GPCRs overexpression and impaired fMLP-induced functions in neutrophils from chronic kidney disease patients.

Introduction: G-protein coupled receptors (GPCRs) expressed on neutrophils regulate their mobilization from the bone marrow into the blood, their half-live in the circulation, and their pro- and anti-inflammatory activities during inflammation. Chronic kidney disease (CKD) is associated with systemic inflammatory responses, and neutrophilia is a hallmark of CKD onset and progression. Nonetheless, the role of neutrophils in CKD is currently unclear. Methods: Blood and renal tissue were collected from non-dialysis CKD (grade 3 - 5) patients to evaluate GPCR neutrophil expressions and functions in CKD development. Results: CKD patients presented a higher blood neutrophil-to-lymphocyte ratio (NLR), which was inversely correlated with the glomerular filtration rate (eGFR). A higher frequency of neutrophils expressing the senescent GPCR receptor (CXCR4) and activation markers (CD18+CD11b+CD62L+) was detected in CKD patients. Moreover, CKD neutrophils expressed higher amounts of GPCR formyl peptide receptors (FPR) 1 and 2, known as neutrophil pro- and anti-inflammatory receptors, respectively. Cytoskeletal organization, migration, and production of reactive oxygen species (ROS) by CKD neutrophils were impaired in response to the FPR1 agonist (fMLP), despite the higher expression of FPR1. In addition, CKD neutrophils presented enhanced intracellular, but reduced membrane expression of the protein Annexin A1 (AnxA1), and an impaired ability to secrete it into the extracellular compartment. Secreted and phosphorylated AnxA1 is a recognized ligand of FPR2, pivotal in anti-inflammatory and efferocytosis effects. CKD renal tissue presented a low number of neutrophils, which were AnxA1+. Conclusion: Together, these data highlight that CKD neutrophils overexpress GPCRs, which may contribute to an unbalanced aging process in the circulation, migration into inflamed tissues, and efferocytosis.

Effect of modified citrus pectin on galectin-3 inhibition in cisplatin-induced cardiac and renal toxicity.

This study evaluated the effect of pharmacological inhibition of galectin 3 (Gal-3) with modified citrus pectin (MCP) on the heart and kidney in a model of cisplatin-induced acute toxicity. Male Wistar rats were divided into four groups (n = 6/group): SHAM, which received sterile saline intraperitoneally (i.p.) for three days; CIS, which received cisplatin i.p. (10 mg/kg/day) for three days; MCP, which received MCP orally (100 mg/kg/day) for seven days, followed by sterile saline i.p. for three days; MCP+CIS, which received MCP orally for seven days followed by cisplatin i.p. for three days. The blood, heart, and kidneys were collected six hours after the last treatment. MCP treatment did not change Gal-3 protein levels in the blood and heart, but it did reduce them in the kidneys of the MCP groups compared to the SHAM group. While no morphological changes were evident in the cardiac tissue, increased malondialdehyde (MDA) levels and deregulation of the mitochondrial oxidative phosphorylation system were observed in the heart homogenates of the MCP+CIS group. Cisplatin administration caused acute tubular degeneration in the kidneys; the MCP+CIS group also showed increased MDA levels. In conclusion, MCP therapy in the acute model of cisplatin-induced toxicity increases oxidative stress in cardiac and renal tissues. Further investigations are needed to determine the beneficial and harmful roles of Gal-3 in the cardiorenal system since it can act differently in acute and chronic diseases/conditions.

Galectin-3 is a key hepatoprotective molecule against the deleterious effect of cisplatin.

AIMS: Evaluate the role of galectin-3 in the liver using an acute model of cisplatin-induced toxicity. MATERIAL AND METHODS: Modified citrus pectin (MCP) treatment was used to inhibit galectin-3. Rats were distributed into four groups: SHAM, CIS, MCP and MCP + CIS. On days 1-7, animals were treated by oral gavage with 100 mg/kg/day of MCP (MCP and MCP + CIS groups). On days 8, 9 and 10, animals received intraperitoneal injection of 10 mg/kg/day of cisplatin (CIS and MCP + CIS groups) or saline (SHAM and MCP groups). KEY FINDINGS: Cisplatin administration caused a marked increase in hepatic leukocyte influx and liver degeneration, and promoted reactive oxygen species production and STAT3 activation in hepatocytes. Plasma levels of cytokines (IL-6, IL-10), and hepatic toxicity biomarkers (hepatic arginase 1, α-glutathione S-transferase, sorbitol dehydrogenase) were also elevated. Decreased galectin-3 levels in the livers of animals in the MCP + CIS group were also associated with increased hepatic levels of malondialdehyde and mitochondrial respiratory complex I. Animals in the MCP + CIS group also exhibited increased plasma levels of IL-1ß, TNF-α, and aspartate transaminase 1. Furthermore, MCP therapy efficiently antagonized hepatic galectin-9 in liver, but not galectin-1, the latter of which was increased. SIGNIFICANCE: Reduction of the endogenous levels of galectin-3 in hepatocytes favors the process of cell death and increases oxidative stress in the acute model of cisplatin-induced toxicity.

Effects of galectin-3 protein on UVA-induced damage in retinal pigment epithelial cells.

Several inflammatory molecules have been suggested as biomarkers of age-related macular degeneration (AMD). Galectin-3 (Gal-3), which has been shown to have a protective role in corneal injury by promoting epithelial cells adhesion and migration to the extracellular matrix, is also highly expressed in the retinal pigment epithelium (RPE) of patients with AMD. This study evaluated the role of Gal-3 in an in vitro model of UVA-induced RPE damage, as a proof-of-concept. ARPE-19 cells (human RPE cell line), were incubated with Gal-3 at 0.5-2.5 µg/mL concentrations prior to UVA irradiation for 15, 30, and 45 min, which resulted in accumulated doses of 2.5, 5, and 7.5 J/cm2, respectively. After 24 h incubation, MTT and LDH assays, immunofluorescence, and ELISA were performed. UVA irradiation for 15, 30, and 45 min proved to reduce viability in 83%, 46%, and 11%, respectively. Based on the latter results, we chose the intermediate dose (5-J/cm2) for further analysis. Pretreatment with Gal-3 at concentrations > 1.5 µg/mL showed to increase the viability of UVA-irradiated cells (~ 75%) compared to untreated cells (64%). Increased levels of cleaved caspase 3, a marker of cell death, were detected in the ARPE cells after UVA irradiation with or without addition of exogenous Gal-3. The inhibitory effect of Gal-3 on UVA-induced cell damage was characterized by decreased ROS levels and increased p38 activation, as detected by fluorescence analysis. In conclusion, our study suggests a photoprotective effect of Gal-3 on RPE by reducing oxidative stress and increasing p38 activation.

Effects of Formyl Peptide Receptor Agonists Ac9-12 and WKYMV in In Vivo and In Vitro Acute Inflammatory Experimental Models.

Formyl peptide receptors (Fprs) are a G-protein-coupled receptor family mainly expressed on leukocytes. The activation of Fpr1 and Fpr2 triggers a cascade of signaling events, leading to leukocyte migration, cytokine release, and increased phagocytosis. In this study, we evaluate the effects of the Fpr1 and Fpr2 agonists Ac9-12 and WKYMV, respectively, in carrageenan-induced acute peritonitis and LPS-stimulated macrophages. Peritonitis was induced in male C57BL/6 mice through the intraperitoneal injection of 1 mL of 3% carrageenan solution or saline (control). Pre-treatments with Ac9-12 and WKYMV reduced leukocyte influx to the peritoneal cavity, particularly neutrophils and monocytes, and the release of IL-1ß. The addition of the Fpr2 antagonist WRW4 reversed only the anti-inflammatory actions of WKYMV. In vitro, the administration of Boc2 and WRW4 reversed the effects of Ac9-12 and WKYMV, respectively, in the production of IL-6 by LPS-stimulated macrophages. These biological effects of peptides were differently regulated by ERK and p38 signaling pathways. Lipidomic analysis evidenced that Ac9-12 and WKYMV altered the intracellular lipid profile of LPS-stimulated macrophages, revealing an increased concentration of several glycerophospholipids, suggesting regulation of inflammatory pathways triggered by LPS. Overall, our data indicate the therapeutic potential of Ac9-12 and WKYMV via Fpr1 or Fpr2-activation in the inflammatory response and macrophage activation.

Expression Pattern and Immunoregulatory Roles of Galectin-1 and Galectin-3 in Atopic Dermatitis and Psoriasis.

The pathogenesis of atopic dermatitis (AD) and psoriasis (Ps) overlaps, particularly the activation of the immune response and tissue damage. Here, we evaluated galectin (Gal)-1 and Gal-3 levels, which are beta-galactoside-binding proteins with immunomodulatory functions and examined their effects on human keratinocytes stimulated with either interleukin (IL)-4 or IL-17A. Skin biopsies from AD, Ps, and control patients were evaluated using histological and immunohistochemical analyses. Six studies containing publicly available transcriptome data were individually analyzed using the GEO2R tool to detect Gal-1 and Gal-3 mRNA levels. In vitro, IL-4- or IL-17A-stimulated keratinocytes were treated with or without Gal-1 or Gal-3 to evaluate cytokine release and migration. Our findings showed different patterns of expression for Gal-1 and Gal-3 in AD and Ps skins. Densitometric analysis in skin samples showed a marked increase in the protein Gal-1 levels in Ps epidermis and in both AD and Ps dermis compared to controls. Protein and mRNA Gal-3 levels were downregulated in AD and Ps lesional skin compared with the control samples. In vitro, both galectins addition abrogated the release of IL-8 and RANTES in IL-17-stimulated keratinocytes after 24 h, whereas IL-6 release was downregulated by Gal-3 and Gal-1 in IL-4- and IL-17-stimulated cells, respectively. Administration of both galectins also increased the rate of keratinocyte migration under IL-4 or IL-17 stimulation conditions compared with untreated cells. Altogether, the immunoregulatory and migration effects of Gal-1 and Gal-3 on keratinocytes under inflammatory microenvironment make them interesting targets for future therapies in cutaneous diseases.

Bellis perennis extract mitigates UVA-induced keratinocyte damage: Photoprotective and immunomodulatory effects.

A need exists for further research elucidating the benefits of environmentally safe photoprotective agents against ultraviolet (UV) exposure, and plant extracts represent a human-friendly alternative formulation. This study was designed to evaluate the potential use of Bellis perennis extract (BPE), from the Asteraceae family, known as the common daisy or the English daisy, in cosmeceuticals as a photoprotective factor, using an in vitro model of UVA-induced keratinocyte damage. Human skin keratinocytes (HaCaT cell line) were incubated with BPE at 0.01, 0.1, or 1% in Dulbecco's Modified Eagle Medium (DMEM), and after 15 min they were submitted to UVA radiation at 5, 10, and 15 J/cm2 doses, respectively. For comparative purposes, Polypodium leucotomos extract (PLE), known as the fern, was used as a positive control in assessing the photoprotective effect. After 24 h of UVA exposure, cell viability (MTT and LDH assays), levels of cleaved caspase-3, cyclooxygenase-2, IL-6, reactive oxygen species (ROS) and antioxidant enzyme (catalase, SOD, and glutathione peroxidase) activity were determined. UVA radiation at 5, 10, and 15 J/cm2 doses reduced cell viability to 63%, 43%, and 23%, respectively; we selected 10 J/cm2 for our purposes. After 24 h of UVA exposure, treatment with 1% BPE and 1% PLE significantly recovered cell viability (p < 0.05). Furthermore, treatment was associated with lower cleaved caspase-3 and ROS levels, higher catalase activity, and lower IL-6 levels in the treated UVA keratinocytes compared with the untreated UVA group (p < 0.01). Our results demonstrate photoprotective and immunomodulatory effects of BPE in skin keratinocytes and support its use as a bioactive agent in cosmetic formulations to prevent skin damage caused by exposure to the UV light.

The Role of Galectin-9 as Mediator of Atopic Dermatitis: Effect on Keratinocytes.

Galectin-9 (Gal-9) is a beta-galactoside-binding protein with a variety of biological functions related to immune response. However, in allergic diseases, its mechanism of action is not fully understood. This study evaluates the expression pattern of Gal-9 in patients with atopic dermatitis (AD), in ovalbumin (OVA)-induced experimental atopic dermatitis (AD) in mice, as well as its effect on human keratinocytes. The skin of OVA-immunized BALB/c mice was challenged with drops containing OVA on days 11, 14-18, and 21-24. HaCaT cells were cultured in the following experimental conditions: control (growth medium only) or stimulated with TNF-α/IFN-γ, or IL-4, or IL-17 with or without Gal-9 treatment. AD was characterized by increased levels of Gal-9 in mouse and human skin, especially in the epidermis, and with a marked influx of Gal-9 positive eosinophils and mast cells compared to the control group. Gal-9 showed an immunomodulatory effect on keratinocytes by decreasing the release of IL-6 by IL-4-stimulated keratinocytes or increasing the IL-6 and RANTES levels by IL-17- or TNF-α/IFN-γ-stimulated cells, respectively. Under IL-17, Gal-9 treatment also altered the proliferation rate of cells. Overall, increased levels of Gal-9 in AD skin contribute to the control of inflammatory response and the proliferative process of keratinocytes, suggesting this lectin as a relevant therapeutic target.

Role of Annexin A1 in NLRP3 Inflammasome Activation in Murine Neutrophils.

This study evaluated the role of endogenous and exogenous annexin A1 (AnxA1) in the activation of the NLRP3 inflammasome in isolated peritoneal neutrophils. C57BL/6 wild-type (WT) and AnxA1 knockout mice (AnxA1-/-) received 0.3% carrageenan intraperitoneally and, after 3 h, the peritoneal exudate was collected. WT and AnxA1-/- neutrophils were then stimulated with lipopolysaccharide, followed by the NLRP3 agonists nigericin or ATP. To determine the exogenous effect of AnxA1, the neutrophils were pretreated with the AnxA1-derived peptide Ac2-26 followed by the NLRP3 agonists. Ac2-26 administration reduced NLRP3-derived IL-1ß production by WT neutrophils after nigericin and ATP stimulation. However, IL-1ß release was impaired in AnxA1-/- neutrophils stimulated by both agonists, and there was no further impairment in IL-1ß release with Ac2-26 treatment before stimulation. Despite this, ATP- and nigericin-stimulated AnxA1-/- neutrophils had increased levels of cleaved caspase-1. The lipidomics of supernatants from nigericin-stimulated WT and AnxA1-/- neutrophils showed potential lipid biomarkers of cell stress and activation, including specific sphingolipids and glycerophospholipids. AnxA1 peptidomimetic treatment also increased the concentration of phosphatidylserines and oxidized phosphocholines, which are lipid biomarkers related to the inflammatory resolution pathway. Together, our results indicate that exogenous AnxA1 negatively regulates NLRP3-derived IL-1ß production by neutrophils, while endogenous AnxA1 is required for the activation of the NLRP3 machinery.