Dataset Information

Mechanical stimulation improves rotator cuff tendon-bone healing via activating IL-4/JAK/STAT signaling pathway mediated macrophage M2 polarization.

ABSTRACT:

Background

It is well known that appropriate mechanical stimulation benefits tendon-bone (T-B) healing, however, the mechanisms behind this are still uncovered completely. Here, we aimed to explore whether the IL-4/JAK/STAT signaling pathway mediated macrophage polarization was involved in mechanical stimulation induced T-B healing.

Method

C57BL/6 mice rotator cuff (RC) repair model was established, and the mice were randomly allocated to the following group. 1. Mice were allowed for free cage activities after surgery (FC group); 2. Mice received treadmill running initiated on postoperative day 7 (TR group); 3. Mice only received a local injection of hydrogel containing IL-4 neutralizing antibody without postoperative intervention (FC + AF-404-SP group); 4. Mice received a local injection of hydrogel containing IL-4 neutralizing antibody and postoperative treadmill running (TR + AF-404-SP group). The expression of IL-4 within supraspinatus tendon (SST) enthesis was measured by Enzyme-linked immunosorbent assay (ELISA). In addition, the activation of JAK/STAT signaling pathway in macrophages and identification of macrophage phenotype at the RC insertion site was detected by Flow cytometry and qRT-PCR. T-B healing quality in this RC repair model was evaluated by histological staining, Micro-computed tomography (Micro-CT) scanning, and biomechanical testing.

Result

In this study, using the RC repair model, we confirmed that generation of IL-4, activation of the JAK/STAT signaling pathway in macrophages, the ability of macrophages to polarize towards M2 subtype, and T-B healing quality were significantly enhanced in TR group compared to FC group. When comparing FC + AF-404-SP group with TR + AF-404-SP group, it was found that the mechanical stimulation induced this effect was depleted following the blockade of the IL-4/JAK/STAT signaling pathway.

Conclusion

Our finding suggested that mechanical stimulation could accelerate T-B healing via activating the IL-4/JAK/STAT signaling pathway that modulates macrophages to polarize towards M2 subtype.

The translational potential of this article

This is the first study to reveal a significant role of mechanical stimulation in the IL-4/JAK/STAT signaling pathway activation and macrophage polarization during RC T-B healing, which highlights the IL-4/JAK/STAT signaling pathway as a potential target to mediate macrophage M2 polarization and improves T-B healing for RC repair.

SUBMITTER: Liu Y

PROVIDER: S-EPMC9550856 | biostudies-literature | 2022 Nov

REPOSITORIES: biostudies-literature

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Publications

Mechanical stimulation improves rotator cuff tendon-bone healing via activating IL-4/JAK/STAT signaling pathway mediated macrophage M2 polarization.

Liu Yuqian Y Wang Linfeng L Li Shengcan S Zhang Tao T Chen Can C Hu Jianzhong J Sun Deyi D Lu Hongbin H

Journal of orthopaedic translation 20221006

<h4>Background</h4>It is well known that appropriate mechanical stimulation benefits tendon-bone (T-B) healing, however, the mechanisms behind this are still uncovered completely. Here, we aimed to explore whether the IL-4/JAK/STAT signaling pathway mediated macrophage polarization was involved in mechanical stimulation induced T-B healing.<h4>Method</h4>C57BL/6 mice rotator cuff (RC) repair model was established, and the mice were randomly allocated to the following group. 1. Mice were allowed ...[more]

PMID: 36262964

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Project description:BackgroundScar tissue formation at the tendon-bone interface caused by excessive inflammation leads to insufficient healing strength, while the phagocytic clearance of dying cells (efferocytosis) has profound consequences on macrophage polarisation and the inflammatory response. Modulating the inflammatory microenvironment may have satisfactory curative effects in patients with anterior cruciate ligament reconstruction (ACLR).MethodsBone marrow-derived macrophages (BMDMs) and polymorphonuclear leukocytes (PMNs) were harvested from bone marrow. The effects of milk fat globulin protein E8 (MFG-E8) on macrophage polarisation were compared with those of M1 and M2 macrophages induced by conventional methods. The BMDMs and apoptotic PMNs co-culture system was used to assess the efficiency of efferocytosis. The biological functions of MFG-E8 in tendon-bone healing by regulating macrophage efferocytosis and polarisation were further investigated using a rat ACLR model.ResultsBMDMs and PMNs were successfully isolated. Compared to conventional induction methods, MFG-E8 alone did not significantly induce macrophage M1 or M2 polarisation, but it could partially reverse the expression of inducible nitric oxide synthase (iNOS) in M1 macrophages. In vitro studies revealed that appropriate dosing of MFG-E8 could significantly promote the efficiency of macrophage efferocytosis and subsequently increase M2 polarisation. More importantly, significantly increased peri-tunnel new bone formation, tighter connected interface and better mechanical properties were observed after ACLR when treated with MFG-E8 in vivo. We further demonstrated that MFG-E8 remarkably facilitated the clearance of apoptotic cells and increased the number of M2 macrophages at the interface between the tendon graft and bone tunnel in the early postoperative stage.ConclusionMFG-E8 promoted tendon-bone healing histologically and biomechanically, probably by the regulation of inflammatory processes via macrophage efferocytosis and M2 polarisation.The translational potential of this article: Regulation of macrophage efferocytosis and M2 polarization by MFG-E8 is expected to be a therapeutic strategy for promoting tendon-bone healing in patients undergoing ACLR.

Project description:BackgroundMore than 450,000 rotator cuff repairs are performed annually, yet healing of tendon to bone often fails. This failure is rooted in the fibrovascular healing response, which does not regenerate the native attachment site. Better healing outcomes may be achieved by targeting inflammation during the early period after repair. Rather than broad inhibition of inflammation, which may impair healing, the current study utilized a molecularly targeted approach to suppress IKKβ, shutting down only the inflammatory arm of the nuclear factor κB (NF-κB) signaling pathway.PurposeTo evaluate the therapeutic potential of IKKβ inhibition in a clinically relevant model of rat rotator cuff repair.Study designControlled laboratory study.MethodsAfter validating the efficacy of the IKKβ inhibitor in vitro, it was administered orally once a day for 7 days after surgery in a rat rotator cuff repair model. The effect of treatment on reducing inflammation and improving repair quality was evaluated after 3 days and 2, 4, and 8 weeks of healing, using gene expression, biomechanics, bone morphometry, and histology.ResultsInhibition of IKKβ attenuated cytokine and chemokine production in vitro, demonstrating the potential for this inhibitor to reduce inflammation in vivo. Oral treatment with IKKβ inhibitor reduced NF-κB target gene expression by up to 80% compared with a nontreated group at day 3, with a subset of these genes suppressed through 14 days. Furthermore, the IKKβ inhibitor led to enhanced tenogenesis and extracellular matrix production, as demonstrated by gene expression and histological analyses. At 4 weeks, inhibitor treatment led to increased toughness, no effects on failure load and strength, and decreases in stiffness and modulus when compared with vehicle control. At 8 weeks, IKKβ inhibitor treatment led to increased toughness, failure load, and strength compared with control animals. IKKβ inhibitor treatment prevented the bone loss near the tendon attachment that occurred in repairs in control.ConclusionPharmacological inhibition of IKKβ successfully suppressed excessive inflammation and enhanced tendon-to-bone healing after rotator cuff repair in a rat model.Clinical relevanceThe NF-κB pathway is a promising target for enhancing outcomes after rotator cuff repair.

Dataset Information

Mechanical stimulation improves rotator cuff tendon-bone healing via activating IL-4/JAK/STAT signaling pathway mediated macrophage M2 polarization.

Background

Method

Result

Conclusion

The translational potential of this article

Publications

Mechanical stimulation improves rotator cuff tendon-bone healing via activating IL-4/JAK/STAT signaling pathway mediated macrophage M2 polarization.

Similar Datasets

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