Modulation of the Wnt pathway through inhibition of CLK2 and DYRK1A by lorecivivint as a novel, potentially disease-modifying approach for knee osteoarthritis treatment.

OBJECTIVES: Wnt pathway upregulation contributes to knee osteoarthritis (OA) through osteoblast differentiation, increased catabolic enzymes, and inflammation. The small-molecule Wnt pathway inhibitor, lorecivivint (SM04690), which previously demonstrated chondrogenesis and cartilage protection in an animal OA model, was evaluated to elucidate its mechanism of action. DESIGN: Biochemical assays measured kinase activity. Western blots measured protein phosphorylation in human mesenchymal stem cells (hMSCs), chondrocytes, and synovial fibroblasts. siRNA knockdown effects in hMSCs and BEAS-2B cells on Wnt pathway, chondrogenic genes, and LPS-induced inflammatory cytokines was measured by qPCR. In vivo anti-inflammation, pain, and function were evaluated following single intra-articular (IA) lorecivivint or vehicle injection in the monosodium iodoacetate (MIA)-induced rat OA model. RESULTS: Lorecivivint inhibited intranuclear kinases CDC-like kinase 2 (CLK2) and dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A). Lorecivivint inhibited CLK2-mediated phosphorylation of serine/arginine-rich (SR) splicing factors and DYRK1A-mediated phosphorylation of SIRT1 and FOXO1. siRNA knockdowns identified a role for CLK2 and DYRK1A in Wnt pathway modulation without affecting ß-catenin with CLK2 inhibition inducing early chondrogenesis and DYRK1A inhibition enhancing mature chondrocyte function. NF-κB and STAT3 inhibition by lorecivivint reduced inflammation. DYRK1A knockdown was sufficient for anti-inflammatory effects, while combined DYRK1A/CLK2 knockdown enhanced this effect. In the MIA model, lorecivivint inhibited production of inflammatory cytokines and cartilage degradative enzymes, resulting in increased joint cartilage, decreased pain, and improved weight-bearing function. CONCLUSIONS: Lorecivivint inhibition of CLK2 and DYRK1A suggested a novel mechanism for Wnt pathway inhibition, enhancing chondrogenesis, chondrocyte function, and anti-inflammation. Lorecivivint shows potential to modify structure and improve symptoms of knee OA.

Open wedge high tibial osteotomies: Calcium-phosphate ceramic spacer versus autologous bonegraft.

INTRODUCTION: Valgus tibial osteotomy (VTO) is a well-known procedure for the treatment of medial compartment femoro-tibial osteoarthritis. Good and very good results have been reported with calcium phosphate wedges, which avoid the inconveniences of autologous grafts use. The hypothesis of this study is that with equivalent results in the treatment of osteoarthritis of the knee, the use of calcium phosphate wedges (BMCaPh) to fill the bone defect created by osteotomy would result in fewer specific complications and less pain associated with autologous grafts (AUTO) harvesting. PATIENTS AND METHODS: This prospective, controlled, randomised study included one arm that received a macroporous, biphasic calcium phosphate wedge (BMCaPh group) and one arm that received an autologous tricortical graft (AUTO group) for filling. The same plate with locked screws was used for fixation in all cases. All patients underwent at least two years of clinical and radiographic post-operative follow-up. RESULTS: Forty patients were included. Loss of correction occurred in six of the twenty-two patients in the BMCaPh group (27%), resulting in three early surgical revisions, compared to one loss of correction in the AUTO group. Lateral cortical hinge tears were a risk factor for loss of correction for the entire cohort and in the BMCaPh group. (relative risk 13.3 [1.9-92]. Moreover, union took significantly longer and pain lasted significantly longer in the BMCaPh group, although results were comparable at 6 months. DISCUSSION: A significant number of undesirable events (loss of correction) occurred in this study, limiting the number of included patients. Nevertheless, the results show that although there was no difference in the two groups for overall complications, number of revisions all causes combined, or clinical results, filling with BMCaPh was less tolerated and increased the risk of loss of correction when local mechanical conditions of the knee were unfavourable (lateral cortical hinge tears). Moreover, although it is not possible to draw a conclusion because of methodology bias in this study, early weight-bearing resumption on the knee also seemed to favour these complications. LEVEL OF EVIDENCE: Level II. Prospective randomized study.

Different mechanisms mediate the rejection of porcine neurons and endothelial cells transplanted into the rat brain.

In order to investigate the early cellular responses mediating xenograft rejection in the brain, porcine aortic endothelial cells (PAEC) or porcine fetal mesencephalic neurons (PNEU) were transplanted into the striatum of LEW.1A rats. PAEC were detected with a specific anti-beta1 integrin antibody, and PNEU with an anti-porcine neurofilament antibody, or an antibody recognizing the NeuN antigen. PAEC grafts were massively infiltrated within 24 h by OX42-positive cells, which may correspond to polymorphonuclear (PMN) cells or macrophages. At that moment, the graft contained numerous cells expressing the inducible isoform of NO-synthase (iNOS). Infiltration by ED1-positive macrophages was effective after three days. The beta1-integrin labeling decreased from that time-point to day 7 post-implantation, and vanished after 11 days. Although some OX8-positive cells were present around the graft as soon as 3 days after transplantation, cells expressing the T-cell receptor (TCR)-beta chain infiltrated the graft after 7 days and their number remained low. A strong, diffuse OX8-and ED1-positive immunoreactive material remained in the scar up to the third week. In striking contrast, PNEU grafts remained poorly infiltrated by OX42- or ED1-positive cells during the first two weeks. A massive infiltration by macrophages and TCRbeta-positive lymphocytes occurred after 3 weeks. Natural killer (NK) cells were more scarce. The inflammation territory enlarged, and blood vessels were overloaded with macrophages or lymphocytes. Nevertheless, the graft contained NeuN-positive nuclei and neurites harbouring the porcine neurofilament protein. Hence, rejection was not completed at this time-point. These results suggest that the rapid rejection of PAEC is mainly driven by macrophages and possibly PMN cells, unlike PNEU, whose rejection is delayed and also involves lymphocytes. Differences in immunogenicity of grafted cells and/or patterns of production of pro-inflammatory cytokines may account for these contrasted rejection kinetics.

[Bone hemangioma of the limbs. A report of two cases in children]. / Les angiomes osseux des membres. A propos de deux cas chez l'enfant.

Hemangiomas of bone are rare lesions corresponding approximately to 1% of all primary bone tumors. Cases of hemangiomas in the vertebral bodies and in the skull occur fairly frequently but are unusual in other bones. The authors reported two cases of unusual and fairly rare aspects of this vascular tumor in children. In both cases, recurrences occurred and leaded to a wide bone resection in case one and to several curettage in case two. In these two case the histological type of hemangioma was the capillary one. In reviewing the literature we found no indication for wide resection of the benign forms in children.

[Impact of angiodysplasia on bones]. / Retentissement osseux des angiodysplasies.

Vascular malformations usually have an impact on bones because of hemodynamic disturbances in the muscular and osteoperiosteal systems. In fact, even when these structures are not involved by arterial or venous malformations, the blood flow is altered in them. The consequences for bones affect the longitudinal growth of the skeleton of the malformed limb. Growth rarely becomes slower. On the contrary, the condition usually results in an acceleration of bone growth, which results in an excess in the length of the limb presenting with the vascular malformation. This overlengthening may be variably great, and the therapeutic indications must be adapted to its extent. When it is slight, compensation is sufficient to balance the pelvis. Conversely, when it is greater, its correction must be surgical. This surgery is aimed at equalizing the lower limbs, either by slowing down epiphyseal growth and shortening the longer side, or by progressively lengthening the other side, as the case may be. The respective indications of these methods must be carefully considered and adapted to each case, in order to obtain the best possible result with the smallest surgical risk.

Lower limb bone hemangiomas in children: report of two cases.

Hemangiomas of the bone are rare lesions, accounting for approximately 1% of all primary bone tumors. Hemangiomas occur fairly frequently in the vertebral bodies and the skull, but are unusual in other bones. We report two cases of unusual and fairly rare aspects of this vascular tumor in children. Both cases involved recurrences, which led to a wide bone resection in case 1 and to several curettages in case 2. In these two cases the histological type of hemangioma was capillary. In reviewing the literature we found no indication of wide resection of the benign forms in children.

[Epiphyseal fractures-dislocations of the lower extremity of the tibia]. / Les fractures-décollements épiphysaires de l'extrémité inférieure du tibia.

Ninety six distal tibial epiphyseal fractures were identified and treated in our institution from 1976 to 1988. The average age was twelve years and eight months (range two to seventeen years), but seventy-one were between eleven and fourteen years old. Using the Salter-Harris classification we have found twelve type 1 tibial fractures, fourty-two type 2, thirty type 3 and twelve type 4. Four were triplane fractures and seven were Tillaux fractures. Twenty-six had injuries in the medial corner of the ankle mortise (Mac-Farland). Fifty patients were treated non-operatively with closed reduction and plaster cast. Fourty-six fractures were treated surgically. Seventy patients were available for follow-up evaluation. The average follow-up was thirty-two months (range 6 months to eleven years). The tibial distal epiphyseal cartilage was closed in 48 patients. As short-term complications we have seen three post-operative displacements after closed reduction; all of them were treated surgically. Five incomplete closed reduction needed open reduction needed open reduction and bone fixation. Two infections occurred after a surgical approach. Among late complications we have seen eleven premature epiphyseal cartilage closure (rate 15%). Four were responsible of angular deformities. One child has a tibial osteotomy for varus deformity after a medial closure. Two ankle arthritis occurred: one of them was seen after a post-operative infection. In two cases of fracture of the medial mortise corner, a valgus deformity with hypertrophy of the medial malleolus occurred. Ankle arthritis is the most severe complication of the adolescent articular fractures (Tillaux and triplane fractures).(ABSTRACT TRUNCATED AT 250 WORDS)