Hua Liao

Background: This study aimed to investigate the role of myofiber-specific TGF-β signaling in the development of muscle inflammation by modulating Treg-cell-mediated macrophage efferocytosis. Methods: CTX-induced muscle injury was performed in the tibialis anterior (TA) of control (TGF-βr2 ^flox/flox ) and transgenic mice with skeletal muscle-specific deletion of TGF-β receptor 2 (SM TGF-βr2 ^−/− ). Gene levels of regulatory T cell (Treg) activation markers and inflammatory mediators produced by macrophages or Tregs were assessed using qRT-PCR. Intramuscular infiltration of Tregs and macrophages, as well macrophage phenotypes, efferocytic function, and associated signaling molecules, were evaluated using hematoxylin and eosin (HE) staining, immunofluorescence, immunoblotting and FACS analysis. The correlation of myofibers with Tregs-mediated macrophage efferocytosis were addressed under an in vitro co-culture system, which including Tregs, macrophages, and the differentiated myogenic precursor cells (MPC-myotubes) isolated from control or SM TGF-βr2 ^−/− mice. Apoptotic cells were generated by UV irradiation prior to transfer into inflamed muscle. Results: Deficiency in muscle TGF-β signaling resulted in more severe muscle inflammation, characterized by an increased number of M1 macrophages and a decreased number of M2 macrophages. Notably, the absence of muscle TGF-β signaling impaired the efferocytic capacity of macrophages and reduced the proportion of Tregs in inflamed muscle. Further, we monitored that activation of intrinsic TGF-β signaling suppresses myofiber IL-6 production, which in turn impacted on IL-13 production from Tregs accumulated in damaged muscle. This ultimately facilitates IL-10-STAT3-Vav1-mediated macrophage efferocytosis in inflamed muscle. Conclusions: Our findings establish a link between muscle-specific TGF-β signaling, myokine IL-6, Tregs derived IL-13 and macrophage efferocytosis in inflamed muscle. These results suggest that therapeutic targeting of this axis may hold promise for promoting muscle regeneration.

To enhance the biocompatibility and drug delivery efficiency of graphene oxide (GO), poly(ethylene glycol) (PEG), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), or its triblock copolymer PEG-PHBV-PEG (PPP) were used to chemically modify GO. However, it is still unknown whether non-toxic polymer-modified GO mediates muscle toxicity or triggers intramuscular inflammation. This study aims to investigate the biological reactivity and inflammation/immune response induced by PEG, PHBV, or PPP modified GO when injected into the tibialis anterior (TA) muscle of mice prior to drug loading. The results showed that after muscle exposure, the coating of biocompatible polymers on GO is more likely to provoke muscle necrosis. Muscle regeneration was found to occur earlier and more effectively in muscle treated with hydrophilic PEG-GO and PPP-GO compared to muscle treated with hydrophobic PHBV-GO. When observing the transient muscle macrophage invasion of three modified GOs, PHBV-GO caused severe muscle necrosis in the early stage, induced a delayed peak of macrophage aggregation, and caused severe inflammatory progression. All three kinds of modified GO induced T cell aggregation to varying degrees, but PEG-GO induced early mass muscle recruitment of CD4⁺ T cells and was more sensitive to cytotoxic T cells. Based on the higher biocompatibility of PPP-GO in muscles, PPP-GO was implanted into the muscles of old or adult mice. Compared to adult mice, aged mice are more vulnerable to the stress from PPP-GO, as demonstrated by a delayed inflammatory response and muscle regeneration.

Objectives: Treating femoral neck fractures remains a significant challenge for orthopedic surgeons and imposes a substantial economic burden on developing regions. Current novel internal fixation methods demonstrate excellent biomechanical performance. However, these new internal fixation methods are still associated with various complications. This study aimed to report the clinical complications of femoral neck system (FNS) and biplane double‐supported screw fixation (BDSF) treatments for femoral neck fractures at our institution and provide directions for selecting cost‐effective internal fixation methods.Methods: A retrospective case–control study of adult patients with femoral neck fractures treated with BDSF or FNS was conducted at Nanfang Hospital from April 2019 to April 2022. General medical records were collected both preoperatively and intraoperatively. Primary complication measures included osteonecrosis of the femoral head, nonunion, screw‐out, and subtrochanteric fractures, along with femoral neck shortening. The primary functional measure evaluated was the Harris hip score. This study employed t‐test, Wilcoxon rank‐sum test, and chi‐square test to statistically analyze the data.Results: Statistically significant differences were observed between the BDSF and FNS groups in terms of surgery duration (60.8 ± 12.6 min vs. 71.0 ± 12.0 min), incision length (5.5 ± 1.2 cm vs. 9.1 ± 1.6 cm) and hospitalization costs (39563.8 ± 9086.4 RMB vs. 24960.4 ± 10154.4 RMB). No statistically significant differences between the BDSF and FNS groups were found in the baseline data, blood loss or hospital stay. Moderate femoral neck shortening was significantly less common in the BDSF group than in the FNS group (27.1% vs. 61.5%, p = 0.016). Postoperatively, no statistically significant differences in complication rates, such as femoral head necrosis, nonunion, subtrochanteric fractures or screw‐out, were observed between the BDSF and FNS groups.Conclusions: This study revealed no significant difference in the incidence of postoperative complications such as femoral head necrosis, nonunion or screw cut‐out between BDSF and FNS. Although BDSF has drawbacks, such as a long learning curve and the potential to cause subtrochanteric fractures, it is cost‐effective and better maintains the length of the femoral neck. The modified BDSF technique may be more suitable for developing regions with limited health care budgets.

Ouyang L, et al. Clin Orthop Surg. 2025 Oct;17(5):763-772. https://doi.org/10.4055/cios25125

Summary: Background: The descending genicular artery (DGA) and medial thigh region have been underused as donor sites for perforator flaps. This study evaluated the anatomical relationship between the perforators of the DGA and the saphenous vein (SV) to review the clinical applications of the free descending genicular artery perforator (DGAP) flap for locoregional reconstruction. Methods: Fifteen cadavers were arterially perfused with red latex and dissected. Thirty-one patients with extremity tissue defects were treated with a free DGAP flap, including six patients who received a chimeric flap. The minimum distance between the DGAP and the SV was measured during surgery. Results: In all patients, the skin branch of the descending genicular artery was found in the medial femoral condyle plane in front of the SV. The average distance between the descending genicular artery perforator and the SV was 3.71 ± 0.38 cm (range: 2.9–4.3 cm). Thirty flaps survived completely, and one flap developed partial necrosis; however, this flap healed two weeks after skin grafting. The average follow-up time was 11.23 months. Conclusions: We conclude that the SV can be preserved when harvesting the descending genicular artery perforator flap, causing less damage to the donor site and having no effect on flap survival. The free descending genicular artery perforator flap without the SV is a better therapy for complicated tissue defects.

Background: Minimally invasive reduction and fixation of intra‐articular calcaneal fractures poses great challenges for orthopaedic surgeons. The aim of the present study was to report the technical points, evaluate the efficacy of minimally invasive reduction and internal fixation assisted by the temporary limb reconstruction system (LRS) external fixator for intra‐articular calcaneal fractures, and propose the indications of our protocol.Methods: In this retrospective study, a series of 34 consecutive closed and displaced intra‐articular calcaneal fractures involving the articular surface were treated by this technology between June 2016 and April 2018. X‐ray and computed tomography (CT) scans were performed before and after surgery to measure Bohler's angle; the length, height, and width of the calcaneus; and the mechanical axis of the hindfoot. Postoperative complications were recorded. Imaging and clinical outcomes were comprehensively evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot‐ankle scoring system. After testing the normality of the data, Bohler's angle and the length of calcaneus were compared using the Wilcoxon signed‐rank test. The height, width of the calcaneus, and the mechanical axis of the hindfoot were compared using the Paired‐Samples t‐test.Results: Thirty‐two fractures were followed up for an average of 20.66 months (from 12 to 32 months). All fractures achieved stable reduction and bony union. The articular surface was reduced and fixed with direct vision through the sinus tarsi incision. No failure of internal fixation or loss of reduction was detected during follow‐up. There were no soft tissue complications. Bohler's angle; the length, height, and width of the calcaneus; and the mechanical axis of the hindfoot improved significantly. The AOFAS scores averaged 84.12 points; seven cases were rated excellent, 20 good, four fair, and one poor.Conclusions: For intra‐articular calcaneal fractures, minimally invasive surgery assisted with temporary LRS external fixation can reconstruct the calcaneal shape and the sub‐talar articular surface. This simple surgical modality with limited complications may be helpful in the surgical treatment of most type II and III calcaneal fractures except comminuted fractures of the calcaneal tuberosity.

Background: To explore the role of skeletal muscle specific TGF-β signaling on macrophages efferocytosis in inflamed muscle caused by Cardiotoxin (CTX) injection. Methods: CTX myoinjury was manipulated in TGF-βr2^flox/flox (control) mice or transgenic mice with TGF-β receptor 2 (TGF-βr2) being specifically deleted in skeletal muscle (SM TGF-βr2^−/−). Gene levels of TGF-β signal molecules, special inflammatory mediators in damaged muscle or in cultured and differentiated myogenic precursor cells (MPC-myotubes) were monitored by transcriptome microarray or qRT-PCR. TGF-β pathway molecules, myokines and embryonic myosin heavy chain in regenerating myofibers, the phenotype and efferocytosis of macrophages were evaluated by immunofluorescence, immunoblotting, Luminex, or FACS analysis. In vitro apoptotic cells were prepared by UV-irradiation. Results: In control mice, TGF-β-Smad2/3 signaling were significantly up-regulated in regenerating centronuclear myofibers after CTX-myoinjury. More severe muscle inflammation was caused by the deficiency of muscle TGF-β signaling, with the increased number of M1, but the decreased number of M2 macrophages. Notably, the deficiency of TGF-β signaling in myofibers dramatically affected on the ability of macrophages to conduct efferocytosis, marked by the decreased number of Annexin-V⁻F4/80⁺Tunel⁺ macrophages in inflamed muscle, and the impaired uptake of macrophages to PKH67⁺ apoptotic cells transferred into damaged muscle. Further, our study suggested that, the intrinsic TGF-β signaling directed IL-10-Vav1-Rac1 efferocytosis signaling in muscle macrophages. Conclusions: Our data demonstrate that muscle inflammation can be suppressed potentially by activating the intrinsic TGF-β signaling in myofibers to promote IL-10 dependent-macrophages efferocytosis.

Endoplasmic reticulum stress (ERS) and the unfolded protein response (UPR) are involved in various muscle pathological states. The IRE1α arm of UPR can affect immunological properties of myofiber through restraining p38 mitogen-activated protein kinases (MAPK) activation under inflammatory milieu. However, the relevant pathway molecules regulating the initiation of the IRE1α arm in myofiber remain unclear. In this work, expression of transforming growth factor-beta (TGF-β) and TGF-β receptor II (TGF-βr2), and UPR pathway activation were examined in cardiotoxin (CTX)-damaged mouse muscle, which revealed the activation of TGF-β signaling and UPR in CTX-damaged muscle and in regenerating myofibers. Using control or transgenic mice with TGF-βr2 deleted in skeletal muscle (SM TGF-βr2^−/−) and the derived primary differentiating myogenic precursor cells (MPCs) treated with/without ERS activator or inhibitor, IRE1α pathway inhibitor, or TGF-β signaling activator, this study further revealed an essential role of intrinsic TGF-β signaling in regulating muscle cell to express inflammation-related molecules including H-2K^b, H2-Eα, TLR3, and special myokines. TGF-β signaling prompted UPR IRE1α arm and restrained p38 MAPK activation in myofiber under inflammatory milieu. This study uncovers a previously unrecognized function of TGF-β signaling acting as an upstream factor controlling myofiber immune capacities in the inflamed state through the UPR–IRE1α–p38 MAPK pathway.

As the understanding of skeletal muscle inflammation is increasingly clarified, the role of Treg cells in the treatment of skeletal muscle diseases has attracted more attention in recent years. A consensus has been reached that the regulation of Treg cells is the key to completing the switch of inflammation and repair of skeletal muscle, whose presence directly determine the repairing quality of the injured skeletal muscle. However, the functioning process of Treg cells remains unreported, thereby making it necessary to summarize the current role of Treg cells in skeletal muscle. In this review, the characteristics, origins, and cellular kinetics of these Treg cells are firstly described; Then, the relationship between Treg cells and muscle satellite cells (MuSCs), conventional T cells (Tconv) is discussed (the former is involved in the entire repair and regeneration process, while the latter matters considerably in causing most skeletal muscle autoimmune diseases); Next, focus is placed on the control of Treg cells on the phenotypic switch of macrophages, which is the key to the switch of inflammation; Finally, factors regulating the functional process of Treg cells are analyzed, and a regulatory network centered on Treg cells is summarized. The present study summarizes the cell-mediated interactions in skeletal muscle repair over the past decade, and elucidates the central role of regulatory T cells in this process, so that other researchers can more quickly and comprehensively understand the development and direction of this very field. It is believed that the hereby proposed viewpoints and problems can provide fresh visions for the latecomers.