Microbiology and Immunology Program, Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH.
Microbiology and Immunology Program, Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH
Immunohorizons. 2022 Jun 13;6(6):334-343. doi: 10.4049/immunohorizons.2100104.
Cardiac resident macrophages facilitate electrical conduction by interacting with cardiomyocytes via connexin-43 (Cx43) hemichannels. Cx43 is critical for impulse propagation and coordination between muscle contractions. Cardiomyocyte electrophysiology can be altered when coupled with noncardiomyocyte cell types such as M2c tissue-resident macrophages. Using cocultures of murine HL-1 cardiomyocytes and RAW 264.7 macrophages, we examined the hypothesis that cytokine signals, TGF-β1 and IL-10, upregulate Cx43 expression at points of contact between the two cell types. These cytokine signals maintain the macrophages in an M2c anti-inflammatory phenotype, mimicking cardiac resident macrophages. The electrophysiology of cardiomyocytes was examined using di-8-ANEPPS potentiometric dye, which reflects a change in membrane potential. Greater fluorescence intensity of di-8-ANEPPS occurred in areas where macrophages interacted with cardiomyocytes. Suppressor of cytokine signaling 3 (SOCS3) peptide mimetic downregulated fluorescence of this membrane potentiometric stain. Cx43 expression in cocultures was confirmed by fluorescence microscopy and flow cytometry. Confocal images of these interactions demonstrate the Cx43 hemichannel linkages between the cardiomyocytes and macrophages. These results suggest that TGF-β1 and IL-10 upregulate Cx43 hemichannels, thus enhancing macrophage-cardiomyocyte coupling, raising the cellular resting membrane potential and leading to a more excitatory cardiomyocyte.
心脏驻留巨噬细胞通过缝隙连接蛋白 43（Cx43）半通道与心肌细胞相互作用，促进电传导。Cx43 对冲动传播和肌肉收缩之间的协调至关重要。当与非心肌细胞类型（如 M2c 组织驻留巨噬细胞）偶联时，心肌细胞电生理学可以发生改变。我们使用 HL-1 心肌细胞和 RAW 264.7 巨噬细胞共培养物，检验了这样一个假设，即细胞因子信号 TGF-β1 和 IL-10 在两种细胞类型的接触点上调 Cx43 的表达。这些细胞因子信号维持巨噬细胞处于抗炎的 M2c 表型，模拟心脏驻留巨噬细胞。使用 di-8-ANEPPS 电势染料检测心肌细胞的电生理学，该染料反映膜电位的变化。巨噬细胞与心肌细胞相互作用的区域，di-8-ANEPPS 的荧光强度更大。细胞因子信号转导抑制因子 3（SOCS3）肽模拟物下调了这种膜电势染色的荧光。通过荧光显微镜和流式细胞术证实了共培养物中的 Cx43 表达。这些相互作用的共聚焦图像显示了心肌细胞和巨噬细胞之间的 Cx43 半通道连接。这些结果表明，TGF-β1 和 IL-10 上调 Cx43 半通道，从而增强巨噬细胞-心肌细胞偶联，提高细胞静息膜电位，并导致心肌细胞更兴奋。
