Is FoxO1 the culprit, partner in crime, or a protector in systemic inflammation?

New insights of DsbA-L in the pathogenesis of metabolic diseases

Metabolic diseases, such as obesity, diabetes mellitus, and non-alcoholic fatty liver disease (NAFLD), are abnormal conditions that result from disturbances of metabolism. With the improvement of living conditions, the morbidity and mortality rates of metabolic diseases are steadily rising, posing a significant threat to human health worldwide. Therefore, identifying novel effective targets for metabolic diseases is crucial. Accumulating evidence has indicated that disulfide bond A oxidoreductase-like protein (DsbA-L) delays the development of metabolic diseases. However, the underlying mechanisms of DsbA-L in metabolic diseases remain unclear. In this review, we will discuss the roles of DsbA-L in the pathogenesis of metabolic diseases, including obesity, diabetes mellitus, and NAFLD, and highlight the potential mechanisms. These findings suggest that DsbA-L might provide a novel therapeutic strategy for metabolic diseases.

Functional Polymorphisms Regulate FOXO1 Transcript Expression and Contribute to the Risk and Symptom Severity of HDM-Induced Allergic Rhinitis

INTRODUCTION

FOXO1 plays an important role in regulating immune processes that contribute to allergic inflammation; however, genetic variants influencing FOXO1 expression in AR pathogenesis remains unclear. This study aimed to investigate the functional effect of FOXO1 single nucleotide polymorphisms (SNPs) on AR development by performing genetic association and functional analysis studies.

METHODS

This study belongs to a part of an ongoing Singapore/Malaysia cross-sectional genetics and epidemiological study (SMCSGES). We assessed the associations of FOXO1 transcript expression levels in peripheral blood mononuclear cells (PBMC) with AR phenotype, total nasal symptom score (TNSS), and SNP genotype in a sub-cohort of n = 658 individuals from the SMCSGES population. Associations of FOXO1 SNPs with AR were assessed in a cohort of n = 5,072 individuals from the SMCSGES population. In vitro promoter luciferase assay was used to evaluate the effect of AR-associated SNPs on FOXO1 promoter activity.

RESULTS

FOXO1 transcript expression in PBMC was significantly associated with the risk of AR (p < 0.05) and TNSS among AR patients (p < 0.0001). We identified a significant association between tag-SNPs rs9549246 and FOXO1 transcript expression in PBMC from the SMCSGES sub-cohort and the multiethnic eQTLGen consortium (false discovery rate-adjusted p < 0.05). The minor allele "A" of tag-SNP rs9549246 was significantly associated with a higher risk of AR (p = 0.04422, odds ratio = 1.21, 95% confidence interval = 1.01-1.45) in the SMCSGES genotyping cohort (n = 5,072). In vitro luciferase assay showed the minor allele "A" of rs35594717 (tagged by rs9549246) was significantly associated with a higher FOXO1 promoter activity (p < 0.05).

CONCLUSION

FOXO1 transcript expression in PBMC has a strong association with the risk and symptom severity of AR. Genetic variants tagged by rs9549246 were shown to affect the expression of FOXO1 and contribute to the development of AR in the SMCSGES population.

Starch and protein hydrolysis in cooked quinoa (Chenopodium quinoa Willd.) during static and dynamic in vitro oral and gastric digestion

Quinoa is a pseudocereal that has a favorable nutrient profile and may be a beneficial addition to the diet. To evaluate potential health-promoting properties of foods, it is important to understand the rate of macronutrient hydrolysis, which is commonly quantified through in vitro digestion studies. Additionally, limited information is available comparing starch and protein hydrolysis of solid foods using static and dynamic digestion models. The objective of this study was to examine starch and protein hydrolysis in cooked quinoa using a combination of a static (saliva only) or dynamic (saliva + mincing) oral digestion model with a static (gastric fluids only) or dynamic (Human Gastric Simulator) gastric digestion model. Disruption of the pericarp of the cooked quinoa seeds during dynamic oral digestion released additional surface area, which led to faster gastric emptying during dynamic gastric digestion. Starch and protein hydrolysis were impacted by type of gastric model due to differences in pH and variations in structural breakdown. Starch hydrolysis was 29.04 ± 1.83% after 180 min dynamic gastric digestion compared to 2.85 ± 1.88% during static gastric digestion (averaged across both oral digestion models). The degree of protein hydrolysis was 4.85 ± 0.01% after 180 min in the static gastric model compared to 3.94 ± 0.18% in the dynamic gastric model (averaged across both oral digestion models). This information provides evidence on the role of food structure and breakdown (through use of static vs. dynamic oral and gastric digestion models) on quinoa starch and protein hydrolysis.

Propofol alleviates postoperative cognitive dysfunction by inhibiting inflammation via up-regulating miR-223-3p in aged rats

OBJECTIVE

Postoperative cognitive dysfunction (POCD) affects 15-25% of surgical patients and causes significant morbidity and mortality. This study aims to investigate the mechanism of propofol reducing POCD in aged rats.

METHOD

Rats in Operate group and Propofol group were anesthetized with isoflurane and propofol, respectively, and then underwent cardiac surgery. Rats in Antagomir group were anesthetized with propofol and underwent cardiac surgery with preoperative injection of miR-223-3p antagomir. Barnes maze and Morris water maze (MWM) were used to test spatial learning and memory of rats. Immunofluorescence was used to detect the level of microglial cell marker IBA1. In addition, qRT-PCR was performed to measure the expression of miR-223-3p and inflammatory factors TNF-α, IL-1β and IL-6. Western blotting was conducted to detect the protein expression of Foxo1, TNF-α, IL-1β and IL-6.

RESULT

Isoflurane-anesthetized rats undergoing cardiac surgery showed significantly reduced spatial learning and memory, promoted microglia activation, decreased miR-223-3p expression and increased inflammatory response in the hippocampus, while isoflurane-anesthetized rats without surgery showed insignificant changes in these indices. Compared to isoflurane anesthesia, propofol anesthesia exhibited less effect on spatial learning and memory of rats with cardiac surgery and contributed to a relative reduction in activated microglia in the hippocampus, a notable increase in miR-223-3p expression, and a decrease in inflammation. The results were reversed after miR-223-3p antagomir was injected into propofol-anesthetized surgical rats. miR-223-3p negatively regulated Foxo1 to suppress the expression of inflammatory factors.

CONCLUSION

Propofol reduced inflammation by up-regulating miR-223-3p, thereby reducing POCD in aged rats.

C-type lectin receptor Dectin3 deficiency balances the accumulation and function of FoxO1-mediated LOX-1+ M-MDSCs in relieving lupus-like symptoms

Recent studies indicate that Toll-like receptors (TLRs) and C-type lectin receptors (CLRs) can function as the signal of pattern recognition receptors, which play a pivotal role in the pathogenesis of the autoimmune disease. Systemic lupus erythematosus (SLE) is a classic autoimmune disease. Previous reports mainly focused on the potential role of TLRs in regulating the development of SLE, but little is known about the role of CLRs in the progression of SLE. Our previous studies showed that the inflammation-mediated accumulation of myeloid-derived suppressor cells (MDSCs) including granulocytic (G-MDSCs) and monocytic (M-MDSCs) participated in the pathogenesis of lupus. Mice deficient in Card9 (the downstream molecule of CLRs) were more susceptible to colitis-associated cancer via promoting the expansion of MDSCs. Whether the abnormal activation of CLRs regulates the expansion of MDSCs to participate in the pathogenesis of lupus remains unknown. In the present study, the expressions of CLRs were examined in both SLE patients and mouse models, revealing the expression of Dectin3 was positively correlated with SLEDAI. Dectin3 deficiency retarded the lupus-like disease by regulating the expansion and function of MDSCs. The mechanistic analysis revealed that Dectin3 deficiency promoted FoxO1-mediated apoptosis of MDSCs. Syk-Akt1-mediated nuclear transfer of FoxO1 increased in Dectin3-deficient MDSCs. Notedly, the accumulation of M-MDSCs mainly decreased in Dectin3^-/- lupus mice, and the nuclear transfer of FoxO1 negatively correlated with the expression of LOX-1 on M-MDSCs. The silencing of FoxO1 expression in Dectin3^-/- mice promoted the expansion of LOX-1⁺ M-MDSCs in vivo, and LOX-1⁺ M-MDSCs increased the differentiation of Th17 cells. Both LOX-1 expression on M-MDSCs and Dectin3 expression on MDSCs increased in patients with SLE. These data indicated that increased LOX-1⁺ M-MDSCs were related to the exacerbation of SLE development and might be potential target cells for the treatment of SLE.

rhKGF-2 Attenuates Smoke Inhalation Lung Injury of Rats via Activating PI3K/Akt/Nrf2 and Repressing FoxO1-NLRP3 Inflammasome

Smoke inhalation injury is an acute pathological change caused by thermal stimulation or toxic substance absorption through respiratory epithelial cells. This study aims to probe the protective effect and mechanism of recombinant human keratinocyte growth factor 2 (rhKGF-2) against smoke inhalation-induced lung injury (SILI) in rats. The SILI was induced in rats using a smoke exposure model, which were then treated with rhKGF-2. The rat blood was collected for blood-gas analysis, and the levels of inflammatory factors and oxidative stress markers in the plasma were measured. The rat lung tissues were collected. The pathological changes and cell apoptosis were determined by hematoxylin-eosin (HE) staining and TdT-mediated dUTP nick end labeling (TUNEL) assay, and the PI3K/Akt/Nrf2/HO-1/NQO1, and FoxO1-NLRP3 inflammasome expression were verified by western blot (WB). Both of the human alveolar epithelial cell (HPAEpiC) and primary rat alveolar epithelial cell were exposed to lipopolysaccharide (LPS) for making in-vitro alveolar epithelial cell injury model. After treatment with rhKGF-2, GSK2126458 (PI3K inhibitor) and AS1842856 (FoxO1 inhibitor), the cell viability, apoptosis, inflammation, oxidative stress, reactive oxygen species (ROS), PI3K/Akt/Nrf2, HO-1/NQO1, and FoxO1-NLRP3 in HPAEpiC and primary rat alveolar epithelial cell were examined. The data suggested that rhKGF-2 reduced LPS-induced HPAEpiC cell and primary rat alveolar epithelial cell apoptosis and the expression of inflammatory factors and oxidative stress factors. Moreover, rhKGF-2 improved the blood gas and alleviated SILI-induced lung histopathological injury in vivo via repressing inflammation, NLRP3 inflammasome activation and oxidative stress. Mechanistically, rhKGF-2 activated PI3K/Akt pathway, enhanced Nrf2/HO-1/NQO1 expression, and attenuated FoxO1-NLRP3 inflammasome both in vitro and in vivo. However, pharmaceutical inhibition of PI3K/Akt pathway attenuated rhKGF-2-mediated protective effects against SILI, while suppressing FoxO1 promoted rhKGF-2-mediated protective effects. Taken together, this study demonstrated that rhKGF-2 mitigated SILI by regulating the PI3K/Akt/Nrf2 pathway and the FoxO1-NLRP3 axis, which provides new reference in treating SILI.

Genetic and Functional Evaluation of the Role of FOXO1 in Antituberculosis Drug-Induced Hepatotoxicity

Background

The accumulation of the hepatotoxic substance protoporphyrin IX (PPIX) induced by aminolevulinate synthase 1 (ALAS1) activation is one of the important mechanisms of antituberculosis drug-induced hepatotoxicity (ATDH). Forkhead box protein O1 (FOXO1) may activate ALAS1 transcription. However, little is known about their roles in ATDH; we performed a study to determine the association between polymorphisms in the two genes and ATDH susceptibility. Then, we verified this possible association by cellular functional experiments.

Materials and Methods

Tag single-nucleotide polymorphisms (TagSNPs) in the two genes were genotyped in 746 tuberculosis patients. The frequencies of the alleles, genotypes, genetic models, and haplotype distribution of the variants were compared between the case and control groups. L-02 cells and HepG2 cells were incubated with the indicated concentration of isoniazid (INH) and rifampicin (RIF) for the desired times, and then the expression levels of ALAS1 and FOXO1 mRNAs and proteins were detected. HepG2 cells were transiently transfected with FOXO1 siRNA to observe the effect of changes in the FOXO1 expression on the cell survival rate and ALAS1 expression.

Results

The C allele at rs2755237 and the T allele at rs4435111 in the FOXO1 gene were associated with a decreased risk of ATDH. The expression of ALAS1 in both L-02 cells and HepG2 cells was increased by the coadministration of INH/RIF (600/200 μM) for 24 h. Although FOXO1 expression was reduced slightly by the same treatment, its content in the nucleus was significantly increased. However, the cell survival rate and ALAS1 expression level were not significantly altered by the downregulation of FOXO1 in HepG2 cells.

Conclusions

Variants of the rs4435111 and rs2755237 loci in the FOXO1 gene were associated with susceptibility to ATDH. Coadministration of INH/RIF promoted the transfer of FOXO1 from the cytoplasm to the nucleus, but the functional significance of its nuclear translocation requires further verification.

Tracking physical breakdown of rice- and wheat-based foods with varying structures during gastric digestion and its influence on gastric emptying in a growing pig model

There is currently a limited understanding of the effect of food structure on physical breakdown and gastric emptying of solid starch-based foods during gastric digestion. Moisture uptake, pH, particle size, rheological, and textural properties of six solid starch-based diets from different sources (Durum wheat and high amylose white rice) and of different macrostructures (porridge, native grain, agglomerate/couscous, and noodle) were monitored during 240 min of gastric digestion in a growing pig model. Changes in the physical properties of the gastric digesta were attributed to the influence of gastric secretions and gastric emptying, which were both dependent on the buffering capacity and initial macrostructure of the diets. Differences between the proximal and distal stomach regions were found in the intragastric pH and texture of the gastric digesta. For example, rice couscous, which had the smallest particle size and highest buffering capacity among the rice-based diets, had the shortest gastric emptying half-time and no significant differences between proximal and distal stomach digesta physical properties. Additionally, a relationship between gastric breakdown rate, expressed as gastric softening half-time from texture analysis, and gastric emptying half-time of dry matter was also observed. These findings provide new insights into the breakdown processes of starch-based solid foods in the stomach, which can be beneficial for the development of food structures with controlled rates of breakdown and gastric emptying during digestion.

A protected complex of biofactors and antioxidants improved growth performance and modulated the immunometabolic phenotype of broiler chickens undergoing early life stress

We evaluated the supplementation of a protected complex of biofactors and antioxidants [P(BF+AOx)] on growth performance, antioxidant activity, expression of immune-related genes, and immunometabolic phenotype of broilers submitted to early life stressors. The treatments were a nutritionally complete basal diet supplemented or not with P(BF+AOx) (Jefo Nutrition Inc., Saint-Hyacinthe, QC, Canada) from 1 to 14 d of age. 720 one-day old male Ross 308 chickens were placed into pens of 30 birds (12 replicates/treatment). Birds were double-vaccinated against infectious bronchitis (IB; MILDVAC-Ma5^T) at the hatchery and submitted, on d 3, to an acute reduction on environmental temperature (from 32° C to 20°C) for 48 h. Feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR) were calculated weekly. On d 7 and 15, samples were collected for expression of immune-related genes and kinome array analysis, and serum to evaluate the antioxidant status. Data were analyzed by ANOVA using SAS (SAS 9.4). From d 1 to 21 and d 1 to 28, the dietary supplementation of P(BF+AOx) significantly increased BWG (P < 0.05) by 3.6 and 3.8%, respectively, and improved FCR (P < 0.05) by 1.2 and 1.8%, respectively. From d 1 to 35, dietary supplementation enhanced BWG (P = 0.03) by 4%. Serum glutathione reductase activity on d 15 was higher in birds fed diets supplemented with P(BF+AOx) compared to the control diet-fed birds (P = 0.04). Dietary supplementation reduced the expression of IL-1β (P = 0.03) in the lungs on d 7. On d 15, dietary supplementation increased the expression of IL-6 (P = 0.02) and IL-10 (P = 0.03) in the liver. It was observed that, via decreased phosphorylation, catalase was activated in the jejunum and liver, and the phosphorylation of immunoregulatory or proinflammatory proteins was decreased. Other important cellular signaling pathways were also changed in the liver and jejunum due to the supplementation. The supplementation of P(BF+AOx) improves growth performance by promoting a general anti-inflammatory and antioxidant response in chickens undergoing early life stress.

FoxO1 as a Regulator of Aquaporin 5 Expression in the Salivary Gland

Forkhead box O1 (FoxO1) is a multifunctional initiator, mediator, and repressor of autoimmune diseases in an organ- or disease-specific manner. However, the role of FoxO1 in the salivary gland has not yet been elucidated. In this study, we discovered that FoxO1 and aquaporin 5 (AQP5) are both significantly downregulated in the patients with primary Sjögren syndrome, an autoimmune disease accompanying salivary gland dysfunction. Pharmacologic or genetic perturbation of FoxO1 in the rat salivary gland acinar cell line, SMG-C6, induced a significant downregulation of AQP5 expression, as observed in clinical specimens. There was a strong correlation between FoxO1 and AQP5 expression because FoxO1 is a direct regulator of AQP5 expression in salivary gland acinar cells through its interaction with the promoter region of AQP5. Serial injection of a FoxO1 inhibitor into mice induced a reduction of AQP5 expression in submandibular glands and, consequently, hyposalivation, which is one of the major clinical symptoms of primary Sjögren syndrome. However, there was no sign of inflammation or cell damage in the submandibular glands harvested from mice treated with the FoxO1 inhibitor. In conclusion, our findings indicate that FoxO1 in salivary gland tissue acts as a direct regulator of AQP5 expression. Thus, downregulation of FoxO1 observed in primary Sjögren syndrome is a putative mechanism for hyposalivation without the involvement of previously reported soluble factors in primary Sjögren syndrome patient sera.

FoxO1 is a critical regulator of M2-like macrophage activation in allergic asthma

BACKGROUND

The pathogenesis of asthma and airway obstruction is the result of an abnormal response to different environmental exposures. The scientific premise of our study was based on the finding that FoxO1 expression is increased in lung macrophages of mice after allergen exposure and human asthmatic patients. Macrophages are capable of switching from one functional phenotype to another, and it is important to understand the mechanisms involved in the transformation of macrophages and how their cellular function affects the peribronchial stromal microenvironment.

METHODS

We employed a murine asthma model, in which mice were treated by intranasal insufflation with allergens for 2-8 weeks. We used both a pharmacologic approach using a highly specific FoxO1 inhibitor and genetic approaches using FoxO1 knockout mice (FoxO1fl/fl LysMcre). Cytokine level in biological fluids was measured by ELISA and the expression of encoding molecules by NanoString assay and qRT-PCR.

RESULTS

We show that the levels of FoxO1 gene are significantly elevated in the airway macrophages of patients with mild asthma in response to subsegmental bronchial allergen challenge. Transcription factor FoxO1 regulates a pro-asthmatic phenotype of lung macrophages that is involved in the development and progression of chronic allergic airway disease. We have shown that inhibition of FoxO1 induced phenotypic conversion of lung macrophages and downregulates pro-asthmatic and pro-fibrotic gene expression by macrophages, which contribute to airway inflammation and airway remodeling in allergic asthma.

CONCLUSION

Targeting FoxO1 with its downstream regulator IRF4 is a novel therapeutic target for controlling allergic inflammation and potentially reversing fibrotic airway remodeling.