Early-life origin of prostate cancer through deregulation of miR-206 networks in maternally malnourished offspring rats

The Developmental Origins of Health and Disease (DOHaD) concept has provided the framework to assess how early life experiences can shape health and disease throughout the life course. While maternal malnutrition has been proposed as a risk factor for the developmental programming of prostate cancer (PCa), the molecular mechanisms remain poorly understood. Using RNA-seq data, we demonstrated deregulation of miR-206-Plasminogen (PLG) network in the ventral prostate (VP) of young maternally malnourished offspring. RT-qPCR confirmed the deregulation of the miR-206-PLG network in the VP of young and old offspring rats. Considering the key role of estrogenic signaling pathways in prostate carcinogenesis, in vitro miRNA mimic studies also revealed a negative correlation between miR-206 and estrogen receptor α (ESR1) expression in PNT2 cells. Together, we demonstrate that early life estrogenization associated with the deregulation of miR-206 networks can contribute to the developmental origins of PCa in maternally malnourished offspring. Understanding the molecular mechanisms by which early life malnutrition affects offspring health can encourage the adoption of a governmental policy for the prevention of non-communicable chronic diseases related to the DOHaD concept.

Adiponectin reverses β-Cell damage and impaired insulin secretion induced by obesity

Obesity significantly decreases life expectancy and increases the incidence of age-related dysfunctions, including β-cell dysregulation leading to inadequate insulin secretion. Here, we show that diluted plasma from obese human donors acutely impairs β-cell integrity and insulin secretion relative to plasma from lean subjects. Similar results were observed with diluted sera from obese rats fed ad libitum, when compared to sera from lean, calorically restricted, animals. The damaging effects of obese circulating factors on β-cells occurs in the absence of nutrient overload, and mechanistically involves mitochondrial dysfunction, limiting glucose-supported oxidative phosphorylation and ATP production. We demonstrate that increased levels of adiponectin, as found in lean plasma, are the protective characteristic preserving β-cell function; indeed, sera from adiponectin knockout mice limits β-cell metabolic fluxes relative to controls. Furthermore, oxidative phosphorylation and glucose-sensitive insulin secretion, which are completely abrogated in the absence of this hormone, are restored by the presence of adiponectin alone, surprisingly even in the absence of other serological components, for both the insulin-secreting INS1 cell line and primary islets. The addition of adiponectin to cells treated with plasma from obese donors completely restored β-cell functional integrity, indicating the lack of this hormone was causative of the dysfunction. Overall, our results demonstrate that low circulating adiponectin is a key damaging element for β-cells, and suggest strong therapeutic potential for the modulation of the adiponectin signaling pathway in the prevention of age-related β-cell dysfunction.

Stromal cell interplay in prostate development, physiology, and pathological conditions

Advances in prostatic stroma studies over the past few decades have demonstrated that the stroma not only supports and nourishes the gland's secretory epithelium but also participates in key aspects of morphogenesis, in the prostate's hormonal metabolism, and in the functionality of the secretory epithelium. Furthermore, the stroma is implicated in the onset and progression of prostate cancer through the formation of the so-called reactive stroma, which corresponds to a tumorigenesis-permissive microenvironment. Prostatic stromal cells are interconnected and exchange paracrine signals among themselves in a gland that is highly sensitive to endocrine hormones. There is a growing body of evidence that telocytes, recently detected interstitial cells that are also present in the prostate, are involved in stromal organization, so that their processes form a network of interconnections with both the epithelium and the other stromal cells. The present review provides an update on the different types of prostate stromal cells, their interrelationships and implications for prostate development, physiology and pathological conditions.

Study protocol to investigate biomolecular muscle profile as predictors of long-term urinary incontinence in women with gestational diabetes mellitus

BACKGROUND

Pelvic floor muscles (PFM) and rectus abdominis muscles (RAM) of pregnant diabetic rats exhibit atrophy, co-localization of fast and slow fibers and an increased collagen type I/III ratio. However, the role of similar PFM or RAM hyperglycemic-related myopathy in women with gestational diabetes mellitus (GDM) remains poorly investigated. This study aims to assess the frequency of pelvic floor muscle disorders and pregnancy-specific urinary incontinence (PS-UI) 12 months after the Cesarean (C) section in women with GDM. Specifically, differences in PFM/RAM hyperglycemic myopathy will be evaluated.

METHODS

The Diamater is an ongoing cohort study of four groups of 59 pregnant women each from the Perinatal Diabetes Research Centre (PDRC), Botucatu Medical School (FMB)-UNESP (São Paulo State University), Brazil. Diagnosis of GDM and PS-UI will be made at 24-26 weeks, with a follow-up at 34-38 weeks of gestation. Inclusion in the study will occur at the time of C-section, and patients will be followed at 24-48 h, 6 weeks and 6 and 12 months postpartum. Study groups will be classified as (1) GDM plus PS-UI; (2) GDM without PS-UI; (3) Non-GDM plus PS-UI; and (4) Non-GDM without PS-UI. We will analyze relationships between GDM, PS-UI and hyperglycemic myopathy at 12 months after C-section. The mediator variables to be evaluated include digital palpation, vaginal squeeze pressure, 3D pelvic floor ultrasound, and 3D RAM ultrasound. RAM samples obtained during C-section will be analyzed for ex-vivo contractility, morphological, molecular and OMICS profiles to further characterize the hyperglycemic myopathy. Additional variables to be evaluated include maternal age, socioeconomic status, educational level, ethnicity, body mass index, weight gain during pregnancy, quality of glycemic control and insulin therapy.

DISCUSSION

To our knowledge, this will be the first study to provide data on the prevalence of PS-UI and RAM and PFM physical and biomolecular muscle profiles after C-section in mothers with GDM. The longitudinal design allows for the assessment of cause-effect relationships between GDM, PS-UI, and PFMs and RAMs myopathy. The findings may reveal previously undetermined consequences of GDM.

Telocytes role during the postnatal development of the Mongolian gerbil jejunum

Telocytes are recently categorised CD34-positive interstitial cells that comprise the cells which were previously called interstitial Cajal-like cells (ICLCs). These were detected in the stroma of various organs such as the prostate, lungs, mammary glands, liver, gallbladder, and jejunum, among others. Several functions have been proposed for telocytes, such as a supportive role in smooth muscle contraction and immune function in adult organs, and tissue organisation and paracrine signalling during development, as well as others. In the jejunum, little is known about the function of telocytes in the adult organ, or is there any information about when these cells develop or if they could have an auxiliary role in the development of the jejunum. The present study employed histological, immunohistochemical and immunofluorescence techniques on histological sections of the jejunum of Mongolian gerbil pups on two different days of postnatal development of the jejunum, covering the maturation period of the organ. By immunolabelling for CD34, it was observed that telocytes are already present in the jejunum during the first week of postnatal life and exist in close association with the developing muscularis mucosae, which are therefore TGFβ1-positive. The telocytes are still present at the end of the first month of life, and a portion of them present co-localisation with c-Kit. Fibroblast-like cells, which are exclusively c-Kit-positive, are also observed, which may indicate the presence of interstitial Cajal cells (ICCs). Finally, it can be hypothesised that a portion of the telocytes may give rise to ICCs, which are c-Kit-positive but CD34 negative.

Morphological changes in rat rectus abdominis muscle induced by diabetes and pregnancy

The urethral muscle of diabetic pregnant rats is affected by long-term mild diabetes and short-term severe diabetes, which plays a crucial role in the pathogenesis of pelvic floor disorders. We hypothesized that muscles outside the pelvis are subject to similar changes. The current study aimed at analyzing the effects of long-term mild and short-term severe diabetes on the structure and ultrastructure of fiber muscles and collagen in rats' rectus abdominis (RA) muscle. Therefore, the RA muscle of virgin, pregnant, long-term mild diabetic, short-term severe diabetic, long-term mild diabetic pregnant and short-term severe diabetic pregnant 3-month-old Wistar rats were collected. The structure was analyzed by picrosirius red staining, immunohistochemistry for fast and slow muscle fibers and transmission electron microscopy. We investigated two levels of STZ- induced diabetes: long-term mild diabetes (blood glucose level: 120–200 mg/dL) and short-term severe diabetes (blood glucose level >300 mg/dL). Long-term mild diabetic pregnant and short-term severe diabetic pregnant rats had decreased fast fibers and increased slow fibers, disrupted areas of sarcomere, intermyofibrillar mitochondria and myelin figures in the RA muscle. Both groups enabled us to analyze the specific influence of pregnancy, separately from diabetes. The current study demonstrated that diabetes and pregnancy induced intramuscular transformation and reorganization of RA muscle with a switch of fiber type adjusting their architecture according to intensity and duration of hyperglycemic insult within pregnancy.

ID: 85: CROSS-TALK BETWEEN ESTROGEN RECEPTORS AND INSULIN-LIKE GROWTH FACTOR TYPE-1 RECEPTOR MODULATES HUMAN PROSTATE STEM/PROGENITOR CELL AMPLIFICATION

We previously demonstrated that estrogen regulates human prostate stem/progenitor cell amplification by directly targeting estrogen receptors (ERs); ERα stimulates whereas ERβ suppresses stem cell self-renewal. In addition to ERα and ERβ, we find that human prostate stem/progenitor cells express robust level of IGF-1R. Since ER actions can be modified by IGF-1R through ligand-independent ER phosphorylation, we herein sought to characterize potential cross-talk between estrogen and IGF-1 signaling pathways in regulating human prostate stem/progenitor cell amplification. Human prostate stem/progenitor cells were isolated from normal primary prostate epithelial cells (PrEC) using 3-D prostasphere (PS) culture. Similar to estradiol-17β (E2), 5 nM IGF-1 treatment increased the number of PS as well as long-term BrdU-retaining prostate stem cells. Conversely, knockdown of IGF-1R by siRNA decreased both parameters and consistently increased PS ERβ expression. Together these findings suggest that IGF-1R activation may drive prostate stem cell amplification through suppression of ERβ. Further studies revealed that E2 (10 nM) exposure induced IGF-1R phosphorylation while IGF-1R knockdown inhibited the non-genomic E2-induced pAkt and pERK confirming the cross-talk between these two signaling pathways. IGF-1R knockdown decreased PHLDA1, a known IGF-1 target gene, inhibited E2-induced ERα phosphorylation, suggesting a positive interaction between IGF-1R and ERα. In summary, the present results document robust crosstalk between estrogen and IGF-1 signaling which together regulate their downstream signal molecules including pAKT/pERK and PHLDA1. We propose that these pathways coordinately modulate prostate stem and progenitor cell numbers to effectively maintain glandular homeostasis. Supported by NIH/NCI award R01 CA172220; scholarship by FAPESP grant#2014/10965-6.

Abstract A123: Preclinical evaluation of dual mTOR inhibitor, AZD2014, in prostate cancer

Background: An estimated 220,800 cases and 27,540 deaths from prostate cancer (PCa) will occur in the USA during 2015. Altered PI3K/AKT/mTOR signalling contributes to prostate cancer progression and transition to androgen-independent disease, for example one study reported 42% of primary and 100% of metastatic PCa tumours exhibited mutations, altered expression or copy number variations within this pathway. First generation mTOR inhibitors (preferentially inhibit mTORC1), have had limited anti-cancer effect in patients with PCa, possibly due to negative feedback activation of the AKT pathway via mTORC2. The dual mTORC1/2 inhibitor, AZD2014, may overcome this liability. Using a genetically engineered PTEN conditional mouse model (Ptenloxp/loxp;PB-Cre4), we have investigated the effects of AZD2014. The studies complement a clinical trial (NCT02064608) of AZD2014, given to men before radical prostatectomy and are timed for when invasive prostate carcinomas develop in the model around 10-14 months prior to onset of resistance to castration through AKT pathway activation. AZD2014, 15mg/kg daily, oral (with or without castration) or vehicle were administered for 14 days.

Results: AZD2014 was well tolerated with no overt toxicity observed. Pharmacokinetic (PK) analysis revealed mean concentrations of 4.4±2.1μM of AZD2014 in the plasma samples collected 4 hours after day 14 dose. AZD2014 alone or combined with castration inhibited mTORC1 and mTORC2 measured by reductions in p4EBP1(Thr37/46) by approximately 48%±27% (p<0.001) and 37%±11% (p<0.001); pS6(Ser235/236) by 74%±43% (p<0.001) and 44%±13% (p<0.001) and pAKT(Ser473) by 36%±8% (p<0.001) and 20%±3% (p<0.01) as compared to vehicle-treated mice. AZD2014 treatment was anti-proliferative; Ki67 was significantly reduced in AZD2014-treated mice (70%±45%, p<0.001) or AZD2014 plus castration (42%±16%, p<0.001). Apoptosis was detected with cleaved caspase 3 and increased by 3.3-fold (p<0.001) in both AZD2014 or AZD2014 plus castration groups and 2-fold (p<0.001) in the castration only group, respectively. In all cases, 10 mice were used in each group and 80-120 randomly chosen images were analysed using Aperio automatic quantitative algorithms. Tumour volumes (ultrasound imaging) were reduced by 51% (p<0.05) comparing AZD2014 plus castration against control. HRMAS 1H NMR spectroscopy was used on tumour tissue to determine changes in metabolites following treatment and identified that the total choline to creatine ratio (t-Cho/Cr) was reduced by 40% in AZD2014-treated mice tumour samples (p<0.05) as compared to control-treated mice.

Conclusions: Short term (14 days) treatment with AZD2014 with or without castration was associated with both pharmacodynamic and anti-tumour effects. The t-Cho/Cr ratio, previously reported as positively correlated with Gleason score in PCa patients, might be, in addition to our standard mTOR PD markers, utilised as a non-invasive biomarker of AZD2014 activity. The primary and phenotypic biomarker effects of monotherapy with AZD2014 in this relevant genetically engineered mouse model of prostate cancer will be compared with paired biopsies from the ongoing exploratory window study in the prostate cancer patients prior to prostatectomy, and may inform potential novel combination approaches that are translatable to the clinic.

Citation Format: Chiranjeevi Sandi, Antonio Ramos-Montoya, Sergio L. Felisbino, Sarah Jurmeister, Basetti Madhu, Karan Wadhwa, John R. Griffiths, Frances M. Richards, Duncan I. Jodrell, David E. Neal, Sabina Cosulich, Barry Davies, Simon Pacey. Preclinical evaluation of dual mTOR inhibitor, AZD2014, in prostate cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A123.

Gestational protein restriction delays prostate morphogenesis in male rats

Maternal malnutrition due to a low-protein diet is associated with functional disorders in adulthood, which may be related to embryonic development failures. The effects of gestational protein restriction on prostate morphogenesis in male offspring were investigated. Pregnant rat dams were divided into normoprotein (NP; fed a normal diet containing 17% protein) and hypoprotein (LP; fed a diet containing 6% protein) groups. On the day of birth (PND1), anogenital distance and bodyweight were measured in male pups. Seven males per experimental group (one male per litter) were killed, and the pelvic urethra was evaluated. LP offspring showed a significant reduction in bodyweight and anogenital distance on PND1. On three-dimensional reconstruction of the prostate, the number of prostatic buds was lower in LP than in NP males. Mesenchymal cells surrounding the buds were androgen-receptor positive, and the quantity and intensity of nucleus immunoreactivity was decreased in LP. The proliferation index was lower in LP than in NP prostatic buds. Immunoreactivity for α-actin in mesenchymal cells and that for epidermal growth factor receptor in epithelial cells was higher in NP than in LP. Our findings demonstrate that maternal protein restriction delays prostatic morphogenesis, probably because of considerable disruption in the epithelium–mesenchyme interaction.

MMP-2 and TIMP-2 in the prostates of male and female mongolian gerbils: effects of hormonal manipulation

TIMPs in the prostates of male and female gerbils and evaluated the effects of testosterone on the expression of these enzymes. Ventral prostates from male gerbils that were either intact or had been castrated for 7 or 21 days, along with prostates from female gerbils that were either intact or had been treated with testosterone for 7 or 21 days, were submitted to histological, stereological and immunohistochemical analyses. Stereology of prostatic components showed significant alterations of tissue compartments in the ventral male prostate after castration, especially after 21 days, with a significant increase in stroma. Administration of testosterone led to disorganization in the female prostate, with a significant increase in collagen fibers and smooth muscle cells after 21 days, along with the development of epithelial lesions such as PINs. MMP-2 increased after 21 days of castration in males; however, the TIMP-2 immunoreaction for this group was weak or absent. In females, the expression of MMP-2 appeared to decrease after 7 days of treatment with testosterone, but after 21 days, both epithelium and stroma showed a stronger reaction for MMP-2 than the controls. The expression of TIMP-2 in the treated females was similar to its expression in the castrated males. We conclude that the distribution of MMPs and TIMPs in both male and female prostates is altered by androgen manipulation, but the mechanism of stromal regulation appears to be distinct between genders because both the lack of T in castrated males and the excess levels of T in treated females lead to the same effect.

Matrix metalloproteinase (MMP)-2 and MMP-9 activity and localization during ventral prostate atrophy and regrowth

Matrix metalloproteinses (MMPs) are enzymes involved in prostatic development, growth, disease-induced tissue remodelling and secretory fluid. Although the prostate function depends upon androgen regulation, the relationship between MMPs and androgen has not been well established. Here, we evaluated MMP-2 and MMP-9 gelatinolytic activity in association with tissue localization during ventral prostate atrophy and regrowth induced by testosterone replacement (TR). Adult male Wistar rats were divided into three experimental groups: control, castrated (CS) and TR 21 days after castration. Ventral prostate (VP) was excised at 3, 5, 7 and 21 days after castration in CS group, and at 3, 5, 7 and 10 days after TR (4 mg/kg/day) in TR group. The VP was dissected, weighed and processed for histology, immunohistochemistry, ultrastructure and zymography analyses. Castration elicited the typical parenchymal atrophy and stromal condensation. TR induced intense epithelial growth towards the stromal space to restore the prostate histoarchitecture. MMP-2 and MMP-9 immunostaining presented intense reaction in CS and TR groups, mainly in the epithelial and endothelial cells. After TR, a strong immunoreaction for MMP-2 was observed in the activated stromal fibroblasts. Zymography showed that MMP-2 and MMP-9 activity, mainly the active form, increased after castration. In contrast, TR induced an additional increase in MMP-2 activity, but not in MMP-9. In conclusion, the overall behaviour of MMP-2 and MMP-9 within the prostate under androgen handling is highly complex, as each glandular compartment and cell type is affected differently by the androgenic status. Prostate regrowth appears to involve a more effective participation of MMP-2 in both epithelial and stromal compartments, while MMP-9 plays a major role in the late prostate atrophy and early regrowth.

Epithelial-stromal transition of MMP-7 immunolocalization in the rat ventral prostate following bilateral orchiectomy

Epithelial cells from involuting rat ventral prostate (VP) express Matrilysin (MMP-7) mRNA. Herein, we investigated by immunohistochemistry the MMP-7 protein location and its association with tissue changes following castration in the VP. Normal and castrated adult male Wistar rats were sacrificed at different times after surgery. VP was examined by immunocytochemistry and immunoprecipitation. Castration promoted a shrinking of prostate ducts with an extensive stromal remodeling. In the VP from normal rats, MMP-7 immunoreactivity was found in epithelial secretory granules. Three days after castration, immunostaining for MMP-7 was found in both the epithelial secretory granules and in the stroma just below the epithelium, mainly at the distal ductal tips. At seven and 21 days after castration, the immunostaining for MMP-7 was found only in the stromal space. Immunoprecipitation confirmed the specificity of the primary antibody by rescuing a pro-enzyme form (28kDa) in the prostate extracts. The present results suggest that MMP-7 participates in the epithelial-stromal interface remodeling of the ventral prostate during the involution achieved by castration, probably in the degradation of components of the epithelial basement membrane.

Differential proliferative response of the ventral prostate and seminal vesicle to testosterone replacement

We have investigated epithelial cell proliferation and the rate of glandular recovery of the ventral prostate (VP) and seminal vesicle (SV) promoted by testosterone replacement (TR) in castration-induced regressed glands. Adult male Wistar rats were castrated and, after 21 days, they were treated with testosterone propionate (4 mg/kg/day). Intact (CT) and castrated rats without TR (CS) were also analysed. VP and SV were processed for histochemistry, morphometric-stereological analysis and immunocytochemistry to determine the PCNA index (PI). After 10 days of TR, the VP weight reached approximately 72% of the CT values, while the SV weight exceeded approximately 17% of the CT values. By the third day of TR, VP and SV presented a mean PI of 34% and 94% for distal region and 14% and 22% for proximal region, respectively. SV also had more luminal cells PCNA-positive than VP, mainly in the distal region. The PI values fell on days 5, 7 and 10, but were still higher than CT. These findings indicate that epithelial cells from involuted SV are more responsive to TR than those from VP when stimulated to proliferate and replace the luminal cell population, suggesting a different mechanism regulating cell proliferation in response to androgenic stimuli.

Variations in the glycosaminoglycan content, swelling properties and morphological aspects of different regions of the superficial digital flexor tendon of pigs

The superficial digital flexor tendon of pigs is a wrap around tendon supporting compressive in addition to the tensional forces in its proximal region, and only tensional forces in the intermediate region. Clear distinctions were observed in the physical properties, composition of proteoglycan and morphology for the different regions. A greater swelling in water and a larger amount of glycosaminoglycan were found in the proximal region compared to the intermediate one. Dermatan sulfate was detected in all regions of this tendon, while chondroitin sulfate was prominent only near the bone. In the toluidine blue stained sections, intense metachromasy was observed in the sites under compressive forces, especially in the portion close to the bone. Chondrocyte like cells were also observed in these arms. Crimp morphology, observed in the intermediate region, exhibited a clearly sloped aspect in relation to the main axis of the tendon. Elastic fibers were found in all regions, and were disposed in different directions in the areas under compressive forces, and parallel to the collagen bundles in the region under tension. These results reinforce the idea that mechanical forces contribute to a differentiated composition and organization of the extracellular matrix of tendons.

Growth cartilage calcification and formation of bone trabeculae are late and dissociated events in the endochondral ossification of Rana catesbeiana

Endochondral ossification in the growth cartilage of long bones from the bullfrog Rana catesbeiana was examined. In stage-46 tadpoles and 1-year-old animals, the hypertrophic cartilage had a smooth contact with the bone marrow and the matrix showed no calcification or endochondral bone formation. In spite of showing no aspects of calcification, the chondrocytes exhibited alkaline phosphatase activity and some of them died by apoptosis. However, matrix calcification and endochondral ossification were observed in 2-year-old bullfrogs. Calcium deposits appeared as isolated or coalesced spherical structures in the extracellular matrix of hypertrophic cartilage. Bone trabeculae were restricted to the central area at the sites where the hypertrophic cartilage surface was exposed to the bone marrow. Cartilage matrix calcification and the formation of bone trabeculae were not dependent on each other. Osteoclasts were involved in calcified matrix resorption. These results demonstrate that the calcification of hypertrophic cartilage and the deposition of bone trabeculae are late events in R. catesbeiana and do not contribute to the development and growth of long bones in adults. These processes may play a role in reinforcing bony structures as the bullfrog gains weight in adulthood. In addition, the deposition of bone trabeculae is not dependent on cartilage matrix calcification.

Regional adaptations in three rat tendons

Although detailed histological and immunocytochemical studies have been published for the rat calcanear tendon (CT), little is known of the structure, composition and biomechanics of the deep (DFT) and superficial (SFT) flexor tendons. In this study, we examined the structural specialization of these three tendons in 90-day-old rats by applying histochemical and biochemical assays to different tendon regions (proximal, intermediate and distal regions of the DFT and SFT, and proximal and distal regions of the CT). There were regional differences in tissue structure, glycosaminoglycan type and content, swelling properties and in the amount and distribution of elastic fibers. Dermatan sulfate occurred in all regions, but chondroitin sulfate predominated in the intermediate region of the DFT and in the distal region of the CT. These two chondroitin sulfate-bearing regions showed swelling in water, while all other regions lost fluid in water. Fibrocartilaginous sites were observed on the CT, one at the insertion to the bone and another distally at the innermost area of the tendon. The intermediate region of the DFT showed round cells disposed in lacunae, while the proximal and distal regions were typically fibrous. The intermediate region of the SFT showed a wavy array of collagen bundles but neither toluidine blue staining in the matrix nor round cells. Elastic fibers were present in each region of the three tendons, but were more prominent in the intermediate zone of the SFT. These results demonstrate regional variation in the three tendons. Tendon differentiation may occur by an increase in the number of elastic fibers and by variations in the arrangement of collagen fibers, without fibrocartilage formation.

The osteochondral ligament: a fibrous attachment between bone and articular cartilage in Rana catesbeiana

The anuran epiphyseal cartilage shows a lateral expansion that covers the external surface of the bone, besides other features that distinguish it from the corresponding avian and mammalian structures. The fibrous structure that attaches the lateral cartilage to the bone was characterized in this work. It was designated osteochondral ligament (OCL) and presented two main areas. There was an inner area that was closer to the periosteal bone and contained a layer of osteoblasts and elongated cells aligned to and interspersed with thin collagen fibers. The thin processes of the cells in this area showed strong alkaline phosphatase activity. The outer area, which was closer to the cartilage, was rich in blood vessels and contained a few cells amongst thick collagen fibers. TRITC-phaloidin staining showed the cells of the inner area to be rich in F-actin, and were observed to form a net around the cell nucleus and to fill the cell processes which extended between the collagen fibers. Cells of the outer area were poor in actin cytoskeleton, while those associated with the blood vessels showed intense staining. Tubulin-staining was weak, regardless of the OCL region. The main fibers of the extracellular matrix in the OCL extended obliquely upwards from the cartilage to the bone. The collagen fibers inserted into the bone matrix as Sharpey's fibers and became progressively thicker as they made their way through the outer area to the cartilage. Immunocytochemistry showed the presence of type I and type III collagen. Microfibrils were found around the cells and amongst the collagen fibrils. These microfibrils were composed of either type VI collagen or fibrilin, as shown by immunocytochemistry. The results presented in this paper show that the osteochondral ligament of Rana catesbeiana is a complex and specialized fibrous attachment which guarantees a strong and flexible anchorage of the lateral articular cartilage to the periosteal bone shaft, besides playing a role in bone growth.

Collagen fiber reorganization in the rat ventral prostate following androgen deprivation: a possible role for smooth muscle cells

BACKGROUND

Stroma plays an essential role in glandular function in different systems. In the prostate, it is responsible for the development and maintenance of the differentiated state of the epithelium. The marked reduction in the epithelial compartment of the prostate gland following castration is followed by a similarly important reorganization of the stroma. In this work, we characterized the reorganization of collagen fibers in the ventral prostate of castrated rats.

METHODS

Histochemical tests and immunohistochemistry for type I and III collagens plus confocal microscopy of triple-labeled (collagen III, actin, and DNA) tissue sections were employed.

RESULTS

We showed that collagen fibers are composed of type I and type III collagens and that they are progressively concentrated around the epithelial structures (ducts and acini) and become increasingly undulated and folded. Double-labeling of collagen fibers and F-actin demonstrated that smooth muscle cells (SMC) are intimately associated with collagen fibers.

CONCLUSIONS

The results demonstrated a marked reorganization of the collagen fibers, and suggest an active role of the SMC in the reorganization of the fibrillar components of the stroma.

Structure and proteoglycan composition of specialized regions of the elastic tendon of the chicken wing

The elastic tendon of the avian wing has been described by others as a unique structure with elastic properties due to the predominance of elastic fibers in the midsubstance. Further analyses of the tendon have shown it to possess five anatomically distinct regions. Besides the major elastic region, a distally located fibrocartilage and three tendinous regions are present. The tendinous regions connect: (1) the muscle to the elastic region, (2) the elastic region to the fibrocartilage and (3) the latter to the insertion site. The elastic region possesses thick and abundant elastic fibers and very thin, interconnecting collagen fibers. The collagen fibers in the sesamoid fibrocartilage are thick and interwoven, defining spaces occupied by fibrochondrocytes embedded in a non-fibrillar and highly metachromatic matrix. Biochemical analyses have shown that the fibrocartilage has about tenfold the amount of glycosaminoglycans (GAGs) found in the other regions. The main GAG in this region was chondroitin sulfate (CS) (plus keratan sulfate as detected immunocytochemically), while the other regions showed variable amounts of CS, dermatan sulfate (DS) and heparan sulfate. Further analyses have shown that a large CS-bearing proteoglycan is found in the fibrocartilage. The elastic region possesses two main proteoglycans, a large CS-bearing proteoglycan (which reacted with an antibody against keratan sulfate after chondroitinase ABC treatment) and a predominant DS-bearing proteoglycan, which showed immunoreactivity when assayed with an anti-biglycan antibody. The results demonstrate that the elastic tendon is a complex structure with complex regional structural and compositional adaptations, suited to different biomechanical roles.

The development of the pressure-bearing tendon of the bullfrog, Rana catesbeiana

The plantaris longus tendon of the bullfrog is a pressure-bearing tendon and develops a fibrocartilage-like arrangement in the area subjected to compressive forces. The fibrocartilage-like tissue shows some distinct aspects of cellular and fibrillar structure and distribution as compared to the mammalian counterparts. In this work, the development of the plantaris longus tendon was assessed by investigating some of its structural, cytochemical and immunocytochemical aspects in developing tadpoles. The pressure-bearing region is structurally distinct from the tension region as early as at stage 35 of larval development. There is little extracellular matrix in both regions, but the former shows round mesenchymal-like cells with many processes and cell junctions, while the latter is populated by fibroblasts. As development proceeds, the cells in the compression region retract the processes, loose the connections to each other, become rounded and produce abundant proteoglycans and some collagen fibers. Progressively, their organelles become localized in a restricted perinuclear area and are surrounded by a constantly increasing amount of vimentin. The fibroblasts of the tension region produce mostly collagen fibrils, which are packed and aligned to each other. These cells become more elongated and show a diminished cytoplasmic area. The results allow for the conclusion that the compression region does not arise by simple hyperplasia of the peripheral layers of a normal tendon, but from a programmed sequence of developmental steps. This assumption is based on the fact that muscle fibers are still developing when the tendon is already showing a differentiated compression region. We further suggest that mechanical stimulation is a secondary factor most likely associated with the maintenance of the differentiated phenotype of this tendon.

The epiphyseal cartilage and growth of long bones in Rana catesbeiana

The structure of the epiphyseal cartilage of the bullfrog Rana catesbeiana and its role in the growth of long bones were examined. The epiphyseal cartilage was inserted into the end of a tubular bone shaft, defining three regions: articular cartilage, lateral articular cartilage and growth cartilage. Joining the lateral cartilage to the bone was a fibrous layer of periosteum, rich in blood vessels. Osteoblasts with alkaline phosphatase activity were found on the surface of the periosteal bone, which presented a fibrous non-mineralised tip. The growth cartilage was inside the bone. The proliferative chondrocytes presented perpendicular separation of daughter cells and there was no columnar arrangement of the cells. Furthermore, chondrocyte hypertrophy was not associated with either calcification or endochondral ossification, in apparent contrast to the avian and mammalian models. Finally, there was no reinforcement system capable of directing cell volume increase into longitudinal growth. Since bone extension depends on the intramembranous ossification of the periosteum, the growth cartilage is inside and not at the end of the bone and the cells in the growth cartilage show no columnar arrangement and separate in a direction perpendicular to the long bone axis, we conclude that the growth cartilage mainly contributes to the radial expansion of the bone.

Identification and distribution of type VI collagen in tendon fibrocartilages

Structural and compositional variations are marked in tendon fibrocartilages, which appear at the insertion to bone and in areas subjected to compressive plus frictional loading regime. We are interested in characterizing the extracellular matrix adaptations in these areas, in an attempt to understand cellular responses to biomechanics. In this work, we have applied immunocytochemistry and an ATP treatment for the ultrastructural identification of type VI collagen, to tendons subjected to compressive forces in different species. Immunocytochemistry, after testicular hyaluronidase or pepsin digestion, revealed the presence of type VI collagen in tensional and compressive areas of the plantaris longus tendon of the bullfrog, in the deep flexor tendon of dogs and rabbits, in the calcanear tendon and the suprapatela of rats and in the gastrocnemius tendon of chickens. In each tendon, the tensional region showed a weak reaction, restricted to the collagen fiber surface. However, the compression region was especially rich in type VI collagen, which accumulates in the interfibrillar spaces and is concentrated around the fibrochondrocytes. Intense reaction was also found in the paratenon. The ATP treatment not only allowed for the detection of the typical ladder-like aggregates of type VI collagen in the same areas identified by immunocytochemistry, but also demonstrated that type VI collagen forms a microfibrillar network around the fibrochondrocytes. Besides the function of organizing groups of collagen fibrils, type VI collagen seems to assemble the pericellular matrix in tendon fibrocartilages, perhaps through physical interactions with the large proteoglycans that concentrate in the same area.