Expression Of Lysyl Hydroxylase Research Articles

Glimpses into the molecular pathogenesis of Peyronie’s disease

Peyronie's disease (PD) is a fibroproliferative disease of the penis. Since little is known about the molecular pathogenesis of PD, we compared the biochemical make-up of PD plaques with normal tunica albuginea to clarify pathological processes in the scarred tissue. Protein and mRNA levels were measured in plaques and in unaffected pieces of the tunica albuginea. We investigated the presence of myofibroblasts, the deposition of collagens, and some key elements of Wnt and YAP1 signaling at protein level. The expression of 45 genes, all related to collagen homeostasis and extracellular matrix proteins, was quantified. In plaques, more myofibroblasts were present, and we observed an activation of Wnt signaling and YAP1 signaling. Increased levels of the collagens types I and III confirm the fibrotic nature of plaques. The mRNA ratio of collagen types III, IV, and VI to type I was increased. The expression of lysyl hydroxylase 3 was higher, whereas a decreased expression level was seen for fibronectin and cathepsin K. The biochemical composition of plaques was different from unaffected tunica albuginea: the relative and absolute abundance of various extracellular matrix proteins were changed, as well as the quality of collagen and the level of the collagen-degrading enzyme cathepsin K.

Collagen cross-linking mediated by lysyl hydroxylase 2: an enzymatic battlefield to combat fibrosis

The hallmark of fibrosis is an excessive accumulation of collagen, ultimately leading to organ failure. It has become evident that the deposited collagen also exhibits qualitative modifications. A marked modification is the increased cross-linking, leading to a stabilization of the collagen network and limiting fibrosis reversibility. Not only the level of cross-linking is increased, but also the composition of cross-linking is altered: an increase is seen in hydroxyallysine-derived cross-links at the expense of allysine cross-links. This results in irreversible fibrosis, as collagen cross-linked by hydroxyallysine is more difficult to degrade. Hydroxyallysine is derived from a hydroxylysine in the telopeptides of collagen. The expression of lysyl hydroxylase (LH) 2 (LH2), the enzyme responsible for the formation of telopeptidyl hydroxylysine, is universally up-regulated in fibrosis. It is expected that inhibition of this enzyme will lead to reversible fibrosis without interfering with the normal repair process. In this review, we discuss the molecular basis of collagen modifications and cross-linking, with an emphasis on LH2-mediated hydroxyallysine cross-links, and their implications for the pathogenesis and treatment of fibrosis.

Cervical Softening During Pregnancy: Regulated Changes in Collagen Cross-Linking and Composition of Matricellular Proteins in the Mouse1

A greater understanding of the parturition process is essential in the prevention of preterm birth, which occurs in 12.7% of infants born in the United States annually. Cervical remodeling is a critical component of this process. Beginning early in pregnancy, remodeling requires cumulative, progressive changes in the cervical extracellular matrix (ECM) that result in reorganization of collagen fibril structure with a gradual loss of tensile strength. In the current study, we undertook a detailed biochemical analysis of factors in the cervix that modulate collagen structure during early mouse pregnancy, including expression of proteins involved in processing of procollagen, assembly of collagen fibrils, cross-link formation, and deposition of collagen in the ECM. Changes in these factors correlated with changes in the types of collagen cross-links formed and packing of collagen fibrils as measured by electron microscopy. Early in pregnancy there is a decline in expression of two matricellular proteins, thrombospondin 2 and tenascin C, as well as a decline in expression of lysyl hydroxylase, which is involved in cross-link formation. These changes are accompanied by a decline in both HP and LP cross-links by gestation Days 12 and 14, respectively, as well as a progressive increase in collagen fibril diameter. In contrast, collagen abundance remains constant over the course of pregnancy. We conclude that early changes in tensile strength during cervical softening result in part from changes in the number and type of collagen cross-links and are associated with a decline in expression of two matricellular proteins thrombospondin 2 and tenascin C.

A10 TRANSFORMING GROWTH FACTOR-BETA INDUCES PERSISTENT SYNOVIAL FIBROSIS WHILE CONNECTIVE TISSUE GROWTH FACTOR-INDUCED FIBROSIS IS REVERSIBLE. ROLE FOR LYSYS HYDROXYLASE

Purpose: The main characteristics of osteoarthritis are cartilage damage, osteophyte formation and synovial fibrosis. Synovial fibrosis can contribute to the loss of the function of an OA joint. TGF-b is considered one of the main players in fibrotic diseases. However, CTGF, which can be induced by TGF-b, has been reported to be an important player as well, stated to contribute to maintenance of fibrotic tissue. We investigated the underlying mechanism in that leads to the observed difference in fibrosis persistence between TGF-band CTGF. Methods: We injected C57Bl/6 mice intra-articularly with Ad-TGF-b or Ad-CTGF. After 3, 7 and 21 days knee joint synovial tissue was isolated for RNA isolation or whole knee joints for histology. With Q-RT-PCR relative mRNA levels were determined of matrix molecules, proteases, protease inhibitors, and growth factors. To analyze the enzymes involved in collagen cross link formation, mRNA expression of lysyl hydroxylase (LH) was determined. CTGF-levels induced by TGF-b were measured by ELISA in 24 hour patella-synovial wash-outs of C57Bl/6 mice intra-articularly injected with Ad-TGF-b (3, 7 and 14 days). Results: TGF-b and CTGF induced synovial fibrosis in murine knee joints as shown by histology (as observed by an increase in synovial width). However, TGF-b-induced fibrosis was very persistent, whereas CTGFinduced fibrosis resorbed by day 28. TGF-b induced elevated collagen type I and very high levels of aggrecan expression and hardly any changes in collagen type II and III. CTGF induced no clear changes in collagen type I, II and III. CTGF even decreased aggrecan expression (day 21 only). CTGF induced no changes in MMP3, -9, -13, ADAMTS-4 or -5, whereas TGF-b increased MMP-3, -13 and ADAMTS4. Thus elevated levels of matrix degrading enzyme expression cannot explain the less persistent CTGF-induced fibrosis. TIMP1 (associated with matrix accumulation in fibrotic disorders), was highly up regulated by TGF-b (all days) and only slightly up regulated by CTGF (day 7). TGF-b also induced elevated mRNA levels of TGF-b1 and CTGF. Only TGF-b induced high levels of LH expression, especially LH2b, which has been implicated in hard-to-degrade collagen linkage and was found up regulated in fibrotic lesions. As TGF-b can induce CTGF and up regulated CTGF mRNA in our experiments, we measured CTGF levels in 24 hour patella-synovial wash outs and found that TGF-b induced 64 ng CTGF/ml after 3 days and that CTGF levels were still elevated by day 14. Conclusions: TGF-b induced increased collagen type I and aggrecan mRNA levels in synovial tissue, but also high levels of degrading enzymes. The latter does not explain the persistent nature of TGF-b versus CTGFinduced synovial fibrosis. Lack of collagen type I mRNA induced by CTGF corresponds to findings of other groups. Despite this fact, fibrosis is found. Only TGF-b induced high levels of TIMP1 expression, which was previously found associated with strain dependent fibrosis sensitivity in mice and implicated in accumulation of ECM in fibrotic disorders. TGF-b, not CTGF, induced high levels of LH which are crucial for ECM cross linking. Moreover, LH2b was reported by van der Slot et al. to induce harder-to-degrade crosslinks compared to LH2a. The 2b splicing variant was highly expressed upon stimulation with TGF-b. Since TGF-b clearly up regulated MMP expression a dominant role for TIMP appears unlikely. The strong induction of LH2b by TGF-b compared to CTGF, and consequently harder to degrade cross links, appears to be the most likely cause of the induction of irreversible fibrosis by TGF-b. A11 EFFICACY OF A SINGLE ULTRASOUND GUIDED INJECTION IN HIP OSTEOARTHRITIS