Bradykinin, as a Reprogramming Factor, Induces Transdifferentiation of Brain Astrocytes into Neuron-like Cells

Activation of Bradykinin B2 Receptors in Astrocytes Stimulates the Release of Leukemia Inhibitory Factor for Autocrine and Paracrine Signaling

Communications between different cell types within a tissue are often critical for the proper functioning of an organ. In the central nervous system, interactions among neurons and glial cells are known to modulate neurotransmission, energy metabolism, extracellular ion homeostasis, and neuroprotection. Here we showed that bradykinin, a proinflammatory neuropeptide, can be detected by astrocytes, resulting in the secretion of cytokines that act on neurons. In astrocytic cell lines and primary astrocytes, bradykinin and several other ligands acting on Gq-coupled receptors stimulated Ca2+ mobilization, which subsequently led to the release of leukemia inhibitory factor (LIF) and interleukin-6 (IL-6). The bradykinin B2 receptor antagonist, HOE-140, effectively blocked the ability of bradykinin to mobilize Ca2+ and stimulate mitogen-activated protein kinases (MAPKs) in astrocytes. Interestingly, incubation of neuronal cell lines and primary cortical neurons with conditioned media from bradykinin-treated astrocytes resulted in the activation of STAT3, a key component downstream of LIF and IL-6 receptors. LIF was apparently the major active factor in the conditioned media as the STAT3 response was almost completely neutralized by an anti-LIF antiserum. The presence of kininogen and kallikrein transcripts in neuronal cells but not in astrocytic cells indicates that neurons can produce bradykinin. Correspondingly, conditioned media from neuronal cells stimulated MAPKs in astrocytes in a HOE-140-sensitive manner. These studies demonstrate that paracrine signaling between neurons and astrocytes may involve ligands of Gq-coupled receptors and cytokines such as LIF.

Advancements of 3D bioprinting in regenerative medicine: Exploring cell sources for organ fabrication

3D bioprinting has unlocked new possibilities for generating complex and functional tissues and organs. However, one of the greatest challenges lies in selecting the appropriate seed cells for constructing fully functional 3D artificial organs. Currently, there are no cell sources available that can fulfill all requirements of 3D bioprinting technologies, and each cell source possesses unique characteristics suitable for specific applications. In this review, we explore the impact of different 3D bioprinting technologies and bioink materials on seed cells, providing a comprehensive overview of the current landscape of cell sources that have been used or hold potential in 3D bioprinting. We also summarized key points to guide the selection of seed cells for 3D bioprinting. Moreover, we offer insights into the prospects of seed cell sources in 3D bioprinted organs, highlighting their potential to revolutionize the fields of tissue engineering and regenerative medicine.

Somatic Cell Reprogramming for Nervous System Diseases: Techniques, Mechanisms, Potential Applications, and Challenges

Nervous system diseases present significant challenges to the neuroscience community due to ethical and practical constraints that limit access to appropriate research materials. Somatic cell reprogramming has been proposed as a novel way to obtain neurons. Various emerging techniques have been used to reprogram mature and differentiated cells into neurons. This review provides an overview of somatic cell reprogramming for neurological research and therapy, focusing on neural reprogramming and generating different neural cell types. We examine the mechanisms involved in reprogramming and the challenges that arise. We herein summarize cell reprogramming strategies to generate neurons, including transcription factors, small molecules, and microRNAs, with a focus on different types of cells.. While reprogramming somatic cells into neurons holds the potential for understanding neurological diseases and developing therapeutic applications, its limitations and risks must be carefully considered. Here, we highlight the potential benefits of somatic cell reprogramming for neurological disease research and therapy. This review contributes to the field by providing a comprehensive overview of the various techniques used to generate neurons by cellular reprogramming and discussing their potential applications.

Quercetin exerts anti-inflammatory effects via inhibiting tumor necrosis factor-α-induced matrix metalloproteinase-9 expression in normal human gastric epithelial cells

BACKGROUND

Gastric injury is the most common digestive system disease worldwide and involves inflammation, which can lead to gastric ulcer or gastric cancer (GC). Matrix metallopeptidase-9 [MMP-9 (gelatinase-B)] plays an important role in inflammation and GC progression. Quercetin and quercetin-rich diets represent potential food supplements and a source of medications for treating gastric injury given their anti-inflammatory activities. However, the effects and mechanisms of action of quercetin on human chronic gastritis and whether quercetin can relieve symptoms remain unclear.

AIM

To assess whether tumor necrosis factor-α (TNF-α)-induced MMP-9 expression mediates the anti-inflammatory effects of quercetin in normal human gastric mucosal epithelial cells.

METHODS

The normal human gastric mucosa epithelial cell line GES-1 was used to establish a normal human gastric epithelial cell model of TNF-α-induced MMP-9 protein overexpression to evaluate the anti-inflammatory effects of quercetin. The cell counting Kit-8 assay was used to evaluate the effects of varying quercetin doses on cell viability in the normal GES-1 cell line. Cell migration was measured using Transwell assay. The expression of proto-oncogene tyrosine-protein kinase Src (c-Src), phospho (p)-c-Src, extracellular-signal-regulated kinase 2 (ERK2), p-ERK1/2, c-Fos, p-c-Fos, nuclear factor kappa B (NF-κB/p65), and p-p65 and the effects of their inhibitors were examined using Western blot analysis and measurement of luciferase activity. p65 expression was detected by immunofluorescence. MMP-9 mRNA and protein levels were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and gelatin zymography, respectively.

RESULTS

qRT-PCR and gelatin zymography showed that TNF-α induced MMP-9 mRNA and protein expression in a dose- and time-dependent manner. These effects were reduced by the pretreatment of GES-1 cells with quercetin or a TNF-α antagonist (TNFR inhibitor) in a dose- and time-dependent manner. Quercetin and TNF-α antagonists decreased the TNF-α-induced phosphorylation of c-Src, ERK1/2, c-Fos, and p65 in a dose- and time-dependent manner. Quercetin, TNF-α antagonist, PP1, U0126, and tanshinone IIA (TSIIA) reduced TNF-α-induced c-Fos phosphorylation and AP-1-Luciferase (Luc) activity in a dose- and time-dependent manner. Pretreatment with quercetin, TNF-α antagonist, PP1, U0126, or Bay 11-7082 reduced TNF-α-induced p65 phosphorylation and translocation and p65-Luc activity in a dose- and time-dependent manner. TNF-α significantly increased GES-1 cell migration, and these results were reduced by pretreatment with quercetin or a TNF-α antagonist.

CONCLUSION

Quercetin significantly downregulates TNF-α-induced MMP-9 expression in GES-1 cells via the TNFR-c-Src-ERK1/2 and c-Fos or NF-κB pathways.