Effects of Androgens on the Amyloid-β Protein in Alzheimer's Disease

Causal effects of genetically predicted testosterone on Alzheimer's disease: a two-sample mendelian randomization study

OBJECTIVE

Although several studies have reported that testosterone may protect against Alzheimer's disease, no evidence of a causal relationship has been demonstrated.

METHODS

A Mendelian randomization (MR) study was performed to determine the causal role of testosterone in Alzheimer's disease. The study utilized public databases obtained from separately published genome-wide associationstudies (GWAS). Single-nucleotide polymorphisms (SNPs) for testosterone were extracted from the most recent and largest published GWAS meta-analysis (178,782 participants), and SNPs for Alzheimer's disease were extracted from UK Biobank (954 AD cases and 487,331 controls). The odds ratio (OR) of the inverse variance weighting (IVW) approach was the primary outcome, and the weighted median and MR Egger regression were used for sensitivity analysis.

RESULTS

Through IVW, we observed a causal association between genetically predicted testosterone and the risk of Alzheimer's disease, with an OR of 0.99 (95% confidence interval [CI] = 0.998-0.999, p = 0.047). In the sensitivity analyses, the weighted median regression showed directionally similar estimates (OR = 0.99, 95% CI = 0.998-0.999, p = 0.048). The MR Egger regression showed similar estimates (OR = 0.99, 95% CI = 0.998-1.00, p = 0.35), but with lower precision. Funnel plots, MR Egger intercepts, and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) analysis indicated the absence of directional pleiotropy effects.

CONCLUSION

In conclusion, our MR study provides evidence of a causal relationship between testosterone levels and Alzheimer's disease; however, this relationship must be validated in future studies with larger sample sizes. Early testosterone monitoring may enable the prevention of Alzheimer's and related diseases.

Androgen Deprivation Therapy for Prostate Cancer: Focus on Cognitive Function and Mood

Prostate cancer is the second leading cause of cancer death in men in the United States. Androgen deprivation therapy (ADT) is currently the primary treatment for metastatic prostate cancer, and some studies have shown that the use of anti-androgen drugs is related to a reduction in cognitive function, mood changes, diminished quality of life, dementia, and possibly Alzheimer's disease. ADT has potential physiological effects such as a reduction in white matter integrity and a negative impact on hypothalamic functions due to the lowering of testosterone levels or the blockade of downstream androgen receptor signaling by first- and second-generation anti-androgen drugs. A comparative analysis of prostate cancer patients undergoing ADT and Alzheimer patients identified over 30 shared genes, illustrating common ground for the mechanistic underpinning of the symptomatology. The purpose of this review was to investigate the effects of ADT on cognitive function, mood, and quality of life, as well as to analyze the relationship between ADT and Alzheimer's disease. The evaluation of prostate cancer patient cognitive ability via neurocognitive testing is described. Future studies should further explore the connection among cognitive deficits, mood disturbances, and the physiological changes that occur when hormonal balance is altered.

Possible cognition changes in women with polycystic ovary syndrome: a narrative review

Nowadays, polycystic ovary syndrome (PCOS) and cognitive dysfunction are major health problems among female. This narrative review aimed to investigate cognitive dysfunction in female with PCOS. English and Persian articles published in PubMed, Scopus, Web of Science, Google Scholar, PsycINFO, Scientific Information Database, and Cochrane Database of Systematic Reviews until May 2022 were searched. Sixteen studies involving 850 female with PCOS and 974 controls were assessed. In these studies, the association between biochemical factors and symptoms of PCOS and memory, attention, executive functioning, information processing speed, and visuospatial skills was evaluated. The literature review revealed the possible cognitive changes in female with PCOS. This study summarized the different aspects of cognitive function in female with PCOS due to medication, psychological problems (mood disorders caused by disease symptoms and complications), and biochemical markers, such as metabolic and sex hormone abnormalities. Considering the existing scientific gap regarding the possibility of cognitive complications in female with PCOS, further biological studies should be conducted to evaluate the potential mechanisms involved.

The Potential Roles of Exosomes Carrying APP and Tau Cleavage Products in Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of dementia throughout the world. It is characterized by major amyloid plaques and neurofibrillary tangles (NFTs), which are composed of amyloid-β (Aβ) peptide and hyperphosphorylated Tau (p-Tau), respectively. Exosomes, which are secreted by cells, are single-membrane lipid bilayer vesicles found in bodily fluids and they have a diameter of 30-150 nm. Recently, they have been considered as critical carriers and biomarkers in AD, as they facilitate communication between cells and tissues by delivering proteins, lipids, and nucleic acids. This review demonstrates that exosomes are natural nanocontainers that carry APP as well as Tau cleavage products secreted by neuronal cells and that their formation is associated with the endosomal-lysosomal pathway. Moreover, these exosomes can transfer AD pathological molecules and participate in the pathophysiological process of AD; therefore, they have potential diagnostic and therapeutic value for AD and might also provide novel insights for screening and prevention of the disease.

Androgens and NGF Mediate the Neurite-Outgrowth through Inactivation of RhoA

Steroid hormones and growth factors control neuritogenesis through their cognate receptors under physiological and pathological conditions. We have already shown that nerve growth factor and androgens induce neurite outgrowth of PC12 cells through a reciprocal crosstalk between the NGF receptor, TrkA and the androgen receptor. Here, we report that androgens or NGF induce neuritogenesis in PC12 cells through inactivation of RhoA. Ectopic expression of the dominant negative RhoA N19 promotes, indeed, the neurite-elongation of unchallenged and androgen- or NGF-challenged PC12 cells and the increase in the expression levels of βIII tubulin, a specific neuronal marker. Pharmacological inhibition of the Ser/Thr kinase ROCK, an RhoA effector, induces neuritogenesis in unchallenged PC12 cells, and potentiates the effect of androgens and NGF, confirming the role of RhoA/ROCK axis in the neuritogenesis induced by androgen and NGF, through the phosphorylation of Akt. These findings suggest that therapies based on new selective androgen receptor modulators and/or RhoA/ROCK inhibitors might exert beneficial effects in the treatment of neuro-disorders, neurological diseases and ageing-related processes.

Biological and Clinical Implications of Sex-Specific Differences in Alzheimer's Disease

Mounting evidence indicates that the female sex is a risk factor for Alzheimer's disease (AD), the most common cause of dementia worldwide. Decades of research suggest that sex-specific differences in genetics, environmental factors, hormones, comorbidities, and brain structure and function may contribute to AD development. However, although significant progress has been made in uncovering specific genetic factors and biological pathways, the precise mechanisms underlying sex-biased differences are not fully characterized. Here, we review several lines of evidence, including epidemiological, clinical, and molecular studies addressing sex differences in AD. In addition, we discuss the challenges and future directions in advancing personalized treatments for AD.

Increased cytokine gene expression and cognition risk associated with androgen deprivation therapy

BACKGROUND

Androgen deprivation therapy (ADT) is a standard treatment modality for locally advanced, high-risk, and metastatic hormone-sensitive prostate cancer. Long-term ADT treatment likely develops side-effects that include changes in cognition or onset of dementia. However, the molecular understanding of this effect remains elusive. We attempt to establish a link between ADT and changes in cognitive function using patient databases and bioinformatics analyses.

METHODS

Gene expression profiling was performed using RNA sequencing data from Alzheimer patient cohort and compared with the data from advanced-stage prostate cancer patients receiving neoadjuvant antiandrogen therapy. Differentially expressed genes (DEGs) were analyzed using the Ingenuity knowledge database.

RESULTS

A total of 1952 DEGs in the Alzheimer patient cohort and 101 DEGs were identified in ADT treated prostate cancer patients. Comparing both data sets provided a subset of 33 commonly expressed genes involving cytokine-cytokine signaling with an over representation of cytokine-cytokine receptor interaction, inflammatory cytokines, signaling by interleukins together with alterations in the circulating lymphocyte repertoire, adaptive immune responses, regulation of cytokine production, and changes in T-cell subsets. Additionally, lipopolysaccharide, tumor necrosis factor, and toll-like receptors were identified as upstream transcriptional regulators of these pathways. The most commonly expressed genes viz. IL-17A, CCL2, IL-10, IL-6, IL-1RN, LIF/LIFR were further validated by quantitative RT-PCR exhibited higher expression in antiandrogen treated neuronal, glial, and androgen-responsive prostate cancer cells, compared to no-androgen antagonist treatment.

CONCLUSIONS

Our findings suggest that changes in cytokine signaling under the influence of ADT in prostate cancer patients may be linked with cognitive impairment presenting new avenues for diagnostic and therapeutic development in combating brain deficits.

Salivary Testosterone and Cortisol Levels in Tunisian Elderly Male Patients With Mild Alzheimer’s Disease. Implications of Musical Therapy And/Or Physical Rehabilitation

Changes in salivary testosterone (T) and cortisol (C) levels were assessed in elderly Tunisian male patients with mild Alzheimer’s disease (AD) subjected to music therapy and/or physical rehabilitation. Male patients with mild AD (N = 26; age = 76.23 ± 4.27 years; weight: 74.76 ± 5.36 kg) were randomly assigned into four groups for three 60-min sessions per week for 4 months; including Group1 or control group (Co) (n = 6); Group2 (n = 6), participated in physical rehabilitation (PR); Group3 (n = 7), subjected to music therapy (MT) and Group4 (n = 7), participated simultaneously in music therapy and physical rehabilitation (MT + PR). Salivary T levels increased (ηp² = 0.7) and C levels decreased (ηp² = 0.69), significantly (p < 0.001) in the PR, MT and MT + PR groups compared to the Co group respectively. Also, increases in salivary T levels and decreases in C levels in MT + PR group were greater compared to the other groups. MT increased T levels (p < 0.001) and decreased C levels (p < 0.05) to a greater extent than the PR group respectively. Changes in salivary T levels were positively (r = 0.83; p < 0.001) and C levels were negatively (r = -0.86; p < 0.001) correlated in the PR, MT and MT + PR groups with changes in MMSE in AD patients. This study highlights that combination of MT and PR holds potential to treat AD.

Molecular mechanisms of sex hormones in the development and progression of Alzheimer's disease

Alzheimer's disease (AD) is a form of brain disorder characterized by various pathological changes in the brain. Numerous studies have shown that sex hormones are involved in the disease. For instance, progesterone, estrogen, and testosterone are well-known steroid sex hormones that play an essential role in AD pathogenesis. The Gender-dependency of AD is attributed to the effect of these hormones on the brain, which plays a neuroprotective role. In recent years, much research has been performed on the protective role of these hormones against nerve cell damage, which are promising for AD management. Hence, in the current review, we aim to decipher the protective role of steroid hormones in AD. Accordingly, we will discuss their functional mechanisms at the genomic and non-genomic scales.

Identification of potential biomarkers for pathogenesis of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is an extremely complicated neurodegenerative disorder, which accounts for almost 80 % of all dementia diagnoses. Due to the limited treatment efficacy, it is imperative for AD patients to take reliable prevention and diagnosis measures. This study aimed to explore potential biomarkers for AD.

METHODS

GSE63060 and GSE140829 datasets were downloaded from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEG) between AD and control groups in GSE63060 were analyzed using the limma software package. The mRNA expression data in GSE140829 was analyzed using weighted gene co-expression network analysis (WGCNA) function package. Protein functional connections and interactions were analyzed using STRING and key genes were screened based on the degree and Maximal Clique Centrality (MCC) algorithm. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed on the key genes.

RESULTS

There were 65 DEGs in GSE63060 dataset between AD patients and healthy controls. In GSE140829 dataset, the turquoise module was related to the pathogenesis of AD, among which, 42 genes were also differentially expressed in GSE63060 dataset. Then 8 genes, RPS17, RPL26, RPS3A, RPS25, EEF1B2, COX7C, HINT1 and SNRPG, were finally screened. Additionally, these 42 genes were significantly enriched in 12 KEGG pathways and 119 GO terms.

CONCLUSIONS

In conclusion, RPS17, RPL26, RPS3A, RPS25, EEF1B2, COX7C, HINT1 and SNRPG, were potential biomarkers for pathogenesis of AD, which should be further explored in AD in the future.

Bactericidal/Permeability-Increasing Protein Improves Cognitive Impairment in Diabetic Mice via Blockade of the LPS-LBP-TLR4 Signaling Pathway

Emerging evidence suggests that the bactericidal/permeability-increasing protein (BPI) is involved in the process of cognitive impairment in diabetes. However, its underlying mechanism remains elusive. In this study, we found that BPI affects cognitive impairment due to diabetes through the lipopolysaccharide (LPS)-lipopolysacharide-binding protein (LBP)-toll-like receptor 4 (TLR4) signaling pathway. We examined the expression of BPI, LPS, LBP, CD14, and TLR4 in established mouse models of diabetes induced by high-fat diet (HFD) in combination with streptozotocin (STZ). Diabetic mice were then injected with adeno-associated-virus carrying BPI overexpression vectors and LPS. Fasting blood glucose, plasma insulin, and serum levels of inflammatory factors were examined. Then, glucose tolerance and, insulin resistance tests were used to measure systemic insulin sensitivity. Next, hippocampal tissue injury and cell apoptosis were examined by hematoxylin-eosin (HE) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. Diabetic mice displayed increased LPS expression and activation of the LPS-CD14-TLR4 signaling pathway. HFD mice following LPS treatment showed significantly increased serum levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6, and expressions of Bcl-2-associated X protein (Bax) and Aβ but decreased expression of Bcl-2 in hippocampal tissues, as well as enhanced fasting blood glucose, plasma insulin, glucose tolerance, insulin tolerance, cell apoptosis, aggravated hippocampal tissue injury and, ultimately, cognitive impairment. However, overexpression of BPI was able to rescue the aforementioned phenotypes driven by LPS treatment. Taken together, BPI could potentially provide relief from cognitive impairment in diabetic mice by disrupting the LPS-LBP-TLR4 signaling pathway, underscoring a possible alternative therapeutic strategy against the cognitive impairment associated with diabetes.

Neuroprotection of dihydrotestosterone via suppression of the toll-like receptor 4/nuclear factor-kappa B signaling pathway in high glucose-induced BV-2 microglia inflammatory responses

Hyperglycemia is considered to induce neuronal apoptosis via activating microglia inflammatory responses, thus involving in the development and progression of diabetic encephalopathy and neurodegenerative disorders. Increasing evidences suggest that androgen exerts neuroprotective functions including antiapoptosis, anti-inflammation and antioxidative stress. In this study, we investigate the anti-inflammatory role of dihydrotestosterone (DHT) in high glucose (HG)-induced neuroinflammatory response in BV-2 microglia. Our results revealed that DHT significantly inhibited HG-induced production of nitric oxide and prostaglandin E2 through suppressing the expression of corresponding regulatory enzymes - inducible NO synthase and cyclooxygenase-2. Also, DHT inhibited HG-induced expression of TNF-α and IL-1β. Moreover, DHT suppressed the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway. Furthermore, when SH-SY5Y neurons were cultured in HG-treated BV-2 microglial supernatant, DHT pretreatment significantly increased neuronal survival, indicating the neuroprotective role of DHT. Collectively, these results suggest that DHT could protect SH-SY5Y neurons from HG-mediated BV-2 microglia inflammatory damage through inhibiting TLR4/NF-κB signaling, suggesting that maintenance of androgen level in brain might have potential benefit in neurodegenerative diseases, especially in diabetes patients combined with cognitive disorders.

Apoptosis in hippocampal tissue induced by oxidative stress in testosterone deprived male rats

The testosterone decline is one of the potential causes of oxidative stress-induced anxiety and depressive behaviors, and cognitive impairment induces irreversible neuronal damage, which is not clearly understood. The orchidectomized rat model was used; the hippocampal neurons and anxiety behavior were analyzed. Adult male albino rats were divided into control and orchidectomy (ORX) groups, orchidectomy (ORX + T), and normal (Cont + T) groups. Testosterone propionate was used as a testosterone supplement. The anxiety and depressive-like behavior observed in ORX animals in the open field (OF) and elevated plus-maze experiments were effectively overturned in the ORX + T group. Studies on isolated hippocampus showed reduced antioxidant enzymes (SOD, CAT, and glutathione (GSH) compounds), increased lipid peroxidation (LPO), elevated caspase3, and reduced anti-apoptotic protein Bcl-2, and increased apoptotic nuclei in TUNEL staining of the hippocampus in the ORX rats. These observations indicate free radical-mediated neural damage. Testosterone presence promoted the antioxidant defense system and restored normal pyramidal neuron morphology in ORX + T. This study confirms that testosterone is indispensable in the normal adult hippocampus and deficiency seems to be a potential risk factor for neurodegenerative disorders. Besides, androgen appears to be a possible therapeutic strategy for treating depression/neurodegenerative diseases in aging men.

Blood-brain barrier integrity in the pathogenesis of Alzheimer's disease

The blood-brain barrier (BBB) tightly controls the molecular exchange between the brain parenchyma and blood. Accumulated evidence from transgenic animal Alzheimer's disease (AD) models and human AD patients have demonstrated that BBB dysfunction is a major player in AD pathology. In this review, we discuss the role of the BBB in maintaining brain integrity and how this is mediated by crosstalk between BBB-associated cells within the neurovascular unit (NVU). We then discuss the role of the NVU, in particular its endothelial cell, pericyte, and glial cell constituents, in AD pathogenesis. The effect of substances released by the neuroendocrine system in modulating BBB function and AD pathogenesis is also discussed. We perform a systematic review of currently available AD treatments specifically targeting pericytes and BBB glial cells. In summary, this review provides a comprehensive overview of BBB dysfunction in AD and a new perspective on the development of therapeutics for AD.

Age-Related Changes and Sex-Related Differences in Brain Iron Metabolism

Iron is an essential element that participates in numerous cellular processes. Any disruption of iron homeostasis leads to either iron deficiency or iron overload, which can be detrimental for humans' health, especially in elderly. Each of these changes contributes to the faster development of many neurological disorders or stimulates progression of already present diseases. Age-related cellular and molecular alterations in iron metabolism can also lead to iron dyshomeostasis and deposition. Iron deposits can contribute to the development of inflammation, abnormal protein aggregation, and degeneration in the central nervous system (CNS), leading to the progressive decline in cognitive processes, contributing to pathophysiology of stroke and dysfunctions of body metabolism. Besides, since iron plays an important role in both neuroprotection and neurodegeneration, dietary iron homeostasis should be considered with caution. Recently, there has been increased interest in sex-related differences in iron metabolism and iron homeostasis. These differences have not yet been fully elucidated. In this review we will discuss the latest discoveries in iron metabolism, age-related changes, along with the sex differences in iron content in serum and brain, within the healthy aging population and in neurological disorders such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, and stroke.

Androgen Therapy in Neurodegenerative Diseases

Neurodegenerative diseases, including Alzheimer disease (AD), Parkinson disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington disease, are characterized by the loss of neurons as well as neuronal function in multiple regions of the central and peripheral nervous systems. Several studies in animal models have shown that androgens have neuroprotective effects in the brain and stimulate axonal regeneration. The presence of neuronal androgen receptors in the peripheral and central nervous system suggests that androgen therapy might be useful in the treatment of neurodegenerative diseases. To illustrate, androgen therapy reduced inflammation, amyloid-β deposition, and cognitive impairment in patients with AD. As well, improvements in remyelination in MS have been reported; by comparison, only variable results are observed in androgen treatment of PD. In ALS, androgen administration stimulated motoneuron recovery from progressive damage and regenerated both axons and dendrites. Only a few clinical studies are available in human individuals despite the safety and low cost of androgen therapy. Clinical evaluations of the effects of androgen therapy on these devastating diseases using large populations of patients are strongly needed.

The Role of Sex and Sex Hormones in Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are a wide class of disorders of the central nervous system (CNS) with unknown etiology. Several factors were hypothesized to be involved in the pathogenesis of these diseases, including genetic and environmental factors. Many of these diseases show a sex prevalence and sex steroids were shown to have a role in the progression of specific forms of neurodegeneration. Estrogens were reported to be neuroprotective through their action on cognate nuclear and membrane receptors, while adverse effects of male hormones have been described on neuronal cells, although some data also suggest neuroprotective activities. The response of the CNS to sex steroids is a complex and integrated process that depends on (i) the type and amount of the cognate steroid receptor and (ii) the target cell type-either neurons, glia, or microglia. Moreover, the levels of sex steroids in the CNS fluctuate due to gonadal activities and to local metabolism and synthesis. Importantly, biochemical processes involved in the pathogenesis of NDs are increasingly being recognized as different between the two sexes and as influenced by sex steroids. The aim of this review is to present current state-of-the-art understanding on the potential role of sex steroids and their receptors on the onset and progression of major neurodegenerative disorders, namely, Alzheimer's disease, Parkinson's diseases, amyotrophic lateral sclerosis, and the peculiar motoneuron disease spinal and bulbar muscular atrophy, in which hormonal therapy is potentially useful as disease modifier.

Neuroprotection by dihydrotestosterone in LPS-induced neuroinflammation

Microglia-induced neuroinflammation plays a vital role in the etiology and progression of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease and multiple sclerosis. The neuroprotective role of androgens, including testosterone and its metabolite dihydrotestosterone (DHT), has been increasingly demonstrated in these diseases, but few studies investigated the effects of androgen on neuroinflammation. This study investigated the role of DHT in lipopolysaccharide (LPS)-induced neuroinflammation, neuronal damage and behavioral dysfunction, as well as underlying mechanisms. We showed that DHT inhibited LPS-induced release of proinflammatory factors, including TNF-α, IL-1β, IL-6; iNOS, COX-2, NO, and PGE2 in BV2 cells and primary microglia by suppressing the TLR4-mediated NF-κB and MAPK p38 signaling pathways, thus protecting SH-SY5Y neurons from inflammatory damage induced by activated microglia. In an LPS-induced neuroinflammation mouse model, endogenous DHT depletion by castration exacerbated inflammatory responses by upregulating the levels of TNF-α, IL-1β, IL-6, iNOS, and COX-2 in the serum and brain by increasing the LR4-mediated NF-κB and MAPK pathway activation, but these effects were restored by exogenous DHT supplementation. Moreover, DHT also regulated the mRNA levels of the anti-inflammatory cytokines IL-10 and IL-13 in the brain. In addition, DHT modulated the expression of Aβ, the apoptotic proteins caspase-3, Bcl-2, and Bax, and synaptophysin, as well as neuronal damage in LPS-treated mouse brains. Further behavioral tests revealed that DHT ameliorated LPS-induced spatial and learning impairment and motor incoordination, and partly improved the locomotor activity in LPS-injected mice. Therefore, this study suggests that DHT exerts anti-neuroinflammatory and neuroprotective effects; thus, androgen replacement therapy is a potential therapeutic strategy for improving cognitive and behavioral function in neuroinflammation-related diseases.

The epididymal amyloid matrix: structure and putative functions

BACKGROUND

We previously demonstrated the normal mouse epididymal lumen contains a non-pathological amyloid matrix that surrounds spermatozoa and plays important roles in sperm maturation and protection.

OBJECTIVE

The objective herein was to present a review of this work, including studies showing the amyloid structures of four members of the CRES (cystatin-related epididymal spermatogenic) subgroup are integral and essential components of the amyloid matrix.

METHODS

We used conformation-dependent reagents that recognize the cross-β-sheet structure characteristic of amyloid, including thioflavin S (ThS), thioflavin T (ThT), anti-amyloid antibodies, and X-ray diffraction, as well as negative-stain transmission electron microscopy (TEM) to visualize amyloid structures in the epididymal lumen. Antibodies that specifically detect each CRES subgroup family member were also used in indirect immunofluorescence analysis.

RESULTS AND DISCUSSION

The epididymal lumen contains an amyloid matrix that surrounds maturing spermatozoa and represents a functional amyloid. Alterations in the structure of the amyloid matrix by the loss of the CRES subgroup members or the overexpression of cystatin C result in epididymal pathologies, including infertility. Preliminary data suggest the epididymal amyloid matrix is structurally and functionally similar to bacterial biofilms.

CONCLUSION

Together, these results suggest the amyloid matrix serves important roles in epididymal function including sperm maturation and protection.