Aspirin-Triggered Resolvin D1 (AT-RvD1) Protects Mouse Skin against UVB-Induced Inflammation and Oxidative Stress.

Intense exposure to UVB radiation incites excessive production of reactive oxygen species (ROS) and inflammation. The resolution of inflammation is an active process orchestrated by a family of lipid molecules that includes AT-RvD1, a specialized proresolving lipid mediator (SPM). AT-RvD1 is derived from omega-3, which presents anti-inflammatory activity and reduces oxidative stress markers. The present work aims to investigate the protective effect of AT-RvD1 on UVB-induced inflammation and oxidative stress in hairless mice. Animals were first treated with 30, 100, and 300 pg/animal AT-RvD1 (i.v.) and then exposed to UVB (4.14 J/cm2). The results showed that 300 pg/animal of AT-RvD1 could restrict skin edema, neutrophil and mast cell infiltration, COX-2 mRNA expression, cytokine release, and MMP-9 activity and restore skin antioxidant capacity as per FRAP and ABTS assays and control O2•- production, lipoperoxidation, epidermal thickening, and sunburn cells development. AT-RvD1 could reverse the UVB-induced downregulation of Nrf2 and its downstream targets GSH, catalase, and NOQ-1. Our results suggest that by upregulating the Nrf2 pathway, AT-RvD1 promotes the expression of ARE genes, restoring the skin's natural antioxidant defense against UVB exposition to avoid oxidative stress, inflammation, and tissue damage.

Pimenta pseudocaryophyllus (Gomes) Landrum extract inhibits inflammatory pain in mice: targeting neutrophil recruitment, oxidative stress, and cytokine production.

Pimenta pseudocaryophyllus (Gomes) Landrum is a Brazilian native plant. The mechanisms by which it promotes analgesia are unknown. We demonstrated the analgesic effect of P. pseudocaryophyllus dried extract (3 mg/kg; i.p.) in the following models of inflammatory pain (maximal inhibition): phenyl-p-benzoquinone (89%), formalin (72% - 1st phase and 96% - 2nd phase for flinches, and 50% - 1st phase and 71% - 2nd phase for licking behavior), complete Freund's adjuvant (95% - flinches and 33% - licking behavior), and carrageenin (56% - mechanical and 85% - thermal hyperalgesia) without motor impairment. Its analgesic effect depends on inhibiting neutrophil recruitment (95% - histopathology, 83% - myeloperoxidase activity, and 80% - LysM-eGFP mice), oxidative stress (86% - GSH and 98% - superoxide anion), and cytokine production (35% - IL-33, 80% - TNF-α, and 95% - IL-1ß). The present study advances in understanding the analgesic mechanisms of P. pseudocaryophyllus.

Sphagneticola trilobata (L.) Pruski-derived kaurenoic acid prevents ovalbumin-induced asthma in mice: Effect on Th2 cytokines, STAT6/GATA-3 signaling, NFκB/Nrf2 redox sensitive pathways, and regulatory T cell phenotype markers.

ETHNOPHARMACOLOGICAL RELEVANCE: Sphagneticola trilobata (L.) Pruski is used in traditional medicine in Brazil for inflammatory diseases treatment including asthma. The diterpene kaurenoic acid (KA) is one of its active compounds, but whether KA activity could explain the traditional use of S. trilobata in asthma is unknown. AIM: Investigate KA effect and mechanisms in asthma. METHODS: Experimental asthma was induced by ovalbumin immunization and challenge in male Swiss mice. KA (0.1-10 mg/kg, gavage) was administered 1 h before the ovalbumin challenge. Total leukocytes, eosinophil, and mast cell were counted in bronchoalveolar lavage fluid (BALF), and lung histopathology was performed. Lung mRNA expression of Th2 and regulatory T cells markers, and BALF type 2 cytokine production were quantitated. NFκB activation and oxidative stress-related components in pulmonary tissue were measured. RESULTS: KA inhibited the migration of total leukocytes and eosinophils to BALF, reduced lung histopathology (inflammatory cells and mast cells), mRNA expression of IL-33/ST2, STAT6/GATA-3 and NFκB activation in the lung, and reduced IL-33, IL-4, IL-5 production in the BALF. KA also reduced the mRNA expression of iNOS and gp91phox, and superoxide anion production accompanied by the induction of Nrf2, HO-1 and NQO1 mRNA expression, thus, exerting an antioxidant effect. Finally, KA induced nTreg-like and Tr1-like, but not Th3-like markers of suppressive T cell phenotypes in the lung tissue. CONCLUSION: KA prevents antigen-induced asthma by down-regulating Th2 and NFκB/cytokine-related pathways, and up-regulating Nrf2 and regulatory T cells' markers. Thus, explaining the ethnopharmacological use of S. trilobata for the treatment of lung inflammatory diseases.

The Lipoxin Receptor/FPR2 Agonist BML-111 Protects Mouse Skin Against Ultraviolet B Radiation.

Excessive exposure to UV, especially UVB, is the most important risk factor for skin cancer and premature skin aging. The identification of the specialized pro-resolving lipid mediators (SPMs) challenged the preexisting paradigm of how inflammation ends. Rather than a passive process, the resolution of inflammation relies on the active production of SPMs, such as Lipoxins (Lx), Maresins, protectins, and Resolvins. LXA4 is an SPM that exerts its action through ALX/FPR2 receptor. Stable ALX/FPR2 agonists are required because SPMs can be quickly metabolized within tissues near the site of formation. BML-111 is a commercially available synthetic ALX/FPR2 receptor agonist with analgesic, antioxidant, and anti-inflammatory properties. Based on that, we aimed to determine the effect of BML-111 in a model of UVB-induced skin inflammation in hairless mice. We demonstrated that BML-111 ameliorates the signs of UVB-induced skin inflammation by reducing neutrophil recruitment and mast cell activation. Reduction of these cells by BML-111 led to lower number of sunburn cells formation, decrease in epidermal thickness, collagen degradation, cytokine production (TNF-α, IL-1ß, IL-6, TGF, and IL-10), and oxidative stress (observed by an increase in total antioxidant capacity and Nrf2 signaling pathway), indicating that BML-111 might be a promising drug to treat skin disorders.

Treatment with maresin 1, a docosahexaenoic acid-derived pro-resolution lipid, protects skin from inflammation and oxidative stress caused by UVB irradiation.

Acute exposure to UVB irradiation causes skin inflammation and oxidative stress, and long-term exposure to UVB irradiation may lead to carcinogenesis. Our organism has endogenous mechanisms to actively limit inflammation. Maresin 1 (MaR1; 7R,14S-dihydroxy-docosa-4Z,8E,10E,12Z,16Z,19Z-hexaenoic acid) is a pro-resolution lipid mediator derived from the docosahexaenoic acid, which presents anti-inflammatory and pro-resolution effects. However, it remains to be determined if treatment with MaR1 can inhibit inflammatory and oxidative alterations in the skin triggered by UVB. The treatment with MaR1 (0.1-10 ng/mice at -10 min relative to the UVB irradiation protocol) reduced UVB-induced skin edema, neutrophil recruitment (MPO; myeloperoxidase activity, and migration of LysM-eGFP+ cells), cytokine production, matrix metalloproteinase-9 activity, keratinocyte apoptosis, epidermal thickening, mast cells counts and degradation of skin collagen in hairless mice. UVB irradiation caused a decrease of GSH (reduced glutathione) levels, activity of the enzyme catalase, ferric reducing ability (FRAP), and ABTS radical scavenging capacity as well as induced lipid hydroperoxide, superoxide anion production, and gp91phox mRNA expression. These parameters that indicate oxidative stress were inhibited by MaR1 treatment. Therefore, these data suggest MaR1 as a promising pharmacological tool in controlling the deleterious effects related to UVB irradiation.

The citrus flavanone naringenin attenuates zymosan-induced mouse joint inflammation: induction of Nrf2 expression in recruited CD45+ hematopoietic cells.

BACKGROUND: Naringenin is a biologically active analgesic, anti-inflammatory, and antioxidant flavonoid. Naringenin targets in inflammation-induced articular pain remain poorly explored. METHODS: The present study investigated the cellular and molecular mechanisms involved in the analgesic/anti-inflammatory effects of naringenin in zymosan-induced arthritis. Mice were pre-treated orally with naringenin (16.7-150 mg/kg), followed by intra-articular injection of zymosan. Articular mechanical hyperalgesia and oedema, leucocyte recruitment to synovial cavity, histopathology, expression/production of pro- and anti-inflammatory mediators and NFκB activation, inflammasome component expression, and oxidative stress were evaluated. RESULTS: Naringenin inhibited articular pain and oedema in a dose-dependent manner. The dose of 50 mg/kg inhibited leucocyte recruitment, histopathological alterations, NFκB activation, and NFκB-dependent pro-inflammatory cytokines (TNF-α, IL-1ß, and IL-33), and preproET-1 mRNA expression, but increased anti-inflammatory IL-10. Naringenin also inhibited inflammasome upregulation (reduced Nlrp3, ASC, caspase-1, and pro-IL-1ß mRNA expression) and oxidative stress (reduced gp91phox mRNA expression and superoxide anion production, increased GSH levels, induced Nrf2 protein in CD45+ hematopoietic recruited cells, and induced Nrf2 and HO-1 mRNA expression). CONCLUSIONS: Naringenin presents analgesic and anti-inflammatory effects in zymosan-induced arthritis by targeting its main physiopathological mechanisms. These data highlight this flavonoid as an interesting therapeutic compound to treat joint inflammation, deserving additional pre-clinical and clinical studies.

The Lipid Mediator Resolvin D1 Reduces the Skin Inflammation and Oxidative Stress Induced by UV Irradiation in Hairless Mice.

UV irradiation-induced oxidative stress and inflammation contribute to the development of skin diseases. Therefore, targeting oxidative stress and inflammation might contribute to reduce skin diseases. Resolvin D1 (RvD1) is a bioactive metabolite generated during inflammation to actively orchestrate the resolution of inflammation. However, the therapeutic potential of RvD1 in UVB skin inflammation remains undetermined, which was, therefore, the aim of the present study. The intraperitoneal treatment with RvD1 (3-100 ng/mouse) reduced UVB irradiation-induced skin edema, myeloperoxidase activity, matrix metalloproteinase 9 activity, and reduced glutathione depletion with consistent effects observed with the dose of 30 ng/mouse, which was selected to the following experiments. RvD1 inhibited UVB reduction of catalase activity, and hydroperoxide formation, superoxide anion production, and gp91phox mRNA expression. RvD1 also increased the Nrf2 and its downstream targets NQO1 and HO-1 mRNA expression. Regarding cytokines, RvD1 inhibited UVB-induced production of IL-1ß, IL-6, IL-33, TNF-α, TGF-ß, and IL-10. These immuno-biochemical alterations by RvD1 treatment had as consequence the reduction of UVB-induced epidermal thickness, sunburn and mast cell counts, and collagen degradation. Therefore, RvD1 inhibited UVB-induced skin oxidative stress and inflammation, rendering this resolving lipid mediator as a promising therapeutic agent.

Quercetin attenuates zymosan-induced arthritis in mice.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by articular lesions, recruitment of inflammatory cells and increased levels of pro-inflammatory cytokine. The intra-articular administration of zymosan is an experimental model that promotes inflammatory parameters resembling RA. Therefore, this model was used to investigate the efficacy of quercetin as a treatment of articular inflammation. Treatment with quercetin dose-dependently reduced zymosan-induced hyperalgesia, articular edema and the recruitment of neutrophils to the knee joint cavity. Histological analysis confirmed that quercetin inhibited zymosan-induced arthritis. The treatment with quercetin also inhibited zymosan-induced depletion of reduced glutathione (GSH) levels, TNFα and IL-1ß production, and gp91phox, prepro-endothelin-1 (preproET-1), and cyclooxygenase-2 mRNA expression. These molecular effects of quercetin were related to the inhibition of the nuclear factor kappa-B and induction of Nuclear factor erythroid 2- related factor (Nrf2)/home oxygenase (HO-1) pathway. Thus, quercetin exerted anti-inflammatory, analgesic and antioxidant effects in experimental arthritis, suggesting quercetin is a possible candidate for arthritis treatment.

trans-Chalcone, a flavonoid precursor, inhibits UV-induced skin inflammation and oxidative stress in mice by targeting NADPH oxidase and cytokine production.

trans-Chalcone is a plant flavonoid precursor, which lacks broad investigation on its biological activity in inflammatory processes. In the present study, anti-inflammatory and antioxidant mechanisms of systemic administration with trans-chalcone, a flavonoid precursor, on ultraviolet (UV) irradiation-induced skin inflammation and oxidative stress in hairless mice were investigated by the following parameters: skin edema, myeloperoxidase activity (neutrophil marker), matrix metalloproteinase-9 activity, reduced glutathione levels, catalase activity, lipid peroxidation products, superoxide anion production, gp91phox (NADPH oxidase subunit) mRNA expression by quantitative PCR and cytokine production by ELISA. Systemic treatment with trans-chalcone inhibited skin inflammation by reducing skin edema and neutrophil recruitment, and also inhibited matrix metalloproteinase-9 activity. trans-Chalcone also inhibited oxidative stress, gp91phox mRNA expression, and the production of a wide range of pro-inflammatory cytokines, while it did not affect anti-inflammatory cytokines induced by UV irradiation. However, trans-chalcone did not prevent oxidative stress in vitro, suggesting that its in vivo effect is more related to anti-inflammatory properties rather than a direct antioxidant effect. In conclusion, treatment with trans-chalcone inhibited UV-induced skin inflammation resulting in oxidative stress inhibition in vivo. Therefore, systemic supplementation with this compound may represent an important therapeutic approach in inflammatory skin diseases induced by UV irradiation.

Trans-chalcone added in topical formulation inhibits skin inflammation and oxidative stress in a model of ultraviolet B radiation skin damage in hairless mice.

Trans-chalcone (TC) is a common precursor of flavonoids. However, the pharmacological properties of TC remain to be fully understood. The present study investigated whether topical formulation containing TC (TFcTC) presents therapeutic effect in UVB radiation-induced skin damage using disease, enzyme activity, antioxidant activity, protein and mRNA parameters. Control topical formulation (CTF) and TFcTC were applied in hairless mice before and after exposure to UVB radiation. Dorsal skin samples were collected after UVB exposure to evaluate: i) skin edema (weight) was measured by punch biopsy; ii) spectrophotometric assays were used to measure myeloperoxidase (MPO) and catalase activities, ferric (FRAP) and ABTS cation reducing antioxidant power, superoxide anion production and levels of reduced glutathione (GSH); iii) enzymography was used to measure matrix metalloproteinase-9 (MMP-9) activity; iv) chemiluminescence was used to measure the lipid peroxidation (LPO); v) enzyme-linked immunosorbent assay (ELISA) was used to measure tumor necrosis factor alpha (TNF-α) levels; vi) reverse transcription quantitative PCR (RT-qPCR) was used to measure cyclooxygenase-2 (COX-2), gp91phox (NADPH oxidase sub-unity), glutathione peroxidase-1 (Gpx1), glutathione reductase (Gr), nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) mRNA expression. TFcTC inhibited UVB-induced skin edema, MPO activity, MMP-9 activity, TNF-α production, and COX-2 mRNA expression. TFcTC inhibited UVB-induced LPO, down-regulated superoxide anion levels and gp91phox mRNA expression, and improved antioxidant potential and GSH skin levels. The mRNA expression of detoxification systems such as Nrf2, HO-1, Gpx1 and Gr, and catalase activity were also enhanced by treatment with TFcTC. In conclusion, TFcTC protects mice skin from UVB radiation by inhibiting inflammation, and improving antioxidant and detoxification systems. Therefore, topical treatment with TC is a novel therapeutic approach for the treatment of UVB radiation skin damages, which merits further pre-clinical and clinical investigation.

Quercetin Inhibits Peripheral and Spinal Cord Nociceptive Mechanisms to Reduce Intense Acute Swimming-Induced Muscle Pain in Mice.

The present study aimed to evaluate the effects of the flavonoid quercetin (3,3´,4´,5,7-pentahydroxyflavone) in a mice model of intense acute swimming-induced muscle pain, which resembles delayed onset muscle soreness. Quercetin intraperitoneal (i.p.) treatment dose-dependently reduced muscle mechanical hyperalgesia. Quercetin inhibited myeloperoxidase (MPO) and N-acetyl-ß-D- glucosaminidase (NAG) activities, cytokine production, oxidative stress, cyclooxygenase-2 (COX-2) and gp91phox mRNA expression and muscle injury (creatinine kinase [CK] blood levels and myoblast determination protein [MyoD] mRNA expression) as well as inhibited NFκB activation and induced Nrf2 and HO-1 mRNA expression in the soleus muscle. Beyond inhibiting those peripheral effects, quercetin also inhibited spinal cord cytokine production, oxidative stress and glial cells activation (glial fibrillary acidic protein [GFAP] and ionized calcium-binding adapter molecule 1 [Iba-1] mRNA expression). Concluding, the present data demonstrate that quercetin is a potential molecule for the treatment of muscle pain conditions related to unaccustomed exercise.

Topical Formulation Containing Naringenin: Efficacy against Ultraviolet B Irradiation-Induced Skin Inflammation and Oxidative Stress in Mice.

Naringenin (NGN) exhibits anti-inflammatory and antioxidant activities, but it remains undetermined its topical actions against ultraviolet B (UVB)-induced inflammation and oxidative stress in vivo. The purpose of this study was to evaluate the physicochemical and functional antioxidant stability of NGN containing formulations, and the effects of selected NGN containing formulation on UVB irradiation-induced skin inflammation and oxidative damage in hairless mice. NGN presented ferric reducing power, ability to scavenge 2,2'-azinobis (3-ethylbenzothiazoline- 6-sulfonic acid) (ABTS) and hydroxyl radical, and inhibited iron-independent and dependent lipid peroxidation. Among the three formulations containing NGN, only the F3 kept its physicochemical and functional stability over 180 days. Topical application of F3 in mice protected from UVB-induced skin damage by inhibiting edema and cytokine production (TNF-α, IL-1ß, IL-6, and IL-10). Furthermore, F3 inhibited superoxide anion and lipid hydroperoxides production and maintained ferric reducing and ABTS scavenging abilities, catalase activity, and reduced glutathione levels. In addition, F3 maintained mRNA expression of cellular antioxidants glutathione peroxidase 1, glutathione reductase and transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2), and induced mRNA expression of heme oxygenase-1. In conclusion, a formulation containing NGN may be a promising approach to protecting the skin from the deleterious effects of UVB irradiation.

Naringenin Inhibits UVB Irradiation-Induced Inflammation and Oxidative Stress in the Skin of Hairless Mice.

Ultraviolet B (UVB) irradiation may cause inflammation- and oxidative-stress-dependent skin cancer and premature aging. Naringenin (1) has been reported to have anti-inflammatory and antioxidant properties, but its effects and mechanisms on UVB irradiation-induced inflammation and oxidative stress are still not known. Thus, the present study aimed to investigate the potential of naringenin to mitigate UVB irradiation-induced inflammation and oxidative damage in the skin of hairless mice. Skin edema, myeloperoxidase (neutrophil marker) and matrix metalloproteinase-9 (MMP-9) activity, and cytokine production were measured after UVB irradiation. Oxidative stress was evaluated by 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS) scavenging ability, ferric reducing antioxidant power (FRAP), reduced glutathione levels, catalase activity, lipid peroxidation products, superoxide anion production, and gp91phox (NADPH oxidase subunit) mRNA expression by quantitative PCR. The intraperitoneal treatment with naringenin reduced skin inflammation by inhibiting skin edema, neutrophil recruitment, MMP-9 activity, and pro-inflammatory (TNF-α, IFN-γ, IL-1ß, IL-4, IL-5, IL-6, IL-12, IL-13, IL-17, IL-22, and IL-23) and anti-inflammatory (TGF-ß and IL-10) cytokines. Naringenin also inhibited oxidative stress by reducing superoxide anion production and the mRNA expression of gp91phox. Therefore, naringenin inhibits UVB irradiation-induced skin damage and may be a promising therapeutic approach to control skin disease.

Hesperidin methyl chalcone inhibits oxidative stress and inflammation in a mouse model of ultraviolet B irradiation-induced skin damage.

Hesperidin methyl chalcone (HMC) is a safe flavonoid used to treat chronic venous diseases, but its effects and mechanisms on UVB irradiation-induced inflammation and oxidative stress have never been described in vivo. Thus, the purpose of this study was to evaluate the effects of systemic administration of HMC in skin oxidative stress and inflammation induced by UVB irradiation. To induce skin damage, hairless mice were exposed to an acute UVB irradiation dose of 4.14 J/cm(2), and the dorsal skin samples were collected to evaluate oxidative stress and inflammatory response. The intraperitoneal treatment with HMC at the dose of 300 mg/kg inhibited UVB irradiation-induced skin edema, neutrophil recruitment, and matrix metalloproteinase-9 activity. HMC also protected the skin from UVB irradiation-induced oxidative stress by maintaining ferric reducing antioxidant power (FRAP), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS) scavenging ability and antioxidant levels (reduced glutathione and catalase). Corroborating, HMC inhibited UVB irradiation-induced superoxide anion generation and gp91phox (NADPH oxidase subunit) mRNA expression. Furthermore, the antioxidant effect of HMC resulted in lower production of inflammatory mediators, including lipid hydroperoxides and a wide range of cytokines. Taken together, these results unveil a novel applicability of HMC in the treatment of UVB irradiation-induced skin inflammation and oxidative stress.