Inflammasomes and Natural Ingredients towards New Anti-Inflammatory Agents

The anti-caspase 1 inhibitor VX-765 reduces immune activation, CD4+ T cell depletion, viral load, and total HIV-1 DNA in HIV-1 infected humanized mice

HIV-1 infection results in the activation of inflammasome that may facilitate viral spread and establishment of viral reservoirs. We evaluated the effects of the caspase-1 inhibitor VX-765 on HIV-1 infection in humanized NSG mice engrafted with human CD34⁺ hematopoietic stem cells. Expression of caspase-1, NLRP3, and IL-1β was increased in lymph nodes and bone marrow between day 1 and 3 after HIV-1 infection (mean fold change (FC) of 2.08, 3.23, and 6.05, p<0.001, respectively). IFI16 and AIM2 expression peaked at day 24 and coincides with increased IL-18 levels (6.89 vs 83.19 pg/ml, p=0.004), increased viral load and CD4⁺ T cells loss in blood (p<0.005 and p<0.0001, for the spleen respectively). Treatment with VX-765 significantly reduced TNF-α at day 11 (0.47 vs 2.2 pg/ml, p=0.045), IL-18 at day 22 (7.8 vs 23.2 pg/ml, p=0.04), CD4⁺ T cells (44.3% vs 36,7%, p=0.01), viral load (4.26 vs 4.89 log 10 copies/ml, p=0.027), and total HIV-1 DNA in the spleen (1 054 vs 2 889 copies /10⁶ cells, p=0.029). We demonstrated that targeting inflammasome activation early after infection may represent a therapeutic strategy towards HIV cure to prevent CD4⁺ T cell depletion and reduce immune activation, viral load, and the HIV-1 reservoir formation.

In vitro characterization of bioactive compounds extracted from sea urchin (Stomopneustes variolaris) using green and conventional techniques

This study investigated the in vitro bioactivities of extracts obtained from viscera, spines, shells, and gonads of Stomopneustes variolaris using subcritical water extraction (SWE) at 110 °C, 150 °C, 190 °C, and 230 °C and Soxhlet extraction. The highest amounts of phenolics (22.68 ± 0.05 mg GAE/g), flavonoids (27.11 ± 0.10 mg RE/g), and proteins (40.25 ± 0.84 mg BSA/g) were recorded from gonads at 230 °C, whereas maximum sugar content (23.38 ± 1.30 mg glucose/g) was in viscera at 150 °C. Gonads at 230 °C exhibited the highest DPPH activity (78.68 ± 0.18%), whereas viscera at 150 °C exhibited the highest ABTS⁺ (98.92 ± 1.27%) and protein denaturation inhibition activity (37.13 ± 9.94%). Viscera at 110 °C claimed the highest amylase inhibition (42.46 ± 0.83%), and spines at 150 °C had the highest anticancer activity (IC₅₀ = 767.47 μg/mL). SWE achieved superior results in bioactive compound recovery and detected higher levels of bioactivities (p < 0.05). Results suggest processing sea urchin extracts via SWE has potential application to the food and pharmaceutical industries.

The Anti-Inflammatory Properties of Phytochemicals and Their Effects on Epigenetic Mechanisms Involved in TLR4/NF-κB-Mediated Inflammation

Innate immune response induces positive inflammatory transducers and regulators in order to attack pathogens, while simultaneously negative signaling regulators are transcribed to maintain innate immune homeostasis and to avoid persistent inflammatory immune responses. The gene expression of many of these regulators is controlled by different epigenetic modifications. The remarkable impact of epigenetic changes in inducing or suppressing inflammatory signaling is being increasingly recognized. Several studies have highlighted the interplay of histone modification, DNA methylation, and post-transcriptional miRNA-mediated modifications in inflammatory diseases, and inflammation-mediated tumorigenesis. Targeting these epigenetic alterations affords the opportunity of attenuating different inflammatory dysregulations. In this regard, many studies have identified the significant anti-inflammatory properties of distinct naturally-derived phytochemicals, and revealed their regulatory capacity. In the current review, we demonstrate the signaling cascade during the immune response and the epigenetic modifications that take place during inflammation. Moreover, we also provide an updated overview of phytochemicals that target these mechanisms in macrophages and other experimental models, and go on to illustrate the effects of these phytochemicals in regulating epigenetic mechanisms and attenuating aberrant inflammation.

Alpha-Lipoic Acid Plays a Role in Endometriosis: New Evidence on Inflammasome-Mediated Interleukin Production, Cellular Adhesion and Invasion

Endometriosis is an estrogen-linked gynecological disease defined by the presence of endometrial tissue on extrauterine sites where it forms invasive lesions. Alterations in estrogen-mediated cellular signaling seems to have an essential role in the pathogenesis of endometriosis. Higher estrogen receptor (ER)-β levels and enhanced ER-β activity were detected in endometriotic tissues. It is well known that ER-β interacts with components of the cytoplasmic inflammasome-3 (NALP-3), the NALP-3 activation increases interleukin (IL)-1β and IL-18, enhancing cellular adhesion and proliferation. Otherwise, the inhibition of ER-β activity suppresses the ectopic lesions growth. The present study aims to investigate the potential effect of α-lipoic acid (ALA) on NALP-3 and ER-β expression using a western blot analysis, NALP-3-induced cytokines production by ELISA, migration and invasion of immortalized epithelial (12Z) and stromal endometriotic cells (22B) using a 3D culture invasion assay, and matrix-metalloprotease (MMPs) activity using gelatin zymography. ALA significantly reduces ER-β, NALP-3 protein expression/activity and the secretion of IL-1β and IL-18 in both 12Z and 22B cells. ALA treatment reduces cellular adhesion and invasion via a lower expression of adhesion molecules and MMPs activities. These results provide convincing evidence that ALA might inhibit endometriosis progression.

Dietary total antioxidant capacity and neuromyelitis optica spectrum disorder susceptibility

Purpose

Neuromyelitis Optica Spectrum Disorder (NMOSD) is a rare disease with unknown risk factors. The role of oxidative stress and nutritional factors is imprecise in NMOSD development. Therefore, this paper aims to evaluate the effects of dietary total antioxidant capacity (TAC) on the odds of NMOSD.

Design/methodology/approach

Dietary TAC was determined in 70 definite NMOSD cases and 164 healthy controls in term of Ferric Reducing Antioxidant Power (FRAP) method. A validated 168-item semi-quantitative food frequency questionnaire (FFQ) was used for dietary assessment. Three multivariate regression models were applied to analyze the odds of NMOSD across the TAC quartiles.

Findings

A significant inverse association was found between dietary TAC and odds of being assigned to the NMOSD group in all three regression models. In the fully adjusted model ORs (95% CI) in the second, third and fourth quartiles of TAC vs the first quartile were as follows: 0.11 (0.04-0.29), 0.05 (0.01-0.16) and 0.01 (0.00-0.05), respectively. Odds of NMOSD also indicated a significant decreasing trend across the quartiles of dietary TAC (p-trend: <0.01). Total energy (p < 0.01) as well as consumption of vegetables (p < 0.01), whole grains (p < 0.01), tea and coffee (p < 0.01), legumes (p < 0.01) and poultry (p < 0.01) significantly increased through the TAC quartiles.

Originality/value

In the present study, a new hypothesis was proposed concerning the influence of dietary TAC on the odds of NMOSD. A diet rich in foods with high TAC can be effective in the modification of the NMOSD odds.

In vitro expression of NLRP inflammasome-induced active Caspase-1 expression in normal human epidermal keratinocytes (NHEK) by various exogenous threats and subsequent inhibition by naturally derived ingredient blends

Background

The discovery of the nod-like receptor protein (NLRP) inflammasomes in 2002 has led to the rapid identification of these unique cellular proteins as key targets for studies on innate inflammation pathways. The NLRP inflammasomes have been shown to be expressed in normal human epidermal keratinocytes (NHEK) and human dermal fibroblasts (HDF). NLRP inflammasomes in keratinocytes are interesting as these skin cells are the first living cells in the skin to contact external exogenous threats such as UV energy, chemicals, physical trauma, and bacteria and viruses. Activation of the NLRP Inflammasomes by exogenous threats results in the release of active Caspase-1 (ACasp-1), a key protease enzyme, which targets inactive forms of IL-1β, IL-18 as well as IL-1α and IL-33.

Purpose

This article discusses efforts to examine the release of active Caspase-1 from NHEKs activated by various exogenous threats including UVB energy, ATP, Nigericin and Urban Dust. The work further examines if, after inflammasome activation and Caspase-1 release, certain naturally derived botanical ingredients known to have anti-inflammatory effects can function to inhibit upregulation of active Caspase-1.

Methods

NHEK were treated with various doses of UVB, ATP and Nigericin and with a single dose of Urban Dust. ACasp-1 expression was measured after 3 and 20 hours using the Promega Caspase Glo-1 bioluminescent assay. After confirmation that 60 mJ/cm² of UVB and 5mM of ATP were effective to activate NHEK ACasp-1 release after 20 hrs, these conditions were employed to examine the influence of three botanical blends of ingredients on their ability to inhibit ACasp-1 expression.

Results

Initial results demonstrate that NHEKs can be activated to release active Caspase-1 by ATP and UVB, but not by Nigericin or Urban Dust. In addition, it was unexpectedly found that, while ATP and UVB activated NHEKs, the release of ACasp-1-did not happen within the first 3 hours after exposure but did become significant after 20 hours. Additional results indicate that a blend of polysaccharides and two blends of antioxidants, one oil-soluble and the other water-soluble, known for their anti-inflammatory effects, can reduce expression of active Caspase-1 in activated NHEKs when applied extracellularly.

Conclusion

Expression of NLRP activated release of ACasp-1 was found to be influenced by UVB and ATP but not by Nigericin or Urban Dust. The effects were also time dependent. Several botanical extract blends were found to reduce ACasp-1 expression in previously activated NHEKs. Links between these inflammatory effects and processes of cellular inflammaging are discussed.

Characterization of NLRP3-like gene from Apostichopus japonicus provides new evidence on inflammation response in invertebrates

Inflammatory/defensive response after pathogen invasion is considered a local defense reaction in vertebrates. Inflammation response in Apostichopus japonicus was hardly determined due to scarce information available for nucleotide binding domain-like receptor family, pyrin domain-containing (NLRP) family. In the present study, invertebrate NLRP homologue was identified from A. japonicus (designated as AjNLRP3-like) by rapid amplification of cDNA ends. Full-length cDNA of AjNLRP3-like measured 2970 bp with 2265 bp open reading frame encoding a 754-amino acid (aa) residue protein. Structural analysis revealed that AjNLRP3-like processed characteristic domains of pyrin (32-102aa) and NACHT (183-339aa). Multiple sequence alignment and phylogenetic analysis supported that AjNLRP3-like belongs to a new member of NLRP3 protein subfamily. Spatial expression analysis revealed that AjNLRP3-like was ubiquitously expressed in all examined tissues with larger magnitude in coelomocytes. Both Vibrio splendidus challenge in vivo and lipopolysaccharide stimulation in vitro significantly upregulated mRNA expression of AjNLRP3-like when compared with the control group. NLRP3-mediated inflammation response depended on release of lysosomal cathepsin B (CTSB) and subsequent activation of high-mobility group box (HMGB) in vertebrates. We investigated expression profiles of AjNLRP3-like and AjHMGB after AjCTSB knock-down and discovered that AjNLRP3-like was depressed by 0.66-fold and 0.47-fold, whereas AjHMGB was depressed by 0.70-fold and 0.50-fold at 24 and 48 h in AjCTSB-silenced group, respectively. Similarly, down-regulation of AjHMGB was also observed after AjNLRP3-like knock-down. This study therefore suggests that A. japonicus feature similar inflammatory events as those in vertebrates, and activation of AjNLRP3-like depends on AjCTSB expression and release of AjHMGB.

Natural Products and Inflammation

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