Biology subjects

Li, T. M.

Publications and source records attributed to Li, T. M..

3 recordsLinked to original sources

bioRxiv2024

Tendon Inversion Improves Tendon-to-Bone Healing in a Rat Bicep Tenodesis Model

PurposeTendon- or ligament-to-bone repair remains a surgical challenge. While bone tunnel fixation is a common surgical technique whereby soft tissue is expected to heal against a bone tunnel interface, contemporary methods have yet to recapitulate biomechanical similarity to the native enthesis. In this study, we aim to demonstrate that inside-out longitudinal tendon inversion may improve bone tunnel healing with the hypothesis that inversion removes the gliding epitenon surface from the healing interface thereby improving tunnel interface healing. Methods40 male Sprague-Dawley rats underwent either native tendon tenodesis (control group) or tendon inversion tenodesis (experimental group). Interface tissue was harvested 8 weeks post-operatively. Biomechanical testing was performed to assess tensile strength and modes of failure. Histology was performed to assess tissue architecture, and immunohistochemistry was used confirmed abrogation of epitendinous lubricin from interface tissue. ResultsNeither surgical intervention led to discernible adverse effects on animal health. Maximum tensile strength increased after tendon inversion compared to control surgery. The extracellular matrix protein lubricin was reduced with tendon inversion, and specimens with tendon inversion had greater healing scores and collagen fibril alignment at the healing interface. ConclusionsTendon inversion improves bone tunnel healing in rats. Clinical RelevanceOur findings suggest that longitudinal tendon inversion, or inverse tubularization, in a rat biceps tenodesis model improves tendon-to-bone healing in part due to disruption of the epitendinous surface at the bone healing interface. This work provides molecular insight into future improvements for tendon-to-bone repair surgical techniques.

physiology↗

bioRxiv2021

Type I interferon modulates Langerhans cell ADAM17 to promote photosensitivity in lupus

BackgroundThe autoimmune disease lupus erythematosus (lupus) is characterized by photosensitivity, where even ambient ultraviolet radiation (UVR) exposure inflames skin. Beneficial effects of anifrolumab (anti-interferon /breceptor (anti-IFNAR)) on lupus skin disease support a pathogenic role for IFN-I, but mechanistic understanding is limited. We have shown that Langerhans cell (LC) dysfunction contributes to photosensitivity. Healthy LCs act via a disintegrin and metalloprotease 17 (ADAM17) to release epidermal growth factor receptor (EGFR) ligands that limit UVR-induced keratinocyte apoptosis and photosensitivity. However, LC ADAM17 activity is reduced in non-lesional lupus model skin, and data point to reduced LC-mediated protection in human lupus. Here, we asked about the role of the IFN-rich lupus skin environment in LC dysfunction and the implications of this regulation for photosensitivity. MethodsGene expression patterns in non-lesional skin from human lupus and multiple murine models were examined. We used MRL/lpr, B6.Sle1yaa, and imiquimod models of lupus in in vivo studies to assess the role of IFN-I in LC ADAM17 dysfunction and photosensitivity. ResultsWe show a shared IFN-rich environment in non-lesional skin across human and murine model systems, that IFN-I inhibits LC ADAM17 activity, and that anti-IFNAR in lupus models restores LC ADAM17 function and reduces photosensitivity in EGFR and LC ADAM17-dependent manners. Reactive oxygen species (ROS) can mediate ADAM17 activity, and we show reduced LC ROS expression in lupus models that is restored by anti-IFNAR. ConclusionsOur findings suggest that IFN-I promotes photosensitivity by causing LC ADAM17 dysfunction and that anifrolumab ameliorates lupus skin disease at least in part by restoring LC function. This work provides insight into IFN-I-mediated disease mechanisms, LC regulation, and a mechanism of action for anifrolumab in lupus.

immunology↗

bioRxiv2019

Adaptive and Innate Immune Cell Responses in Tendons and Lymph Nodes After Tendon Injury and Repair

Tendon injuries are a common clinical condition with limited treatment options. The cellular components of the innate system, such as neutrophils and macrophages, have been well studied in tendon injuries. However the adaptive immune system, comprised of specialized lymphocytes, plays an important role in orchestrating the healing of numerous tissues but less is known about these cells in tendon healing. To gain a greater understanding of the biological processes that regulate tendon healing, we sought to determine how the cellular components of the adaptive and innate immune system respond to a tendon injury using two-month old male mice. We determined that the lymphatic vasculature is present in the epitenon and superficial regions of Achilles tendons. We then created an acute Achilles tenotomy followed by repair, and collected tendons and draining lymph nodes one, two, and four weeks after injury. Using flow cytometry and histology, after tendon injury we observed a robust adaptive immune cell response that followed an initial innate immune cell response. There was an accumulation of monocytes, neutrophils, and macrophages one week after injury that declined thereafter. Dendritic cells and CD4+ T cells peaked two weeks after injury, while B cells and CD8+ T cells progressively increased over time. In parallel, immune cells of the draining popliteal lymph node demonstrated a similarly coordinated response to the injury. These results suggest that there is an adaptive immune response to tendon injury and adaptive immune cells may play a role in regulating tendon healing.

physiology↗