High-Fat Diet Enhances Neutrophil Adhesion in LDLR-Null Mice Via Hypercitrullination of Histone H3.
Ontology highlight
ABSTRACT:
SUBMITTER: Osaka M
PROVIDER: S-EPMC8246031 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:In the course of atherogenesis, the spleen plays an important role in the regulation of extramedullary hematopoiesis, and in the control of circulating immune cells, which contributes to plaque progression. Here, we have investigated the role of splenic nucleotide-binding oligomerization domain 1 (NOD1) in the recruitment of circulating immune cells, as well as the involvement of this immune organ in extramedullary hematopoiesis in mice fed on a high-fat high-cholesterol diet (HFD). Under HFD conditions, the absence of NOD1 enhances the mobilization of immune cells, mainly neutrophils, from the bone marrow to the blood. To determine the effect of NOD1-dependent mobilization of immune cells under pro-atherogenic conditions, Apoe-/- and Apoe-/-Nod1-/- mice fed on HFD for 4 weeks were used. Splenic NOD1 from Apoe-/- mice was activated after feeding HFD as inferred by the phosphorylation of the NOD1 downstream targets RIPK2 and TAK1. Moreover, this activation was accompanied by the release of neutrophil extracellular traps (NETs), as determined by the increase in the expression of peptidyl arginine deiminase 4, and the identification of citrullinated histone H3 in this organ. This formation of NETs was significantly reduced in Apoe-/-Nod1-/- mice. Indeed, the presence of Ly6G+ cells and the lipidic content in the spleen of mice deficient in Apoe and Nod1 was reduced when compared to the Apoe-/- counterparts, which suggests that the mobilization and activation of circulating immune cells are altered in the absence of NOD1. Furthermore, confirming previous studies, Apoe-/-Nod1-/- mice showed a reduced atherogenic disease, and diminished recruitment of neutrophils in the spleen, compared to Apoe-/- mice. However, splenic artery ligation reduced the atherogenic burden in Apoe-/- mice an effect that, unexpectedly was lost in Apoe-/-Nod1-/- mice. Together, these results suggest that neutrophil accumulation and activity in the spleen are driven in part by NOD1 activation in mice fed on HFD, contributing in this way to regulating atherogenic progression.
| S-EPMC9256580 | biostudies-literature
Project description:The peptide toxin candidalysin, secreted by Candida albicans hyphae, promotes stimulation of neutrophil extracellular traps (NETs). However, candidalysin alone triggers a distinct mechanism for NET-like structures (NLS), which are more compact and less fibrous than canonical NETs. Candidalysin activates NADPH oxidase and calcium influx, with both processes contributing to morphological changes in neutrophils resulting in NLS formation. NLS are induced by leucotoxic hypercitrullination, which is governed by calcium-induced protein arginine deaminase 4 activation and initiation of intracellular signalling events in a dose- and time-dependent manner. However, activation of signalling by candidalysin does not suffice to trigger downstream events essential for NET formation, as demonstrated by lack of lamin A/C phosphorylation, an event required for activation of cyclin-dependent kinases that are crucial for NET release. Candidalysin-triggered NLS demonstrate anti-Candida activity, which is resistant to nuclease treatment and dependent on the deprivation of Zn2+ . This study reveals that C. albicans hyphae releasing candidalysin concurrently trigger canonical NETs and NLS, which together form a fibrous sticky network that entangles C. albicans hyphae and efficiently inhibits their growth.
| S-EPMC10626426 | biostudies-literature
Project description:Neutrophils are critical to host defence, executing diverse strategies to perform their antimicrobial and regulatory functions. One tactic is the production of neutrophil extracellular traps (NETs). In response to certain stimuli, neutrophils decondense their lobulated nucleus and release chromatin into the extracellular space through a process called NETosis. However, NETosis, and the subsequent degradation of NETs, can become dysregulated. NETs are proposed to play a role in infectious as well as many non-infection related diseases including cancer, thrombosis, autoimmunity and neurological disease. Consequently, there is a need to develop specific tools for the study of these structures in disease contexts. In this study, we identified a NET-specific histone H3 cleavage event and harnessed this to develop a cleavage site-specific antibody for the detection of human NETs. By microscopy, this antibody distinguishes NETs from chromatin in purified and mixed cell samples. It also detects NETs in tissue sections. We propose this antibody as a new tool to detect and quantify NETs.
| S-EPMC9665850 | biostudies-literature
Project description:Orthodontic tooth movement is a complex periodontal remodeling process triggered by compression that involves sterile inflammation and immune responses. Macrophages are mechanically sensitive immune cells, but their role in orthodontic tooth movement is unclear. Here, we hypothesize that orthodontic force can activate macrophages, and their activation may be associated with orthodontic root resorption. After force-loading and/or adiponectin application, the migration function of macrophages was tested via scratch assay, and Nos2, Il1b, Arg1, Il10, ApoE, and Saa3 expression levels were detected using qRT-PCR. Furthermore, H3 histone acetylation was measured using an acetylation detection kit. The specific inhibitor of H3 histone, I-BET762, was deployed to observe its effect on macrophages. In addition, cementoblasts were treated with macrophage-conditioned medium or compression force, and OPG production and cellular migration were measured. We further detected Piezo1 expression in cementoblasts via qRT-PCR and Western-blot, and its effect on the force-induced impairment of cementoblastic functions was also analyzed. Compressive force significantly inhibited macrophage migration. Nos2 was up-regulated 6 h after force-loading. Il1b, Arg1, Il10, Saa3, and ApoE increased after 24 h. Meanwhile, higher H3 histone acetylation was detected in the macrophages subjected to compression, and I-BET762 dampened the expression of M2 polarization markers (Arg1 and Il10). Lastly, even though the activated macrophage-conditioned medium showed no effect on cementoblasts, compressive force directly impaired cementoblastic function by enhancing mechanoreceptor Piezo1. Compressive force activates macrophages; specifically, it causes M2 polarization via H3 histone acetylation in the late stage. Compression-induced orthodontic root resorption is macrophage-independent, but it involves the activation of mechanoreceptor Piezo1.
| S-EPMC9958841 | biostudies-literature
Project description:Introduction Subclinical ketosis (SCK) in dairy cows, a common metabolic disorder during the perinatal period, is accompanied by systemic inflammation and a high concentration of blood β-hydroxybutyrate (BHB). BHB induced adhesion of neutrophils may play a crucial role in the development of systemic inflammation in SCK cows. Autophagy, an intracellular degradation system, regulates the recycling of membrane adhesion molecules and may be involved in BHB regulating adhesion and pro-inflammatory activation of bovine neutrophils. Thus, the objective of this study was to determine the relationship between BHB, autophagy, and neutrophil adhesion. Results and discussion Here, elevated abundance of serum amyloid A, haptoglobin, C-reactive protein, interleukin-1β, interleukin-6, and tumor necrosis factor-α were found in SCK cows, and all these pro-inflammatory factors had a strong positive correlation with serum BHB. After BHB treatment, the number of adherent neutrophils and the adhesion associated protein abundance of both total and membrane CD11a, CD11b, and CD18 was greater, confirming that BHB promoted the adhesion of bovine neutrophils. However, the mRNA abundance of ITGAL (CD11a), ITGAM (CD11b), and ITGB2 (CD18) did not show a significant difference, suggesting that the degradation of adhesion molecules may be impaired. Transmission electron microscopy revealed a decreased number of autophagosomes and a decrease in mRNA abundance of SQSTM1 (p62) and MAP1LC3B (LC3) after BHB treatment. In parallel, protein abundance of p62 increased while the ratio of protein LC3 II to LC3 I decreased after BHB treatment, indicating that BHB inhibits autophagy of bovine neutrophils. To confirm the regulatory role of autophagy in BHB promoting neutrophil adhesion, we used an autophagy activator rapamycin (RAPA). Data showed that RAPA relieved the inhibitory effect on autophagy and the promotive effect on cell adhesion induced by BHB. Importantly, BHB inhibited the colocalization of LC3 and CD11b, which was relieved by RAPA, further confirming the regulatory role of autophagy in the recycling of the above adhesion molecules. Furthermore, BHB treatment increased the mRNA abundance and the release of pro-inflammatory factors IL-1B, IL-6, and TNF of bovine neutrophils, and these effects were attenuated by RAPA. Overall, the present study revealed that BHB promotes the adhesion of bovine neutrophils by inhibiting autophagy.
| S-EPMC9874688 | biostudies-literature
Project description:Formation of neutrophil extracellular traps (NETs) has been associated with multiple pathologies including cancer. While the visualization of NETs by microscopy is a routine technique, their quantification presents a number of challenges. Commonly, as citrullination of histone H3 is required for NET formation, the presence of this modified histone along with DNA is considered to be a hallmark of NETs. Here, we describe and validate a novel assay for the quantification of NETs based on the detection of citrullinated histone H3 bound to DNA (CitH3DNA binding assay). Using this assay, we investigated the effect of phorbol 12-myristate 13-acetate (PMA) on NET formation by neutrophils isolated from the bone marrow of control and myeloma-bearing mice. We found that PMA induced citrullination of histone H3, an increase in the level of CitH3DNA, and NET formation in neutrophils from both tumor-free and myeloma-bearing mice. The levels of CitH3DNA in the NET fractions, as measured by our assay, directly correlated with the citrullination of histone H3 in neutrophils, as detected by Western blotting, and were significantly higher in PMA-stimulated compared to unstimulated neutrophils. Neutrophils from tumor-bearing mice produced more NETs than those from tumor-free counterparts following stimulation with PMA. The increase in NET production correlated with significantly higher histone H3 citrullination levels and increased measurements of CitH3DNA. Thus, our data indicate that bone marrow neutrophils from myeloma-bearing hosts are prone to NET formation.
| S-EPMC7698949 | biostudies-literature
Project description:Recent studies indicate a role for the constitutive androstane receptor (CAR), pregnane X-receptor (PXR), and hepatic xenobiotic detoxifying CYPs in fatty liver disease or obesity. Therefore, we examined whether Cyp3a-null mice show increased obesity and fatty liver disease following 8-weeks of exposure to a 60% high-fat diet (HFD). Surprisingly, HFD-fed Cyp3a-null females fed a HFD gained 50% less weight than wild-type (WT; B6) females fed a HFD. In contrast, Cyp3a-null males gained more weight than WT males, primarily during the first few weeks of HFD-treatment. Cyp3a-null females also recovered faster than WT females from a glucose tolerance test; males showed no difference in glucose tolerance between the groups. Serum concentrations of the anti-obesity hormone, adiponectin are 60% higher and β-hydroxybutyrate levels are nearly 50% lower in Cyp3a-null females than WT females, in agreement with reduced weight gain, faster glucose response, and reduced ketogenesis. In contrast, Cyp3a-null males have higher liver triglyceride concentrations and lipidomic analysis indicates an increase in phosphatidylinositol, phosphatidylserine and sphingomyelin. None of these changes were observed in females. Last, Pxr, Cyp2b, and IL-6 expression increased in Cyp3a-null females following HFD-treatment. Cyp2b and Fatp1 increased, while Pxr, Cpt1a, Srebp1 and Fasn decreased in Cyp3a-null males following a HFD, indicating compensatory biochemical responses in male (and to a lesser extent) female mice fed a HFD. In conclusion, lack of Cyp3a has a positive effect on acclimation to a HFD in females as it improves weight gain, glucose response and ketosis.
| S-EPMC6717702 | biostudies-literature
Project description:Lipodystrophy is a severe adipose dysfunction that can be classified as congenital or acquired lipodystrophy, in term of the etiology. Previous knowledge about the metabolic disorders and cardiovascular consequences were mostly obtained from lipodystrophic mice with genetic defects. To completely rule out the genetic influence, we established a mouse model of acquired generalized lipodystrophy by surgical removal of multiple fat depots, including subcutaneous fat in the inguinal, visceral fat in the epididymis and brown fat in the scapula, in atherosclerosis-prone LDLR-/- mice which were fed with a high-fat diet (HFD). It was observed that fat removal increased diet-induced hyperlipidemia, especially hypercholesteremia, as early as 2 weeks after HFD and till the end of HFD feeding. After 12 weeks on the HFD, the residual fats of fat-removed mice were found expanded. Although fat removal aggravated diet-induced lipid deposition in the liver and systemic insulin resistance, there was no significant difference in atherogenesis in fat-removed mice compared with sham-operated control mice. Acquired generalized lipodystrophy by surgical fat removal promoted metabolic disorders but not atherogenesis in LDLR-/- mice fed on HFD.
| S-EPMC6883051 | biostudies-literature
Project description:Calcium/calmodulin-dependent protein kinase II (CaMKII) plays a central role in pathological cardiac hypertrophy, but the mechanisms by which it modulates gene activity in the nucleus to mediate hypertrophic signaling remain unclear. Here, we report that nuclear CaMKII activates cardiac transcription by directly binding to chromatin and regulating the phosphorylation of histone H3 at serine-10. These specific activities are demonstrated both in vitro and in primary neonatal rat cardiomyocytes. Activation of CaMKII signaling by hypertrophic agonists increases H3 phosphorylation in primary cardiac cells and is accompanied by concomitant cellular hypertrophy. Conversely, specific silencing of nuclear CaMKII using RNA interference reduces both H3 phosphorylation and cellular hypertrophy. The hyper-phosphorylation of H3 associated with increased chromatin binding of CaMKII occurs at specific gene loci reactivated during cardiac hypertrophy. Importantly, H3 Ser-10 phosphorylation and CaMKII recruitment are associated with increased chromatin accessibility and are required for chromatin-mediated transcription of the Mef2 transcription factor. Unlike phosphorylation of H3 by other kinases, which regulates cellular proliferation and immediate early gene activation, CaMKII-mediated signaling to H3 is associated with hypertrophic growth. These observations reveal a previously unrecognized function of CaMKII as a kinase signaling to histone H3 and remodeling chromatin. They suggest a new epigenetic mechanism controlling cardiac hypertrophy.
| S-EPMC3763528 | biostudies-literature
Project description:The acetylation levels of lysine residues in nucleosomes, which are determined by the opposing activities of histone acetyltransferases (HATs) and deacetylases, play an important role in regulating chromatin-related processes, including transcription. We report that HMGN1, a nucleosomal binding protein that reduces the compaction of the chromatin fiber, increases the levels of acetylation of K14 in H3. The levels of H3K14ac in Hmgn1-/- cells are lower than in Hmgn1+/+ cells. Induced expression of wild-type HMGN1, but not of a mutant that does not bind to chromatin, in Hmgn1-/- cells elevates the levels of H3K14ac. In vivo, HMGN1 elevates the levels of H3K14ac by enhancing the action of HAT. In vitro, HMGN1 enhances the ability of PCAF to acetylate nucleosomal, but not free, H3. Thus, HMGN1 modulates the levels of H3K14ac by binding to chromatin. We suggest that HMGN1, and perhaps similar architectural proteins, modulates the levels of acetylation in chromatin by altering the equilibrium generated by the opposing enzymatic activities that continuously modify and de-modify the histone tails in nucleosomes.
| S-EPMC1201349 | biostudies-literature