Effects of PPAR-γ Agonist Treatment on LPS-Induced Mastitis in Rats

MyD88 deficiency in mammary epithelial cells attenuates lipopolysaccharide (LPS)-induced mastitis in mice

Lactation mastitis is a debilitating inflammatory mammary disease in postpartum animals. Myeloid differentiation primary response protein MyD88 is the key downstream adapter for innate pattern recognition receptor toll-like receptor 4 (TLR4), which plays an important role in inflammation. However, the specific role of MyD88 in mammary epithelial cells in the progression of mastitis has not been investigated. In this study, lipopolysaccharide (LPS)-induced mouse mastitis model was used and cytokines such as Tnf-α, Il-1β, Il-6, Cxcl1, Cxcl2 and Ccl2 were significantly increased in inflammatory mammary gland as shown by real time-qPCR. However, the mice with MyD88-deficienet in mammary epithelial cells (cKO) showed a reduction in the expression of Tnf-α, Il-1β, Il-6, Cxcl1 and Cxcl2 in mammary gland compared with control mice, when subjected to LPS induced mastitis. Immunohistochemical staining of cleaved caspase-3 showed that the cell apoptosis induced by inflammation were decreased in MyD88 cKO mice. Furthermore, there were significantly fewer infiltrating inflammatory cells in alveolar lumen of MyD88 cKO mice, including Ly6G-positive neutrophils and F4/80-positive macrophages. RNA-seq in LPS treated mammary glands showed that MyD88 cKO mice had significantly downregulated inflammation-related genes and upregulated genes related to anti-inflammation processes and lipid metabolism compared with control mice. Thus, these results demonstrate that MyD88 in mammary epithelial cells is essential for mastitis progression. And this study not only has important implications for understanding the innate immune response in mammary epithelial cells, but also potentially helps the development of new therapeutic drugs for treating mastitis.

Unleashing the Potential of Nrf2: A Novel Therapeutic Target for Pulmonary Vascular Remodeling

Pulmonary vascular remodeling, characterized by the thickening of all three layers of the blood vessel wall, plays a central role in the pathogenesis of pulmonary hypertension (PH). Despite the approval of several drugs for PH treatment, their long-term therapeutic effect remains unsatisfactory, as they mainly focus on vasodilation rather than addressing vascular remodeling. Therefore, there is an urgent need for novel therapeutic targets in the treatment of PH. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a vital transcription factor that regulates endogenous antioxidant defense and emerges as a novel regulator of pulmonary vascular remodeling. Growing evidence has suggested an involvement of Nrf2 and its downstream transcriptional target in the process of pulmonary vascular remodeling. Pharmacologically targeting Nrf2 has demonstrated beneficial effects in various diseases, and several Nrf2 inducers are currently undergoing clinical trials. However, the exact potential and mechanism of Nrf2 as a therapeutic target in PH remain unknown. Thus, this review article aims to comprehensively explore the role and mechanism of Nrf2 in pulmonary vascular remodeling associated with PH. Additionally, we provide a summary of Nrf2 inducers that have shown therapeutic potential in addressing the underlying vascular remodeling processes in PH. Although Nrf2-related therapies hold great promise, further research is necessary before their clinical implementation can be fully realized.

Phillyrin protects mice from traumatic brain injury by inhibiting the inflammation of microglia via PPARγ signaling pathway

The neuroinflammatory response induced by microglia plays a vital role in causing secondary brain damage after traumatic brain injury (TBI). Previous studies have found that the improved regulation of activated microglia could reduce neurological damage post-TBI. Phillyrin (Phi) is one of the main active ingredients extracted from the fruits of the medicinal plant Forsythia suspensa (Thunb.) with anti-inflammatory effects. Our study attempted to investigate the effects of phillyrin on microglial activation and neuron damage after TBI. The TBI model was applied to induce brain injury in mice, and neurological scores, brain water content, hematoxylin and eosin staining and Nissl staining were employed to determine the neuroprotective effects of phillyrin. Immunofluorescent staining and western blot analysis were used to detect nuclear factor-kappa B (NF-κB) and peroxisome proliferator-activated receptor gamma (PPARγ) expression and nuclear translocation, and the inflammation-related proteins and mRNAs were assessed by western blot analysis and quantitative real-time PCR. The results revealed that phillyrin not only inhibited the proinflammatory response induced by activated microglia but also attenuated neurological impairment and brain edema in vivo in a mouse TBI model. Additionally, phillyrin suppressed the phosphorylation of NF-κB in microglia after TBI insult. These effects of phillyrin were mostly abolished by the antagonist of PPARγ. Our results reveal that phillyrin could prominently inhibit the inflammation of microglia via the PPARγ signaling pathway, thus leading to potential neuroprotective treatment after traumatic brain injury.

Leocarpinolide B attenuates LPS-induced inflammation on RAW264.7 macrophages by mediating NF-κB and Nrf2 pathways

Macrophages-mediated inflammation is involved in the regulation of rheumatoid arthritis (RA). Sigesbeckiae Herba (SH) has been traditionally used for rheumatism. However, the bioactive ingredients of SH are still unclear. Recently, we isolated a compound (Leocarpinolide B, LB) from SH and identified its potent anti-inflammatory and antioxidant effects on RAW264.7 macrophages for the first time. LB effectively inhibited excessive production of nitric oxide (NO), prostaglandin E2 (PGE₂), cytokines (IL-6, TNF-α and MCP-1), and the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthases (iNOS) in lipopolysaccharide (LPS)-induced RAW264.7 cells. LB blocked the degradation of inhibitor of kappa B (IκBα) and translocation of nuclear factor kappa B (NF-κB) p65. Additionally, LB reduced the intracellular reactive oxygen species, and increased the expression of heme oxygenase-1 (HO-1) and the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) in the presence or absence of LPS. The results suggested that LB might be one of the bioactive components of SH, and be potential for the treatment of RA and valuable to be further investigated.

Ameliorative effect of rosiglitazone, a peroxisome proliferator gamma agonist on adriamycin-induced cardio toxicity via suppressing oxidative stress and apoptosis

We investigated the rosiglitazone (RSG) effect on adriamycin (ADM)-induced cardio toxicity in experimental animals. Forty adult Wistar male rats were separated into four groups as follows: normal control; RSG (10 mg/kg)-treated; ADM (10 mg/kg)-administered; and ADM (10 mg/kg) + RSG (10 mg/kg)-treated. Serum lipid level, different biochemical biomarkers, histological analysis, and nuclear factor erythroid 2-related factor/heme oxygenase-1 (Nrf2/HO-1), Caspase 3, B-cell lymphoma 2 (Bcl-2), and Bax gene expression were assessed in serum and cardiac tissue samples. Our results show that RSG treatment in ADM-administered animals significantly diminished low-density lipoprotein cholesterol, triglyceride, and total cholesterol, and increases high-density lipoprotein cholesterol (HDL-c) in comparison with the ADM group. RSG treatment reduced the effect of ADM administration on cardiac dysfunction markers such as cardiac troponin T Creatine Kinase-MB, aspartate aminotransferase, and lactate dehydrogenase, showing the amelioration of cardio toxicity in ADM-administered rats. Additionally, RSG treatment significantly decreased the level of malondialdehyde and nitric oxide in cardiovascular tissue. RSG-treated rats in combination with ADM likewise showed a significant increase in reduced glutathione, superoxide dismutase, catalase content, and the activity of glutathione peroxidase (GPx) as compared with ADM group. Moreover, RSG treatment in ADM rats significantly increased an Nrf2 and HO-1 expression in comparison with ADM group. While in apoptosis parameters, RSG treatment in ADM rats significantly diminished a cleaved caspase-3 and Bax expression as well as expanded Bcl-2 expression when contrasted with ADM group of rats. In conclusion, RSG is capable of protecting heart toxicity in ADM-treated animals through defensive effects on oxidative stress and biochemical markers.

Rosiglitazone Improves Glucocorticoid Resistance in a Sudden Sensorineural Hearing Loss by Promoting MAP Kinase Phosphatase-1 Expression

In this study, we investigated the role of MAP kinase phosphatase-1 (MKP-1) and rosiglitazone (RSG) in glucocorticoid resistance and glucocorticoid sensitivity, respectively, using a guinea pig model of lipopolysaccharide- (LPS-) induced sudden sensorineural hearing loss (SSHL). The pigs were divided into control, LPS, LPS+dexamethasone (DEX), LPS+RSG, and LPS+DEX+RSG groups. Their hearing was screened by auditory brainstem response measurement. Immunofluorescence staining was used to identify the location of MKP-1 in the inner ear. The expression levels of MKP-1 and the related proteins in the inner ear were detected using western blotting. The morphological changes in the cochlea were observed via hematoxylin-eosin staining. Severe hearing loss was observed in the LPS group, as opposed to the protection from hearing loss observed in the LPS+DEX+RSG group. A positive correlation was observed between MKP-1 expression levels and protection from hearing loss. RSG and DEX synergistically influenced inner ear inflammation. In conclusion, resistance of LPS-induced SSHL guinea pig models to glucocorticoids may result from impaired MKP-1 function in inner ear tissues, induced by glucocorticoids, impairing the inhibition of inflammation. Our findings present novel targets to develop potential therapeutics to treat inflammatory diseases of the inner ear.

1,8-Cineole Ameliorates LPS-Induced Vascular Endothelium Dysfunction in Mice via PPAR-γ Dependent Regulation of NF-κB

1,8-Cineole (eucalyptol), a monoterpene, has been widely reported for the anti-inflammatory effects. Our previous data confirmed that 1,8-cineole ameliorated the inflammatory phenotype of human umbilical vein endothelial cells (HUVECs) by mediating NF-κB expression in vitro. At present, we investigated the protection effects of 1,8-cineole on vascular endothelium in lipopolysaccharide (LPS)-induced acute inflammatory injury mice and the potential mechanisms involved in the protection in HUVECs. Results from enzyme linked immunosorbent assays revealed that 1,8-cineole suppressed the secretion of interleukin (IL)-6 and IL-8 and increased the expression of IL-10 in the serum of LPS-induced mice. 1,8-Cineole reduced the inflammatory infiltration and the expression of vascular cell adhesion molecular 1 (VCAM-1) in the sections of thoracic aorta in LPS-induced acute inflammatory mice. Western blotting indicated that 1,8-cineole significantly decreased the phosphorylation of NF-κB p65 and increased the expression of PPAR-γ in the thoracic aorta tissue. 1,8-Cineole increased the expression of PPAR-γ in LPS-induced HUVECs. 1,8-Cineole and rosiglitazone reduced the protein and mRNA levels of VCAM-1, E-selectin, IL-6, and IL-8 in LPS-induced HUVECs, which could be reversed by the action of GW9662 (inhibitor of PPAR-γ). 1,8-Cineole and rosiglitazone blocked the LPS-induced IκBα degradation and NF-κB p65 nucleus translocation, which could be reversed by the pretreatment of GW9662 or silence of PPAR-γ gene. In conclusion, 1,8-cineole attenuated LPS-induced vascular endothelial cells injury via PPAR-γ dependent modulation of NF-κB.

Clinical relevance of peroxisome proliferator-activated receptor-γ gene polymorphisms with sepsis

BACKGROUND

Peroxisome proliferator-activated receptor-γ (PPARγ) is a regulator of inflammation. This study aimed to explore associations between PPARγ gene single-nucleotide polymorphisms (SNPs) and susceptibility to and clinical outcome of sepsis in the North China Han population.

METHODS

This study included 303 patients with sepsis and 303 controls. We conducted genetic typing for 13 common PPARγ gene SNPs (improved multiplex ligation detection reaction), linkage disequilibrium mapping, and haplotype inference. Associations between SNP genotypes/haplotypes and sepsis susceptibility and outcome (septic shock, organ dysfunction, or death) were assessed using unconditional logistic regression analysis.

RESULTS

For rs2972164, patients with genotypes CT/CT+TT had higher risk of sepsis than genotype CC (odds ratio [95% CI]: 1.74 [1.05-2.86], P = .03 and 1.72 [1.06-2.80], P = .026, respectively); the T allele was associated with increased sepsis risk compared with the C allele (1.64 [1.04-2.58], P = .033). For rs1801282, genotypes CG/CG+GG had lower risk of sepsis than genotype CC (0.55 [0.33-0.92], P = .024 and 0.57 [0.35-0.95], P = .03, respectively); the G allele was associated with decreased sepsis risk compared with the C allele (0.62 [0.39-1.01], P = .055). For rs4135275, genotypes AG/AG+GG had higher risk of severe organ dysfunction (multiple organ dysfunction syndrome score >8) than genotype AA (2.66 [1.16-6.09], P = .038 and 2.21 [1.00-4.85], P = .042, respectively). Haplotype TAT (rs2972164, rs4684846, and rs17036188) was associated with increased sepsis risk (1.66 [1.03-2.67], P = .038).

CONCLUSIONS

No mutation was correlated with septic shock or death. PPARγ gene polymorphisms may play a role in the occurrence and progression of sepsis in the North China Han population.

Protective effects of melatonin on lipopolysaccharide-induced mastitis in mice

Melatonin, a secretory product of the pineal gland, has been reported to have antioxidant and anti-inflammatory effects. However, the protective effects of melatonin on lipopolysaccharide (LPS)-induced mastitis have not been reported. The purpose of this study was to investigate the anti-inflammatory effects and the underlying mechanisms of melatonin on LPS-induced mastitis both in vivo and in vitro. In vivo, our results showed that melatonin attenuated LPS-induced mammary histopathologic changes and myeloperoxidase (MPO) activity. Melatonin also inhibited LPS-induced inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) production in mammary tissues. In vitro, melatonin was found to inhibit LPS-induced TNF-α and IL-6 production in mouse mammary epithelial cells. Melatonin also suppressed LPS-induced Toll-like receptor 4 (TLR4) expression and nuclear factor-kappaB (NF-κB) activation in a dose-dependent manner. In addition, melatonin was found to up-regulate the expression of PPAR-γ. Inhibition of PPAR-γ by GW9662 reduced the anti-inflammatory effects of melatonin. In conclusion, we found that melatonin, for the first time, had protective effects on LPS-induced mastitis in mice. The anti-inflammatory mechanism of melatonin was through activating PPAR-γ which subsequently inhibited LPS-induced inflammatory responses.