Paeonol Suppresses Neuroinflammatory Responses in LPS-Activated Microglia Cells

Blood-Brain Barrier-Penetrating and Lesion-Targeting Nanoplatforms Inspired by the Pathophysiological Features for Synergistic Ischemic Stroke Therapy

Ischemic stroke is a dreadful vascular disorder that poses enormous threats to the public health. Due to its complicated pathophysiological features, current treatment options after ischemic stroke attack remains unsatisfactory. Insufficient drug delivery to ischemic lesions impeded by the blood-brain barrier (BBB) largely limits the therapeutic efficacy of most anti-stroke agents. Herein, inspired by the rapid BBB penetrability of 4T1 tumor cells upon their brain metastasis and natural roles of platelet in targeting injured vasculatures, a bio-derived nanojacket is developed by fusing 4T1 tumor cell membrane with platelet membrane, which further clothes on the surface of paeonol and polymetformin-loaded liposome to obtain biomimetic nanoplatforms (PP@PCL) for ischemic stroke treatment. The designed PP@PCL could remarkably alleviate ischemia-reperfusion injury by efficiently targeting ischemic lesion, preventing neuroinflammation, scavenging excess reactive oxygen species (ROS), reprogramming microglia phenotypes, and promoting angiogenesis due to the synergistic therapeutic mechanisms that anchor the pathophysiological characteristics of ischemic stroke. As a result, PP@PCL exerts desirable therapeutic efficacy in injured PC12 neuronal cells and rat model of ischemic stroke, which significantly attenuates neuronal apoptosis, reduces infarct volume, and recovers neurological functions, bringing new insights into exploiting promising treatment strategies for cerebral ischemic stroke management.

Protective mechanism of Paeonol on central nervous system

Cerebrovascular diseases involve neuronal damage, resulting in degenerative neuropathy and posing a serious threat to human health. The discovery of effective drug components from natural plants and the study of their mechanism are a research idea different from chemical synthetic medicines. Paeonol is the main active component of traditional Chinese medicine Paeonia lactiflora Pall. It widely exists in many medicinal plants and has pharmacological effects such as anti-atherosclerosis, antiplatelet aggregation, anti-oxidation, and anti-inflammatory, which keeps generally used in the treatment of cardiovascular and cerebrovascular diseases. Based on the therapeutic effects of Paeonol for cardiovascular and cerebrovascular diseases, this article reviewed the pharmacological effects of Paeonol in Alzheimer's disease, Parkinson's disease, stroke, epilepsy, diabetes encephalopathy, and other neurological diseases, providing a reference for the research of the mechanism of Paeonol in central nervous system diseases.

Insights on Natural Products Against Amyotrophic Lateral Sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that causes the death of motor neurons and consequent muscle paralysis. Despite many efforts to address it, current therapy targeting ALS remains limited, increasing the interest in complementary therapies. Over the years, several herbal preparations and medicinal plants have been studied to prevent and treat this disease, which has received remarkable attention due to their blood-brain barrier penetration properties and low toxicity. Thus, this review presents the therapeutic potential of a variety of medicinal herbs and their relationship with ALS and their physiopathological pathways.

Effects of Jatrorrhizine on inflammatory response induced by H2O2 in microglia by regulating the MAPK/NF-κB/NLRP3 signaling pathway

Microglia-induced neuroinflammation is a contributing factor to neurodegenerative diseases. Jatrorrhizine (JAT), an alkaloid isolated from Huanglian, has been shown to have neuroprotective effects against various neurodegenerative diseases, but its impact on microglia-induced neuroinflammation remains unclear. In this study, we investigated the role of JAT in MAPK/NF-κB/NLRP3 signaling pathway in an H2O2-induced oxidative stress model using microglia (N9 cells). We divided cells into six groups, including control, JAT, H2O2, H2O2 + 5 μmol/L JAT, H2O2 + 10 μmol/L JAT, and H2O2 + 20 μmol/L minocycline groups. Cell viability was measured using MTT assay and TNF-α levels were detected with an ELISA Kit. Western blot was used to detect NLRP3, HMGB1, NF-κB, p-NF-κB, ERK, p-ERK, p38, p-p38, p-JNK, JNK, IL-1β, and IL-18 expressions. Our results showed that JAT intervention improved H2O2-induced cytotoxicity in N9 cells and reduced the elevated expression of TNF-α, IL-1β, IL-18, p-ERK/ERK, p-p38/p38, p-JNK/JNK, p-p65/p65, NLRP3, and HMGB1 in H2O2 group. Furthermore, treatment with ERK inhibitor SCH772984 specifically blocked ERK phosphorylation, resulting in decreased protein levels of p-NF-κB, NLRP3, IL-1β, and IL-18 in H2O2 group. These results suggest that the MAPK/NF-κB signaling pathway may regulate the protein levels of NLRP3. Overall, our study indicates that JAT may have a protective effect on H2O2-treated microglia via inhibition the MAPK/NF-κB/NLRP3 pathway and could be a potential therapeutic approach for neurodegenerative diseases.

Paeonol, the active component of Cynanchum paniculatum, ameliorated schizophrenia-like behaviors by regulating the PI3K-Akt-GSK3β-NF-κB signalling pathway in MK-801-treated mice

ETHNOPHARMACOLOGICAL RELEVANCE

Cynanchum paniculatum (Bunge) Kitag. ex H. Hara (Asclepiadaceae) have been traditionally used in East Asia as analgesic or antiviral agents. Interestingly, some Chinese and Korean traditional medicinal books reported that the use of C. paniculatum in the treatment of psychotic symptoms, such as hallucinations and delusions.

AIM OF THE STUDY

In this study, we aimed to investigate whether C. paniculatum could improve sensorimotor gating disruption in mice with MK-801-induced schizophrenia-like behaviors. We also aimed to identify the active component of C. paniculatum that could potentially serve as a treatment for schizophrenia and found that paeonol, the major constituent compound of C. paniculatum, showed potential as a treatment for schizophrenia.

MATERIALS AND METHODS

To assess the effect of paeonol on mice with MK-801-induced schizophrenia-like behaviors, we carried out a series of behavioral tests related with symptoms of schizophrenia. In addition, we utilized Western blotting and ELISA techniques to investigate the antipsychotic actions of paeonol.

RESULT

C. paniculatum extract (100 or 300 mg/kg) and paenol (10 or 30 mg/kg) significantly reversed MK-801-induced prepulse deficits in acoustic startle response test. In addition, paeonol (10 or 30 mg/kg) attenuated social novelty preference and novel object recognition memory on MK-801-induced schizophrenia-like behaviour in mice. Furthermore, the phosphorylation levels of PI3K, Akt, GSK3β and NF-κB, as well as related pro-inflammatory cytokine, such as IL-1β and TNF-α, were significantly reversed by the administration of paeonol (10 or 30 mg/kg) in the prefrontal cortex of MK-801-treated mice.

CONCLUSIONS

Collectively, these data show that paeonol can potentially be used as an agent for treating sensorimotor gating deficits, negative symptoms, and cognitive deficits, such as those observed in schizophrenia with few adverse effects.

Efficacy of a toothpaste containing paeonol, potassium nitrate, and strontium chloride on dentine hypersensitivity: A double-blind randomized controlled trial in Chinese adults

Objective

The purpose of this randomized controlled trial was to compare the efficacy of a toothpaste containing paeonol, potassium nitrate, and strontium chloride with control toothpaste on dentine hypersensitivity (DH).

Methods

DH patients who had at least two sensitive teeth and did not use desensitization toothpaste in the past 3 months were randomly allocated to either test or control group. The toothpaste containing paeonol, potassium nitrate, and strontium chloride was used in the test group, while the placebo toothpaste used in control group. The outcome measures included Yeaple probe score and Schiff Index score at 4 and 8 weeks. The patients, personnel and assessors were blinded to the allocation. The differences in Yeaple probe score and Schiff Index score between groups were analyzed with ANOVA.

Results

91 eligible subjects were randomized. 88 of them completed 8-week follow-up and were analyzed (45 in the test group and 43 in the control group). In both groups, the Yeaple probe score showed an upward trend, while the Schiff sensitivity score showed a downward trend. At week 8, the Yeaple probe score had increased by 30.22 g in the test group, and the Schiff Index score had decreased by 0.89. Compared with the control group, the Yeaple probe score in the test group increased by 286.85% from baseline, and the Schiff Index score decreased by 42.96%, showing a statistically significant difference. Five cases of adverse events were observed.

Conclusion

The toothpaste containing paeonol, potassium nitrate, and strontium chloride was effective against DH.

Clinical significance

This combination of paeonol, potassium nitrate and strontium chloride could be a novel functional ingredient choice for anti-hypersensitivity products in future.

Registration

The trial was registered in the Chinese Clinical Trial Registry (ChiCTR2000041417).

Research Progress on Small Molecular Inhibitors of the Type 3 Secretion System

The overuse of antibiotics has led to severe bacterial drug resistance. Blocking pathogen virulence devices is a highly effective approach to combating bacterial resistance worldwide. Type three secretion systems (T3SSs) are significant virulence factors in Gram-negative pathogens. Inhibition of these systems can effectively weaken infection whilst having no significant effect on bacterial growth. Therefore, T3SS inhibitors may be a powerful weapon against resistance in Gram-negative bacteria, and there has been increasing interest in the research and development of T3SS inhibitors. This review outlines several reported small-molecule inhibitors of the T3SS, covering those of synthetic and natural origin, including their sources, structures, and mechanisms of action.

Protective effects of paeonol against lipopolysaccharide-induced liver oxidative stress and inflammation in gibel carp (Carassius auratus gibelio)

Paeonol (2'-hydroxy-4'-methoxyacetophenone) is a phenol that exhibits antioxidant and anti-inflammatory capabilities. In this study, the underlying mechanism of paeonol against LPS-induced oxidative stress and inflammatory responses in gibel carp was investigated. Three hundred healthy gibel carp were divided into five groups (n = 9), intraperitoneally injected with LPS and thereafter treated with paeonol (16 mg/kg and 64 mg/kg). Fish were anesthetized with MS-222 (100 mg/L), and samples were collected at 72 h to investigate plasma biochemical indexes, liver histopathology, antioxidant enzymatic activity, and TLR receptor-related gene expression. Fish injected with LPS (20 mg/kg) exhibited significantly increased plasma aminotransferase (ALT), aminotransferase (AST), lactate dehydrogenase (LDH), glucose (GLU), diamine oxidase (DAO), and alkaline phosphatase (ALP) levels (P < 0.05). In addition, LPS challenge significantly enhanced myeloperoxidase (MPO) and malondialdehyde (MDA) contents, whereas those of catalase (CAT) and glutathione peroxidase (GSH-Px) decreased (P < 0.05). However, treatment with paeonol attenuated these LPS-induced changes (P < 0.05). The mRNA expression of TLR4, TIRAP, MyD88, TRAF6, NF-κB, TNF-α, IL-1β, and IL-8, which were activated by LPS challenge (P < 0.05), were downregulated by paeonol. Additionally, histopathological examination demonstrated that paeonol alleviates LPS-induced hepatic tissue lesions in fish. Taken together, the results suggest that paeonol mitigates LPS-induced liver oxidative stress and inflammation in gibel carp.

Paeonol regulates NLRP3 inflammasomes and pyroptosis to alleviate spinal cord injury of rat

Background

Spinal cord injury (SCI) is a life-threatening traumatic disorder. Paeonol has been confirmed to be involved in a variety of diseases. The purpose of this study is to investigate the role of paeonol on SCI progression.

Methods

Sprague Dawley (SD) rat was used for the establishment of SCI model to explore the anti-inflammation, anti-oxidation, and neuroprotective effects of paeonol (60 mg/kg) on SCI in vivo. For in vitro study, mouse primary microglial cells (BV-2) were induced by lipopolysaccharide (LPS)/adenosine triphosphate (ATP) treatment. The effect of paeonol on the polarization of LPS/ATP-induced BV-2 cells was determined by detection the expression inducible nitric oxide synthase (iNOS), tumour necrosis factor alpha (TNF-α), arginase-1 (Arg-1), and interleukin (IL)-10 using qRT-PCR. ELISA was used to assess the levels of IL-1β, IL-18, TNF-α, malondialdehyde (MDA), and glutathione (GSH). Western blotting was conducted to determine the levels of NLRP3 inflammasomes and TLR4/MyD88/NF-κB (p65) pathway proteins.

Results

Paeonol promoted the recovery of locomotion function and spinal cord structure, and decreased spinal cord water content in rats following SCI. Meanwhile, paeonol reduced the levels of apoptosis-associated speck-like protein (ASC), NLRP3, active caspase 1 and N-gasdermin D (N-GSDMD), repressed the contents of IL-1β, IL-18, TNF-α and MDA, and elevated GSH level. In vitro, paeonol exerted similarly inhibiting effects on pyroptosis and inflammation. Meanwhile, paeonol promoted BV-2 cells M2 polarization. In addition, paeonol also inactivated the expression of TLR4/MyD88/NF-κB (p65) pathway.

Conclusion

Paeonol may regulate NLRP3 inflammasomes and pyroptosis to alleviate SCI, pointing out the potential for treating SCI in clinic.

Small molecule natural compound targets the NF-κB signaling and ameliorates the development of osteoarthritis

Osteoarthritis (OA) is a multifactorial and chronic disease describing the destruction of cartilage that can lead to defects in the elderly. There is currently no practical strategy that can reverse the OA process. Here, we describe nepetin, a small natural compound with extracellular matrix (ECM) and inflammation regulating functions. In this study, we investigated the therapeutic effects of nepetin on interleukin-1β (IL-1β)-induced inflammation in mice chondrocyte and OA model. In chondrocytes, treatment with nepetin inhibited the overexpression of pro-inflammatory cytokines and mediators induced by IL-1β. Moreover, pretreatment or posttreatment with nepetin also reduced the ECM catabolism and enhanced the ECM anabolism. Mechanistically, nepetin suppressed NF-κB signaling pathway in IL-1β stimulated chondrocyte. Meanwhile, our molecular docking studies indicated nepetin had a powerful binding capacity to p65. Furthermore, nepetin showed a protective and therapeutic effect on the mouse OA model. To sum up, this study indicated nepetin had a new potential therapeutic option in OA.

Paeonol Pretreatment Attenuates Anoxia-Reoxygenation Induced Injury in Cardiac Myocytes via a BRCA1 Dependent Pathway

Breast cancer type 1 sensitive protein (BRCA1) is a well-known tumor suppressor and its role in oxidative stress has been confirmed. The purpose of this study is to evaluate whether paeonol has a protective effect on myocardial hypoxia-reoxygenation (A/R) injury, and to explore H9C2 cells through a mechanism-dependent pathway mediated by BRCA1. H9C2 cells were pretreated with paeonol (10 µM) for 18 h before hypoxia was induced to establish a cell model of myocardial ischemia/reperfusion (I/R) injury. Use commercial kits to detect antioxidant indicators, including relative oxygen content (ROS) levels, total antioxidant capacity (T-AOC), superoxide dismutase (SOD), lactate dehydrogenase (LDH) activity, and creatine kinase (CK-MB) and nuclear factor-kappaB (NF-κB) activity. The cell viability was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction method. Real-time fluorescent quantitative PCR was used to detect BRCA1 mRNA and protein levels. The expression levels of BRCA1, NLRP3 and ACS were determined by Western blotting. In addition, the release of interleukin (IL)-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) was also evaluated by an enzyme-linked immunosorbent assay (ELISA) kit. The results showed that paeonol (10 µM) can significantly improve the hypoxic A/R damage of H9C2 cells, and the BRCA1 expression of H9C2 cells pretreated with paeonol was significantly increased before A/R damage was induced. BRCA1 is widely known in breast and ovarian cancer. Our data proves that the down-regulation of BRCA1 participates in the decrease of cell viability and the decrease of CK-MB and LDH activities, and protects cells by inhibiting the production of ROS and the activation of Nod-like receptor protein 3 (NLRP3) inflammasomes and NF-κB. In conclusion, paeonol significantly improved the A/R damage of H9C2 cells induced by hypoxia through the BRCA1/ROS-regulated NLRP3 inflammasome/IL-1β and NF-κB/TNF-α/IL-6 pathways. It may be a potential drug against myocardial I/R injury.

A chondroprotective effect of moracin on IL-1β-induced primary rat chondrocytes and an osteoarthritis rat model through Nrf2/HO-1 and NF-κB axes

Osteoarthritis (OA) is a common joint disease characterized by cartilage degeneration and inflammation. Although moracin is known to play a role in anti-inflammation and anti-oxidation in several inflammatory diseases, its anti-inflammatory effect on OA remains largely unknown. Therefore, in order to explore the role of moracin in OA, we investigated the anti-inflammatory effect of moracin on interleukin (IL)-β-induced rat chondrocytes in vitro and surgically induced OA rat models in vivo. Rat chondrocytes were pretreated using moracin (0, 5, 10, 15 μmol L-1) and then stimulated with IL-β (10 ng ml-1). Results showed that moracin reduced the expression of IL-1β-induced nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), IL-6, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)-2 in both rat chondrocytes and cell culture supernatants. Besides, IL-1β-induced degradation of aggrecan and collage II, and the high expression of matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS)-5 were also reversed by moracin. Moreover, moracin inhibited the translocation of p65 from the cytoplasm to nucleus induced by IL-1β and activated the Nrf2/HO-1 signaling pathway in chondrocytes. In OA rat models, moracin prevented cartilage of rats from destruction. All these findings above indicated that moracin could be a potentially effective drug for treating OA.

Plant-Derived Natural Compounds for the treatment of Amyotrophic Lateral Sclerosis: An Update

Background

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease (MND) that typically causes death within 3-5 years after diagnosis. Regardless of the substantial scientific knowledge accrued more than a century ago, truly effective therapeutic strategies remain distant. Various conventional drugs are being used but are having several adverse effects.

Objective/Aim

The current study aims to thoroughly review plant-derived compounds with well-defined ALS activities and their structure-activity relationships. Moreover, the review also focuses on complex genetics, clinical trials, and the use of natural products that might decrypt the future and novel therapeutics in ALS.

Methods

The collection of data for the compilation of this review work was searched in PubMed Scopus, Google Scholar, and Science Direct.

Results

Results showed that phytochemicals like-Ginkgolides, Protopanaxatriol, Genistein, epigallocatechingallate, resveratrol, cassoside, and others possess Amyotrophic lateral sclerosis (ALS) activity by various mechanisms.

Conclusion

These plant-derived compounds may be considered as supplements for conventional (ALS). Moreover, further preclinical and clinical studies are required to understand the structure-activity relationships, metabolism, absorption, and mechanisms of plant-derived natural agents.

Non-invasive intranasal administration route directly to the brain using dendrimer nanoplatforms: An opportunity to develop new CNS drugs

There are several routes of administration to the brain, including intraparenchymal, intraventricular, and subarachnoid injections. The blood-brain barrier (BBB) impedes the permeation and access of most drugs to the central nervous system (CNS), and consequently, many neurological diseases remain undertreated. For past decades, to circumvent this effect, several nanocarriers have been developed to deliver drugs to the brain. Importantly, intranasal (IN) administration can allow direct delivery of drugs into the brain through the anatomical connection between the nasal cavity and brain without crossing the BBB. In this regard, dendrimers may possess great potential to deliver drugs to the brain by IN administration, bypassing the BBB and reducing systemic exposure and side effects, to treat diseases of the CNS. In this original concise review, we highlighted the few examples advocated regarding the use of dendrimers to deliver CNS drugs directly via IN. This review highlighed the few examples of the association of dendrimer encapsulating drugs (e.g., small compounds: haloperidol and paeonol; macromolecular compounds: dextran, insulin and calcitonin; and siRNA) using IN administration. Good efficiencies were observed. In addition, we will present the in vivo effects of PAMAM dendrimers after IN administration, globally, showing no general toxicity.

Effects of a dammarane-type saponin, ginsenoside Rd, in nicotine-induced vascular endothelial injury

BACKGROUND

Panax notoginseng (Burk.) F.H. Chen is a traditional medicinal plant widely used to prevent and treat cardiovascular diseases. Ginsenoside Rd (GRd) is a major bioactive component of P. notoginseng, but specific effects on cardiovascular disease-related pathogenic processes are rarely studied, especially vascular endothelial injury.

PURPOSE

This study investigated the potential protective efficacy of GRd against nicotine-induced vascular endothelial cell injury, disruption of vascular nitric oxide (NO) signaling, aberrant endothelium-monocyte adhesion, platelet aggregation, and vasoconstriction.

STUDY DESIGN/METHODS

Vascular endothelial injury and functional disruption were investigated in cultured human umbilical vein endothelial cells (HUVECs) by biochemical assays for nitric oxide (NO) and angiotensin II (Ang II), immunofluorescence (IF) and western blotting for expression analyses of apoptosis- related proteins, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), Ang II type receptor 1 (AGTR1), toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), and nuclear factor-kappa B (NF-κB). In addition, vascular protection by GRd was examined in nicotine-administered Sprague-Dawley (SD) rats by serum NO and Ang II assays, and by hematoxylin-eosin (HE) and immunostaining of aorta. We also examined effects of GRd on monocyte (THP-1 cells) adhesion assays, adenosine diphosphate (ADP)-induced platelet aggregation, and phenylephrine (PE)-induced vasoconstriction of isolated rat aortic rings.

RESULTS

In HUVECs, nicotine significantly suppressed NO production, enhanced Ang II production, downregulated eNOS expression, and upregulated expression levels of AGTR1, TLR4, MyD88, NF-κB, iNOS, Bax/Bcl-2 ratio, cleaved caspase-3, and cytochrome c (cyt c). All of these changes were significantly reversed by GRd. In rats, oral GRd reversed the reduction NO and enhanced Ang II production in serum induced by nicotine administration, and HE staining revealed protection of aortic endothelial cells. In addition, GRd reversed nicotine-mediated enhancement of HUVECs-monocyte adhesion, inhibited ADP-induced platelet aggregation and PE-induced vasoconstriction.

CONCLUSION

GRd may prevent nicotine-induced cardiovascular diseases by preserving normal vascular endothelial NO signaling, suppressing platelet aggregation and vasoconstriction, and by preventing endothelial cell-monocyte adhesion.

Nomilin targets the Keap1-Nrf2 signalling and ameliorates the development of osteoarthritis

Osteoarthritis (OA) is a long-term and inflammatory disorder featured by cartilage erosion. Here, we describe nomilin (NOM), a triterpenoid with inflammation modulatory properties in variety of disorders. In this study, we demonstrated the latent mechanism of NOM in alleviating the progress of OA both in vitro and in vivo studies. The results showed that NOM pre-treatment suppressed the IL-1β-induced over-regulation of pro-inflammation factors, such as NO, IL-6, PGE2 , iNOS, TNF-α and COX-2. Moreover, NOM also down-regulates the degradation of ECM induced by IL-1β. Mechanistically, the NOM suppressed NF-κB signalling via disassociation of Keap1-Nrf2 in chondrocytes. Furthermore, NOM delays the disease progression in the mouse OA model. To sum up, this research indicated NOM possessed a new potential therapeutic option in osteoarthritis.

Cynanchum paniculatum and Its Major Active Constituents for Inflammatory-Related Diseases: A Review of Traditional Use, Multiple Pathway Modulations, and Clinical Applications

Cynanchum paniculatum Radix, known as Xuchangqing in Chinese, is commonly prescribed in Chinese Medicine (CM) for the treatment of various inflammatory diseases. The anti-inflammatory property of Cynanchum paniculatum can be traced from its wind-damp removing, collaterals' obstruction relieving, and toxins counteracting effects as folk medicine in CM. This paper systematically reviewed the research advancement of the pharmacological effects of Cynanchum paniculatum among a variety of human diseases, including diseases of the respiratory, circulatory, digestive, urogenital, hematopoietic, endocrine and metabolomic, neurological, skeletal, and rheumatological systems and malignant diseases. This review aims to link the long history of clinical applications of Cynanchum paniculatum in CM with recent biomedical investigations. The major bioactive chemical compositions of Cynanchum paniculatum and their associated action mechanism unveiled by biomedical investigations as well as the present clinical applications and future perspectives are discussed. The major focuses of this review are on the diverse mechanisms of Cynanchum paniculatum and the role of its active components in inflammatory diseases.

Hederacoside-C protects against AGEs-induced ECM degradation in mice chondrocytes

Hederacoside-C (HDC), a natural compound extracted from the leaves of Hedera helix with inflammation modulatory properties in variety of disorders. In this study, we investigated the latent mechanism of HDC in alleviating of the progress of OA in vitro experiment. The results showed that HDC pretreatment suppressed the advanced glycation end-products (AGEs) induced over-regulation of ROS level and inflammatory factors. Moreover, HDC also downregulate the degradation of ECM induced by AGEs. Mechanistically, the HDC suppressed NF-κB signaling pathway in chondrocyte. To sum up, this study indicated HDC possessed a new potential therapeutic option in osteoarthritis.

Primary Studies on Construction and Evaluation of Ion-Sensitive in situ Gel Loaded with Paeonol-Solid Lipid Nanoparticles for Intranasal Drug Delivery

Background

Paeonol (PAE) is a potential central neuroprotective agent with poor water solubility and rapid metabolism in vivo. The key to improve the clinical application of PAE in the treatment of neurodegenerative diseases is to improve the brain delivery of it. The purpose of this study was to construct a paeonol-solid lipid nanoparticles-in situ gel (PAE-SLNs-ISG) drug delivery system based on nose-brain transport pathway.

Materials and Methods

In this study, the stability of PAE in simulated biological samples was studied firstly in order to clarify the reasons for low oral bioavailability. Paeonol-solid lipid nanoparticles (PAE-SLNs) were prepared by high-temperature emulsification-low-temperature curing combined with ultrasound. The PAE-SLNs-ISG drug delivery system was constructed, and related formulation optimization, preparation characterization, cell evaluation and in vivo evaluation were performed.

Results

The metabolic mechanism of PAE incubated in the liver microsomes metabolic system was in accordance with the first-order kinetics, and the half-life was 0.23 h. PAE-SLNs were polyhedral or spherical particles with good dispersion and the particle size was 166.79 nm ± 2.92 nm. PAE-SLNs-ISG solution was a Newtonian fluid with a viscosity of 44.36 mPa · S ± 2.89 mPa · S. The viscosity of PAE-SLNs-ISG gel was 1542.19 mPa · S ± 19.30 mPa · S, and the rheological evaluation showed that the gel was a non-Newtonian pseudoplastic fluid with shear thinning, thixotropy and yield value. The release mechanism of PAE from PAE-SLNs was drug diffusion; the release mechanism of PAE from PAE-SLNs-ISG was a synergistic effect of skeleton erosion and drug diffusion. The cell viabilities of PAE-SLNs and PAE-SLNs-ISG in the concentration range of 0.001 µg/mL to 10 µg/mL were higher than 90%, showing a low level of cytotoxicity. The geometric mean fluorescent intensities of RPMI 2650 cells incubated with fluorescein isothiocyanate-solid lipid nanoparticles (FITC-SLNs) for 1 h, 4 h and 6 h were 1841 ± 24, 2261 ± 27 and 2757 ± 22, respectively. Cyanine7 NHS ester-solid lipid nanoparticles-in situ gel (Cy7-SLNs-ISG) accumulated effectively in the brain area after administration through the olfactory area, and the fluorescence response was observed in olfactory bulb, cerebellum and striatum.

Conclusion

SLNs-ISG nose-brain drug delivery system can effectively deliver SLNs to brain regions, and it is a potentially effective strategy to realize the brain region delivery of PAE.

Activation of RAW264.7 macrophage by Exopolysaccharide from Aphanothece halaphytica (EPSAH) and the underlying mechanisms

Exopolysaccharide from Aphanothece halophytica (EPSAH), a potent antitumor agent and immunological adjuvant, was investigated for the activation effect on RAW264.7 macrophages and the underlying mechanisms. EPSAH could significantly enhance macrophage phagocytosis and the secretion of nitric oxide, increase the mRNA expression levels of the pro-inflammatory cytokines (IL-1β, IL-6, IL-12, and TNF-α), anti-inflammatory cytokine IL-10, and chemokines (MCP-1 and MIP-1α). When RAW264.7 cells were treated with EPSAH, the mRNA expression of TLR4 and its downstream molecules TRAF6 and MyD88 were upregulated. When TLR4 was blocked using a TLR4-specific neutralizing antibody, nitric oxide secretion from the macrophages was significantly inhibited. EPSAH was further shown to induce phosphorylation of the mitogen-activated protein kinases (MAPKs) ERK, JNK, and p38, and promote cytoplasmic IκB phosphorylation and increase nuclear NF-κB p65 levels remarkably in RAW264.7 cells. These data demonstrate the capacity of EPSAH to induce macrophage activation possibly via TLR4/MyD88 pathway, which leads to the activation of its main signaling downstream molecules MAPKs and NF-κB.

Paeonol at Certain Doses Alleviates Aggressive and Anxiety-Like Behaviours in Two Premenstrual Dysphoric Disorder Rat Models

Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS), a common mental health disturbance associated with several periodic psychological symptoms in women. Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for PMS/PMDD patients; however, side effects are inevitable, especially in long-term treatment. In previous studies, the natural compound paeonol in Moutan Cortex was found to play effective roles in central nervous system disorders with its anti-inflammatory, anti-oxidant, and neuroprotective effects. Consequently, we assume that paeonol might produce positive effects in the treatment of PMS/PMDD. In this study, the open-field test (OFT) and elevated plus maze (EPM) and light dark box (LDB) tests were performed in mice to determine the optimal dose of paeonol for treating anxiety. Then, paeonol was used to treat the progesterone withdrawal (PWD) and resident intruder paradigm (RIP) rat models of PMDD. Using these two reliable models, the OFT and EPM, LDB, and composite aggressive tests were performed to evaluate the effect of the drug on behavioural symptoms of PMDD. From the dosage screening results, the optimal anti-anxiety dose of paeonol was identified as 17.5 mg/kg/d for 7 days. With regard to the effect of paeonol on PMDD rat models, a significantly improvement was found in the behavioural symptoms, but the effective dose varied in different models. For the PWD model rats, treatment with 6.05 mg/kg paeonol could significantly improve anxiety and irritability, while that with 24.23 mg/kg paeonol resulted in anxiety-like effects in behavioural tests. In RIP model rats, treatment with 12.11 mg/kg paeonol demonstrated excellent effects in improving anxiety, particularly irritable emotional behaviour. In conclusion, our study indicates that paeonol is a potential therapeutic compound for PMS/PMDD; it is a drug option that helps establish dosage guidance for treatment of this condition.

Network pharmacology based research into the effect and mechanism of Xijiao Dihuang decoction against sepsis

Sepsis is a critical illness that contributes a high mortality, while Xijiao Dihuang decoction (XJDHT) has been used in treatment against sepsis for many years by clinical doctors. Clinical studies confirmed a good efficacy of XJDHT against sepsis. The aim of this study is to observe the efficacy of XJDHT in sepsis model rats and macrophages activated by LPS, and to verify the underlying mechanisms. The key components of XJDHT and its targets against sepsis were analyzed and selected by network pharmacology. The potential mechanisms that XJDHT regulates the progress of sepsis were verified in sepsis rats and NR8383 cell lines. XJDHT at a dose of 25 mg/kg was administrated to rats which endured cecal ligation and perforation (CLP). After MTT assay, XJDHT at a dose of 4 mg/mL was selected to treat NR8383 cell lines activated by LPS. In vivo experiment, the survival of the rats was assessed. The content of cytokine in serum were assessed by Enzyme-linked immunosorbent assays (ELISA). Contents of cytokine and key molecules in relative signaling pathway were assessed by immunohistochemical method. The pathway protein expressions were detected by Western blotting. In vitro experiment, immunofluorescence was used to assess the content of cytokine and signaling pathway. A total of 42 targets of XJDHT against sepsis were identified by network pharmacology. After eliminating overlapping compounds and proteins, there were 8 compounds in XJDHT that associating with the 42 sepsis-related targets. NF-κB and HIF-1α signaling pathway were recognized to play important role for XJDHT against sepsis. XJDHT improved survival rate in the XJDHT group compared with the model group. The contents of IL-6 increased in the model group compared with the control group with ELISA and immunohistochemistry, while XJDHT reduced the content of IL-6. The expressions of p65 and HIF-1α reduced significantly in the XJDHT group compared with the model group. In vitro study, the content of IL-6 elevated significantly after LPS stimulation, while XJDHT reduced this increase. Furthermore, expressions of protein of p65 and HIF-1α decreased significantly compared with the LPS group. To conclude, our study demonstrated that XJDHT at a dose of 25 g/kg is capable of improving the survival of sepsis via regulating the NF-κB and HIF-1α signaling pathway.

Dibromoacetic Acid Induced Hepatotoxicity in Mice through Oxidative Stress and Toll-Like Receptor 4 Signaling Pathway Activation

Dibromoacetic acid (DBA) is one of haloacetic acids, often as a by-product of disinfection in drinking water. DBA is a multiple-organ carcinogen in rodent animals, but little research on its hepatotoxicity has been conducted and its mechanism has not been elucidated. In this study, we found that DBA could induce obvious hepatotoxcity in Balb/c mice as indicated by histological changes, increasing serum level of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and accumulation of hepatic glycogen, after the mice were administered DBA at doses of 1.25, 5, and 20 mg/kg body weight for 28 days via oral gavage. In mechanism study, DBA induced oxidative stress as evidenced by increasing the level of malondialdehyde (MDA), reactive oxygen species (ROS) in the liver, advanced oxidative protein products (AOPPs) in the serum, and decreasing the level of glutathione (GSH) in the liver. DBA induced inflammation in the liver of the mice which is supported by increasing the production of tumor necrosis factor-α (TNF-α) and the mRNA levels of TNF-α, interleukin-6 (IL-6), interleukin-1β (IL-1β), and nuclear factor κB (NF-κB) in the liver. DBA also upregulated the protein levels of Toll-like receptor (TLR) 4, myeloid differentiation factor 88 (MyD88), tumor necrosis factor receptor-associated factor 6 (TRAF6), inhibitor of nuclear factor κB alpha (IκB-α), nuclear factor κB p65 (NF-κB p65), and the phosphoralation of P38 mitogen-activated protein kinase (P38MAPK) and c-Jun N-terminal kinase (JNK). Conclusion. DBA could induce hepatotoxicity in mice by oral exposure; the mechanism is related to oxidative stress, inflammation, and Toll-like receptor 4 signaling pathway activation.

Inhibiting the LPS-induced enhancement of mEPSC frequency in superficial dorsal horn neurons may serve as an electrophysiological model for alleviating pain

Pain is a major primary health care problem. Emerging studies show that inhibition of spinal microglial activation reduces pain. However, the precise mechanisms by which microglial activation contributes to nociceptive synaptic transmission remain unclear. In this study, we measured spontaneous synaptic activity of miniature excitatory postsynaptic currents (mEPSCs) in rat spinal cord superficial dorsal horn (SDH, laminae I and II) neurons. Lipopolysaccharide (LPS) and adenosine triphosphate (ATP) increased the frequency, but not amplitude, of mEPSCs in SDH neurons. Microglial inhibitors minocycline and paeonol, as well as an astrocyte inhibitor, a P2Y1 receptor (P2Y1R) antagonist, and a metabotropic glutamate receptor 5 (mGluR5) antagonist, all prevented LPS-induced enhancement of mEPSC frequency. In mouse behavioral testing, minocycline and paeonol effectively reduced acetic acid-induced writhing and LPS-induced hyperalgesia. These results indicate that LPS-activated microglia release ATP, which stimulates astrocyte P2Y1Rs to release glutamate, triggering presynaptic mGluR5 receptors and increasing presynaptic glutamate release, leading to an increase in mEPSC frequency and enhancement of nociceptive transmission in SDH neurons. We propose that these effects can serve as a new electrophysiological model for evaluating pain. Moreover, we predict that pharmacologic agents capable of inhibiting the LPS-induced enhancement of mEPSC frequency in SDH neurons will have analgesic effects.

Green Tea Polyphenol (-)-Epigallocatechin Gallate (EGCG) Attenuates Neuroinflammation in Palmitic Acid-Stimulated BV-2 Microglia and High-Fat Diet-Induced Obese Mice

Obesity is closely associated with neuroinflammation in the hypothalamus, which is characterized by over-activated microglia and excessive production of pro-inflammatory cytokines. The present study was aimed at elucidating the effects of (−)-epigallocatechin gallate (EGCG) on palmitic acid-stimulated BV-2 microglia and high-fat-diet-induced obese mice. The results indicated the suppressive effect of EGCG on lipid accumulation, pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) release, and microglial activation in both cellular and high-fat-diet rodent models. These results were associated with lower phosphorylated levels of the janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) signaling pathway. In conclusion, EGCG can attenuate high-fat-induced hypothalamic inflammation via inhibiting the JAK2/STAT3 signaling pathways in microglia.

Paeonol ameliorates monosodium urate-induced arthritis in rats through inhibiting nuclear factor-κB-mediated proinflammatory cytokine production

Moutan Cortex has been widely used to treat various types of arthritis in traditional Chinese medicine. Paeonol is isolated as an active ingredient from Moutan Cortex. However, the effect and potential mechanism of paeonol on gouty arthritis have not been evaluated. In this study, rats were treated intragastrically with paeonol for consecutive 7 days. On Day 5, rats were intra-articularly injected with monosodium urate (MSU) crystals in the ankle joints to induce MSU-induced arthritis (MIA). Paw volume was detected at various time points. Gait score was measured at 24 hr after MSU crystal injection. Ankle joints were collected for evaluation of histological score and expression of proinflammatory cytokines using hematoxylin and eosin staining and immunohistochemistry staining, respectively. Nuclear level of nuclear factor (NF)-κBp65 in synovial tissues was analyzed by western blot assay. NF-κB DNA-binding activity was measured by enzyme linked immunosorbent assay. Paeonol markedly lowered the paw volume, gait score, and histological score in MIA rats. Mechanistically, paeonol markedly reduced the expression of TNF-α, IL-1β, and IL-6 in synovial tissues of MIA rats. In addition, the elevated level of p65 in nucleus and NF-κB DNA-binding activity in synovial tissues of MIA rats were reduced significantly by paeonol treatment. These findings suggest that paeonol exerts anti-inflammatory effect in MIA rats through inhibiting expression of proinflammatory cytokines and NF-κB activation.

Paeonol: pharmacological effects and mechanisms of action

Paeonia suffruticosa possesses various medicinal benefits and has been used extensively in traditional oriental medicine for thousands of years. Paeonol is the main component isolated from the root bark of Paeonia suffruticosa. The pharmacological effects of Paeonia suffruticosa are mostly attributed to paeonol. Paeonol injection has been successfully applied in China for nearly 50 years for inflammation/pain-related indications. Currently, the dosage forms of paeonol approved by China Food and Drug Administration include tablet, injection, and external preparations such as ointment and adhesive plaster. So far, the clinical applications of paeonol are mainly focusing on the anti-inflammatory activity. Studies of other pharmacological activities of paeonol are developing rapidly, and which may play an important role in the future. Besides, substantial mechanisms of pharmacological action of paeonol have been clarified in recent years. In this review, we summarize the pharmacological effects anti-inflammatory, neuroprotective, anti-tumor, anti-cardiovascular diseases and associated mechanisms of action of paeonol up to date.

The protective effect of sinapic acid in osteoarthritis: In vitro and in vivo studies

The anti-inflammatory effect of sinapic acid (SA) has been reported in several studies. However, whether SA has the same effect on osteoarthritis (OA) has yet to be clearly elucidated. We designed a series of in vitro and in vivo procedures to verify the above conjecture. Compared with controls, SA-pretreated human chondrocytes showed lower levels of interleukin (IL)-1β-induced IL-6, prostaglandin E2 (PGE2), nitric oxide (NO) and tumour necrosis factor-α (TNF-α) in vitro. Meanwhile, SA could also reverse the degradation of type II collage and aggrecan, as well as the overproduction of matrix metalloproteinase-9 (MMP-9) and matrix metalloproteinase-13 (MMP-13), inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2 and a disintegrin and metalloproteinase thrombospondin motifs (ADAMTS)-5. Furthermore, activation of nuclear factor κB (NF-κB), which was induced by IL-1β, was also inhibited by SA through the pathway of nuclear factor-erythroid 2-related factor-2 (Nrf2)/heme oxygenase 1. In vivo, SA could delay the progress of mice OA models. We propose that SA may be applied as a potential therapeutic drug in OA treatment.

An Available Strategy for Nasal Brain Transport of Nanocomposite Based on PAMAM Dendrimers via In Situ Gel

Polyamidoamine (PAMAM) dendrimers are efficient drug carriers. The presence of a physiological pathway for nasal brain transport provides a potential path for direct brain-targeted delivery of dendrimer nanocomposites. In this study, we synthesized PAMAM dendrimer composites with a nanoscale size; the particle size of PAE (Paeonol)/mPEG (the heterofunctional PEG polymer with a methoxy)-PAMAM G5.NHAc and mPEG-PAMAM G5.NH₂-FITC were 72.41 ± 11.58 nm and 96.51 ± 7.77 nm, and the zeta potential of PAE/mPEG-PAMAM G5.NHAc and mPEG-PAMAM G5.NH₂-FITC were + 0.57 ± 0.11 mv and + 9.60 ± 0.41 mv, respectively. The EE% and DL% of PAE in PAE/mPEG-PAMAM G5.NHAc were 53.77% and 13.92%, respectively. PAE/mPEG-PAMAM G5.NHAc/DGG ionic-sensitive in situ gel was prepared, the viscosity of solution and gel state were 112 ± 3.2 mPa and 1403 ± 38.5 mPa, respectively. The in vitro goat mucoadhesive strength of the gel was 4763.36 ± 85.39 dyne/cm². In situ gel system was proven to be a non-Newtonian pseudo-plastic fluid with shear thinning, thixotropy and yield stress. The optimal model of PAE released from PAE/mPEG-PAMAM G5.NHAc and PAE/mPEG-PAMAM G5.NHAc/DGG were the Higuchi equation and the Korsmeyer-Peppas equation, respectively. The cytotoxicity of the nanocomposites showed a concentration-dependence, and the cell viabilities of PAE/mPEG-PAMAM G5.NHAc were both higher than 95% between 0.0001 μM and 10 μM. mPEG-PAMAM G5.NH₂-FITC was efficiently taken up by cells and exhibited strong fluorescence in the cytoplasm and nucleus. Significant accumulation of nanocomposites was observed in the brain after administration of the in situ gel group, and maximum accumulation was reached at 12 h. A small amount of accumulation was observed in the nanocomposite solution group only at 2 h. Therefore, the direct nasal brain transport efficiency of PAMAM dendrimer nanocomposites can be significantly improved after combining with in situ gel. PAMAM dendrimer nanocomposite/DGG is a potential drug delivery system for nasal brain transport.

Mechanisms underlying gastroprotective effect of paeonol against indomethacin-induced ulcer in rats

Paeonol, a natural phenolic compound, possesses diverse beneficial effects including antioxidant and anti-inflammatory effects. Gastric ulcer is still the most prevalent irritant illness among the gastrointestinal diseases. The present study explored the protective effect of paeonol at two dose levels in indomethacin (IND)-induced gastric ulcer in rats. Forty-eight male Wistar rats were arranged into six groups: control, paeonol-treated, IND-treated, IND/paeonol (low and high doses)-treated, and ranitidine-treated groups. The oxidative status was evaluated by determining malondialdehyde level, superoxide dismutase activity, reduced glutathione content as well as hemoxygenase-1 (HO-1) gene expressions, and the antioxidant protein; NAD(P)H quinone oxidoreductase 1 (NQO1) immunostaining. The pro-inflammatory genes nuclear factor κB (NF-κB) and interleukin 1β (IL-1β) were estimated together with the proapoptotic gene of caspase 3. IND caused multiple gastric ulcers with evident oxidative damage and elevated pro-inflammatory and proapoptotic markers. Paeonol protected significantly, in a dose-dependent manner, the gastric mucosa from ulcerative lesion of IND similar to the reference drug ranitidine. Paeonol pretreatment diminished gastric oxidative stress and restored the gastric antioxidant capacity by elevating gastric gene expression of HO-1 and protein expression of NQO1. Paeonol also reduced NF-κB, IL-1β, and caspase 3 gene expressions. In conclusion, paeonol offered a gastroprotection dependent on its antioxidant, anti-inflammatory, and antiapoptotic effects.

Paeonol Ameliorates Ovalbumin-Induced Asthma through the Inhibition of TLR4/NF-κB and MAPK Signaling

Asthma is a chronic inflammatory disease of the airways, with complex signaling pathways involved in its pathogenesis. It was reported that paeonol attenuated airway inflammation of ovalbumin (OVA)-induced mice. Therefore, it is of importance to further investigate the underlying mechanism. BALB/c mice were challenged with OVA for the asthma model, which was validated by the changed levels of IL-4, IFN-γ, and IgE. The elevation of IL-4 and the decreasing of IFN-γ were significantly in middle (p<0.05) or high (p<0.01) paeonol dose groups compared with OVA group. MIP-1β in bronchoalveolar lavage fluid (BALF) also decreased significantly in middle and high paeonol group compared with OVA group (p<0.01), which is similar to the change of its mRNA in lung tissues. Moreover, the inflammatory cells infiltration and collagen deposition were attenuated by paeonol and montelukast sodium via histology examination. At last the immune blot of the protein extracted from lung tissues demonstrated that paeonol decreased the expression of TLR4 and the nuclear translocation of NF-κB, as well as the phosphorylation levels of P38 and ERK in asthma model. In conclusion, paeonol ameliorated OVA-induced asthma through the TLR4/NF-κB and mitogen-activated protein kinase (MAPK) signaling.

Downregulating PI3K/Akt/NF-κB signaling with allicin for ameliorating the progression of osteoarthritis:in vitroandvivostudies

A schematic illustration of the potential protective effects of allicin on osteoarthritis development.

Prevention of Bleomycin-Induced Pulmonary Inflammation and Fibrosis in Mice by Paeonol

Pulmonary fibrosis is a severe and progressive disease that is characterized by an abnormal deposition of extracellular matrix, such as collagens. The pathogenesis of this disease may be initiated by oxidative damage of lung epithelial cells by fibrogenic stimuli, leading to lung inflammation, which in turn promotes various lung fibrotic responses. The profibrogenic effect of transforming growth factor-β1 (TGF-β1) on lung fibroblasts is crucial for the pathogenesis of this disease. Paeonol, the main phenolic compound present in the Chinese herb Paeonia suffruticosa, has antioxidant and anti-inflammatory properties. However, whether paeonol has therapeutic effects against pulmonary fibrosis remains unclear. Using a murine model, we showed that 21 days after the insult, intratracheal bleomycin caused pulmonary inflammation and fibrosis, as evidenced by lung histopathological manifestations and increase in various indices. The inflammatory indices included an increase in total cell count, differential cell count, and total protein concentration in bronchoalveolar lavage fluid. The fibrotic indices included an increase in lung levels of TGF-β1, total collagen, type 1α1 collagen (COL1A1), and α-smooth muscle actin (α-SMA; a marker of myofibroblasts). Bleomycin also was found to cause an increase in oxidative stress as reflected by increased levels of malondialdehyde and 4-hydroxynonenal in the lungs. Importantly, all these pathophysiological events were suppressed by daily treatment with paeonol. Using human lung fibroblasts, we further demonstrated that exposure of human lung fibroblasts to TGF-β1 increased productions of α-SMA and COL1A1, both of which were inhibited by inhibitors of Jun N-terminal kinase (JNK), p38, and Smad3. JNK and p38 are two subfamily members of mitogen-activated protein kinases (MAPKs), whereas Smad3 is a transcription factor. TGF-β1 exposure also increased the phosphorylation of JNK, p38, and Smad3 prior to the induction of α-SMA and COL1A1. Notably, all these TGF-β1-induced cellular events were suppressed by paeonol treatment. Our findings suggest that paeonol has antioxidant, anti-inflammatory, and anti-fibrotic functions against bleomycin-induced pulmonary fibrosis in mice. The beneficial effect of paeonol may be, at least in part, mediated through the inhibition of the MAPKs/Smad3 signaling.

Optimized Triton X-114 assisted lipopolysaccharide (LPS) removal method reveals the immunomodulatory effect of food proteins

SCOPE

Investigations into the immunological response of proteins is often masked by lipopolysaccharide (LPS) contamination. We report an optimized Triton X-114 (TX-114) based LPS extraction method for β-lactoglobulin (BLG) and soy protein extract suitable for cell-based immunological assays.

METHODS AND RESULTS

Optimization of an existing TX-114 based phase LPS extraction method resulted in >99% reduction of LPS levels. However, remaining TX-114 was found to interfere with LPS and protein concentration assays and decreased viability of THP-1 macrophages and HEK-Blue 293 cells. Upon screening a range of TX-114 extraction procedures, TX-114-binding beads were found to most effectively lower TX-114 levels without affecting protein structural properties. LPS-purified proteins showed reduced capacity to activate TLR4 compared to non-treated proteins. LPS-purified BLG did not induce secretion of pro-inflammatory cytokines from THP-1 macrophages, as non-treated protein did, showing that LPS contamination masks the immunomodulatory effect of BLG. Both HEK293 cells expressing TLR4 and differentiated THP-1 macrophages were shown as a relevant model to screen the protein preparations for biological effects of LPS contamination.

CONCLUSION

The reported TX-114 assisted LPS-removal from protein preparations followed by bead based removal of TX-114 allows evaluation of natively folded protein preparations for their immunological potential in cell-based studies.