Objective. To investigate whether retroviral gene transfer of ribozymes targeting matrix metalloproteinase 1 (MMP-1) inhibits the production of MMP-1 in rheumatoid arthritis synovial fibroblasts (RASFs) and reduces the invasiveness of these cells in vivo.Methods. MMP-1-specific ribozymes (RzMMP-1) were designed and cloned into the pLNSX retroviral vector. Cleavage of MMP-1 was determined in vitro, and the most effective ribozyme was selected for further investigation. RASFs were transduced with replication-deficient viruses carrying RzMMP-1 or with empty viruses (mock). Quantitative polymerase chain reaction with cleavage sitespanning fluorescent probes was used to measure the levels of MMP-1, MMP-9, and MMP-13 messenger RNA. In addition, protein levels of MMP-1 in cell culture supernatants were determined by enzyme linked immunosorbent assay. The effects of stimulation with lipopolysaccharide (LPS) and tumor necrosis factor ␣ (TNF␣) on the production of MMP-1 were assessed accordingly. The invasiveness of RzMMP-1-transduced, mock-transduced, and untransduced RASFs was analyzed in the SCID mouse in vivo model of RA.Results. Transduction of RASFs with RzMMP-1 significantly decreased the production of MMP-1 in RASFs without affecting other MMPs, such as MMP-9 and MMP-13. RzMMP-1 not only reduced the spontaneous production of MMP-1, but also prevented the LPS-and TNF␣-induced increase in MMP-1 production. Inhibition of MMP-1 was maintained for at least 2 months and was accompanied by a significant reduction of the invasiveness of RASFs in the SCID mouse model of RA.Conclusion. Intracellular expression of ribozymes constitutes a feasible tool for inhibiting the production of matrix-degrading enzymes. Inhibition of MMP-1 alone results in a significant reduction of cartilage invasion by RASFs.

Rheumatoid arthritis (RA) is a chronic, inflammatory joint disease with systemic involvement that affects about 1% of the Western population. The progressive destruction of affected joints is a major characteristic of the disease and distinguishes RA from other acute and chronic arthritides. The etiology of RA is unknown, and a variety of genetic and environmental factors are being discussed as potential causes of the disease. However, in contrast to our incomplete understanding of the etiology, the knowledge about molecular mechanisms leading to joint destruction has advanced considerably over the past years. Thus, a large number of studies have investigated the presence and interplay of several types of cells in rheumatoid synovium, such as lymphocytes, macrophages and fibroblasts. They have led to the understanding that cells in the rheumatoid synovium form a network, which interacts through direct cell-to cell contacts as well as the release of a multitude of cytokines. The use of novel molecular techniques together with the development of new animal models has revised our concept on the pathogenesis of RA and specifically on the role of fibroblasts in initiation and progression of joint destruction. This article will review current data and hypotheses on disease mechanisms by which fibroblasts are involved in the destruction of joints in RA.

Conclusion. The data demonstrate that an antisense RNA expression construct against MT1-MMP can be generated and expressed in RASFs for at least 60 days. Inhibition of MT1-MMP significantly reduces the cartilage degradation by RASFs.Membrane-type matrix metalloproteinases (MTMMPs) are cell membrane-anchored MMPs that have been associated with both normal tissue remodeling and various diseases. Six different MT-MMPs have thus far been described, of which membrane type 1 MMP (MT1-MMP) has been studied most intensively. MT1-MMP (also called MMP-14) has a specific structural organization that is characterized by a hydrophobic transmembrane domain and a short cytoplasmic tail. It also contains a recognition site for furin-like proprotein convertases, which, by furin-dependent cleavage, activate MT1-MMP intracellularly (1). MT1-MMP digests interstitial collagens as well as other extracellular matrix components, including fibronectin, laminin, aggrecan,

Rivaroxaban is an oral, direct Factor Xa inhibitor, approved for the prevention and treatment of several thromboembolic disorders. Rivaroxaban does not require routine coagulation monitoring and has a short half-life. However, confirmation of rivaroxaban levels may be required in circumstances such as life-threatening bleeding or perioperative management. Here, we explore the management strategies in patients receiving rivaroxaban who have a bleeding emergency or require emergency surgery. Rivaroxaban plasma concentrations can be assessed quantitatively using anti-Factor Xa chromogenic assays, or qualitatively using prothrombin time assays (using rivaroxaban-sensitive reagents). In patients receiving long-term rivaroxaban therapy who require elective surgery, discontinuation of rivaroxaban 20–30 hours beforehand is normally sufficient to minimize bleeding risk. For emergency surgery, we advise against prophylactic use of hemostatic blood products, even with high rivaroxaban concentrations. Temporary rivaroxaban discontinuation is recommended if minor bleeding occurs; for severe bleeding, rivaroxaban withdrawal may be necessary, along with compression or appropriate surgical treatment. Supportive measures such as blood product administration might be beneficial. Life-threatening bleeding demands comprehensive hemostasis management, including potential use of agents such as prothrombin complex concentrate. Patients taking rivaroxaban who require emergency care for bleeding or surgery can be managed using established protocols and individualized assessment.

An understanding of reversal strategies alone is important to safely and effectively care for patients in cases of bleeding or invasive procedures. The recent diversification in the number of licensed anticoagulants makes an understanding of drug-specific reversal strategies essential. Intravenous or oral vitamin K can reverse the effect of vitamin K antagonists (VKAs) within 12 to 48 hours and is indicated for any bleeding or an international normalized ratio >10 or 4.5 to 10 in patients with additional risk factors for bleeding. Furthermore, an additional administration of prothrombin complex concentrate (PCC) may be necessary in cases of major bleeding related to VKA. Protamine (chloride or sulfate) fully reverses the effect of unfractionated heparin and partially in low-molecular-weight heparin. Idarucizumab has been approved for dabigatran reversal, whereas andexanet alfa is approved for the reversal of some oral factor Xa inhibitors (apixaban, rivaroxaban). PCC seems to enhance the haemostatic potential for the reversal of the effect of FXa-inhibitors. So far, there are promising but only limited data on the efficacy of this approach available. Each reversal strategy needs an adequate management beyond the hemostatic treatment (volume replacement, stabilization of homeostasis, e.g., pH and temperature, resumption of anticoagulation after successful treatment of bleeding, etc.) that is crucial for the successful management of acute bleedings, urgent high-risk surgery, thrombolytic therapies or thrombectomies as well as overdosing of anticoagulants.