Secreted Protein Acidic Rich In Cysteine Research Articles

Effect of aerobic and resistance training on secreted protein acidic rich in cysteine, decorin, and myonectin muscle genes expression in rats fed with a high-fat diet

Background and aims: Fatty diet can affect the expression of myokines. Thus, the aim of this study was to evaluate the effect of aerobic and resistance training secreted protein acidic rich in cysteine (SPARC), decorin (DCN), and myonectin muscle gene expression in rats fed with a high-fat diet. Methods: In this experimental study, 32 rats were randomly divided into healthy control, obese control, obese+aerobic exercise, and obese+resistance exercise groups. The training program was implemented for 4 weeks at aerobic moderate intensity (50% VO2max in the first week and 65% VO2max in the last week). For resistance training, the animals were also trained to climb the ladder (height 110 cm, slope 80%, and the distance between the bars of the ladder 2 cm), which is based on the determination of one-repetition maximum (1RM). Obese rats received a dose of 0.5 mL/100 g of body weight orally by gavage for 4 weeks and 5 days a week. Results: There was no significant difference between the groups in terms of DCN expressions (P=0.702). However, the expression of SPARC (P=0.039) and myonectin in the obese control group was significantly increased compared to the healthy control (P=0.038). The expression of SPARC and myonectin in the aerobic training group (P=0.038, P=0.042) and the resistance training group (P=0.048, P=0.049) was significantly decreased in comparison to obesity control. Resistance training caused a greater decrease in myonectin compared to aerobic training (P=0.049). Conclusion: The findings revealed that aerobic and resistance exercises are effective in reducing SPARC and myonectin expression in the skeletal muscle of rats fed with a high-fat diet.

MiR‑29a‑3p regulates the epithelial‑mesenchymal transition via the SPARC/ERK signaling pathway in human bronchial epithelial cells.

Neutrophilic asthma (NA) is a subtype of asthma that responds poorly to corticosteroid treatment. In certain diseases, microRNA (miR)-29a-3p is considered to be a key regulatory molecule for remodeling of the extracellular matrix. However, the effect of miR-29a-3p on airway remodeling is unknown. The present study aimed to investigate the role of miR-29a-3p in NA. A mouse model of NA was established and these animals were compared to normal controls. Both groups of mice were subjected to lung function tests and histopathological analysis. Human bronchial epithelial cells (16HBE) were grown in culture and incubated with secreted protein acidic rich in cysteine (SPARC) and a miR-29a-3p mimic. The expression of miR-29a-3p, SPARC and epithelial-mesenchymal transition (EMT)-related markers were measured using reverse transcription-quantitative PCR and western blotting. Luciferase reporter assay was performed to identify the direct regulatory relationship between miR-29a-3p and SPARC. miR-29a-3p expression was significantly decreased, while SPARC expression was increased in the NA mouse model with a phenotype of EMT. Overexpression of SPARC downregulated the expression of E-cadherin, while it increased the expression of vimentin in 16HBE cells. miR-29a-3p administration reversed the SPARC-induced effects on E-cadherin and vimentin expression. Luciferase assays confirmed that SPARC was the target gene for miR-29a-3p. Furthermore, SPARC overexpression increased the protein expression of phosphorylated (p)-ERK, while transfection with miR-29a-3p mimics significantly inhibited this increase. The data suggested that EMT in the NA mouse model was associated with decreased levels of miR-29a-3p and elevated SPARC. Furthermore, SPARC could induce the formation of EMT in 16HBE cells in vitro and this was directly targeted by miR-29a-3p and mediated by p-ERK, suggesting that miR-29a-3p may participate in the airway remodeling of NA.

Abstract 2495: SPARC: a bladder cancer tumor-suppressor via targeting metabolic programming

Abstract Bladder cancer (BC) is the sixth most common cancer in the United States. Approximately, 75% of BC patients present with non-muscle invasive bladder cancer (NMIBC), which is responsive to local treatment and surveillance. However, recurrence is common with progression to muscle-invasive bladder cancer (MIBC). Forty percent of MIBC patients develop distant metastases, with few treatment options and poor survival. Limited advances have been made in BC therapy with only a few FDA-approved new treatments for advanced disease since 2016 with response rates hovering around 15%. Thus, there is an unmet need for better understanding of the pathobiology of the disease to develop more effective therapeutics. Metabolic re-programming of cancer is increasingly recognized as a hallmark of cancer as cancer cells take advantage of metabolic products to meet the increasing demands of proliferating cells. Our lab has identified the Secreted Protein Acidic Rich in Cysteine (SPARC) as a multi-faceted tumor suppressor within the BC tumor microenvironment. Herein, we sought to elucidate the role of SPARC in regulating metabolic programming in BC and identify pathways that may serve as diagnostic and therapeutic targets. We used three BC cell lines UMUC3, T24 (SPARChigh) and its isogenic SPARClow T24T. We treated BC cells with recombinant SPARC protein and genetically manipulated SPARC expression in these cells. We performed real-time monitoring of the effect of SPARC on bioenergetics using Seahorse assays. In tandem, we profiled transcriptomes of T24, T24T, and T24shSP-cell lines to identify aggressive phenotype signatures using GSEA. We then compared signatures with survival data from BC cohorts from the GEO and TCGA. We found that SPARC inhibited ATP production, basal and maximal respiration, and spare respiratory capacity in BC cell lines. This effect is more pronounced in more aggressive SPARClow T24T cells compared to its isogenic SPARChigh T24 cells. Knockdown of SPARC in BC cell lines not only induced an aggressive phenotype, but also increased ATP production and mitochondrial respiration. Integrated transcriptomic profiling indicated that SPARC-loss is associated with enriched glycolytic, lipidomic, and mitochondrial metabolic pathways. Importantly, in patient samples, SPARC expression negatively correlated with rate limiting enzymes in metabolic pathways associated with lower survival. SPARC loss also associated with oncogenic signatures of EMT, PI3K-AKT-mTOR signaling, and G1/S cell cycle arrest. Our data reveals a novel function of SPARC inhibiting mitochondrial bioenergetics and ATP production that fuel growth and invasion in BC cells. The SPARC-regulated metabolic profile highlights potential vulnerabilities that can be exploited as therapeutic targets. Citation Format: Sameh Waleed Almousa, Alia Ghoneum, Hesham Afify, Neveen Said. SPARC: a bladder cancer tumor-suppressor via targeting metabolic programming [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2495.

SPARC coordinates extracellular matrix remodeling and efficient recruitment to and migration of antigen-specific T cells in the brain following infection

Central nervous system (CNS) injury and infection can result in profound tissue remodeling in the brain, the mechanism and purpose of which is poorly understood. Infection with the protozoan parasite Toxoplasma gondii causes chronic infection and inflammation in the brain parenchyma. Control of parasite replication requires the continuous presence of IFNγ-producing T cells to keep T. gondii in its slowly replicating cyst form. During infection, a network of extracellular matrix fibers, revealed using multiphoton microscopy, forms in the brain. The origin and composition of these structures are unknown but the fibers have been observed to act as a substrate for migrating T cells. In this study, we show a critical regulator of extracellular matrix (ECM) remodeling, Secreted Protein, Acidic, Rich in Cysteine (SPARC), is upregulated in the brain during the early phases of infection in the frontal cortex. In the absence of SPARC, a reduced and disordered fibrous network, increased parasite burden, and reduced antigen-specific T cell entry into the brain points to a role for SPARC in T cell recruitment to and migration within the brain. We also report SPARC can directly bind to CCR7 ligands CCL19 and CCL21 but not CXCL10, and enhance migration toward a chemokine gradient. Measurement of T cell behavior points to tissue remodeling being important for access of immune cells to the brain and facilitating cellular locomotion. Together, these data identify SPARC as an important regulatory component of immune cell trafficking and access to the inflamed CNS.

Exercise-Induced Myokines can Explain the Importance of Physical Activity in the Elderly: An Overview.

Physical activity has been found to aid the maintenance of health in the elderly. Exercise-induced skeletal muscle contractions lead to the production and secretion of many small proteins and proteoglycan peptides called myokines. Thus, studies on myokines are necessary for ensuring the maintenance of skeletal muscle health in the elderly. This review summarizes 13 myokines regulated by physical activity that are affected by aging and aims to understand their potential roles in metabolic diseases. We categorized myokines into two groups based on regulation by aerobic and anaerobic exercise. With aging, the secretion of apelin, β-aminoisobutyric acid (BAIBA), bone morphogenetic protein 7 (BMP-7), decorin, insulin-like growth factor 1 (IGF-1), interleukin-15 (IL-15), irisin, stromal cell-derived factor 1 (SDF-1), sestrin, secreted protein acidic rich in cysteine (SPARC), and vascular endothelial growth factor A (VEGF-A) decreased, while that of IL-6 and myostatin increased. Aerobic exercise upregulates apelin, BAIBA, IL-15, IL-6, irisin, SDF-1, sestrin, SPARC, and VEGF-A expression, while anaerobic exercise upregulates BMP-7, decorin, IGF-1, IL-15, IL-6, irisin, and VEGF-A expression. Myostatin is downregulated by both aerobic and anaerobic exercise. This review provides a rationale for developing exercise programs or interventions that maintain a balance between aerobic and anaerobic exercise in the elderly.

The predicted collagen-binding domains of Drosophila SPARC are essential for survival and for collagen IV distribution and assembly into basement membranes

The assembly of basement membranes (BMs) into tissue-specific morphoregulatory structures requires non-core BM components. Work in Drosophila indicates a principal role of collagen-binding matricellular glycoprotein SPARC (Secreted Protein, Acidic, Rich in Cysteine) in larval fat body BM assembly. We report that SPARC and collagen IV (Col(IV)) first colocalize in the trans-Golgi of hemocyte-like cell lines. Mutating the collagen-binding domains of Drosophila SPARC led to the loss of colocalization with Col(IV), a fibrotic-like BM, and 2nd instar larval lethality, indicating that SPARC binding to Col(IV) is essential for survival. Analysis of this mutant at 2nd instar reveals increased Col(IV) puncta within adipocytes, reflecting a disruption in the intracellular chaperone-like activity of SPARC. Removal of the disulfide bridge in the C-terminal EF-hand2 of SPARC, which is known to enhance Col(IV) binding, did not lead to larval lethality; however, a less intense fat body phenotype was observed. Additionally, both SPARC mutants exhibited altered fat body BM pore topography. Wing imaginal disc-derived SPARC did not localize within Col(IV)-rich matrices. This raises the possibility that SPARC interaction with Col(IV) requires initial intracellular interaction to colocalize at the BM or that wing-derived SPARC undergoes differential post-translational modifications that impacts its function. Collectively, these data provide evidence that the chaperone-like activity of SPARC on Col(IV) begins just prior to their co-secretion and demonstrate for the first time that the Col(IV) chaperone-like activity of SPARC is necessary for Drosophila development beyond the 2nd instar.

Plasma Myokine Concentrations After Acute Exercise in Non-obese and Obese Sedentary Women.

Exercise and physical activity levels influence myokine release from skeletal muscle and contribute to circulating concentrations. Indeed, many myokines, including interleukin (IL)-6, IL-15, secreted protein acidic rich in cysteine (SPARC), and fibroblast growth factor (FGF) 21 are higher in the circulation after an exercise bout. Since these peptides modulate muscle metabolism and can also be targeted toward other tissues to induce adaptations to energy demand, they are of great interest regarding metabolic diseases. Therefore, we set out to compare, in six women with obesity (BMI ≥30 kg/m2) and five healthy women (BMI 22–29.9 kg/m2), the effect of an acute bout of moderate-intensity, continuous cycling exercise (60 min, 60% VO2peak) on the release of myokines (IL-6, IL-8, IL-10, IL-13, IL-15, SPARC, and FGF21) in plasma for a 24-h time course. We found that plasma IL-8 and SPARC levels were reduced in the group of women with obesity, whereas plasma IL-13 concentrations were elevated in comparison to non-obese women both before and after the exercise bout. We also found that plasma FGF21 concentration during the 24 h following the bout of exercise was regulated differently in the non-obese in comparison to obese women. Plasma concentrations of FGF21, IL-6, IL-8, IL-15, and IL-18 were regulated by acute exercise. Our results confirm the results of others concerning exercise regulation of circulating myokines while providing insight into the time course of myokine release in circulation after an acute exercise bout and the differences in circulating myokines after exercise in women with or without obesity.

Efficacy and safety of nanoparticle albumin-bound paclitaxel as neoadjuvant chemotherapy in HER2-negative breast cancer.

Nanoparticle albumin-bound paclitaxel (Nab-PTX) is a form of paclitaxel bound to albumin nanoparticles and is used widely in a neoadjuvant setting for patients with breast cancer. We conducted a retrospective study to compare the efficacy and safety of Nab-PTX to PTX as neoadjuvant chemotherapy for patients with operable HER2-negative breast cancer. In total, 50 patients were enrolled. Nab-PTX was administered in the study group, and PTX was administered in the control group. The clinical response and safety profile were recorded. The expression of secreted protein acidic rich in cysteine (SPARC) in tumor tissue was examined. The efficacy and safety analyses were computed using SPSS statistical software. Multiple logistic regression analysis was performed to evaluate the exploratory variables (age, stage, estrogen receptor, partial response, and SPARC expression) for the pathological complete response (pCR), and Fisher's exact test was performed to evaluate the relationship between SPARC and pCR. Both groups of patients achieved a good clinical response. The pCR rate for the Nab-PTX regimen was significantly higher than that for the PTX regimen. The most common adverse events were neutropenia, peripheral sensory neuropathy, arthralgia, and myalgia. In 68% of cases in the Nab-PTX group, high SPARC expression was observed. As neoadjuvant therapy, the Nab-PTX regimen has advantages over conventional taxane regimen in patients with HER2-negative breast cancer. With this regimen, a high pCR rate was achieved with a good safety profile.

No effect of acute and chronic supramaximal exercise on circulating levels of the myokine SPARC

Myokines may play a role in the health benefits of regular physical activity. Secreted protein acidic rich in cysteine (SPARC) is a pleiotropic myokine that has been shown to be released into the bloodstream by skeletal muscle in response to aerobic exercise. As there is evidence suggesting that SPARC release may be linked to glycogen breakdown and activation of 5’ adenosine monophosphate-activated protein kinase, we hypothesised that brief supramaximal exercise may also be associated with increased serum SPARC levels. In the present study, 10 participants (3 women; mean ± SD age: 21 ± 3 y, body mass index (BMI): 22 ± 3 kg m−2, and V˙O2max: 39 ± 6 mL kg−1 min−1) performed an acute bout of supramaximal cycle exercise (20-s Wingate sprint against 7.5% of body mass, with a 1-min warm-up and a 3-min cool-down consisting of unloaded cycling). Serum SPARC levels were determined pre-exercise as well as 0, 15, and 60 min post-exercise and corrected for plasma volume change. To determine whether regular exercise affected the acute SPARC response, participants repeated the acute exercise protocol three times per week for four weeks, and serum SPARC response to supramaximal exercise was reassessed after this period. Acute supramaximal exercise significantly decreased plasma volume (−10%; p < .001), but was not associated with a significant change in serum SPARC levels at either the pre-training or post-training testing sessions. In conclusion, in contrast to aerobic exercise, a single brief supramaximal cycle sprint is not associated with an increase in serum SPARC levels, suggesting that SPARC release is not related to skeletal muscle glycogen breakdown.

Tracheal Aspirate Levels of the Matricellular Protein SPARC Predict Development of Bronchopulmonary Dysplasia.

BackgroundIsolation of tracheal aspirate mesenchymal stromal cells (MSCs) from premature infants has been associated with increased risk of bronchopulmonary dysplasia (BPD). MSCs show high levels of mRNAs encoding matricellular proteins, non-structural extracellular proteins that regulate cell-matrix interactions and participate in tissue remodeling. We hypothesized that lung matricellular protein expression predicts BPD development.MethodsWe collected tracheal aspirates and MSCs from mechanically-ventilated premature infants during the first week of life. Tracheal aspirate and MSC-conditioned media were analyzed for seven matricellular proteins including SPARC (for Secreted Protein, Acidic, Rich in Cysteine, also called osteonectin) and normalized to secretory component of IgA. A multiple logistic regression model was used to determine whether tracheal aspirate matricellular protein levels were independent predictors of BPD or death, controlling for gestational age (GA) and birth weight (BW).ResultsWe collected aspirates from 89 babies (38 developed BPD, 16 died before 36 wks post-conceptual age). MSC-conditioned media showed no differences in matricellular protein abundance between cells from patients developing BPD and cells from patients who did not. However, SPARC levels were higher in tracheal aspirates from babies with an outcome of BPD or death (p<0.01). Further, our logistic model showed that tracheal aspirate SPARC (p<0.02) was an independent predictor of BPD/death. SPARC deposition was increased in the lungs of patients with BPD.ConclusionsIn mechanically-ventilated premature infants, tracheal aspirate SPARC levels predicted development of BPD or death. Further study is needed to determine the value of SPARC as a biomarker or therapeutic target in BPD.

Behavioral signs of axial low back pain and motor impairment correlate with the severity of intervertebral disc degeneration in a mouse model

Background ContextChronic low back pain is debilitating and difficult to treat. Depending on the etiology, responses to treatments vary widely. Although chronic low back pain is frequently related to intervertebral disc degeneration, the relationship between disc degeneration severity and clinical symptoms are still poorly understood.In humans, studies investigating the relationship between disc degeneration severity and low back pain are limited by the difficulty of obtaining disc samples from well-characterized patients and pain-free controls. We have previously described the secreted protein, acidic, rich in cysteine (SPARC)-null mouse model of chronic low back pain. SPARC is a matricellular protein involved in regulating the assembly and composition of extracellular matrix. The SPARC-null mice develop age-dependent disc degeneration of increasing severity accompanied by behavioral signs suggestive of axial low back pain, radiating leg pain, and motor impairment. The existence of this model allows for examination of the relationships between clinical symptoms in vivo and pathological signs of disc degeneration ex vivo. PurposeThe goal of this study was to explore the relationship between behavioral signs of pain and the severity of lumbar disc degeneration using the SPARC-null mouse model of disc degeneration-related low back pain. Study DesignThis study used a cross-sectional, multiple-cohort behavioral and histological study of disc degeneration and behavioral symptoms in a mouse model of low back pain associated with disc degeneration. MethodsSPARC-null and wild-type control mice ranging from 6 to 78 weeks of age were used in this study. The severity of disc degeneration was determined by ex vivo analysis of the lumbar spine using colorimetric histological staining and a scoring system adapted from the Pfirrmann scale. Behavioral signs of axial low back pain, radiating leg pain, and motor impairment were quantified as tolerance to axial stretching in the grip force assay, hypersensitivity to cold or mechanical stimuli on the hindpaw (acetone and von Frey tests), and latency to fall in the rotarod assay, respectively. ResultsThe SPARC-null mice exhibited decreased tolerance to axial stretching, hindpaw cold hypersensitivity, and motor impairment compared with age-matched control mice. The severity of disc degeneration increased with age in both SPARC-null and control mice and by 78 weeks of age, the same proportion of lumbar discs were abnormal in SPARC-null and control mice. However, the degree of degeneration was more severe in the SPARC-null mice. In both SPARC-null and control mice, tolerance to axial stretching but not hindpaw cold sensitivity correlated with disc degeneration severity. Motor impairment correlated with degeneration severity in the SPARC-null mice only. ConclusionsThese data suggest that internal disc disruption contributes to axial low back pain and motor impairment but not to radiating leg pain. These results have implications for the optimization of mechanism-based treatments strategies.

Proteomic analysis of cerebrospinal fluid in canine cervical spondylomyelopathy.

Prospective study. To identify proteins with differential expression in the cerebrospinal fluid (CSF) from 15 clinically normal (control) dogs and 15 dogs with cervical spondylomyelopathy (CSM). Canine CSM is a spontaneous, chronic, compressive cervical myelopathy similar to human cervical spondylotic myelopathy. There is a limited knowledge of the molecular mechanisms underlying these conditions. Differentially expressed CSF proteins may contribute with novel information about the disease pathogenesis in both dogs and humans. Protein separation was performed with 2-dimensional electrophoresis. A Student t test was used to detect significant differences between groups (P < 0.05). Three comparisons were made: (1) control versus CSM-affected dogs, (2) control versus non-corticosteroid-treated CSM-affected dogs, and (3) non-corticosteroid-treated CSM-affected versus corticosteroid-treated CSM-affected dogs. Protein spots exhibiting at least a statistically significant 1.25-fold change between groups were selected for subsequent identification with capillary-liquid chromatography tandem mass spectrometry. A total of 96 spots had a significant average change of at least 1.25-fold in 1 of the 3 comparisons. Compared with the CSF of control dogs, CSM-affected dogs demonstrated increased CSF expression of 8 proteins including vitamin D-binding protein, gelsolin, creatine kinase B-type, angiotensinogen, α-2-HS-glycoprotein, SPARC (secreted protein, acidic, rich in cysteine), calsyntenin-1, and complement C3, and decreased expression of pigment epithelium-derived factor, prostaglandin-H2 D-isomerase, apolipoprotein E, and clusterin. In the CSF of CSM-affected dogs, corticosteroid treatment increased the expression of haptoglobin, transthyretin isoform 2, cystatin C-like, apolipoprotein E, and clusterin, and decreased the expression of angiotensinogen, α-2-HS-glycoprotein, and gelsolin. Many of the differentially expressed proteins are associated with damaged neural tissue, bone turnover, and/or compromised blood-spinal cord barrier. The knowledge of the protein changes that occur in CSM and upon corticosteroid treatment of CSM-affected patients will aid in further understanding the pathomechanisms underlying this disease. N/A.

Slow binding kinetics of secreted protein, acidic, rich in cysteine-VEGF interaction limit VEGF activation of VEGF receptor 2 and attenuate angiogenesis.

VEGF-A (VEGF) drives angiogenesis through activation of downstream effectors to promote endothelial cell proliferation and migration. Although VEGF binds both VEGF receptor 1 (R1) and receptor 2 (R2), its proangiogenic effects are attributed to R2. Secreted protein, acidic, rich in cysteine (SPARC) is a matricellular glycoprotein thought to inhibit angiogenesis by preventing VEGF from activating R1, but not R2. Because R2 rather than R1 mediates proangiogenic activities of VEGF, the role of human SPARC in angiogenesis was reevaluated. We confirm that association of SPARC with VEGF inhibits VEGF-induced HUVEC adherence, motility, and proliferation in vitro and blocks VEGF-induced blood vessel formation ex vivo. SPARC decreases VEGF-induced phosphorylation of R2 and downstream effectors ERK, Akt, and p38 MAPK as shown by Western blot and/or phosphoflow analysis. Surface plasmon resonance indicates that SPARC binds slowly to VEGF (0.865 ± 0.02 × 10(4) M(-1) s(-1)) with a Kd of 150 nM, forming a stable complex that dissociates slowly (1.26 ± 0.003 × 10(-3) s(-1)). Only domain III of SPARC binds VEGF, exhibiting a 15-fold higher affinity than full-length SPARC. These findings support a model whereby SPARC regulates angiogenesis by sequestering VEGF, thus restricting the activation of R2 and the subsequent activation of downstream targets critical for endothelial cell functions.

Predictive biomarkers for chemotherapies in pancreatic cancer

Pancreatic cancer is associated with high rates of mortality especially due to advanced stages of diagnosis. Adjuvant chemotherapy role is thus essential in the attempt to downstage the tumoral grade. In cases of locally advanced tumors, this step could be followed by curative surgical resection. Characterization of predictor biomarkers for adjuvant chemotherapy has drawn increasing interest in molecular biology research of pancreatic cancer. Personalized treatment is one of the solutions proposed for advancing towards a better outcome. In this paper we discuss available predictor biomarkers with focus upon gemcitabine and FOLFIRINOX (5-fluoro uracil (5-FU), irinotecan and oxaliplatin) chemotherapy regimens, present approaches in advanced pancreatic cancer. Many data are current available in relation with gemcitabine chemotherapy regimen, where biomarkers like ribonucleotide reductase large subunit (RRM1), human equilibrative nucleoside transporter-1 (hENT1), deoxycytidine kinase (dCK), human antigen R (HuR), and secreted protein acidic rich in cysteine (SPARC) were proposed. Regarding the response to FOLFIRINOX components, other markers such as thymidylate synthethase (TS), topoisomerase I, and excision repair cross-complementation 1 (ERCC1) or KRAS mutation status were also investigated.

ISSLS Prize Winner

Immunohistochemical and behavioral study using the SPARC (secreted protein, acidic, rich in cysteine)-null mouse model of low back pain (LBP) associated with accelerated intervertebral disc (IVD) degeneration. To determine if behavioral signs of LBP in SPARC-null mice are accompanied by sensory nervous system plasticity. IVD pathology is a significant contributor to chronic LBP. In humans and rodents, decreased expression of SPARC is associated with IVD degeneration. We previously reported that SPARC-null mice exhibit age-dependent behavioral signs of chronic axial LBP and radiating leg pain. SPARC-null and age-matched control young, middle-aged, and old mice (1.5, 6, and 24 mo of age, respectively) were evaluated. Cutaneous hind paw sensitivity to cold, heat, and mechanical stimuli were evaluated as measures of radiating pain. The grip force and tail suspension assays were performed to evaluate axial LBP. Motor impairment was assessed using an accelerating rotarod. IVD innervation was identified by immunohistochemistry targeting the nerve fiber marker PGP9.5 and the sensory neuropeptide calcitonin gene-related peptide (CGRP). Sensory nervous system plasticity was evaluated by quantification of CGRP- and neuropeptide-Y-immunoreactivity (-ir) in dorsal root ganglia neurons and CGRP-ir, GFAP-ir (astrocyte marker), and Iba-1-ir (microglia marker) in the spinal cord. SPARC-null mice developed hypersensitivity to cold, axial discomfort, age-dependent motor impairment, age-dependent increases in sensory innervation in and around the IVDs, age-dependent upregulation of CGRP and neuropeptide-Y in dorsal root ganglia, and age-dependent upregulation of CGRP, microglia, and astrocytes in the spinal cord dorsal horn. Increased innervation of degenerating IVDs by sensory nerve fibers and the neuroplasticity in sensory neurons and spinal cord could contribute to the underlying pathobiology of chronic discogenic LBP. N/A.

Defective stromal remodeling and neutrophil extracellular traps in lymphoid tissues favor the transition from autoimmunity to lymphoma.

Altered expression of matricellular proteins can become pathogenic in the presence of persistent perturbations in tissue homeostasis. Here, we show that autoimmunity associated with Fas mutation was exacerbated and transitioned to lymphomagenesis in the absence of SPARC (secreted protein acidic rich in cysteine). The absence of SPARC resulted in defective collagen assembly, with uneven compartmentalization of lymphoid and myeloid populations within secondary lymphoid organs (SLO), and faulty delivery of inhibitory signals from the extracellular matrix. These conditions promoted aberrant interactions between neutrophil extracellular traps and CD5(+) B cells, which underwent malignant transformation due to defective apoptosis under the pressure of neutrophil-derived trophic factors and NF-κB activation. Furthermore, this model of defective stromal remodeling during lymphomagenesis correlates with human lymphomas arising in a SPARC-defective environment, which is prototypical of CD5(+) B-cell chronic lymphocytic leukemia (CLL).

Central corneal thickness does not correlate with TonoLab-measured IOP in several mouse strains with single transgenic mutations of matricellular proteins

Accurate and reliable measurement of intraocular pressure (IOP) is crucial in the study of glaucoma using the mouse model. The purpose of this study was to determine the relationship between TonoLab-measured IOP and central corneal thickness (CCT) in mouse strains with single gene mutations of matricellular proteins. Wild-type (WT) and transgenic mouse strains with single gene mutations (KO) of thrombospondin-1 (TSP-1), thrombospondin-2 (TSP-2), osteopontin (OPN), hevin, and secreted protein acidic rich in cysteine (SPARC) were imaged at six weeks using optical coherence tomography (Stratus, Zeiss) to determine CCT. IOP was measured between 11am and 3pm using TonoLab, one week later. For all measurements, mice were anesthetized using intraperitoneal injection ketamine:xylazine. CCT and IOP were measured in 583 mice (TSP-1 n = 71 and 41, TSP-2 n = 60 and 32, OPN n = 81 and 50, hevin n = 59 and 76, SPARC n = 54 and 59, WT and KO, respectively). Mean CCT was 5–6% lower in three KO strains—TSP-1, OPN, and SPARC—compared to their corresponding WT (p = 1.55 × 10−7, 1.63 × 10−11, and 1.91 × 10−7, respectively). The mean IOP was 8.3%, 6.6%, and 15.1% lower in three KO strains—TSP-1, TSP-2, and SPARC—compared to corresponding WT (p = 2.11 × 10−5, 2.93 × 10−3, and 3.76 × 10−9, respectively. Linear regression of IOP versus CCT yielded no statistically significant within-strain correlations for TSP-1 (p = 0.12 and 0.073), TSP-2 (p = 0.473 and 0.92), OPN (p = 0.212 and 0.916), Hevin (p = 0.746 and 0.257), and SPARC (p = 0.080 and 0.056), reported as p-values considering a null hypothesis of zero slope (WT and KO, respectively). Neither C57-derived strains (TSP-1 and OPN) nor 129-derived strains (TSP-2, hevin, SPARC) demonstrated a correlation between mean IOP and mean CCT across different strains (p = 0.75 and p = 0.53, respectively). Taken together, these results indicate that CCT is not required to interpret TonoLab IOP readings in the mice when CCT varies 10% about the mean. This does not exclude the possibility of an IOP-CCT correlation for CCT values outside this range or for inter-strain comparisons where the mean CCT differs more than 10%.

Association of SPARC expression with metastatic progression and prostate cancer-specific mortality after radical prostatectomy.

5071 Background: We assessed the expression of the glycoprotein SPARC (secreted protein, acidic, rich in cysteine) in patients with prostate cancer (PCa) treated with radical prostatectomy (RP) and studied its association with adverse clinico-pathological features at RP and long-term clinical outcomes, such as metastatic progression after surgery and cancer-specific death. Methods: Tissues from 78 patients with PCa were used to quantify SPARC expression using tissue microarray (TMA) and immunohistochemistry techniques (IHC). Anti-SPARC mouse monoclonal antibody were use to target the protein and for each patients 4 samples of tissue were used for cytoplasmic staining. Staining of each core was reviewed by an uropathologist who assigned a score (score 0-3) to each core and a global score also assigned to each patient (score 0-3). Analyses of the data relied in cross tables, T-test analyses, survival plots and Cox regression models. Results: Higher expression of SPARC protein was recorded in patients who develop metastases during follow-up after RP (p=0.025) and in patients who died of PCa after RP (p=0.002). Median follow-up of the cohort was 9.3 years after RP. At 5 years, 95.5%, 92.0% and 89.3% of patients were metastases-free for SPARC expression score 1, 2 and 3 respectively. For the same categories, 10 years after RP, 82.2%, 77.0% and 69.9% were metastases-free (Log-rank tests all p≤0.05). Similarly, patients with high SPARC expression had worse cancer-specific survival at 5 and 10 years after RP compared to those with low SPARC expression (Log-rank tests all p≤0.01 when score 1 was compared to score 2 or score 3). Finally, advanced stage at RP (T3-T4) [p=0.04] and high Gleason sum (8-10) [p=0.02] were also associated with higher expression of SPARC. Conclusions: High SPARC expression was associated with worse outcomes in men with prostate cancer treated with radical prostatectomy. Men who developed metastatic disease and men who succumbed to prostate cancer had higher levels of SPARC at radical prostatectomy than their counterpart. SPARC may have an important role in the progression of the disease and may eventually help clinician to better ascertain the risk of progression of the disease.

SPARC Regulates Microgliosis and Functional Recovery following Cortical Ischemia

Secreted protein acidic rich in cysteine (SPARC) is a matricellular protein that modulates the activity of growth factors, cytokines, and extracellular matrix to play multiple roles in tissue development and repair, such as cellular adhesion, migration, and proliferation. Throughout the CNS, SPARC is highly localized in mature ramified microglia, but its role in microglia--in development or during response to disease or injury--is not understood. In the postnatal brain, immature amoeboid myeloid precursors only induce SPARC expression after they cease proliferation and migration, and transform into mature, ramified resting microglia. SPARC null/CX3CR1-GFP reporter mice reveal that SPARC regulates the distribution and branching of mature microglia, with significant differences between cortical gray and white matter in both controls and SPARC nulls. Following ischemic and excitotoxic lesion, reactive, hypertrophic microglia rapidly downregulate and release SPARC at the lesion, concomitant with reactive, hypertrophic perilesion astrocytes upregulating SPARC. After photothrombotic stroke in the forelimb sensorimotor cortex, SPARC nulls demonstrate enhanced microgliosis in and around the lesion site, which accompanies significantly enhanced functional recovery by 32 d after lesion. Microglia from SPARC nulls also intrinsically proliferate at a greater rate in vitro--an enhanced effect that can be rescued by the addition of exogenous SPARC. SPARC is thus a novel regulator of microglial proliferation and structure, and, in addition to regulating glioma progression, may play an important role in differently regulating the gray and white matter microglial responses to CNS lesion--and modulating behavioral recovery--after injury.

In vitro analyses of the anti‐fibrotic effect of SPARC silencing in human Tenon’s fibroblasts: comparisons with mitomycin C

Failure of glaucoma filtration surgery (GFS) is commonly attributed to scarring at the surgical site. The human Tenon’s fibroblasts (HTFs) are considered the major cell type contributing to the fibrotic response. We previously showed that SPARC (secreted protein, acidic, rich in cysteine) knockout mice had improved surgical success in a murine model of GFS. To understand the mechanisms of SPARC deficiency in delaying subconjunctival fibrosis, we used the gene silencing approach to reduce SPARC expression in HTFs and examined parameters important for wound repair and fibrosis. Mitomycin C-treated HTFs were used for comparison. We demonstrate that SPARC-silenced HTFs showed normal proliferation and negligible cellular necrosis but were impaired in motility and collagen gel contraction. The expression of pro-fibrotic genes including collagen I, MMP-2, MMP-9, MMP-14, IL-8, MCP-1 and TGF-β2 were also reduced. Importantly, TGF-β2 failed to induce significant collagen I and fibronectin expressions in the SPARC-silenced HTFs. Together, these data demonstrate that SPARC knockdown in HTFs modulates fibroblast functions important for wound fibrosis and is therefore a promising strategy in the development of anti-scarring therapeutics.