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Introduction: Cardiac fibroblasts (CF) are crucial cells in damaged heart tissues, expressing TLR4, IFN-receptor and responding to lipopolysaccharide (LPS) and interferon-ß (IFN-ß) respectively. While CF interact with immune cells; however, their relationship with neutrophils remains understudied. Additionally, theimpact of LPS and IFN-ß on CF-neutrophil interaction is poorly understood. Methods: Isolated CF from adult rats were treated with LPS, with or without IFN-ß. This study examined IL-8 secretion, ICAM-1 and VCAM-1 expression, and neutrophil recruitment, as well as their effects on MMPs activity. Results: LPS triggered increased IL-8 expression and secretion, along with elevated ICAM-1 and VCAM-1 expression, all of which were blocked by TAK-242. Pre-treatment with IFN-ß countered these LPS effects. LPS treated CF showed higher neutrophil recruitment (migration and adhesion) compared to unstimulated CF, an effect prevented by IFN-ß. Ruxolitinib blocked these IFN-ß anti-inflammatory effects, implicating JAK signaling. Analysis of culture medium zymograms from CF alone, and CF-neutrophils interaction, revealed that MMP2 was mainly originated from CF, while MMP9 could come from neutrophils. LPS and IFN-ß boosted MMP2 secretion by CF. MMP9 activity in CF was low, and LPS or IFN-ß had no significant impact. Pre-treating CF with LPS, IFN-ß, or both before co-culture with neutrophils increased MMP2. Neutrophil co-culture increased MMP9 activity, with IFN-ß pre-treatment reducing MMP9 compared to unstimulated CF. Conclusion: In CF, LPS induces the secretion of IL-8 favoring neutrophils recruitment and these effects were blocked by IFN-. The results highlight that CF-neutrophil interaction appears to influence the extracellular matrix through MMPs activity modulation.

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Cardiac fibroblasts are a cell population that controls the homeostasis of the extracellular matrix and orchestrates a damage response to maintain cardiac architecture and performance. Due to these functions, fibroblasts play a central role in cardiac fibrosis development, and there are large differences in matrix protein secretion profiles between fibroblasts from aged versus young animals. Senescence is a multifactorial and complex process that has been associated with inflammatory and fibrotic responses. After damage, transient cellular senescence is usually beneficial, as these cells promote tissue repair. However, the persistent presence of senescent cells within a tissue is linked with fibrosis development and organ dysfunction, leading to aging-related diseases such as cardiovascular pathologies. In the heart, early cardiac fibroblast senescence after myocardial infarction seems to be protective to avoid excessive fibrosis; however, in non-infarcted models of cardiac fibrosis, cardiac fibroblast senescence has been shown to be deleterious. Today, two new classes of drugs, termed senolytics and senostatics, which eliminate senescent cells or modify senescence-associated secretory phenotype, respectively, arise as novel therapeutical strategies to treat aging-related pathologies. However, further studies will be needed to evaluate the extent of the utility of senotherapeutic drugs in cardiac diseases, in which pathological context and temporality of the intervention must be considered.

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Angiotensin II (Ang-II) is a widely studied hypertensive, profibrotic, and pro-inflammatory peptide. In the heart, cardiac fibroblasts (CF) express type 1 angiotensin II receptors (AT1R), Toll-like receptor-4 (TLR4), and the NLRP3 inflammasome complex, which play important roles in pro-inflammatory processes. When activated, the NLRP3 inflammasome triggers proteolytic cleavage of pro-IL-1, resulting in its activation. However, in CF the mechanism by which Ang-II assembles and activates the NLRP3 inflammasome remains not fully known. To elucidate this important point, we stimulated TLR4 receptors in CF and evaluated the signaling pathways by which Ang-II triggers the assembly and activity. In cultured rat CF, pro-IL-1ß levels, NLRP3, ASC, and caspase-1 expression levels were determined by Western blot. NLRP3 inflammasome complex assembly was analyzed by immunocytochemistry, whereas by ELISA, we analyzed NLRP3 inflammasome activity and [Formula: see text] release. In CF, Ang-II triggered NLRP3 inflammasome assembly and caspase-1 activity; and in LPS-pretreated CF, Ang-II also triggered [Formula: see text] secretion. These effects were blocked by losartan (AT1R antagonist), U73221 (PLC inhibitor), 2-APB (IP3R antagonist), and BAPTA-AM (Ca2+ chelator) indicating that the AT1R/PLC/IP3R/Ca2+ pathway is involved. Finally, bafilomycin A1 prevented Ang-II-induced [Formula: see text] secretion, indicating that a non-classical protein secretion mechanism is involved. These findings suggest that in CF, Ang-II by a Ca2+-dependent mechanism triggers NLRP3 inflammasome assembly and activation leading to [Formula: see text] secretion through a non-conventional protein secretion mechanism.

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Cardiac fibroblasts (CF) play an important role in the healing process and in pathological remodeling of cardiac tissue. As sentinel cells in the heart, they respond to inflammatory stimuli, expressing cytokines and cell adhesion proteins, which ultimately lead to increased recruitment of monocytes and enhancement of the inflammatory response. Angiotensin II (Ang II) triggers an inflammatory response, leading to cardiac tissue remodeling. On the other hand, RvD1 has been shown to contribute to the resolution of inflammation; however, its role in Ang II-treated CF has not been addressed until now. The present research aimed to study the effect of RvD1 on cytokine levels, cell adhesion proteins expression in a model of Ang II-triggered inflammatory response. CF from adult Sprague Dawley rats were used to study mRNA and protein levels of MCP-1, IL-6, TNF-a, IL-10, ICAM-1 and VCAM-1; and adhesion of spleen mononuclear cells to CF after Ang II stimulation. Our results show that Ang II increased IL-6, MCP-1 and TNF-a mRNA levels, but only increased IL-6 and MCP-1 protein levels. These effects were blocked by Losartan, but not by PD123369. Moreover, RvD1 was able to prevent all Ang II effects in CF. Additionally, RvD1 reduced the intracellular Ca2+ increase triggered by Ang II, indicating that RvD1 acts in an early manner to block Ang II signaling. Conclusion: our findings confirm the pro-resolutive effects of inflammation by RvD1, which at the cardiovascular level, could contribute to repair damaged cardiac tissue.

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Death of cardiac fibroblasts (CFs) by ischemia/reperfusion (I/R) has major implications for cardiac wound healing. In in vivo models of myocardial infarction, toll-like receptor 4 (TLR4) activation has been reported as a cardioprotector; however, it remains unknown whether TLR4 activation can prevent CF death triggered by simulated I/R (sI/R). In this study, we analyzed TLR4 activation in neonate CFs exposed to an in vitro model of sI/R and explored the participation of the pro-survival kinases Akt and ERK1/2. Simulated ischemia was performed in a free oxygen chamber in an ischemic medium, whereas reperfusion was carried out in normal culture conditions. Cell viability was analyzed by trypan blue exclusion and the MTT assay. Necrotic and apoptotic cell populations were evaluated by flow cytometry. Protein levels of phosphorylated forms of Akt and ERK1/2 were analyzed by Western blot. We showed that sI/R triggers CF death by necrosis and apoptosis. In CFs exposed only to simulated ischemia or only to sI/R, blockade of the TLR4 with TAK-242 further reduced cell viability and the activation of Akt and ERK1/2. Preconditioning with lipopolysaccharide (LPS) or treatment with LPS in ischemia or reperfusion was not protective. However, LPS incubation during both ischemia and reperfusion periods prevented CF viability loss induced by sI/R. Furthermore, LPS treatment reduced the sub-G1 population, but not necrosis of CFs exposed to sI/R. On the other hand, the protective effects exhibited by LPS were abolished when TLR4 was blocked and Akt and ERK1/2 were inhibited. In conclusion, our results suggest that TLR4 activation protects CFs from apoptosis induced by sI/R through the activation of Akt and ERK1/2 signaling pathways.

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Cardiac fibroblasts (CFs) have a key role in the inflammatory response after cardiac injury and are necessary for wound healing. Resolvins are potent agonists that control the duration and magnitude of inflammation. They decrease mediators of pro-inflammatory expression, reduce neutrophil migration to inflammation sites, promote the removal of microbes and apoptotic cells, and reduce exudate. However, whether resolvins can prevent pro-inflammatory-dependent effects in CFs is unknown. Thus, the present work was addressed to study whether resolvin D1 and E1 (RvD1 and RvE1) can prevent pro-inflammatory effects on CFs after lipopolysaccharide (LPS) challenge. For this, CFs were stimulated with LPS, in the presence or absence of RvD1 or RvE1, to analyze its effects on intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion protein 1 (VCAM-1), monocyte adhesion and the cytokine levels of tumor necrosis factor alpha (TNF-α), interleukin-6(IL-6), interleukin-1beta (IL-1ß), monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10). Our results showed that CFs are expressing ALX/FPR2 and ChemR23, RvD1 and RvE1 receptors, respectively. RvD1 and RvE1 prevent the increase of ICAM-1 and VCAM-1 protein levels and the adhesion of spleen mononuclear cells to CFs induced by LPS. Finally, RvD1, but not RvE1, prevents the LPS-induced increase of IL-6, MCP-1, TNF-α, and IL-10. In conclusion, our findings provide evidence that in CFs, RvD1 and RvE1 might actively participate in the prevention of inflammatory response triggered by LPS.

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Acute myocardial infarction is one of the leading causes of death worldwide and thus, an extensively studied disease. Nonetheless, the effects of ischemia/reperfusion injury elicited by oxidative stress on cardiac fibroblast function associated with tissue repair are not completely understood. Ascorbic acid, deferoxamine, and N-acetylcysteine (A/D/N) are antioxidants with known cardioprotective effects, but the potential beneficial effects of combining these antioxidants in the tissue repair properties of cardiac fibroblasts remain unknown. Thus, the aim of this study was to evaluate whether the pharmacological association of these antioxidants, at low concentrations, could confer protection to cardiac fibroblasts against simulated ischemia/reperfusion injury. To test this, neonatal rat cardiac fibroblasts were subjected to simulated ischemia/reperfusion in the presence or absence of A/D/N treatment added at the beginning of simulated reperfusion. Cell viability was assessed using trypan blue staining, and intracellular reactive oxygen species (ROS) production was assessed using a 2',7'-dichlorofluorescin diacetate probe. Cell death was measured by flow cytometry using propidium iodide. Cell signaling mechanisms, differentiation into myofibroblasts and pro-collagen I production were determined by Western blot, whereas migration was evaluated using the wound healing assay. Our results show that A/D/N association using a low concentration of each antioxidant increased cardiac fibroblast viability, but that their separate administration did not provide protection. In addition, A/D/N association attenuated oxidative stress triggered by simulated ischemia/reperfusion, induced phosphorylation of pro-survival extracellular-signal-regulated kinases 1/2 (ERK1/2) and PKB (protein kinase B)/Akt, and decreased phosphorylation of the pro-apoptotic proteins p38- mitogen-activated protein kinase (p38-MAPK) and c-Jun-N-terminal kinase (JNK). Moreover, treatment with A/D/N also reduced reperfusion-induced apoptosis, evidenced by a decrease in the sub-G1 population, lower fragmentation of pro-caspases 9 and 3, as well as increased B-cell lymphomaextra large protein (Bcl-xL)/Bcl-2-associated X protein (Bax) ratio. Furthermore, simulated ischemia/reperfusion abolished serum-induced migration, TGF-ß1 (transforming growth factor beta 1)-mediated cardiac fibroblast-to-cardiac myofibroblast differentiation, and angiotensin II-induced pro-collagen I synthesis, but these effects were prevented by treatment with A/D/N. In conclusion, this is the first study where a pharmacological combination of A/D/N, at low concentrations, protected cardiac fibroblast viability and function after simulated ischemia/reperfusion, and thereby represents a novel therapeutic approach for cardioprotection.