RESUMO
OBJECTIVE: Alkaptonuria (AKU) is a rare autosomal recessive disease resulting from a single enzyme deficiency in tyrosine metabolism. As a result, homogentisic acid cannot be metabolized, causing systemic increases. Over time, homogentisic acid polymerizes and deposits in collagenous tissues, leading to ochronosis. Typically, this occurs in joint cartilages, leading to an early onset, rapidly progressing osteoarthropathy. The aim of this study was to examine tissue turnover in cartilage affected by ochronosis and its role in disease initiation and progression. METHODS: With informed patient consent, hip and knee cartilages were obtained at surgery for arthropathy due to AKU (n = 6; 2 knees/4 hips) and OA (n = 12; 5 knees/7 hips); healthy non-arthritic (non-OA n = 6; 1 knee/5 hips) cartilages were obtained as waste from trauma surgery. We measured cartilage concentrations (normalized to dry weight) of racemized aspartate, GAG, COMP and deamidated COMP (D-COMP). Unpaired AKU, OA and non-OA samples were compared by non-parametric Mann-Whitney U test. RESULTS: Despite more extractable total protein being obtained from AKU cartilage than from OA or non-OA cartilage, there was significantly less extractable GAG, COMP and D-COMP in AKU samples compared with OA and non-OA comparators. Racemized Asx (aspartate and asparagine) was significantly enriched in AKU cartilage compared with in OA cartilage. CONCLUSIONS: These novel data represent the first examination of cartilage matrix components in a sample of patients with AKU, representing almost 10% of the known UK alkaptonuric population. Compared with OA and non-OA, AKU cartilage demonstrates a very low turnover state and has low levels of extractable matrix proteins.
Assuntos
Envelhecimento/metabolismo , Alcaptonúria/metabolismo , Cartilagem Articular/metabolismo , Artropatias/metabolismo , Ocronose/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Ácido Aspártico/metabolismo , Biomarcadores/metabolismo , Proteína de Matriz Oligomérica de Cartilagem/metabolismo , Estudos de Casos e Controles , Feminino , Glicosaminoglicanos/metabolismo , Articulação do Quadril , Humanos , Articulação do Joelho , Masculino , Pessoa de Meia-Idade , Osteoartrite do Quadril/metabolismo , Osteoartrite do Joelho/metabolismo , Adulto JovemRESUMO
ADAMTS (A Disintegrin-like And Metalloprotease domain with ThromboSpondin type I motifs) are multidomain proteins with demonstrated metalloproteinase functionality and have potential roles in embryonic development, angiogenesis and cartilage degradation. We present here investigations of ADAMTS expression in an ocular cell type, ARPE-19, with a view to implicating them in retinal matrix turnover. Expression analysis was undertaken using a combination of reverse transcription polymerase chain reaction (RT-PCR) and Northern blotting experiments, which together detected the expression of mRNAs for several ADAMTS proteins, all of which have active site motifs characteristic of matrix metalloproteases (MMPs). These included ADAMTS1, ADAMTS2, ADAMTS3, ADAMTS5, ADAMTS6, ADAMTS7 and ADAMTS9. The expression of mRNA isoforms for ADAMTS7 and ADAMTS9 were also detected. Following stimulation with TNFalpha, ADAMTS1, ADAMTS6 and both ADAMTS9 transcripts expressed in ARPE-19 cells showed a potent upregulation. The expression of ADAMTS genes in ARPE-19 cells and the transcriptional stimulation of some family members by TNFalpha may implicate them in inflammatory eye disease and the compromise of retinal matrix structure, which is evident in age-related macular degeneration (ARMD) and other retinal pathologies.
Assuntos
Metaloendopeptidases/genética , Epitélio Pigmentado Ocular/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Proteínas ADAM , Proteína ADAMTS7 , Proteína ADAMTS9 , Northern Blotting , Linhagem Celular , Regulação da Expressão Gênica , Humanos , Metaloendopeptidases/biossíntese , Epitélio Pigmentado Ocular/efeitos dos fármacos , Isoformas de Proteínas/biossíntese , Isoformas de Proteínas/genética , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição GênicaRESUMO
We have investigated proteinases that degrade cartilage collagen. We show that pro-inflammatory cytokines act synergistically with oncastatin M to promote cartilage collagen resorption by the up-regulation and activation of matrix metalloproteinases (MMPs). The precise mechanisms are not known, but involve the up-regulation of c-fos, which binds to MMP promoters at a proximal activator protein-1 (AP-1) site. This markedly up-regulates transcription and leads to higher levels of active MMP proteins.
Assuntos
Cartilagem/metabolismo , Colágeno/metabolismo , Colagenases/metabolismo , Citocinas/metabolismo , Animais , Cartilagem/enzimologia , Ativação Enzimática , Humanos , Hidrólise , Inibidores de Metaloproteinases de Matriz , Inibidores de Proteases/farmacologiaAssuntos
Bioensaio/métodos , Meios de Cultivo Condicionados/química , Imunoensaio/métodos , Metaloproteinases da Matriz/análise , Inibidores de Proteases/farmacologia , Líquido Sinovial/enzimologia , Caseínas/metabolismo , Colágeno Tipo I/metabolismo , Ensaio de Imunoadsorção Enzimática/métodos , Fluorometria , Gelatina/metabolismo , Inibidores de Metaloproteinases de Matriz , Metaloproteinases da Matriz/sangue , Kit de Reagentes para Diagnóstico , Especificidade por Substrato , Inibidor Tecidual de Metaloproteinase-1/análiseRESUMO
The destruction of bone and cartilage is characteristic of the progression of musculoskeletal diseases. The present review discusses the developments made with two different classes of drugs, the bisphosphonates and matrix metalloproteinase inhibitors. Bisphosphonates have proven to be an effective and safe treatment for the prevention of bone loss, especially in osteoporotic disease, and may have a role in the treatment of arthritic diseases. The development of matrix metalloproteinase inhibitors and their role as potential therapies are also discussed, especially in the light of the disappointing human trials data so far published.