Mediator Of Cellular Interactions Research Articles

Examination of antagonistic metabolic reactions and nicotinamide/methylnicotinamide as a biomarker in gastric cancer.

442 Background: Immune checkpoint inhibitors (ICIs) have revolutionized the therapy pattern of advanced gastric cancer (GC), but the efficacy is still unsatisfactory. The role of metabolism in the immune landscape of tumor microenvironment (TME) has been emphasized for the past few years. As the mediators of cellular interactions in TME, more metabolic biomarkers and their predictive value remain to be revealed. Methods: Metabolite activity scoring gene sets were constructed based on metabolite-protein interaction network. Integrated metabolite profile was collected from metabolic reactions in KEGG database. Transcriptome of ACRG (n=299) and anti-PD-1 cohort (PRJEB25780, n=45) were utilized to generate metabolite activity scores via GSVA algorithm. Cox regression was performed to calculate the hazard ratio (HR) to overall survival of metabolites in each metabolic reaction. Plasma samples (n=55) were obtained to measure nicotinamide metabolites from GC patients in Nanfang Hospital before and after ICIs treatment. Results: 78 metabolic reactions (78/6429) with opposite prognostic value among metabolic substrates and products were identified via the antagonistic metabolism screening workflow. Notably, nicotinamide (NAM)-methylnicotinamide (MNAM) (KEGG REACTION: R01269) showed significant antagonistic relationship (NAM, HR=0.76, 95% CI: 0.64-0.89, P<0.001; MNAM, HR=1.28, 95% CI: 1.09-1.49, P=0.002). NNMT, the rate-limiting enzyme catalyzing the formation of MNAM from NAM, was also correlated with poor prognosis (log-rank P=0.013). In terms of therapeutic prediction, NAM/MNAM ratio in plasma of GC patients was significantly correlated with anti-PD-1 response (PR vs SD/PD, median NAM/MNAM ratio (ng·mL-1/ng·mL-1) = 26.76 vs 10.40, P<0.0001). Compared with baseline, decreased plasma NAM/MNAM ratio was found in all (7/7) PR patients ( P=0.0011), while 73.33% (11/15) of non-responders showed a higher NAM/MNAM ratio after ICIs treatment ( P=0.0283). Correlation analysis of key metabolites with TME cells revealed that MNAM activity score was positively correlated with fibroblasts, MDSCs and M2 macrophages infiltration (Pearson correlation: R=0.60, P<0.001; R=0.42, P<0.001; R=0.34, P<0.001), suggesting that MNAM has a potential impact on immune-suppressive cells recruitment and functions. Conclusions: Nicotinamide metabolism was an indicator of prognosis in GC patients. Circulating NAM/MNAM ratio can be a novel metabolic biomarker in dynamic monitoring for ICIs therapy.

Exosomal MicroRNAs as Mediators of Cellular Interactions Between Cancer Cells and Macrophages.

Tumor microenvironment consists of cancer cells and various stromal cells such as endothelial cells, cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), neutrophils, macrophages, and other innate and adaptive immune cells. Of these innate immune cells, macrophages are an extremely heterogeneous population, and display both pro-inflammatory and anti-inflammatory functions. While M1 macrophages (classically activated macrophages) display anti-tumoral and pro-inflammatory functions, M2 macrophages display pro-tumoral and anti-inflammatory functions. Cellular interactions and molecular factors in the tumor microenvironment affect the polarization of macrophages. We review molecules and immune cells that influence the polarization status of macrophages. Tumor-associated macrophages (TAMs) generally express M2 phenotype, and mediate many processes that include tumor initiation, angiogenesis, and metastasis. A high number of TAMs has been associated with the poor prognosis of cancers. MicroRNAs (miRNAs) have been known to regulate cellular interactions that involve cancer cells and macrophages. Tumor-derived exosomes play critical roles in inducing the M1 or M2-like polarization of macrophages. The roles of exosomal miRNAs from tumor cells in the polarization of macrophages are also discussed and the targets of these miRNAs are presented. We review the effects of exosomal miRNAs from TAMs on cancer cell invasion, growth, and anti-cancer drug resistance. The relevance of exosomal microRNAs (miRNAs) as targets for the development of anti-cancer drugs is discussed. We review recent progress in the development of miRNA therapeutics aimed at elevating or decreasing levels of miRNAs.

Astrocytes and the TGF-β1 Pathway in the Healthy and Diseased Brain: a Double-Edged Sword.

Transforming growth factor betas (TGF-βs) are known as multifunctional growth factors that participate in the regulation of key events of development, disease, and tissue repair. In the brain, TGF-β1 has been widely recognized as an injury-related cytokine, particularly associated with astrocyte scar formation in response to brain injury. In the last decade, however, evidence has indicated that in addition to its role in brain injury, TGF-β1 might be a crucial regulator of cell survival and differentiation, brain homeostasis, angiogenesis, memory formation, and neuronal plasticity. In this review, we will discuss the emerging scenario of TGF-β1 as a key regulator of astrocyte differentiation and function and the implications of TGF-β1 as a novel mediator of cellular interactions in the central nervous system. First, we will discuss the cellular and molecular basis underlying the effect of TGF-β on astrocyte generation and its impact on angiogenesis and blood-brain barrier function. Then, we will focus on the role of astrocytes in the development and remodeling of synapses and the role of TGF-β1 as a new mediator of these events. Furthermore, we present seminal data that contributed to the emerging concept that astrocyte dysfunction might be associated with neurodegenerative diseases, with a special focus on Alzheimer's disease, and discuss the pros and cons of TGF-β signaling deficits in these processes. Finally, we argue that understanding how astrocytic signals, such as TGF-β1, regulate brain function might offer new insights into human learning, memory, and cognition, and ultimately, this understanding may provide new targets for the treatment of neurological diseases.

Factor h: a complement regulator in health and disease, and a mediator of cellular interactions.

Complement is an essential part of innate immunity as it participates in host defense against infections, disposal of cellular debris and apoptotic cells, inflammatory processes and modulation of adaptive immune responses. Several soluble and membrane-bound regulators protect the host from the potentially deleterious effects of uncontrolled and misdirected complement activation. Factor H is a major soluble regulator of the alternative complement pathway, but it can also bind to host cells and tissues, protecting them from complement attack. Interactions of factor H with various endogenous ligands, such as pentraxins, extracellular matrix proteins and DNA are important in limiting local complement-mediated inflammation. Impaired regulatory as well as ligand and cell recognition functions of factor H, caused by mutations or autoantibodies, are associated with the kidney diseases: atypical hemolytic uremic syndrome and dense deposit disease and the eye disorder: age-related macular degeneration. In addition, factor H binds to receptors on host cells and is involved in adhesion, phagocytosis and modulation of cell activation. In this review we discuss current concepts on the physiological and pathophysiological roles of factor H in light of new data and recent developments in our understanding of the versatile roles of factor H as an inhibitor of complement activation and inflammation, as well as a mediator of cellular interactions. A detailed knowledge of the functions of factor H in health and disease is expected to unravel novel therapeutic intervention possibilities and to facilitate the development or improvement of therapies.

Shedding of microparticles by myofibroblasts as mediator of cellular cross‐talk during normal wound healing

Interactions between cells are a crucial mechanism to correctly heal a wounded tissue. Myofibroblasts have a central role during healing but their means to communicate with other cells is unknown. Microparticles (MP) have demonstrated a potential role as mediators of cellular interactions during various diseases. We have analyzed the production of MP by normal (Wmyo) and pathological (hypertrophic scar, Hmyo) myofibroblasts and human dermal fibroblasts (Fb) when treated with serum or plasma as examples of body fluids. We have shown that the presence of these body fluids induced a very significant increase in MP production by Wmyo while no MP production was denoted for Hmyo and Fb. These effects were at least due to thermally sensitive protein(s) with a molecular mass >30 kDa. Furthermore, the increase in MP production was not linked to an increase in apoptotic Wmyo. MP characterization showed that VEGF and FGF2 were present in MP and that endothelial and (myo)fibroblast cell growth can be stimulated by MP treatment. We postulated that MP production by myofibroblasts could modulate mesenchymal cell growth and angiogenesis during normal healing.

Glycoconjugates as mediators of cellular interactions during development

Glycoconjugates as mediators of cellular interactions during development

Expression and enhanced secretion of proteochondroitin sulphate in a metastatic variant of a mouse lymphoma cell line.

Even though many studies suggest that proteoglycans with their structurally determinative polysaccharide chains, the glycosaminoglycans (GAGs), are important mediators of cellular interactions, little is known about expression and possible functions of these macromolecules expressed by tumour cells during the transition from low to highly metastatic behaviour. Therefore, we investigated the cellular expression and secretion of GAGs in a syngeneic tumour system of DBA/2 mice consisting of a methylcholanthrene-induced low metastatic T lymphoma (Eb), its highly metastatic spontaneous variant (ESb), and a low metastatic derivative of ESb (ESb-MP), selected by its adherent growth properties. The [35S]-sulphate-labelled GAGs were isolated from in vitro cultivated cells and further characterized by separation on Sepharose CL 6B, on Mono-Q ion exchange chromatography, and alkali- and enzymatic digestion. In contrast to Eb-cells which produce chondroitin/dermatan sulphate (CS/DS) and heparan sulphate (HS) (cellular extract: CS/DS 67%, HS 33%; culture medium: CS/DS 61%, HS 39%) ESb- and ESb-MP-cells only express and secrete CS/DS. For ESb cells the CS portions consisted of 42% chondroitin-4-sulphate (CS-4) and 58% chondroitin-6-sulphate (CS-6), for ESb-MP cells of 23% CS-4 and 77% CS-6, for Eb cells of 16% CS-4 and 84% CS-6. The cell surface GAGs of the adherent variant ESb-MP contained a significantly higher portion of DS (65%) compared to ESb cells (25%). GAGs of all tumour cell lines studied had a mol. wt ranging from 35-40 kD compared to GAG molecular weight standards. Ion exchange chromatography indicated that differences in charge density between GAGs of these cell lines were minimal. These findings suggest that the different biological behaviour of the cell lines cannot be attributed to altered size and charge density of their GAG chains. However, highly metastatic ESb-cells secreted significantly more GAG than low metastatic Eb- and ESb-MP-cells. The possible consequences of the enhanced secretion of CS/DS by ESb-cells are discussed in terms of the postulated role of CS/DS in cellular adhesion, growth regulation and interactions with the immune system.