Tumor Necrosis Factor-Alpha Up-Regulates ICAM-1 Expression and Release in Intestinal Myofibroblasts by Redox-Dependent and -Independent Mechanisms

The role of reactive oxygen species in the regulation of the blood-brain barrier

The blood-brain barrier (BBB) regulates the exchange of metabolites and cells between the blood and brain, and maintains central nervous system homeostasis. Various factors affect BBB barrier functions, including reactive oxygen species (ROS). ROS can act as stressors, damaging biological molecules, but they also serve as secondary messengers in intracellular signaling cascades during redox signaling. The impact of ROS on the BBB has been observed in multiple sclerosis, stroke, trauma, and other neurological disorders, making blocking ROS generation a promising therapeutic strategy for BBB dysfunction. However, it is important to consider ROS generation during normal BBB functioning for signaling purposes. This review summarizes data on proteins expressed by BBB cells that can be targets of redox signaling or oxidative stress. It also provides examples of signaling molecules whose impact may cause ROS generation in the BBB, as well as discusses the most common diseases associated with BBB dysfunction and excessive ROS generation, open questions that arise in the study of this problem, and possible ways to overcome them.

Significance of Intercellular adhesion molecule-1 Lys496Glu gene polimorphism on plasma redox status regulation in laryngeal carcinoma

BACKGROUND

Intercellular adhesion molecule-1 (ICAM-1) is a surface glycoprotein important for tumor invasion and angiogenesis. The present research is conducted to investigate whether specific gene polymorphism of ICAM-1 K469E (rs5498) and plasma redox status could be associated with laryngeal cancer (LC) development. Since there is no clear evidence which investigates the relationship between ICAM-1 polymorphism and ROS-mediated plasma protein oxidation in LC, our study is the first significant contribution for investigating the relationship.

METHODS

The study covered patients with primary LC and their age-matched healthy control subjects. Evaluation of ICAM-1 K469E (rs5498) gene polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism. Plasma redox status was assessed with spectrophotometric methods.

RESULTS

In the current paper, we found that LC patients with GG genotype had a decreasing trend for the plasma oxidative damage biomarker levels when compared with all allele genotypes (AA and AG).

CONCLUSION

We concluded that G allele of the ICAM-1 K469E gene plays a significant role in the optimal regulation of plasma redox homeostasis in patients with LC.

Novel approaches to target fibroblast mechanotransduction in fibroproliferative diseases

The ability of cells to sense and respond to changes in mechanical environment is vital in conditions of organ injury when the architecture of normal tissues is disturbed or lost. Among the various cellular players that respond to injury, fibroblasts take center stage in re-establishing tissue integrity by secreting and organizing extracellular matrix into stabilizing scar tissue. Activation, activity, survival, and death of scar-forming fibroblasts are tightly controlled by mechanical environment and proper mechanotransduction ensures that fibroblast activities cease after completion of the tissue repair process. Conversely, dysregulated mechanotransduction often results in fibroblast over-activation or persistence beyond the state of normal repair. The resulting pathological accumulation of extracellular matrix is called fibrosis, a condition that has been associated with over 40% of all deaths in the industrialized countries. Consequently, elements in fibroblast mechanotransduction are scrutinized for their suitability as anti-fibrotic therapeutic targets. We review the current knowledge on mechanically relevant factors in the fibroblast extracellular environment, cell-matrix and cell-cell adhesion structures, stretch-activated membrane channels, stress-regulated cytoskeletal structures, and co-transcription factors. We critically discuss the targetability of these elements in therapeutic approaches and their progress in pre-clinical and/or clinical trials to treat organ fibrosis.

Role of Circadian Transcription Factor Rev-Erb in Metabolism and Tissue Fibrosis

Circadian rhythms significantly affect metabolism, and their disruption leads to cardiometabolic diseases and fibrosis. The clock repressor Rev-Erb is mainly expressed in the liver, heart, lung, adipose tissue, skeletal muscles, and brain, recognized as a master regulator of metabolism, mitochondrial biogenesis, inflammatory response, and fibrosis. Fibrosis is the response of the body to injuries and chronic inflammation with the accumulation of extracellular matrix in tissues. Activation of myofibroblasts is a key factor in the development of organ fibrosis, initiated by hormones, growth factors, inflammatory cytokines, and mechanical stress. This review summarizes the importance of Rev-Erb in ECM remodeling and tissue fibrosis. In the heart, Rev-Erb activation has been shown to alleviate hypertrophy and increase exercise capacity. In the lung, Rev-Erb agonist reduced pulmonary fibrosis by suppressing fibroblast differentiation. In the liver, Rev-Erb inhibited inflammation and fibrosis by diminishing NF-κB activity. In adipose tissue, Rev- Erb agonists reduced fat mass. In summary, the results of multiple studies in preclinical models demonstrate that Rev-Erb is an attractive target for positively influencing dysregulated metabolism, inflammation, and fibrosis, but more specific tools and studies would be needed to increase the information base for the therapeutic potential of these substances interfering with the molecular clock.

Functional expression of mitochondrial KCa3.1 channels in non-small cell lung cancer cells

Lung cancer is one of the leading causes of cancer-related deaths worldwide. The Ca²⁺-activated K⁺ channel K_Ca3.1 contributes to the progression of non-small cell lung cancer (NSCLC). Recently, K_Ca3.1 channels were found in the inner membrane of mitochondria in different cancer cells. Mitochondria are the main sources for the generation of reactive oxygen species (ROS) that affect the progression of cancer cells. Here, we combined Western blotting, immunofluorescence, and fluorescent live-cell imaging to investigate the expression and function of K_Ca3.1 channels in the mitochondria of NSCLC cells. Western blotting revealed K_Ca3.1 expression in mitochondrial lysates from different NSCLC cells. Using immunofluorescence, we demonstrate a co-localization of K_Ca3.1 channels with mitochondria of NSCLC cells. Measurements of the mitochondrial membrane potential with TMRM reveal a hyperpolarization following the inhibition of K_Ca3.1 channels with the cell-permeable blocker senicapoc. This is not the case when cells are treated with the cell-impermeable peptidic toxin maurotoxin. The hyperpolarization of the mitochondrial membrane potential is accompanied by an increased generation of ROS in NSCLC cells. Collectively, our results provide firm evidence for the functional expression of K_Ca3.1 channels in the inner membrane of mitochondria of NSCLC cells.

Protective Role of Natural and Semi-Synthetic Tocopherols on TNFα-Induced ROS Production and ICAM-1 and Cl-2 Expression in HT29 Intestinal Epithelial Cells

Vitamin E, a fat-soluble compound, possesses both antioxidant and non-antioxidant properties. In this study we evaluated, in intestinal HT29 cells, the role of natural tocopherols, α-Toc and δ-Toc, and two semi-synthetic derivatives, namely bis-δ-Toc sulfide (δ-Toc)₂S and bis-δ-Toc disulfide (δ-Toc)₂S₂, on TNFα-induced oxidative stress, and intercellular adhesion molecule-1 (ICAM-1) and claudin-2 (Cl-2) expression. The role of tocopherols was compared to that of N-acetylcysteine (NAC), an antioxidant precursor of glutathione synthesis. The results show that all tocopherol containing derivatives used, prevented TNFα-induced oxidative stress and the increase of ICAM-1 and Cl-2 expression, and that (δ-Toc)₂S and (δ-Toc)₂S₂ are more effective than δ-Toc and α-Toc. The beneficial effects demonstrated were due to tocopherol antioxidant properties, but suppression of TNFα-induced Cl-2 expression seems not only to be related with antioxidant ability. Indeed, while ICAM-1 expression is strongly related to the intracellular redox state, Cl-2 expression is TNFα-up-regulated by both redox and non-redox dependent mechanisms. Since ICAM-1 and Cl-2 increase intestinal bowel diseases, and cause excessive recruitment of immune cells and alteration of the intestinal barrier, natural and, above all, semi-synthetic tocopherols may have a potential role as a therapeutic support against intestinal chronic inflammation, in which TNFα represents an important proinflammatory mediator.

The myofibroblast at a glance

In 1971, Gabbiani and co-workers discovered and characterized the “modification of fibroblasts into cells which are capable of an active spasm” (contraction) in rat wound granulation tissue and, accordingly, named these cells ‘myofibroblasts’. Now, myofibroblasts are not only recognized for their physiological role in tissue repair but also as cells that are key in promoting the development of fibrosis in all organs. In this Cell Science at a Glance and the accompanying poster, we provide an overview of the current understanding of central aspects of myofibroblast biology, such as their definition, activation from different precursors, the involved signaling pathways and most widely used models to study their function. Myofibroblasts will be placed into context with their extracellular matrix and with other cell types communicating in the fibrotic environment. Furthermore, the challenges and strategies to target myofibroblasts in anti-fibrotic therapies are summarized to emphasize their crucial role in disease progression.

ADAM-17 is expressed on rheumatoid arthritis fibroblast-like synoviocytes and regulates proinflammatory mediator expression and monocyte adhesion

Background

To examine the expression of ADAM-17 in rheumatoid arthritis (RA) biological fluids and the role it plays in monocyte adhesion to RA fibroblast-like synoviocytes (FLSs).

Methods

ADAM-17 expression was measured by enzyme-linked immunosorbent assays (ELISAs) in serum from normal (NL) subjects, osteoarthritis (OA) patients, and RA patients. We also analyzed the correlation between ADAM-17 and disease activity score 28 (DAS28) in RA. To determine expression of ADAM-17 in RA synovial tissues (STs) and RA FLS, we performed immunofluorescence analyses. To determine the role of ADAM-17 in RA, we transfected RA FLSs with small interfering RNA (siRNA) against ADAM-17. THP-1 adhesion to ADAM-17 siRNA-transfected RA FLSs was measured. Finally, adhesion molecules on ADAM-17 siRNA-transfected RA FLSs were measured using cell surface ELISAs.

Results

ADAM-17 in RA serum was significantly higher than that in NL and OA serum and correlated with DAS28. ADAM-17 in RA synovial fluids was higher than that in OA synovial fluids. ADAM-17 was expressed on RA cells lining STs and RA FLSs. THP-1 adhesion to ADAM-17 siRNA-transfected RA FLSs was decreased compared with that to control siRNA-transfected RA FLSs. ICAM-1 on TNF-α-stimulated ADAM-17 siRNA-transfected RA FLSs was significantly decreased compared with that on control siRNA-transfected RA FLSs.

Conclusions

These data indicate that ADAM-17 is expressed on RA STs and plays a role in RA inflammation by regulating monocyte adhesion to RA FLSs. ADAM-17 might be an important inflammatory mediator in inflammatory diseases such as RA.

KCa3.1 channel inhibition leads to an ICAM-1 dependent increase of cell-cell adhesion between A549 lung cancer and HMEC-1 endothelial cells

Early metastasis leads to poor prognosis of lung cancer patients, whose 5-year survival rate is only 15%. We could recently show that the Ca²⁺ sensitive K⁺ channel K_Ca3.1 promotes aggressive behavior of non-small cell lung cancer (NSCLC) cells and that it can serve as a prognostic marker in NSCLC. Since NSCLC patients die of metastases, we investigated whether K_Ca3.1 channels contribute to poor patient prognosis by regulating distinct steps of the metastatic cascade. We investigated the extravasation of NSCLC cells and focused on their adhesion to endothelial cells and on transendothelial migration. We quantified the adhesion forces between NSCLC cells and endothelial cells by applying single cell force spectroscopy, and we monitored transendothelial migration using live-cell imaging. Inhibition of K_Ca3.1 channels with senicapoc or K_Ca3.1 silencing increases the adhesion force of A549 lung cancer cells to human microvascular endothelial cells (HMEC-1). Western blotting, immunofluorescence staining and biotinylation assays indicate that the elevated adhesion force is due to increased expression of ICAM-1 in both cell lines when K_Ca3.1 channels are downregulated. Consistent with this interpretation, an anti-ICAM-1 blocking antibody abolishes the K_Ca3.1-dependent increase in adhesion. Senicapoc inhibits transendothelial migration of A549 cells by 50%. Selectively silencing K_Ca3.1 channels in either NSCLC or endothelial cells reveals that transendothelial migration depends predominantly on endothelial K_Ca3.1 channels.

In conclusion, our findings disclose a novel function of K_Ca3.1 channels in cancer. K_Ca3.1 channels regulate ICAM-1 dependent cell-cell adhesion between endothelial and cancer cells that affects the transmigration step of the metastatic cascade.