis (SSVA)".

Amyloidosis of the seminal vesicleA case report and review of the literature

The finding of amyloid deposits in the seminal vesicles has been known for many years. The deposits are usually localized and asymptomatic. In recent years seminal vesicle amyloidosis has been reported to simulate prostate and bladder cancer invasion on MRI. We therefore feel that knowledge of the entity is important and present herein a typical case confirming the previous findings that amyloidosis of the seminal vesicles is a unique form of amyloidosis, a relatively common incidental finding and one that may be related to prostate cancer.

CHARACTERIZATION OF LOCALIZED SEMINAL VESICLE AMYLOIDOSIS CAUSING HEMOSPERMIA: AN ANALYSIS USING IMMUNOHISTOCHEMISTRY AND MAGNETIC RESONANCE IMAGING

PURPOSE

We evaluated the characteristics of seminal vesicle amyloidosis (SVA) associated with hemospermia by immunohistochemistry and magnetic resonance imaging (MRI) as well as the clinical course of hemospermia.

MATERIALS AND METHODS

Of 56 patients with hemospermia 12 underwent transperineal biopsy of the seminal vesicle under transrectal ultrasound monitoring. SVA was proved in 4 men 48 to 59 years old by histological and immunohistochemical examinations of specimens obtained by biopsy. Two men presented with the first episode of hemospermia and 2 presented with recurrent hemospermia. MRI at 1.5 Tesla was performed while hemospermia persisted and after its resolution. Patients were followed for 10 to 86 months with regard to the duration of hemospermia, the time of its resolution and its recurrence.

RESULTS

Amyloid deposits in the subepithelial tissue of the seminal vesicles were permanganate sensitive, and positive for lactoferrin and the amyloid P component but negative for amyloid A protein, lambda and kappa chains, and beta2-microglobulin. The seminal vesicles with obvious intravesicular hemorrhage on needle puncture were hyperintense on T1-weighted images. After hemospermia resolution T1-weighted images became diffusely hypointense. T2-weighted images were of low intensity, representing amyloid deposits. Hemospermia resolved spontaneously in all patients in an average of 14 months. Although disease recurred in 1 patient after 8 months of resolution, it disappeared after 11 months of recurrence.

CONCLUSIONS

Localized SVA with hemospermia shows hypointensity on T2-weighted MRI. Hemospermia is spontaneously resolved with the transition from hyperintense to hypointense T1-weighted MRI.

Senile seminal vesicle amyloid is derived from semenogelin I

Senile seminal vesicle amyloid (SSVA), one of the most common forms of localized amyloidosis, is associated with the male aging process. Although it had been posited that the amyloidogenic component originated from exocrine cells and that, on the basis of immunohistochemistry, that the amyloid was composed of lactoferrin, the nature of SSVA was never established definitively. To address this issue, we have used our microanalytic techniques to characterize the structure of the congophilic green birefringent protein extracted from 5 such amyloid-containing specimens. Mass spectrometric analysis revealed that in all cases, the fibrils were composed mainly of polypeptide fragments identical in sequence to the N-terminal portion of the major secretory product of seminal vesicles, namely semenogelin I (SgI). Although lactoferrin was detected in 3 instances, the trace amount and seemingly intact form of this molecule indicated that it was not the amyloidogenic molecule. The SgI nature of the amyloid was confirmed through demonstration that the deposits were immunostained specifically with Sgl-reactive antibodies. The results of our research provide unequivocal evidence that SSVA is derived from SgI, and we provisionally designate this form of amyloidosis as ASgI.

Implications of amyloidosis on prostatic biopsy

Transrectal ultrasound-guided biopsy of the prostate is an integral step in the investigation of patients at risk of prostate adenocarcinoma. With an increasing number of biopsies being performed, uncommon forms of prostatic pathology will be identified more frequently. Amyloidosis of the prostate and/or the seminal vesicles may be noted on transrectal ultrasound-guided biopsy of the prostate and the implications of this histological diagnosis must be understood. We present our experience of two such cases of amyloidosis and review the literature regarding their management.

Amyloid fibril proteins

Amyloidosis refers to a group of protein folding diseases. Various innocuous and soluble proteins in physiological conditions polymerize to insoluble amyloid fibrils in several serious diseases, including Alzheimer's disease (AD) and prion diseases. In addition, senile amyloidosis is a form of amyloidosis in which the incidence and severity of amyloid deposition increases with age without any apparent predisposing conditions and it was thought that the amyloidosis was related to some physiological changes which accompany ageing. Although the etiology and pathogenesis of amyloid disease are not fully understood, drastic structural changes of the amyloid proteins from the normal forms to the unique beta-sheet fibrils is the most important event in amyloid diseases. The present article introduces the three amyloid diseases, AD, prion diseases and mouse senile amyloidosis in which Abeta, PrP(Sc) and AApoAII amyloid fibrils deposit respectively. We discuss the nucleation dependent polymerization model as a model that explains the kinetics of fibrillization of these amyloid proteins. Exogenous amyloid fibrils may act as templates (nuclei) and change the conformation of endogenous amyloid protein to polymerize into amyloid fibrils. This hypothesis makes the boundary between transmissible and non-transmissible amyloidosis ambiguous and proposes the common pathogenesis for them.

Localized amyloidosis of the seminal vesicle: identification of lactoferrin immunoreactivity in the amyloid material

Three specimens of localized amyloidosis of the seminal vesicle surgically removed for prostatic cancer were immunohistochemically analyzed to clarify the nature of the permanganate-sensitive congophilic subepithelial deposition. A variety of known amyloidogenic substances and secretory products in the seminal fluid were screened using the indirect immunoperoxidase method. In addition to reactivities with antibodies to amyloid P component and human seminal plasma, the amyloid material was immunoreactive for lactoferrin using a rabbit antiserum and two of three mouse monoclonal antibodies. All the antibodies labeled some of the normal seminal vesicle epithelial cells for this ironbinding, bacteriostatic glycoprotein. In the prostate without accompanying amyloid deposition, a considerable proportion of the glandular epithelium and secretory material were positive for lactoferrin. Pre-embedding immunoelectron microscopy showed lactoferrin immunoreactivity on the amyloid fibrils. Focal staining of the amyloid for gross cystic disease fluid protein-15 was also observed in two lesions. These findings strongly suggest that lactoferrin is the major constituent in localized senile amyloidosis of the seminal vesicle.

Dynamics of the seminal vesicle epithelium

In newborn rodents, seminal vesicle epithelium (SVEP) cells display a poorly developed rough endoplasmic reticulum (RER) and Golgi complex, and they show no signs of secretion. From puberty onward, secretory material starts to appear, and the RER and Golgi complex progressively develop and reorganize until the adult ultrastructure is established around 40-60 days of age. Multivesicular bodies and lysosomes follow in this development but lysosomes evolve to lipofucsin granules with aging. The duration of the secretory cycle in SVEP cells is shorter than in other exocrine cells and the secretory protein pattern depends on the animal species, androgen status, and sexual activity. SVEP cells are also involved in endocytosis, which is coupled to exocytosis, and their endocytic pathway intersects the exocytic pathway in Golgi cisterns. The structure and function of SVEP cells depends mainly on testosterone, but other hormones and factors, such as the neuropeptide VIP, also influence their activity. Castration leads to programmed death and regression of SVEP cells to an extent that depends on the animal species. In addition, castration induces changes in the secretory protein pattern and delays its intracellular transport. Endocytic kinetics is also delayed following castration. Primary cultures of SVEP cells in a bicameral system are proposed as a model to investigate the activities of SVEP cells further.