Expression of xylosyltransferases I and II and their role in the pathogenesis of arthrofibrosis

Arthrofibrosis After Total Knee Arthroplasty: A Critical Analysis Review

» Arthrofibrosis after total knee arthroplasty (TKA) is the new formation of excessive scar tissue that results in limited ROM, pain, and functional deficits.» The diagnosis of arthrofibrosis is based on the patient's history, clinical examination, absence of alternative diagnoses from diagnostic testing, and operative findings. Imaging is helpful in ruling out specific causes of stiffness after TKA. A biopsy is not indicated, and no biomarkers of arthrofibrosis exist.» Arthrofibrosis pathophysiology is multifactorial and related to aberrant activation and proliferation of myofibroblasts that primarily deposit type I collagen in response to a proinflammatory environment. Transforming growth factor-beta signaling is the best established pathway involved in arthrofibrosis after TKA.» Management includes both nonoperative and operative modalities. Physical therapy is most used while revision arthroplasty is typically reserved as a last resort. Additional investigation into specific pathophysiologic mechanisms can better inform targeted therapeutics.

Warburg effect enhanced by AKR1B10 promotes acquired resistance to pemetrexed in lung cancer-derived brain metastasis

BACKGROUND

Resistance to pemetrexed (PEM), a rare chemotherapeutic agent that can efficiently cross the blood-brain barrier, limits the therapeutic efficacy for patients with lung cancer brain metastasis (BM). Aldo-keto reductase family 1 B10 (AKR1B10) was recently found to be elevated in lung cancer BM. The link between AKR1B10 and BM-acquired PEM is unknown.

METHODS

PEM drug-sensitivity was assessed in the preclinical BM model of PC9 lung adenocarcinoma cells and the BM cells with or without AKR1B10 interference in vitro and in vivo. Metabolic reprogramming of BM attributed to AKR1B10 was identified by chromatography-mass spectrometry (GC-MS) metabolomics, and the mechanism of how AKR1B10 mediates PEM chemoresistance via a way of modified metabolism was revealed by RNA sequencing as well as further molecular biology experimental approaches.

RESULTS

The lung cancer brain metastatic subpopulation cells (PC9-BrM3) exhibited significant resistance to PEM and silencing AKR1B10 in PC9-BrM3 increased the PEM sensitivity in vitro and in vivo. Metabolic profiling revealed that AKR1B10 prominently facilitated the Warburg metabolism characterized by the overproduction of lactate. Glycolysis regulated by AKR1B10 is vital for the resistance to PEM. In mechanism, AKR1B10 promoted glycolysis by regulating the expression of lactate dehydrogenase (LDHA) and the increased lactate, acts as a precursor that stimulates histone lactylation (H4K12la), activated the transcription of CCNB1 and accelerated the DNA replication and cell cycle.

CONCLUSIONS

Our finding demonstrates that AKR1B10/glycolysis/H4K12la/CCNB1 promotes acquired PEM chemoresistance in lung cancer BM, providing novel strategies to sensitize PEM response in the treatment of lung cancer patients suffering from BM.

Understanding of arthrofibrosis: New explorative insights into extracellular matrix remodeling of synovial fibroblasts

Arthrofibrosis following total knee arthroplasty is a fibroproliferative joint disorder marked by dysregulated biosynthesis of extracellular matrix proteins, such as collagens and proteoglycans. The underlying cellular events remain incompletely understood. Myofibroblasts are highly contractile matrix-producing cells characterized by increased alpha-smooth muscle actin expression and xylosyltransferase-I (XT-I) secretion. Human XT-I has been identified as a key mediator of arthrofibrotic remodeling. Primary fibroblasts from patients with arthrofibrosis provide a useful in vitro model to identify and characterize disease regulators and potential therapeutic targets. This study aims at characterizing primary synovial fibroblasts from arthrofibrotic tissues (AFib) regarding their molecular and cellular phenotype by utilizing myofibroblast cell culture models. Compared to synovial control fibroblasts (CF), AFib are marked by enhanced cell contractility and a higher XT secretion rate, demonstrating an increased fibroblast-to-myofibroblast transition rate during arthrofibrosis. Histochemical assays and quantitative gene expression analysis confirmed higher collagen and proteoglycan expression and accumulation in AFib compared to CF. Furthermore, fibrosis-based gene expression profiling identified novel modifier genes in the context of arthrofibrosis remodeling. In summary, this study revealed a unique profibrotic phenotype in AFib that resembles some traits of other fibroproliferative diseases and can be used for the future development of therapeutic interventions.

SNAI1-activated long non-coding RNA LINC01711 promotes hepatic fibrosis cell proliferation and migration by regulating XYLT1

Liver fibrosis is the result of the accumulation of extracellular matrix (ECM) that cannot be cleared. Bioinformatic analysis showed that LINC01711 was significantly overexpressed in hepatic fibrosis. The regulatory mechanism of LINC01711 was clarified and confirmed the transcription factors associated with LINC01711. Functionally, LINC01711 promoted LX-2 cell proliferation and migration, indicating that it exerts effects promoting the progression of hepatic fibrosis. Mechanistically, LINC01711 increased the expression of xylosyltransferase 1 (XYLT1), which is an important protein for constructing the ECM. We also confirmed that SNAI1 activated LINC01711 transcription. Taking these findings together, LINC01711 was induced by SNAI1 and promoted the proliferation and migration of LX-2 cells via XYLT1. This study will help to understand the function of LINC01711 and its regulatory mechanism in hepatic fibrosis.

Synovial Fluid Inflammatory Profiles did not Differ between Isolated Anterior Cruciate Ligament and Multi-ligament Knee Injuries

Objective and design

The purpose of this study was to compare synovial concentrations of pro- and anti-inflammatory cytokines between multiple-ligament knee injured (MLKI) and anterior cruciate ligament (ACL)-injured patients.

Subjects

14 patients with MLKI and 10 patients with isolated ACL injury.

Methods

Synovial fluid was aspirated from the operative knee at the time of surgery and the concentrations of pro- and anti-inflammatory markers in the synovial fluid were determined. Structures injured, the time between injury and surgery, and demographic factors were collected. Linear regressions were used to determine the association between injury pattern and synovial inflammatory markers when controlling for age, BMI, and time between injury and surgery.

Results

When adjusting for group differences in age, BMI and the time between injury and surgery, no group differences were detected (interferon gamma (p = 0.11), interleukin-1beta (IL-1b, p = 0.35), IL-2 (p = 0.28), IL-4 (p = 0.64), IL-6 (p = 0.37), IL-8 (p = 0.54), IL-10 (p = 0.25), IL-12p70 (p = 0.81), IL-13 (p = 0.31), and tumor necrosis factor-alpha (p = 0.90)).

Conclusion

Synovial fluid inflammatory markers did not differ between MLKI and isolated ACL injuries. MLKIs have a greater prevalence of postoperative arthrofibrosis when compared to isolated ACL injuries; however, this may be due in part to factors other than the inflammatory status of the joint.

Biochemical markers of postsurgical knee arthrofibrosis: A systematic review

Introduction

Postsurgical knee arthrofibrosis is a common complication associated with pain and limited range of motion. Although the mechanism is unclear, many biochemical and genetic markers have been identified within arthrofibrotic knees. The purpose of this systematic review is to synthesize the many biochemical and genetic markers that have been associated with surgery-induced knee arthrofibrosis in order to better guide future therapeutic endeavors.

Methods

A thorough search of literature was conducted on April 27, 2022. Seventeen studies met inclusion criteria for this systematic review. Inclusion criteria for this study were as follows: title or abstract discussed biochemical and genetic markers associated with postoperative knee arthrofibrosis, study design included human and/or animal subjects.

Results

A wide variety of genetic biomarkers (mRNA), proteins/enzymes, and cytokines were identified in both animal models and human subjects with postsurgical knee arthrofibrosis. These included various extracellular matrix-encoding mRNA sequences, matrix metalloproteinases, proteins and mRNA sequences involved in Transforming Growth Factor-β signaling, and interleukin-family cytokines to name just a few.

Conclusion

There are many biomarkers found in postsurgical arthrofibrotic knees. TGF-β, and mRNA/proteins that participate in TGF-β signaling (i.e., LOX, SERPINE1, PAI-1/Akt/mTOR, BMP-2), appear to be particularly common. Future comparative studies should aim to determine which of these are most relevant, and therefore, worthwhile therapeutic targets.

[Histopathological diagnostics of arthrofibrosis]

Joint surgery is one of the most important and successful disciplines in surgery; nevertheless, complications still occur, especially in total knee arthroplasty and surgery of the anterior cruciate ligament. A significant disease in this context is arthrofibrosis. This review article presents the cellular and molecular pathogenetic concept of arthrofibrosis, the spectrum of histopathological diagnostics and differential diagnostics and a classification into joint endoprosthesis-associated and non-joint endoprosthesis-associated arthrofibrosis is proposed. The basis of the histopathological diagnostics is the standardized tissue removal with subsequent fixation in formalin. In the case of joint implant failure and the problem of endoprosthesis-associated arthrofibrosis, the histopathological diagnostics can be carried out according to the consensus classification of synovia-like interface membrane (SLIM). Arthrofibrosis is characterized by fibrosis, a high fibroblast cellularity with immunohistochemical detection of cytoplasmic beta catenin expression. The presence of endoprosthesis-associated arthrofibrosis is probable above a threshold of 20 beta catenin positive fibroblasts per high-power field (HPF). The diagnosis of a non-endoprosthesis-associated arthrofibrosis can be classified according to the joint pathology algorithm. Diffuse non-endoprosthesis-associated arthrofibrosis is characterized by generalized proliferation of connective tissue in the whole joint and localized circumscribed arthrofibrosis is characterized by a nodose cyclops-like fibrosis. The clarification of the cause of arthrofibrosis is based on an interdisciplinary cooperation. In addition to the histopathological diagnostics, this includes clinical, surgical, biomechanical, arthroscopic, microbiological, laboratory parameter and radiological findings.

The Impact of Inflammatory Stimuli on Xylosyltransferase-I Regulation in Primary Human Dermal Fibroblasts

Inflammation plays a vital role in regulating fibrotic processes. Beside their classical role in extracellular matrix synthesis and remodeling, fibroblasts act as immune sentinel cells participating in regulating immune responses. The human xylosyltransferase-I (XT-I) catalyzes the initial step in proteoglycan biosynthesis and was shown to be upregulated in normal human dermal fibroblasts (NHDF) under fibrotic conditions. Regarding inflammation, the regulation of XT-I remains elusive. This study aims to investigate the effect of lipopolysaccharide (LPS), a prototypical pathogen-associated molecular pattern, and the damage-associated molecular pattern adenosine triphosphate (ATP) on the expression of XYLT1 and XT-I activity of NHDF. We used an in vitro cell culture model and mimicked the inflammatory tissue environment by exogenous LPS and ATP supplementation. Combining gene expression analyses, enzyme activity assays, and targeted gene silencing, we found a hitherto unknown mechanism involving the inflammasome pathway components cathepsin B (CTSB) and caspase-1 in XT-I regulation. The suppressive role of CTSB on the expression of XYLT1 was further validated by the quantification of CTSB expression in fibroblasts from patients with the inflammation-associated disease Pseudoxanthoma elasticum. Altogether, this study further improves the mechanistic understanding of inflammatory XT-I regulation and provides evidence for fibroblast-targeted therapies in inflammatory diseases.

Comparison of intra-articular administration of adenosine, lidocaine and magnesium solution and tranexamic acid for alleviating postoperative inflammation and joint fibrosis in an experimental model of knee arthroplasty

BACKGROUND

Dysregulated inflammatory responses are implicated in the pathogenesis of joint stiffness and arthrofibrosis following total knee arthroplasty (TKA). The purpose of this study was to compare the effects of intra-articular (IA) administration of tranexamic acid (TXA), an anti-fibrinolytic commonly used in TKA, and ALM chondroprotective solution on postoperative inflammation and joint tissue healing in a rat model of knee implant surgery.

METHODS

Male Sprague-Dawley rats (n = 24) were randomly divided into TXA or ALM treatment groups. The right knee of each rat was implanted with titanium (femur) and polyethylene (tibia) implants. An IA bolus (0.1 ml) of TXA or ALM was administered after implantation and capsule closure, and before skin closure. Postoperative coagulopathy, haematology and systemic inflammatory changes were assessed. Inflammatory and fibrotic markers were assessed in joint tissue, 28 days after surgery.

RESULTS

Haemostasis was comparable in animals treated with TXA or ALM after knee implant surgery. In contrast to ALM-treated animals, systemic inflammatory markers remained elevated at day 5 (IL-6, IL-12, IL-10, platelet count) and day 28 (IL-1β, IL-10) following surgery in TXA-treated animals. At day 28 following surgery, the extension range of motion of operated knees was 1.7-fold higher for ALM-treated animals compared to the TXA group. Key inflammatory mediators (NF-κB, IL-12, IL-2), immune cell infiltration (CD68+ cells) and markers of fibrosis (α-SMA, TGF-β) were also lower in capsular tissue of ALM-treated knees at day 28.

CONCLUSION

Data suggest that IA administration of ALM is superior to TXA for reducing postoperative systemic and joint inflammation and promoting restoration of healthy joint tissue architecture in a rat model of TKA. Further studies are warranted to assess the clinical translational potential of ALM IA solution to improve patient outcomes following arthroplasty.