MICAL2 regulates myofibroblasts differentiation in epidural fibrosis via SRF/MRTF-A signaling pathway

Insights into the pathophysiology and response of persistent spinal pain syndrome type 2 to spinal cord stimulation: a human genome-wide association study

BACKGROUND

Spinal cord stimulation (SCS) provides pain relief for some patients with persistent spinal pain syndrome type 2 (PSPS 2), but the precise mechanisms of action and prognostic factors for a favorable pain response remain obscure. This in vivo human genome-wide association study provides some pathophysiological clues.

METHODS

We performed a high-density oligonucleotide microarray analysis of serum obtained from both PSPS 2 cases and pain-free controls who had undergone lower back spinal surgery at the study site. Using multivariate discriminant analysis, we tried to identify different expressions between mRNA transcripts from PSPS 2 patients relative to controls, SCS responders to non-responders, or SCS responders to themselves before starting SCS. Gene ontology enrichment analysis was used to identify the biological processes that best discriminate between the groups of clinical interest.

RESULTS

Thirty PSPS 2 patients, of whom 23 responded to SCS, were evaluated together with 15 pain-free controls. We identified 11 significantly downregulated genes in serum of PSPS 2 patients compared with pain-free controls and two significantly downregulated genes once the SCS response became apparent. All were suggestive of enhanced inflammation, tissue repair mechanisms and proliferative responses among the former. We could not identify any gene differentiating patients who responded to SCS from those who did not respond.

CONCLUSIONS

This study points out various biological processes that may underlie PSPS 2 pain and SCS therapeutic effects, including the modulation of neuroimmune response, inflammation and restorative processes.

MICAL2 implies immunosuppressive features and acts as an independent and adverse prognostic biomarker in pancreatic cancer

At present, clinical outcomes of pancreatic cancer patients are still poor. New therapeutic targets for pancreatic cancer are urgently needed. Previous studies have indicated that Microtubule Associated Monooxygenase, Calponin and LIM Domain Containing 2 (MICAL2) is highly expressed in many tumors and promotes tumor progression. However, the role played by MICAL2 in pancreatic cancer remains unclear. Based on gene expression and clinical information from multiple datasets, we used comprehensive bioinformatics analysis in combination with tissue microarray to explore the function and clinical value of MICAL2. The results showed that MICAL2 was highly expressed in pancreatic cancer tissue and exhibited potential diagnostic capability. High expression of MICAL2 was also associated with poor prognosis and acted as an independent prognostic factor. MICAL2, mainly expressed in fibroblasts of pancreatic cancer, was closely related to metastasis and immune-related features, such as epithelial-mesenchymal transformation, extracellular cell matrix degradation, and inflammatory response. Furthermore, higher MICAL2 expression in pancreatic cancer was also associated with an increase in cancer-associated fibroblasts as well as M2 macrophage infiltration, and a reduction in CD8 + T cell infiltration, thereby facilitating the formation of an immunosuppressive microenvironment. Our results helped elucidate the clinical value and function in metastasis and immunity of MICAL2 in pancreatic cancer. These findings provided potential clinical strategies for diagnosis, targeted therapy combination immunotherapy, and prognosis in patients with pancreatic cancer.

Mechanical stiffness promotes skin fibrosis through FAPα-AKT signaling pathway

BACKGROUND

Myofibroblasts contribute to the excessive production, remodeling and cross-linking of the extracellular matrix that characterizes the progression of skin fibrosis. An important insight into the pathogenesis of tissue fibrosis has been the discovery that increased matrix stiffness during fibrosis progression is involved in myofibroblast activation. However, mechanistic basis for this phenomenon remains elusive.

OBJECTIVE

To explore the role of fibroblast activation protein-α (FAPα) in mechanical stiffness-induced skin fibrosis progression.

METHODS

RNA-seq was performed to compare differential genes of mouse dermal fibroblasts (MDFs) grown on low or high stiffness plates. This process identified FAPα, which is a membrane protein usually overexpressed in activated fibroblasts, as a suitable candidate. In vitro assay, we investigate the role of FAPα in mechanical stiffness-induced MDFs activation and downstream pathway. By establishing mouse skin fibrosis model and intradermally administrating FAPα adeno-associated virus (AAV) or a selective Fap inhibitor FAPi, we explore the role of FAPα in skin fibrosis in vivo.

RESULTS

We show that FAPα, a membrane protein highly expressed in myofibroblasts of skin fibrotic tissues, is regulated by increased matrix stiffness. Genetic deletion or pharmacological inhibition of FAPα significantly inhibits mechanical stiffness-induced activation of myofibroblasts in vitro. Mechanistically, FAPα promotes myofibroblast activation by stimulating the PI3K-Akt pathway. Furthermore, we showed that administration of the inhibitor FAPi or FAPα targeted knockdown ameliorated the progression of skin fibrosis.

CONCLUSION

Taken together, we identify FAPα as an important driver of mechanical stiffness-induced skin fibrosis and a potential therapeutic target for the treatment of skin fibrosis.

Evaluation of the effectiveness of oxytocin and enalapril in the prevention of epidural fibrosis developed after laminectomy in rats

INTRODUCTION

Except for methylprednisolone, there is no current low-cost and low-side-effect drug/barrier method to prevent epidural fibrosis after spine surgery. However, the use of methylprednisolone has led to substantial controversy because of its serious side effects on wound healing. This study aimed to evaluate the effects of enalapril and oxytocin on preventing the development of epidural fibrosis in a rat laminectomy model.

MATERIALS

Under sedation anesthesia, T9, T10, and T11 laminectomy was performed on 24 Wistar Albino male rats. The animals were then separated into four groups; Sham group (only laminectomy was performed; n = 6), MP group (laminectomy was performed and 10 mg/kg/day methylprednisolone was administered intraperitoneally (ip) for 14 days; n = 6), ELP group (laminectomy was performed and 0.75 mg/kg/day enalapril was administered ip for 14 days; n = 6), OXT group (laminectomy was performed and 160 µg/kg/day oxytocin was administered ip for 14 days; n = 6). Four weeks after the laminectomy, all the rats were euthanised, and the spines were removed for histopathological, immunohistochemical, and biochemical examinations.

RESULTS

Histopathological examinations revealed that the degree of epidural fibrosis (X²=14.316, p = 0.003), collagen density (X²=16.050, p = 0.001), and fibroblast density (X²=17.500, p = 0.001) was higher in the Sham group and lower in the MP, ELP, and OXT groups. Immunohistochemical examinations showed that collagen type 1 immunoreactivity was higher in the Sham group and lower in the MP, ELP, and OXT groups (F = 54.950, p < 0.001). The highest level of α-smooth muscle actin immunoreactivity was seen in the Sham and OXT groups, and the lowest was in the MP and ELP groups (F = 33.357, p < 0.001). Biochemical analysis revealed that tissue levels of TNF-α, TGF-β, IL-6, CTGF, caspase-3, p-AMPK, pmTOR, and mTOR/pmTOR were higher in the Sham group and lower in MP, ELP, and OXT groups (p < 0.05). The GSH/GSSG levels were lower in the Sham group and higher in the other three groups (X²=21.600, p < 0.001).

CONCLUSION

The study results showed that enalapril and oxytocin, which are known to have anti-inflammatory, antioxidant, anti-apoptotic, and autophagy-related regenerative properties, could reduce the development of epidural fibrosis after laminectomy in rats.

MICAL-mediated oxidation of actin and its effects on cytoskeletal and cellular dynamics

Actin and its dynamic structural remodelings are involved in multiple cellular functions, including maintaining cell shape and integrity, cytokinesis, motility, navigation, and muscle contraction. Many actin-binding proteins regulate the cytoskeleton to facilitate these functions. Recently, actin's post-translational modifications (PTMs) and their importance to actin functions have gained increasing recognition. The MICAL family of proteins has emerged as important actin regulatory oxidation-reduction (Redox) enzymes, influencing actin's properties both in vitro and in vivo. MICALs specifically bind to actin filaments and selectively oxidize actin's methionine residues 44 and 47, which perturbs filaments' structure and leads to their disassembly. This review provides an overview of the MICALs and the impact of MICAL-mediated oxidation on actin's properties, including its assembly and disassembly, effects on other actin-binding proteins, and on cells and tissue systems.

Continuous release of mefloquine featured in electrospun fiber membranes alleviates epidural fibrosis and aids in sensory neurological function after lumbar laminectomy

Recurrent low back pain after spinal surgeries, such as lumbar laminectomy, is a major complication of excessive epidural fibrosis. Although multiple preclinical and clinical methods have been aimed at ameliorating epidural fibrosis, their safety and efficacy remain largely unclear. Single implanted electrospun fibrous membranes provide physical barriers that can decrease tissue fibrosis after surgery; however, they also trigger local inflammation due to the implantation of a foreign body, thus subsequently attenuating their anti-fibrosis properties. Here, we designed a strategy that permits easy incorporation of mefloquine into polylactic acid membranes, and stable long-term mefloquine release, to potentially improve anti-fibrosis effects and relieve or prevent low back pain.

The electrospun fibrous membranes grafted with mefloquine showed a well-controlled early temporary peak release, and secondary drug release occurred smoothly over several weeks. Histopathological and histomorphometric results indicated that the drug-loaded membranes had excellent anti-fibrosis effects after laminectomy in rats. Inflammation and neovascularization at the surgical site indicated that the mefloquine-grafted electrospun fibrous membranes provided sustained anti-inflammatory outcomes while effectively alleviating associated neuropathic pain hypersensitivity. In summary, our study indicated that polylactic acid-mefloquine grafted electrospun fibrous membranes may be a potential local agent to mitigate epidural fibrosis and support sensory neurological function after laminectomy, thereby potentially improving patients’ postoperative outcomes.

Oxidation and reduction of actin: Origin, impact in vitro and functional consequences in vivo

Actin is among the most abundant proteins in eukaryotic cells and assembles into dynamic filamentous networks regulated by many actin binding proteins. The actin cytoskeleton must be finely tuned, both in space and time, to fulfill key cellular functions such as cell division, cell shape changes, phagocytosis and cell migration. While actin oxidation by reactive oxygen species (ROS) at non-physiological levels are known for long to impact on actin polymerization and on the cellular actin cytoskeleton, growing evidence shows that direct and reversible oxidation/reduction of specific actin amino acids plays an important and physiological role in regulating the actin cytoskeleton. In this review, we describe which actin amino acid residues can be selectively oxidized and reduced in many different ways (e.g. disulfide bond formation, glutathionylation, carbonylation, nitration, nitrosylation and other oxidations), the cellular enzymes at the origin of these post-translational modifications, and the impact of actin redox modifications both in vitro and in vivo. We show that the regulated balance of oxidation and reduction of key actin amino acid residues contributes to the control of actin filament polymerization and disassembly at the subcellular scale and highlight how improper redox modifications of actin can lead to pathological conditions.

Mapping the cardiac vascular niche in heart failure

The cardiac vascular and perivascular niche are of major importance in homeostasis and during disease, but we lack a complete understanding of its cellular heterogeneity and alteration in response to injury as a major driver of heart failure. Using combined genetic fate tracing with confocal imaging and single-cell RNA sequencing of this niche in homeostasis and during heart failure, we unravel cell type specific transcriptomic changes in fibroblast, endothelial, pericyte and vascular smooth muscle cell subtypes. We characterize a specific fibroblast subpopulation that exists during homeostasis, acquires Thbs4 expression and expands after injury driving cardiac fibrosis, and identify the transcription factor TEAD1 as a regulator of fibroblast activation. Endothelial cells display a proliferative response after injury, which is not sustained in later remodeling, together with transcriptional changes related to hypoxia, angiogenesis, and migration. Collectively, our data provides an extensive resource of transcriptomic changes in the vascular niche in hypertrophic cardiac remodeling.

The cardiac vascular niche is of major importance in homeostasis and disease, but knowledge of its complexity in response to injury remains limited. Here we combine lineage tracing with single cell RNA sequencing to show alterations in fibroblasts, endothelial and mural cells in hypertrophic remodeling.