Amphiregulin as monitoring biomarker for life-threatening acute graft-versushost disease: secondary analysis of two prospective clinical trials.

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A biomarker signature to predict complete response to itacitinib and corticosteroids in acute graft-versus-host disease.

A broad proteomic analysis was conducted to identify and evaluate candidate biomarkers potentially predictive of response to treatment with an oral selective Janus kinase 1 (JAK1) inhibitor, itacitinib, in acute graft-versus-host disease (GVHD). Plasma samples from 25 participants (identification cohort; NCT02614612) were used to identify novel biomarkers that were tested in a validation cohort from a placebo-controlled, randomised trial (n = 210; NCT03139604). The identification cohort received corticosteroids plus 200 or 300 mg itacitinib once daily. The validation cohort received corticosteroids plus 200 mg itacitinib once daily or placebo. A broad proteomic analysis was conducted using a proximity extension assay. Baseline and longitudinal comparisons were performed with unpaired t-test and one-way analysis of variance used to evaluate biomarker level changes. Seven candidate biomarkers were identified. Monocyte-chemotactic protein (MCP)3, pro-calcitonin/calcitonin (ProCALCA/CALCA), together with a previously identified prognostic acute GVHD biomarker, regenerating islet-derived protein (REG)3A, stratified complete responders from non-responders (participants with progressive disease) to itacitinib, but not placebo, potentially representing predictive biomarkers of itacitinib in acute GVHD. ProCALCA/CALCA, suppressor of tumorigenicity (ST)2, and tumour necrosis factor receptor (TNFR)1 were significantly reduced over time by itacitinib in responders, potentially representing response-to-treatment biomarkers. Novel biomarkers have the potential to identify patients with acute GVHD that may respond to itacitinib plus corticosteroid treatment (NCT02614612; NCT03139604).

A phase 1 trial of itacitinib, a selective JAK1 inhibitor, in patients with acute graft-versus-host disease.

Acute graft-versus-host disease (aGVHD) following allogeneic hematopoietic cell transplantation (HCT) is a primary cause of nonrelapse mortality and a major barrier to successful transplant outcomes. Itacitinib is a Janus kinase (JAK)1-selective inhibitor that has demonstrated efficacy in preclinical models of aGVHD. We report results from the first registered study of a JAK inhibitor in patients with aGVHD. This was an open-label phase 1 study enrolling patients aged ≥18 years with first HCT from any source who developed grade IIB to IVD aGVHD. Patients with steroid-naive or steroid-refractory aGVHD were randomized 1:1 to itacitinib 200 mg or 300 mg once daily plus corticosteroids. The primary endpoint was safety and tolerability; day 28 overall response rate (ORR) was the main secondary endpoint. Twenty-nine patients (200 mg, n = 14; 300 mg, n = 15) received ≥1 dose of itacitinib and were included in safety and efficacy assessments. One dose-limiting toxicity was reported (grade 3 thrombocytopenia attributed to GVHD progression in a patient receiving 300 mg itacitinib with preexisting thrombocytopenia). The most common nonhematologic treatment-emergent adverse event was diarrhea (48.3%, n = 14); anemia occurred in 11 patients (38%). ORR on day 28 for all patients in the 200-mg and 300-mg groups was 78.6% and 66.7%, respectively. Day 28 ORR was 75.0% for patients with treatment-naive aGVHD and 70.6% in those with steroid-refractory aGVHD. All patients receiving itacitinib decreased corticosteroid use over time. In summary, itacitinib was well tolerated and demonstrated encouraging efficacy in patients with steroid-naive or steroid-refractory aGVHD, warranting continued clinical investigations. This trial was registered at www.clinicaltrials.gov as #NCT02614612.

Development of cell-based immunoassays to measure type I collagen in cultured fibroblasts.

Excessive deposition of type I collagen by activated fibroblasts is a hallmark of scarring and fibrotic pathologies. Quantitation of collagen I at the protein level is paramount to measure functionally relevant changes during pathological remodeling of the extracellular matrix. We describe two new cell-based assays to directly quantify the amount of collagen I incorporated into the extracellular matrix of primary human lung fibroblasts. Utilizing a monoclonal antibody specific to native human collagen I, we optimized conditions and parameters including incubation time, specificity and cell density to demonstrate dose-dependent induction of collagen I by transforming growth factor beta, as measured by in-cell enzyme linked immunosorbent assay. The results obtained by this assay were mimicked by an "In situ Quantitative Western Blot" on cultured cells using the same antibody. Results from these assays were comparable to those obtained with a commercial assay for collagen I N-propeptide, which is an index of collagen formation. These assays have been optimized for a 96-well format and provide a novel and useful approach for screening of anti-fibrotic agents in vitro. The assays described here also offer a significant improvement in throughput and specificity over conventional methods that primarily measure soluble collagen.

Development and characterization of a human articular cartilage-derived chondrocyte cell line that retains chondrocyte phenotype.

Chondrocytes, the only cell type present in articular cartilage, regulate tissue homeostasis by a fine balance of metabolism that includes both anabolic and catabolic activities. Therefore, the biology of chondrocytes is critical for understanding cartilage metabolism. One major limitation when studying primary chondrocytes in culture is their loss of phenotype. To overcome this hurdle, limited attempts have been made to develop human chondrocyte cell lines that retain the phenotype for use as a good surrogate model. In this study, we report a novel approach to the establishment and characterization of human articular cartilage-derived chondrocyte cell lines. Adenoviral infection followed by culture of chondrocytes in 3-dimensional matrix within 48 h post-infection maintained the phenotype prior to clonal selection. Cells were then placed in culture either as monolayer, or in 3-dimensional matrix of alginate or agarose. The clones were characterized by their basal gene expression profile of chondrocyte markers. Based on type II collagen expression, 21 clones were analyzed for gene expression following treatment with IL-1 or BMP-7 and compared to similarly stimulated primary chondrocytes. This resulted in selection of two clones that retained the chondrocyte phenotype as evidenced by expression of type II collagen and other extra-cellular matrix molecules. In addition, one clone (AL-4-17) showed similar responses as primary chondrocytes when treated with IL-1 or BMP-7. In summary, this report provides a novel procedure to develop human articular cartilage-derived chondrocyte cell lines, which preserve important characteristics of articular chondrocytes and represent a useful model to study chondrocyte biology.

Bacterial production of biologically active canine interleukin-1beta by seamless SUMO tagging and removal.

Interleukin 1beta (IL-1beta) is a potent stimulator of extracellular matrix degradation in models of osteoarthritis (OA). In contrast to bovine explant models which effectively respond to recombinant human IL-1beta, canine models are relatively refractory to human IL-1beta stimulation. Canine IL-1beta cDNA was cloned in order to produce a fully potent species matched preparation of IL-1beta for use specifically in canine models of OA. Established methods for the production of various orthologous IL-1beta proteins from different species are problematic due to the exquisite sensitivity of the mature IL-1beta product to N-terminal variations and the intrinsic technical challenges associated with producing an unmodified product. We have applied a seamless method of SUMO tagging and removal in order to produce a homogeneous unmodified preparation of canine IL-1beta from Escherichia coli which was found to be a potent inducer of aggrecanase activity in isolated canine articular chondrocytes. This method combines highly efficient aspects of seamless plasmid engineering, protein purification, and precise tag removal.

Mechanisms and kinetics of glycosaminoglycan release following in vitro cartilage injury.

OBJECTIVE: Acute joint injury leads to increased risk for osteoarthritis (OA). Although the mechanisms underlying this progression are unclear, early structural, metabolic, and compositional indicators of OA have been reproduced using in vitro models of cartilage injury. This study was undertaken to determine whether glycosaminoglycan (GAG) loss following in vitro cartilage injury is mediated by cellular biosynthesis, activation of enzymatic activity, or mechanical disruption of the cartilage extracellular matrix. METHODS: Immature bovine cartilage was cultured for up to 10 days. After 3 days, groups of samples were subjected to injurious mechanical compression (single uniaxial unconfined compression to 50% thickness, strain rate 100% per second). GAG release to the medium was measured, and levels were compared with those in location-matched, uninjured controls. The effects of medium supplementation with inhibitors of biosynthesis (cycloheximide), of matrix metalloproteinase (MMP) activity (CGS 27023A or GM 6001), and of aggrecanase activity (SB 703704) on GAG release after injury were assessed. RESULTS: GAG release from injured cartilage was highest during the first 4 hours after injury, but remained higher than that in controls during the first 24 hours postinjury, and was not affected by inhibitors of biosynthesis or degradative enzymes. GAG release during the period 24-72 hours postinjury was similar to that in uninjured controls, but the MMP inhibitor CGS 27023A reduced cumulative GAG loss from injured samples between 1 day and 7 days postinjury. Other inhibitors of enzymatic degradation or biosynthesis had no significant effect on GAG release. CONCLUSION: Injurious compression of articular cartilage induces an initially high rate of GAG release from the tissue, which could not be inhibited, consistent with mechanical damage. However, the finding that MMP inhibition reduced GAG loss in the days following injury suggests a potential therapeutic intervention.

Aggrecan protects cartilage collagen from proteolytic cleavage.

The matrix components responsible for cartilage mechanical properties, type II collagen and aggrecan, are degraded in osteoarthritis through proteolytic cleavage by matrix metalloproteinases (MMPs) and aggrecanases, respectively. We now show that aggrecan may serve to protect cartilage collagen from degradation. Although collagen in freeze-thawed cartilage depleted of aggrecan was completely degraded following incubation with MMP-1, collagen in cartilage with intact aggrecan was not. Using interleukin-1-stimulated bovine nasal cartilage explants where aggrecan depletion occurs during the first week of culture, followed by collagen loss during the second week, we evaluated the effect of selective MMP and aggrecanase inhibitors on degradation. A selective MMP inhibitor did not block aggrecan degradation but caused complete inhibition of collagen breakdown. Similar inhibition was seen with inhibitor addition following aggrecan depletion on day 6-8, suggesting that MMPs are not causing significant collagen degradation prior to the second week of culture. Inclusion of a selective aggrecanase inhibitor blocked aggrecan degradation, and, in addition, inhibited collagen degradation. When the inhibitor was introduced following aggrecan depletion, it had no effect on collagen breakdown, ruling out a direct effect through inhibition of collagenase. These data suggest that aggrecan plays a protective role in preventing degradation of collagen fibrils, and that an aggrecanase inhibitor may impart overall cartilage protection.

A microplate assay specific for the enzyme aggrecanase.

We have identified a 41-residue peptide, bracketing the aggrecanase cleavage site of aggrecan, that serves as a specific substrate for this enzyme family. Biotinylation of the peptide allowed its immobilization onto streptavidin-coated plates. Aggrecanase-mediated hydrolysis resulted in an immobilized product that reveals an N-terminal neoepitope, recognized by the specific antibody BC-3. This assay is highly specific for aggrecanases; MMPs were inactive in this assay. Reduction of the peptide size below 30 amino acids resulted in a significant diminution of activity. Using the immobilized 41-residue peptide as a substrate, we have developed a 96-well microplate-based assay that can be conveniently used for high-throughput screening of samples for aggrecanase activity and for discovery of inhibitors of aggrecanase activity.

Induction of aggrecanase 1 (ADAM-TS4) by interleukin-1 occurs through activation of constitutively produced protein.

OBJECTIVE: To study the production of aggrecanase 1 (ADAM-TS4) in monolayer chondrocytes, capsular fibroblasts, and cartilage. METHODS: Bovine nasal and articular cartilage, monolayer chondrocytes, and capsular fibroblasts were incubated in the absence and presence of interleukin-1 (IL-1). ADAM-TS4 production was evaluated by immunofluorescence or by Western blot analysis. Aggrecanase activity was measured in cells grown on an immobilized peptide substrate, and peptide cleavage was monitored by enzyme-linked immunosorbent assay. RESULTS: There was constitutive production of ADAM-TS4 in both cells and tissue. The protein was associated with the extracellular matrix based on the observation that the staining could be reduced following treatment of chondrocytes with heparin or exposure to chondroitinase ABC. Interestingly, there was no detectable change in the abundance of ADAM-TS4 in response to IL-1. Western blot analysis of cell lysates from IL-1-stimulated chondrocytes showed no evidence of increased ADAM-TS4 production, but resulted in activation of ADAM-TS4. The activation was associated with an increased generation in the aggrecanase neoepitope NITEGE in nasal cartilage in response to IL-1. These data suggest that induction of aggrecanase activity both in cells and in cartilage by IL-1 may involve the stimulation of an activator of ADAM-TS4. Consistent with this observation, culture of chondrocytes on a solid support containing a peptide substrate resulted in the generation of aggrecanase-mediated cleavage that could be blocked by selective inhibitors of ADAM-TS4. CONCLUSION: These data support the hypothesis that ADAM-TS4 is constitutively produced in these cells and tissue, and that stimulation by IL-1 results in aggrecanase activation. Thus, the activator could be a potential target by which to control aggrecanase-mediated degradation in arthritic diseases.