Characterisation of key proteoglycans in the cranial cruciate ligaments (CCLs) from two dog breeds with different predispositions to CCL disease and rupture.

Cranial cruciate ligament disease and rupture (CCLD/R) is one of the most common orthopaedic conditions in dogs, eventually leading to osteoarthritis of the stifle joint. Certain dog breeds such as the Staffordshire bull terrier have an increased risk of developing CCLD/R. Previous studies into CCLD/R have found that glycosaminoglycan levels were elevated in cranial cruciate ligament (CCL) tissue from high-risk breeds when compared to the CCL from a low-risk breed to CCLD/R. Our objective was to determine specific proteoglycans/glycosaminoglycans in the CCL and to see whether their content was altered in dog breeds with differing predispositions to CCLD/R. Disease-free CCLs from Staffordshire bull terriers (moderate/high-risk to CCLD/R) and Greyhounds (low-risk to CCLD/R) were collected and key proteoglycan/glycosaminoglycans were determined by semi-quantitative Western blotting, quantitative biochemistry, quantitative reverse transcription polymerase chain reaction, and immunohistochemistry. Gene expression of fibromodulin (P = 0.03), aggrecan (P = 0.0003), and chondroitin-6-sulphate stubs (P = 0.01) were significantly increased, and for fibromodulin this correlated with an increase in protein content in Staffordshire bull terriers compared to Greyhound CCLs (P = 0.02). Decorin (P = 0.03) and ADAMTS-4 (P = 0.04) gene expression were significantly increased in Greyhounds compared to Staffordshire bull terrier CCLs. The increase of specific proteoglycans and glycosaminoglycans within the Staffordshire bull terrier CCLs may indicate a response to higher compressive loads, potentially altering their risk to traumatic injury. The higher decorin content in the Greyhound CCLs is essential for maintaining collagen fibril strength, while the increase of ADAMTS-4 indicates a higher rate of turnover helping to regulate normal CCL homeostasis in Greyhounds.

Identification of Lumican and Fibromodulin as Hub Genes Associated with Accumulation of Extracellular Matrix in Diabetic Nephropathy.

INTRODUCTION: Diabetic nephropathy (DN) remains a major cause of end-stage renal disease. The development of novel biomarkers and early diagnosis of DN are of great clinical importance. The goal of this study was to identify hub genes with diagnostic potential for DN by weighted gene co-expression network analysis (WGCNA). METHODS: Gene Expression Omnibus database was searched for microarray data including distinct types of CKD. Gene co-expression network was constructed, and modules specific for DN were identified by WGCNA. Gene ontology (GO) analysis was performed, and the hub genes were screened out within the selected gene modules. In addition, cross-validation was performed in an independent dataset and in samples of renal biopsies with DN and other types of glomerular diseases. RESULTS: Dataset GSE99339 was selected, and a total of 179 microdissected glomeruli samples were analyzed, including DN, normal control, and 7 groups of other glomerular diseases. Twenty-three modules of the total 10,947 genes were grouped by WGCNA, and a module was specifically correlated with DN (r = 0.54, p = 9e-15). GO analysis showed that module genes were mainly enriched in the accumulation of extracellular matrix (ECM). LUM, ELN, FBLN1, MMP2, FBLN5, and FMOD were identified as hub genes. Cross verification showed LUM and FMOD were higher in the DN group and were negatively correlated with estimated glomerular filtration rate (eGFR). In renal biopsies, expression levels of LUM and FMOD were higher in DN than IgA nephropathy, membranous nephropathy, and normal controls. CONCLUSION: By using WGCNA approach, we identified LUM and FMOD related to ECM accumulation and were specific for DN. These 2 genes may represent potential candidate diagnostic biomarkers of DN.

Class I and Class II small leucine-rich proteoglycans in human cutaneous pacinian corpuscles.

Pacinian corpuscles are onion bulb-like multilayered mechanoreceptors that consist of a complicated structure of axon terminals, Schwann related cells (inner core), endoneural related cells (intermediate layer) and perineurial related cells (outer core-capsule). The cells forming those compartments are continuous and share the properties of that covering the nerve fibers. Small leucine-rich proteoglycans are major proteoglycans of the extracellular matrix and regulate collagen fibrillogenesis, cell signalling pathways and extracellular matrix assembly. Here we used immunohistochemistry to investigate the distribution of class I (biglycan, decorin, asporin, ECM2 and ECMX) and class II (fibromodulin, lumican, prolargin, keratocan and osteoadherin) small leucine-rich proteoglycans in human cutaneous Pacinian corpuscles. The distribution of these compounds was: the inner core express decorin, biglycan, lumican, fibromodulin, osteoadherin; the intermediate layer display immunoreactivity for osteoadherin; the outer core biglycan, decorin, lumican, fibromodulin and osteoadherin; and the capsule contains biglycan, decorin, fibromodulin, and lumican. Asporin, prolargin and keratocan were undetectable. These results complement our knowledge about the distribution of small leucine-rich proteoglycans in human Pacinian corpuscles, and help to understand the composition of the extracellular matrix in these sensory formations.