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Nociceptive Sensitizers Are Regulated in Damaged Joint Tissues, Including Articular Cartilage, When Osteoarthritic Mice Display Pain Behavior

View Article: PubMed Central - PubMed

ABSTRACT

Objective: Pain is the most common symptom of osteoarthritis (OA), yet where it originates in the joint and how it is driven are unknown. The aim of this study was to identify pain‐sensitizing molecules that are regulated in the joint when mice subjected to surgical joint destabilization develop OA‐related pain behavior, the tissues in which these molecules are being regulated, and the factors that control their regulation.

Methods: Ten‐week‐old mice underwent sham surgery, partial meniscectomy, or surgical destabilization of the medial meniscus (DMM). Pain‐related behavior as determined by a variety of methods (testing of responses to von Frey filaments, cold plate testing for cold sensitivity, analgesiometry, incapacitance testing, and forced flexion testing) was assessed weekly. Once pain‐related behavior was established, RNA was extracted from either whole joints or microdissected tissue samples (articular cartilage, meniscus, and bone). Reverse transcription–polymerase chain reaction analysis was performed to analyze the expression of 54 genes known to regulate pain sensitization. Cartilage injury assays were performed using avulsed immature hips from wild‐type or genetically modified mice or by explanting articular cartilage from porcine joints preinjected with pharmacologic inhibitors. Levels of nerve growth factor (NGF) protein were measured by enzyme‐linked immunosorbent assay.

Results: Mice developed pain‐related behavior 8 weeks after undergoing partial meniscectomy or 12 weeks after undergoing DMM. NGF, bradykinin receptors B1 and B2, tachykinin, and tachykinin receptor 1 were significantly regulated in the joints of mice displaying pain‐related behavior. Little regulation of inflammatory cytokines, leukocyte activation markers, or chemokines was observed. When tissue samples from articular cartilage, meniscus, and bone were analyzed separately, NGF was consistently regulated in the articular cartilage. The other pain sensitizers were also largely regulated in the articular cartilage, although there were some differences between the 2 models. NGF and tachykinin were strongly regulated by simple mechanical injury of cartilage in vitro in a transforming growth factor β–activated kinase 1–, fibroblast growth factor 2–, and Src kinase–dependent manner.

Conclusion: Damaged joint tissues produce proalgesic molecules, including NGF, in murine OA.

No MeSH data available.


Related in: MedlinePlus

Pain behavior following joint destabilization surgery. Ten‐week‐old mice underwent surgical joint destabilization (partial meniscectomy [PMNX] [A–D] or destabilization of the medial meniscus [DMM] [E–G] [blue]) or sham surgery (green). The mice were assessed weekly until consistent pain‐related behavior was observed. A and E, Mechanical allodynia as assessed using von Frey filaments. B and F, Cold allodynia as assessed using a cold plate (10°C). C, Number of vocalizations in response to 10 knee compressions. Each symbol represents an individual mouse; horizontal lines show the mean. D, Mechanical hyperalgesia as assessed using an analgesiometer. G, Mechanical allodynia as assessed by incapacitance testing. H, Histologic scores for destabilized and sham‐operated joints at 8 weeks (PMNX) and 12 weeks (DMM) postsurgery. Values in A,B, and D–H are the mean ± SEM (n = 10 or more per group). ∗ = P ≤ 0.05; ∗∗ = P ≤ 0.01; ∗∗∗ = P ≤ 0.001; ∗∗∗∗ = P ≤ 0.0001 by two‐way analysis of variance followed by the Bonferroni post hoc test. CL = contralateral (control); IL = ipsilateral.
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art39523-fig-0001: Pain behavior following joint destabilization surgery. Ten‐week‐old mice underwent surgical joint destabilization (partial meniscectomy [PMNX] [A–D] or destabilization of the medial meniscus [DMM] [E–G] [blue]) or sham surgery (green). The mice were assessed weekly until consistent pain‐related behavior was observed. A and E, Mechanical allodynia as assessed using von Frey filaments. B and F, Cold allodynia as assessed using a cold plate (10°C). C, Number of vocalizations in response to 10 knee compressions. Each symbol represents an individual mouse; horizontal lines show the mean. D, Mechanical hyperalgesia as assessed using an analgesiometer. G, Mechanical allodynia as assessed by incapacitance testing. H, Histologic scores for destabilized and sham‐operated joints at 8 weeks (PMNX) and 12 weeks (DMM) postsurgery. Values in A,B, and D–H are the mean ± SEM (n = 10 or more per group). ∗ = P ≤ 0.05; ∗∗ = P ≤ 0.01; ∗∗∗ = P ≤ 0.001; ∗∗∗∗ = P ≤ 0.0001 by two‐way analysis of variance followed by the Bonferroni post hoc test. CL = contralateral (control); IL = ipsilateral.

Mentions: We first confirmed the development of pain‐related behavior following joint destabilization, using 2 different models: partial meniscectomy and DMM. Figure 1 shows that pain assessment measurements differentiated sham‐operated mice from mice that underwent partial meniscectomy or DMM‐operated mice at 8 weeks and 12 weeks postsurgery, respectively. These observations are in accordance with those findings of previous studies 7, 8. All pain assessments including mechanical allodynia, thermal hyperalgesia, and mechanical hyperalgesia showed a similar temporal trend, even though some are measuring sensitivity at a site distal to the joint (von Frey test, analgesiometry, cold plate test), and some are measuring sensitivity at the joint itself (vocalizations, Linton incapacitance test). The time of onset and the persistence of pain‐related behavior after DMM (up to 20 weeks) were confirmed by incapacitance testing in several repeat studies (data not shown). Early postoperative pain was not measured in mice that underwent partial meniscectomy, because the first behavioral assessment was performed at week 1 (after postoperative synovitis has largely resolved).


Nociceptive Sensitizers Are Regulated in Damaged Joint Tissues, Including Articular Cartilage, When Osteoarthritic Mice Display Pain Behavior
Pain behavior following joint destabilization surgery. Ten‐week‐old mice underwent surgical joint destabilization (partial meniscectomy [PMNX] [A–D] or destabilization of the medial meniscus [DMM] [E–G] [blue]) or sham surgery (green). The mice were assessed weekly until consistent pain‐related behavior was observed. A and E, Mechanical allodynia as assessed using von Frey filaments. B and F, Cold allodynia as assessed using a cold plate (10°C). C, Number of vocalizations in response to 10 knee compressions. Each symbol represents an individual mouse; horizontal lines show the mean. D, Mechanical hyperalgesia as assessed using an analgesiometer. G, Mechanical allodynia as assessed by incapacitance testing. H, Histologic scores for destabilized and sham‐operated joints at 8 weeks (PMNX) and 12 weeks (DMM) postsurgery. Values in A,B, and D–H are the mean ± SEM (n = 10 or more per group). ∗ = P ≤ 0.05; ∗∗ = P ≤ 0.01; ∗∗∗ = P ≤ 0.001; ∗∗∗∗ = P ≤ 0.0001 by two‐way analysis of variance followed by the Bonferroni post hoc test. CL = contralateral (control); IL = ipsilateral.
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art39523-fig-0001: Pain behavior following joint destabilization surgery. Ten‐week‐old mice underwent surgical joint destabilization (partial meniscectomy [PMNX] [A–D] or destabilization of the medial meniscus [DMM] [E–G] [blue]) or sham surgery (green). The mice were assessed weekly until consistent pain‐related behavior was observed. A and E, Mechanical allodynia as assessed using von Frey filaments. B and F, Cold allodynia as assessed using a cold plate (10°C). C, Number of vocalizations in response to 10 knee compressions. Each symbol represents an individual mouse; horizontal lines show the mean. D, Mechanical hyperalgesia as assessed using an analgesiometer. G, Mechanical allodynia as assessed by incapacitance testing. H, Histologic scores for destabilized and sham‐operated joints at 8 weeks (PMNX) and 12 weeks (DMM) postsurgery. Values in A,B, and D–H are the mean ± SEM (n = 10 or more per group). ∗ = P ≤ 0.05; ∗∗ = P ≤ 0.01; ∗∗∗ = P ≤ 0.001; ∗∗∗∗ = P ≤ 0.0001 by two‐way analysis of variance followed by the Bonferroni post hoc test. CL = contralateral (control); IL = ipsilateral.
Mentions: We first confirmed the development of pain‐related behavior following joint destabilization, using 2 different models: partial meniscectomy and DMM. Figure 1 shows that pain assessment measurements differentiated sham‐operated mice from mice that underwent partial meniscectomy or DMM‐operated mice at 8 weeks and 12 weeks postsurgery, respectively. These observations are in accordance with those findings of previous studies 7, 8. All pain assessments including mechanical allodynia, thermal hyperalgesia, and mechanical hyperalgesia showed a similar temporal trend, even though some are measuring sensitivity at a site distal to the joint (von Frey test, analgesiometry, cold plate test), and some are measuring sensitivity at the joint itself (vocalizations, Linton incapacitance test). The time of onset and the persistence of pain‐related behavior after DMM (up to 20 weeks) were confirmed by incapacitance testing in several repeat studies (data not shown). Early postoperative pain was not measured in mice that underwent partial meniscectomy, because the first behavioral assessment was performed at week 1 (after postoperative synovitis has largely resolved).

View Article: PubMed Central - PubMed

ABSTRACT

Objective: Pain is the most common symptom of osteoarthritis (OA), yet where it originates in the joint and how it is driven are unknown. The aim of this study was to identify pain‐sensitizing molecules that are regulated in the joint when mice subjected to surgical joint destabilization develop OA‐related pain behavior, the tissues in which these molecules are being regulated, and the factors that control their regulation.

Methods: Ten‐week‐old mice underwent sham surgery, partial meniscectomy, or surgical destabilization of the medial meniscus (DMM). Pain‐related behavior as determined by a variety of methods (testing of responses to von Frey filaments, cold plate testing for cold sensitivity, analgesiometry, incapacitance testing, and forced flexion testing) was assessed weekly. Once pain‐related behavior was established, RNA was extracted from either whole joints or microdissected tissue samples (articular cartilage, meniscus, and bone). Reverse transcription–polymerase chain reaction analysis was performed to analyze the expression of 54 genes known to regulate pain sensitization. Cartilage injury assays were performed using avulsed immature hips from wild‐type or genetically modified mice or by explanting articular cartilage from porcine joints preinjected with pharmacologic inhibitors. Levels of nerve growth factor (NGF) protein were measured by enzyme‐linked immunosorbent assay.

Results: Mice developed pain‐related behavior 8 weeks after undergoing partial meniscectomy or 12 weeks after undergoing DMM. NGF, bradykinin receptors B1 and B2, tachykinin, and tachykinin receptor 1 were significantly regulated in the joints of mice displaying pain‐related behavior. Little regulation of inflammatory cytokines, leukocyte activation markers, or chemokines was observed. When tissue samples from articular cartilage, meniscus, and bone were analyzed separately, NGF was consistently regulated in the articular cartilage. The other pain sensitizers were also largely regulated in the articular cartilage, although there were some differences between the 2 models. NGF and tachykinin were strongly regulated by simple mechanical injury of cartilage in vitro in a transforming growth factor β–activated kinase 1–, fibroblast growth factor 2–, and Src kinase–dependent manner.

Conclusion: Damaged joint tissues produce proalgesic molecules, including NGF, in murine OA.

No MeSH data available.


Related in: MedlinePlus