The potency of blumeatin and luteolin as caspase-1 inhibitor by molecular docking

COVID-19 infection induces inflammation by increasing cytokines such as IL-1b, IL-6, IL-18, IFN-γ, and TNF-α. IL-1b is generated by the involvement of caspase-1. Therefore, caspase-1 inhibitor can be potential for inflammation therapy caused by COVID-19 infection. This study aims to determine the potential of blumeatin and luteolin as anti-inflammatory agents by inhibiting caspase-1 using a molecular docking approach. This study was carried out by caspase-1 (PDB ID: 1RWK) preparation, blumeatin and luteolin structure optimization, docking protocol validation, and docking of blumeatin and luteolin on caspase-1. Bluematin and luteolin had a binding affinity of -5,63 kcal/mol and -5,93 kcal/mol, lower than Q158 native ligand (-3.92 kcal/mol). Similar amino acid residues in hydrogen bonds interaction were observed between Q158 native ligand, blumeatin, and luteolin with caspase-1 (GLN 283 and ARG 179). Blumeatin and luteolin are potentially anti-inflammation agents through the inhibition of the caspase-1 in silico.

Persistent Oxidative Stress and Inflammasome Activation in CD14highCD16− Monocytes From COVID-19 Patients

The poor outcome of the coronavirus disease-2019 (COVID-19), caused by SARS-CoV-2, is associated with systemic hyperinflammatory response and immunopathology. Although inflammasome and oxidative stress have independently been implicated in COVID-19, it is poorly understood whether these two pathways cooperatively contribute to disease severity. Herein, we found an enrichment of CD14highCD16− monocytes displaying inflammasome activation evidenced by caspase-1/ASC-speck formation in severe COVID-19 patients when compared to mild ones and healthy controls, respectively. Those cells also showed aberrant levels of mitochondrial superoxide and lipid peroxidation, both hallmarks of the oxidative stress response, which strongly correlated with caspase-1 activity. In addition, we found that NLRP3 inflammasome-derived IL-1β secretion by SARS-CoV-2-exposed monocytes in vitro was partially dependent on lipid peroxidation. Importantly, altered inflammasome and stress responses persisted after short-term patient recovery. Collectively, our findings suggest oxidative stress/NLRP3 signaling pathway as a potential target for host-directed therapy to mitigate early COVID-19 hyperinflammation and also its long-term outcomes.

Enteric α-synuclein impairs intestinal epithelial barrier through caspase-1-inflammasome signaling in Parkinson’s disease before brain pathology

AbstractsBowel inflammation, impaired intestinal epithelial barrier (IEB), and gut dysbiosis could represent early events in Parkinson’s disease (PD). This study examined, in a descriptive manner, the correlation among enteric α-synuclein, bowel inflammation, impairments of IEB and alterations of enteric bacteria in a transgenic (Tg) model of PD before brain pathology. Human A53T α-synuclein Tg mice were sacrificed at 3, 6, and 9 months of age to evaluate concomitance of enteric inflammation, IEB impairments, and enteric bacterial metabolite alterations during the early phases of α-synucleinopathy. The molecular mechanisms underlying the interplay between α-synuclein, activation of immune/inflammatory responses and IEB alterations were investigated with in vitro experiments in cell cultures. Tg mice displayed an increase in colonic levels of IL-1β, TNF, caspase-1 activity and enteric glia activation since 3 months of age. Colonic TLR-2 and zonulin-1 expression were altered in Tg mice as compared with controls. Lipopolysaccharide levels were increased in Tg animals at 3 months, while fecal butyrate and propionate levels were decreased. Co-treatment with lipopolysaccharide and α-synuclein promoted IL-1β release in the supernatant of THP-1 cells. When applied to Caco-2 cells, the THP-1-derived supernatant decreased zonulin-1 and occludin expression. Such an effect was abrogated when THP-1 cells were incubated with YVAD (caspase-1 inhibitor) or when Caco-2 were incubated with anakinra, while butyrate incubation did not prevent such decrease. Taken together, early enteric α-synuclein accumulation contributes to compromise IEB through the direct activation of canonical caspase-1-dependent inflammasome signaling. These changes could contribute both to bowel symptoms as well as central pathology.

Vacuolar Processing Enzymes Modulating Susceptibility Response to Fusarium oxysporum f. sp. cubense Tropical Race 4 Infections in Banana

Fusarium oxysporum f. sp. cubense tropical race 4 (FocTR4) is a destructive necrotrophic fungal pathogen afflicting global banana production. Infection process involves the activation of programmed cell death (PCD). In this study, seven Musa acuminata vacuolar processing enzyme (MaVPE1–MaVPE7) genes associated with PCD were successfully identified. Phylogenetic analysis and tissue-specific expression categorized these MaVPEs into the seed and vegetative types. FocTR4 infection induced the majority of MaVPE expressions in the susceptible cultivar “Berangan” as compared to the resistant cultivar “Jari Buaya.” Consistently, upon FocTR4 infection, high caspase-1 activity was detected in the susceptible cultivar, while low level of caspase-1 activity was recorded in the resistant cultivar. Furthermore, inhibition of MaVPE activities via caspase-1 inhibitor in the susceptible cultivar reduced tonoplast rupture, decreased lesion formation, and enhanced stress tolerance against FocTR4 infection. Additionally, the Arabidopsis VPE-null mutant exhibited higher tolerance to FocTR4 infection, indicated by reduced sporulation rate, low levels of H2O2 content, and high levels of cell viability. Comparative proteomic profiling analysis revealed increase in the abundance of cysteine proteinase in the inoculated susceptible cultivar, as opposed to cysteine proteinase inhibitors in the resistant cultivar. In conclusion, the increase in vacuolar processing enzyme (VPE)-mediated PCD played a crucial role in modulating susceptibility response during compatible interaction, which facilitated FocTR4 colonization in the host.

Scorpion Venom Antimicrobial Peptides Induce Caspase-1 Dependant Pyroptotic Cell Death

Within the last decade, several peptides have been identified according to their ability to inhibit the growth of microbial pathogens. These antimicrobial peptides (AMPs) are a part of the innate immune system of all living organisms. Many studies on their effects on prokaryotic microorganisms have been reported; some of these peptides have cytotoxic properties although the molecular mechanisms underlying their activity on eukaryotic cells remain poorly understood. Smp24 and Smp43 are novel cationic AMPs which were identified from the venom of the Egyptian scorpion Scorpio maurus palmatus. Smp24 and Smp43 showed potent activity against both Gram-positive and Gram-negative bacteria as well as fungi. Here we describe cytotoxicity of these peptides towards two acute leukaemia cell lines (myeloid (KG1-a) and lymphoid (CCRF-CEM) leukaemia cell lines) and three non-tumour cell lines CD34+ (hematopoietic stem progenitor from cord blood), HRECs (human renal epithelial cells) and HaCaT (human skin keratinocytes). Smp24 and Smp43 (4–256 µg/ml) decreased the viability of all cell lines, although HaCaT cells were markedly less sensitive. With the exception HaCaT cells, the caspase-1 gene was uniquely up-regulated in all cell lines studied. However, all cell lines showed an increase in downstream interleukin-1β (IL-1β) expression. Transmission electron microscope studies revealed the formation of cell membrane blebs and the appearance of autolysosomes and lipid droplets in all cell lines; KG1-a leukemia cells also showed the unique appearance of glycogen deposits. Our results reveal a novel mechanism of action for scorpion venom AMPs, activating a cascade of events leading to cell death through a programmed pyroptotic mechanism.

3β,23-Dihydroxy-12-ene-28-ursolic Acid Isolated from Cyclocarya paliurus Alleviates NLRP3 Inflammasome-Mediated Gout via PI3K-AKT-mTOR-Dependent Autophagy

Gout is regarded as a painful inflammatory arthritis induced by the deposition of monosodium urate crystals in joints and soft tissues. Nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome-mediated IL-1β production plays a crucial role in the pathological process of gout. Cyclocarya paliurus (CP) tea was found to have an effect on reducing the blood uric acid level of people with hyperuricemia and gout. However, its medicinal ingredients and mechanism for the treatment of gout are still unclear. Thus, this study was designed to investigate the effects of the active triterpenoids isolated from C. paliurus on gout and explore the underlying mechanism. The results showed that compound 2 (3β,23-dihydroxy-12-ene-28-ursolic acid) from C. paliurus significantly decreased the protein expression of IL-1β, caspase-1, pro-IL-1β, pro-caspase-1, and NLRP3. Furthermore, the production of ROS in the intracellular was reduced after compound 2 treatment. However, ROS agonist rotenone remarkably reversed the inhibitory effect of compound 2 on the protein expression of NLRP3 inflammasome. Additionally, the expression level of LC3 and the ratio of LC3II/LC3I were increased, but the expression level of p62 was suppressed by compound 2 whereas an autophagy inhibitor 3-methyladenine (3-MA) significantly abolished the inhibitory effects of compound 2 on the generation of ROS and the protein expression of NLRP3 inflammasome. Moreover, compound 2 could ameliorate the expression ratio of p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR. Interestingly, mTOR activator MHY-1485 could block the promotion effect of compound 2 on autophagy regulation and inhibitory effect of compound 2 on induction of ROS and IL-1β. In conclusion, these findings suggested that compound 2 may effectively improve NLRP3 inflammasome-mediated gout via PI3K-AKT-mTOR-dependent autophagy and could be further investigated as a potential agent against gout.

Acupuncture at ST36 Alleviates the Behavioral Disorder of Autistic Rats by Inhibiting TXNIP-Mediated Activation of NLRP3

Autism is a common neurodevelopmental disorder that severely affects patients’ quality of life. We aimed to investigate whether acupuncture at Zusanli (ST36) could alleviate the behavior disorder of autistic rats by inhibiting thioredoxin-interacting protein (TXNIP)-mediated activation of NLRP3. An autism model was induced by intraperitoneal injection of pregnant rats with valproic acid (VPA). The pups’ behaviors were analyzed using hot plate, open field, Morris water maze, and 3-chamber social interaction tests. Nissl staining was used to visualize neurons in prefrontal cortex. Levels of TXNIP, NLRP3, interleukin (IL)-1β, and caspase were determined by Western blot or quantitative real-time PCR. After ST36 acupuncture, pain sensitivity, autonomous activity, sociability index, sociability preference index, and learning and memory were improved in the autism model rats. Levels of TXNIP, NLRP3, IL-1β, and caspase 1 were decreased after acupuncture. Interference with TXNIP alleviated the behavior disorders and inhibited NLRP3, caspase 1, and IL-1β levels. In summary, ST36 acupuncture reduced TXNIP expression, inhibited the activation of the NLRP3 inflammasome, and alleviated the behavior disorder related to the prefrontal cortex of the autistic rats. These results point to a potential mechanism for acupuncture-induced improvement of autistic behavioral disorders.