Beneficial effects of soy milk and fiber on high cholesterol diet-induced alteration of gut microbiota and inflammatory gene expression in rats

We sought to evaluate whether a soy milk and fiber mixture could improve high cholesterol diet-induced changes in gut microbiota and inflammation. Sprague-Dawley rats were administered four different diets: CTRL (AIN76A diet), CHOL (AIN76A with 1% (w/w) cholesterol), SOY (CHOL diet, 20% of which was substituted with freeze-dried soy milk), or S.FIBER (SOY diet with 1.2% (w/w) psyllium, 6.2% (w/w) resistant maltodextrin, and 6.2% (w/w) chicory powder). A lipid profile and gene expression analysis demonstrated that SOY and S.FIBER improved the serum HDL-cholesterol and colonic expression levels of genes in tight junction (ZO-1 and occludin) and inflammation-related (IL-1β, IL-10, and Foxp3) proteins. S.FIBER lowered the serum MCP-1 concentration as well. A gut microbial analysis revealed that CHOL increased the ratio of Firmicutes to Bacteroidetes (F/B ratio). SOY increased the F/B ratio due to an increased proportion of Lactobacillus spp. S.FIBER greatly decreased the F/B ratio. Allobaculum spp. and Parabacteroides spp. exhibited a negative correlation with colonic expression of anti-inflammatory genes such as Foxp3, IL-10, occludin and ZO-1. CHOL increased the relative proportions of Allobaculum spp. and Parabacteroides spp. in the gut, while SOY and S.FIBER decreased these proportions. Diets containing soy milk and fiber mixtures could be beneficial by limiting CHOL-induced colonic inflammation and rescuing CHOL-disturbed gut microbiota.

Early recurrent nephrotic syndrome after renal transplantation in children with focal segmental glomerulosclerosis

BACKGROUND

We analysed risk factors to predict the recurrence of nephrotic syndrome and the therapeutic efficacy of plasmapheresis combined with oral cyclophosphamide (PE+CPM) in early recurrent nephrotic syndrome after transplantation in children with focal segmental glomerulosclerosis (FSGS).

METHODS

Medical records after 1990 of 16 children with biopsy-proven idiopathic FSGS and renal transplantation before the age of 18 years were reviewed.

RESULTS

Early recurrence of nephrotic syndrome developed in six cases (37. 5%). While early kidney graft biopsies, performed within the first week after the onset of recurrence, revealed diffuse effacement of foot process only, late biopsies contained segmentally sclerosed glomeruli as well. Among several possible risk factors, the mean duration from onset of original nephrotic syndrome to development of end-stage renal disease was shorter in the recurrent group (P=0.045) and the percentage of globally sclerosed glomeruli was higher in the non-recurrent group (P=0.001). PE+CPM therapy resulted in complete remission of nephrotic syndrome if it was started early and if there was no evidence of accompanying acute rejection.

CONCLUSION

These results support more liberal use of living-related donors for renal transplantation of children with FSGS and ESRD, considering the shortage of cadaveric donors in our society and relatively good efficacy of the early and intensive PE+CPM therapy for early recurrent nephrotic syndrome.

Does human papilloma virus have a role in squamous cell carcinoma of the colon and upper rectum?

AIM

To determine if Human Papilloma Virus (HPV) has a role in the aetiology of adenosquamous and squamous cell carcinoma of the colon and upper rectum, and to describe the clinical features seen in our patients with this condition.

METHODS

Patients were identified with squamous cell carcinoma (SCC), adenosquamous carcinoma (Ad-SCC), or adenocarcinoma with squamous metaplasia (AA) of the colon and upper rectum over the 10 years from 1/1/1990 to 31/12/1999. Patients were identified from a prospective pathology database. All tumours were at least 5cm above the dentate line. Pathology blocks were stained using the Peroxidase labelled Streptavidin technique using mouse monoclonal antibody NCL-HPV-4C4, which identifies HPV 6, 11, 16 and 18. Age, gender and site matched controls (colorectal adenocarcinomas) were also stained. The clinical presentation and management was reviewed from the case notes.

RESULTS

Twenty patients were identified from a pathological database of 2351 colorectal cancers (0.85% of colorectal cancers). 0/20 of the study patients (SCC, Ad-SCC, AA) or adenocarcinoma controls stained positively for HPV 6, 11, 16, 18. The clinical presentation was similar to patients presenting with adenocarcinomas.

CONCLUSIONS

The peroxidase labelled streptavidin technique is an immunohistochemical technique with high specificity but lower sensitivity. There was no apparent association between HPV 6, 11, 16, 18 and squamous cell and adenosquamous carcinoma of the colon and rectum using this technique. Clinical features are similar in squamous and adenosquamous colorectal carcinomas to colorectal adenocarcinomas.

Effects of long-term administration of clozapine on body weight and food intake in rats

Previous reports have shown that long-term administration of typical and atypical neuroleptics induced obesity in female but not in male rats. It has been suggested that impaired ovarian steroidogenesis related to neuroleptic-induced hyperprolactinemia is necessary to observe the body weight changes. This hypothesis was tested with clozapine, an atypical neuroleptic that produces in rats a shorter increase in serum prolactin levels than do other neuroleptics. The effects of clozapine on body weight and food intake were assessed in female and male rats under treatment with any of the following doses: 0.5, 1, 2.5, 5, 10, and 20 mg/kg IP for 21 days. Vaginal cycle under clozapine treatment, as an indirect indicator of ovarian steroidogenesis, was also assessed. Obesity was not observed in any group. By contrast, clozapine at the doses of 10 and 20 mg/kg significantly decreased body weight and feeding in male rats. Clozapine at the doses of 5 and 10 mg/kg IP induced permanent diestrus. The failure of clozapine to induce obesity in female rats, despite impaired vaginal cycle, can be considered indirect evidence that drug-induced hyperprolactinemia is not sufficient to observe neuroleptic-induced obesity in rats.

Potential Photoprotective Effect of Dietary Corn Silk Extract on Ultraviolet B-Induced Skin Damage

Ultraviolet B (UVB) irradiation causes adverse effects on the skin. Corn silk contains flavonoids and other bioactive compounds and antioxidants, which may prevent skin photoaging through antioxidant and anti-inflammatory effects. We aimed to investigate the potential photoprotective effects of dietary corn silk on UVB-induced skin damage in mice and the mechanisms behind these effects on human skin cells. Oral administration of corn silk water extract (CS) (2 or 4 g/kg/day) for 19 weeks decreased epidermal thickness, wrinkle formation, and positive staining for PCNA, Ki67, and 8-OHdG, and increased collagen staining in UVB-irradiated SKH-1 hairless mice compared with controls. The pro-inflammatory NF-κB target genes (IL-1β, iNOS, and COX-2) and MMP-9 expressions were lower in the CS groups, and TGF-β/Smad signaling increased. Low skin lipid peroxidation and blood DNA oxidation levels and high blood glutathione were detected. Antioxidant transcription factor Nrf2-related catalase and SOD1 proteins and glutaredoxin mRNA levels increased. The results of CS extract treatment and UVB irradiation in HaCaT cells showed the same results in Nrf2 and NF-κB target genes. An LC-MS/MS analysis showed that the CS extract contained potential antioxidants, which might have contributed to its anti-photoaging effects in tissues and cells. CS extract may reduce UVB-induced skin damage through antioxidant and anti-inflammatory mechanisms.

Genistein upregulates LDLR levels via JNK-mediated activation of SREBP-2

Background

Genistein has been proved in vitro and in vivo to lower LDLR level. It is also widely consumed and implicated for its anti-atherogenic effects. However, the molecular mechanism by which genistein lowers the LDL level is still unknown.

Objective

To understand the anti-atherogenic molecular mechanism of action, genistein was investigated for its impact on the expression of LDLR, the receptor for LDL cholesterol, and related signaling pathways in a human hepatoma cell line.

Design

HepG2 cell was used for the experiments. Genistein with different concentrations was diluted in media and was incubated for 24 h or more as indicated. Protein levels were measured by western blotting, and mRNA expression was detected by RT-qPCR. Chromatin immunoprecipitation assay (CHIP) assay was used to determine protein binding levels, and luciferase assay was used to measure promoter activity.

Result

Genistein increased the mRNA and protein levels of LDLR in a time-dependent manner. Genistein increased the transcriptional activity of the LDLR promoter containing the reporter gene (pLDLR-luc, −805 to +50). But the sterol regulatory element deletion mutant construct failed to be activated by genistein. Genistein increased the nuclear fraction of SREBP-2 and the DNA-binding activity of SREBP-2 to LDLR promoter, as assessed by CHIP. The genistein-phosphorylated JNK inhibitor (SP600126) abolished the genistein-stimulated levels of LDLR and the nuclear SREBP-2. The addition of cholesterol up to 5 µg/mL for 24 h did not affect the effect of genistein on LDLR protein expression. Even the addition of 40 µM genistein increased the cholesterol uptake by more than 10% in the human hepatoma cell line.

Conclusion

Our data support the idea that genistein may have anti-atherogenic effects by activating JNK signals and SREBP-2 processing, which is followed by the upregulation of LDLR.

Analysis of glucose and lactate in dialysate from hypothalamus of rats after exhausting swimming using microdialysis

A microbore flow injection analysis-immobilized enzyme reactor-electrochemical detection (FIA-IMER-ECD) system for glucose and lactate detection was built up. The assays were precise, sensitive and practicable for determination of glucose and lactate levels in hypothalamic dialysate. The method had been used to detect the dynamic changes of glucose and lactate levels during rat exhausting swimming and recovery. The data showed that after exhausting swimming, the concentration of glucose in hypothalamic dialysate that reflected the concentration in the hypothalamic extracellular fluid decreased. The level fell to its nadir at day 1 after the exercise and then went back to the basal level at day 3 after the swimming. However, lactate levels increased to a maximum at day 3 and went back to the basal level at day 5 after the swimming.

Neuroglycopenia and adrenergic responses to hypoglycaemia: insights from a local epidemic of serendipitous massive overdose of glibenclamide

AIMS

Recently, an unlicensed aphrodisiac formulation originating from China known as 'Power 1 Walnut' penetrated the illicit markets of South East Asia including Singapore. Subsequent toxicological analyses revealed that each 'Power 1 Walnut' pill was illegally adulterated with two prescription drugs--sildenafil 1 mg (a PDE5 inhibitor) and glibenclamide 93-98 mg (a long-acting sulphonylurea). As the drug was peddled to numerous people, a local 'hypoglycaemia epidemic' ensued, of which a small cluster presented to our hospital with severe hypoglycaemia. The aim is to characterize the demographics, clinical and labouratory aspects and postulate mechanisms for the relatively atypical presentation.

METHODS

A retrospective study of all the patients admitted between 13th January to 15th June 2008 with hypoglycaemia was done with acquisition of all relevant data after ethical approval from our DSRB.

RESULTS

15 patients (25-73 years old) presented with severe hypoglycaemia. All of them presented with neuroglycopenic symptoms (5-confusion, 6-drowsiness to loss of consciousness, 4-seizures and 1-coma) 12-36 h after ingestion of 'Power 1 Walnut'. Liquid chromatography-mass spectrometry (LC/MS) confirmed the presence of glibenclamide in the urine. None experienced a full-blown hypoglycaemia-associated autonomic response defined as sweating, sensation of warmth, anxiety, tremor, nausea, palpitations, tachycardia, and hunger. Only 4/16 patients had symptoms of a partial autonomic response, and 3/16 patients had tachycardia and/or hypertension.

CONCLUSIONS

The above suggests an inappropriate autonomic and catecholamine response to severe hypoglycaemia in these cases of serendipitous glibenclamide overdose. Possible reasons for the blunted autonomic responses and apparent autonomic failure are reviewed.

High degree of supervision improves adherence to inhaled corticosteroids in children with asthma

Purpose

Adherence to treatment with inhaled corticosteroids (ICS) is a critical determinant of asthma control. The objective of this study was to assess factors that determine adherence to ICS therapy in children with asthma.

Methods

Fifty-eight children with asthma, aged 5 to 16 years, used ICS with or without a spacer for 3 months. Adherence rates as measured from questionnaires and canisters, asthma symptom scores, and inhalation technique scores were assessed every 30 days. The degree of supervision by caregivers was assessed at day 30.

Results

Adherence rates measured using canisters were lower at day 60 than at day 30 (P=0.044) and did not change thereafter (74.4%±17.4% at day 30, 66.5%±18.4% at day 60, and 67.4%±22.2% at day 90). Adherence rates at days 60 and 90 and during the total study period were significantly different when measured by using questionnaires versus canisters (P<0.001, P=0.022, and P=0.001, respectively). In the comparison of adherence rates repeatedly measured at days 30, 60, and 90 and adherence rates during the total study period among the 3 groups, adherence rates in the high-degree supervision group were significantly higher than those in the low-degree supervision group (82.0±16.0 vs. 66.1±14.5, 75.4±14.4 vs. 56.2±18.4, 75.0±18.3 vs. 55.0±19.7 [P=0.027]; 77.9±12.2 vs. 59.1±11.4 [P=0.021]) after adjustment for sex and age.

Conclusion

The level of caregiver supervision is an important factor affecting adherence to ICS therapy in children with asthma. Therefore, a high degree of supervision may be required to increase adherence to ICS therapy in children with asthma.

[Clinicopathological features of diffuse leptomeningeal glioneuronal tumor]

Objective: To investigate the clinicopathological features, diagnosis and prognosis of diffuse leptomeningeal glioneuronal tumor (DLGNT). Methods: Five cases of DLGNT diagnosed from January 2016 to January 2020 were collected from Xuanwu Hospital, Capital Medical University. The clinical features, histopathologic characteristics, immunohistochemical and molecular genetic findings and prognosis were analyzed and the relevant literature was reviewed. Results: The five patients (two males and three females) were aged 2 to 52 years (median 11 years), and had history of increased intracranial pressure (headache and vomiting) or limb weakness. Three of them were younger than 16 years of age. The imaging studies showed diffuse intracranial and intraspinal nodular leptomeningeal thickening and enhancement, with or without parenchymal involvement. At times there were associated small cyst-like lesions. Imaging interpretations were inflammatory lesions in three cases and space occupying lesions in two. Microscopically, in three cases the tumors showed low to moderate cellularity, consisting of relatively monomorphous oligodendrocyte-like cells arranged in small nests or diffusely distribution. No mitosis and necrosis were observed. In two cases there were increased cellularity with a diffuse honeycomb pattern. The tumor showed mild to moderate polymorphism with hyperchromatic nuclei. Mitosis, endothelial vascular proliferation and glomeruloid vessels were seen. Necrosis was absent. The tumor cells in all five cases were positive for synaptophysin,Olig2 and negative for IDH1 and H3 K27M. GFAP was focally positive in four cases and only one case expressed NeuN partly. The Ki-67 labeling index was 1%-35%. BRAF fusion was detected in four cases. Genetic analysis showed solitary 1p deletion in two cases (2/5), while all cases were negative for 1p/19q co-deletion (0/5). The five patients were followed up for 13 to 28 months (median 15 month). One patient died after 27 months. There was no evidence of tumor progression in the remaining four patients. Conclusions: DLGNT is rare and easily confused with other central nervous system tumors and inflammatory lesions. Therefore, the diagnosis of DLGNT should be made based on comprehensive information including imaging, morphologic and corresponding immunohistochemical examinations and molecular genetics to avoid misdiagnosis and delay in management.

Proton pump inhibitor use and hearing loss in patients with type 2 diabetes: evidence from a hospital-based case-control study and a population-based cohort study

OBJECTIVES

This study aimed to investigate the association between proton pump inhibitor (PPI) use and risk of sensorineural hearing loss (SNHL) or tinnitus in patients with type 2 diabetes using hospital- and population-based data.

METHODS

For the case-control study using the Asan biomedical research environment (ABLE) database, the characteristics between cases and sex-, age-, and index-year-matched controls were compared by the chi-squared test. Conditional logistic regression was used to estimate the odds ratios (ORs). For the cohort study using the Korean National Health Insurance Service-National Sample Cohort, the hazard ratios (HRs) for SNHL or tinnitus associated with PPI use were analyzed by the Cox proportional hazard regression model.

RESULTS

The case-control study included 1,379 cases and 5,512 matched controls. After adjustment, PPI use was associated with an increased risk of SNHL or tinnitus (OR: 1.61, 95% CI: 1.30-1.99). The ORs were higher for current or recent use of PPI and high average daily dose. In the cohort study including 17,233 pairs of PPI users and non-users after propensity score matching, the risk of SNHL or tinnitus increased in PPI users compared with non-users (HR: 1.50, 95% CI: 1.40-1.61). In the stratified analyses, risks remained significant, and the magnitude of association was relatively high in those of younger age, patients without gastroesophageal reflux disease, and patients not receiving histamine 2 receptor blockers.

CONCLUSIONS

Our study suggests that PPI use is associated with an increased risk of SNHL or tinnitus. Given the widespread use of PPIs, the potential ototoxic effects of PPIs remain an important concern.

Nutrient-Sensing Ghrelin Receptor in Macrophages Modulates Bisphenol A-Induced Intestinal Inflammation in Mice

Bisphenols are environmental toxins with endocrine disruptor activity, yet bisphenol A (BPA) and its analogs are still widely used in manufacturing plastic products. There is evidence showing that BPA elicits inflammation in humans and animals, but the target cell types of BPA are not well understood. In this study, we sought to determine BPA's direct effect on macrophages and BPA immunotoxicity in mouse intestine. Ghrelin is an important nutrient-sensing hormone, acting through its receptor growth hormone secretagogue receptor (GHSR) to regulate metabolism and inflammation. We found that BPA promotes intestinal inflammation, showing increased infiltrating immune cells in colons and enhanced expression of Ghsr and pro-inflammatory cytokines and chemokines, such as Il6 and Ccl2, in colonic mucosa. Moreover, we found that both long- and short-term BPA exposure elevated pro-inflammatory monocytes and macrophages in mouse peripheral blood mononuclear cells (PBMC) and peritoneal macrophages (PM), respectively. To determine the role of GHSR in BPA-mediated inflammation, we generated Ghsr deletion mutation in murine macrophage RAW264.7 using CRISPR gene editing. In wild-type RAW264.7 cells, the BPA exposure promotes macrophage pro-inflammatory polarization and increases Ghsr and cytokine/chemokine Il6 and Ccl2 expression. Interestingly, Ghsr deletion mutants showed a marked reduction in pro-inflammatory cytokine/chemokine expression in response to BPA, suggesting that GHSR is required for the BPA-induced pro-inflammatory response. Further understanding how nutrient-sensing GHSR signaling regulates BPA intestinal immunotoxicity will help design new strategies to mitigate BPA immunotoxicity and provide policy guidance for BPA biosafety.

Effect of Bias Frequency on Bottom-Up SiO2 Gap-Filling Using Plasma-Enhanced Atomic Layer Deposition

High-aspect-ratio patterns are required for next-generation three-dimensional (3D) semiconductor devices. However, it is challenging to eliminate voids and seams during gap-filling of these high-aspect-ratio patterns, such as deep trenches, especially for nanoscale high-aspect-ratio patterns. In this study, a SiO2 plasma-enhanced atomic layer deposition process incorporated with ion collision using bias power to the substrate was used for bottom-up trench gap-filling. The effect of bias power frequency on SiO2 trench gap-filling was then investigated. Results showed that changes in bias power frequency did not significantly change the process rate, such as SiO2 growth per cycle. At relatively low bias power frequencies, high-energy ions formed an overhang at the entrance of the high-aspect-ratio trench pattern through sputter etching and redeposition, blocking the pattern entrance. However, at relatively high-frequency bias power, overhang formation due to sputtering did not occur. In the trench interior, due to a scattering effect of ions, deposition was thicker at the bottom of the trench than that at the top, achieving bottom-up gap-filling and void-free gap-filling.

Innate immunity in peripheral tissues is differentially impaired under normal and endotoxic conditions in aging

Chronic low-grade inflammation is a hallmark of aging, aka "inflammaging", which is linked to a wide range of age-associated diseases. Immune dysfunction increases disease susceptibility, and increases morbidity and mortality of aging. Innate immune cells, including monocytes, macrophages and neutrophils, are the first responders of host defense and the key mediators of various metabolic and inflammatory insults. Currently, the understanding of innate immune programming in aging is largely fragmented. Here we investigated the phenotypic and functional properties of innate immune cells in various peripheral tissues of young and aged mice under normal and endotoxic conditions. Under the steady state, aged mice showed elevated pro-inflammatory monocytes/macrophages in peripheral blood, adipose tissue, liver, and colon. Under lipopolysaccharide (LPS)-induced inflammatory state, the innate immune cells of aged mice showed a different response to LPS stimulus than that of young mice. LPS-induced immune responses displayed differential profiles in different tissues and cell types. In the peripheral blood, when responding to LPS, the aged mice showed higher neutrophils, but lower pro-inflammatory monocytes than that in young mice. In the peritoneal fluid, while young mice exhibited significantly elevated pro-inflammatory neutrophils and macrophages in response to LPS, aged mice exhibited decreased pro-inflammatory neutrophils and variable cytokine responses in macrophages. In the adipose tissue, LPS induced less infiltrated neutrophils but more infiltrated macrophages in old mice than young mice. In the liver, aged mice showed a more robust increase of pro-inflammatory macrophages compared to that in young mice under LPS stimulation. In colon, macrophages showed relatively mild response to LPS in both young and old mice. We have further tested bone-marrow derived macrophages (BMDM) from young and aged mice, we found that BMDM from aged mice have impaired polarization, displaying higher expression of pro-inflammatory markers than those from young mice. These data collectively suggest that innate immunity in peripheral tissues is impaired in aging, and the dysregulation of immunity is tissue- and cell-dependent. Our findings in the rodent model underscore the complexity of aging immunity. Further investigation is needed to determine whether the immune profile observed in aged mice is applicable in age-associated diseases in humans.

430 Relation of blood pressure to coronary artery calcium and mortality

Background

Diastolic blood pressure has a J-curve relation with coronary heart disease and death, but it is debating whether a J-curve association exists in general population. We aimed to assess the relation of blood pressure to mortality, and whether their association is interacted with presence of high coronary artery calcium (CAC).

Methods

The KOICA registry is a retrospective, multicenter observational study designed to investigate the effectiveness and prognostic value of CAC score for primary prevention of cardiovascular disease in asymptomatic Korean adults. The association between CAC score and blood pressure was assessed. Patients were divided into 2 groups according to the baseline CACS (&gt; 300 and ≤ 300), and all-cause mortality was assessed.

Results

The study population composed 48903 subjects with a mean age of 54 ± 9. There were 425 (0.9%) deaths during follow-up. At baseline, SBP (systolic blood pressure) more than 110 mmHg and DBP (diastolic blood pressure) more than 80 mmHg was associated with increased risk for CACS &gt; 300. In patients with baseline CACS ≤ 300, all-cause mortality was increased in patients with SBP of 110-119 mmHg (HR 1.47, p = 0.023), 130-139 mmHg (HR 1.72, p = 0.002) and ≥ 140 mmHg (HR 1.47, p = 0.042) compared to SBP of 120-129 mmHg, whereas DBP did not predict all-cause mortality. In contrast, SBP was not associated to all-cause mortality in patients with CACS &gt; 300, whereas DBP &lt; 60 mmHg (HR 3.53, p =0.018) and 70-79 mmHg (HR 2.21, p = 0.042) was associated with increased risk for all-cause mortality compared to DBP of 80-89 mmHg.

Conclusion

Low DBP was associated with increased risk for all-cause mortality in subjects with high CAC score, suggesting high-risk for coronary artery disease. However, this J-curve relation was not shown in the population with low CAC score.

GHSR Deletion in β-Cells of Male Mice: Ineffective in Obesity, but Effective in Protecting against Streptozotocin-Induced β-Cell Injury in Aging

Insulin secretion from pancreatic β cells is a key pillar of glucose homeostasis, which is impaired under obesity and aging. Growth hormone secretagogue receptor (GHSR) is the receptor of nutrient-sensing hormone ghrelin. Previously, we showed that β-cell GHSR regulated glucose-stimulated insulin secretion (GSIS) in young mice. In the current study, we further investigated the effects of GHSR on insulin secretion in male mice under diet-induced obesity (DIO) and streptozotocin (STZ)-induced β-cell injury in aging. β-cell-specific-Ghsr-deficient (Ghsr-βKO) mice exhibited no glycemic phenotype under DIO but showed significantly improved ex vivo GSIS in aging. We also detected reduced insulin sensitivity and impaired insulin secretion during aging both in vivo and ex vivo. Accordingly, there were age-related alterations in expression of glucose transporter, insulin signaling pathway, and inflammatory genes. To further determine whether GHSR deficiency affected β-cell susceptibility to acute injury, young, middle-aged, and old Ghsr-βKO mice were subjected to STZ. We found that middle-aged and old Ghsr-βKO mice were protected from STZ-induced hyperglycemia and impaired insulin secretion, correlated with increased expression of insulin signaling regulators but decreased pro-inflammatory cytokines in pancreatic islets. Collectively, our findings indicate that β-cell GHSR has a major impact on insulin secretion in aging but not obesity, and GHSR deficiency protects against STZ-induced β-cell injury in aging.

Nutrient-sensing growth hormone secretagogue receptor in macrophage programming and meta-inflammation

OBJECTIVE

Obesity-associated chronic inflammation, aka meta-inflammation, is a key pathogenic driver for obesity-associated comorbidity. Growth hormone secretagogue receptor (GHSR) is known to mediate the effects of nutrient-sensing hormone ghrelin in food intake and fat deposition. We previously reported that global Ghsr ablation protects against diet-induced inflammation and insulin resistance, but the site(s) of action and mechanism are unknown. Macrophages are key drivers of meta-inflammation. To unravel the role of GHSR in macrophages, we generated myeloid-specific Ghsr knockout mice (LysM-Cre;Ghsrf/f).

METHODS

LysM-Cre;Ghsrf/f and control Ghsrf/f mice were subjected to 5 months of high-fat diet (HFD) feeding to induce obesity. In vivo, metabolic profiling of food intake, physical activity, and energy expenditure, as well as glucose and insulin tolerance tests (GTT and ITT) were performed. At termination, peritoneal macrophages (PMs), epididymal white adipose tissue (eWAT), and liver were analyzed by flow cytometry and histology. For ex vivo studies, bone marrow-derived macrophages (BMDMs) were generated from the mice and treated with palmitic acid (PA) or lipopolysaccharide (LPS). For in vitro studies, macrophage RAW264.7 cells with Ghsr overexpression or Insulin receptor substrate 2 (Irs2) knockdown were studied.

RESULTS

We found that Ghsr expression in PMs was increased under HFD feeding. In vivo, HFD-fed LysM-Cre;Ghsrf/f mice exhibited significantly attenuated systemic inflammation and insulin resistance without affecting food intake or body weight. Tissue analysis showed that HFD-fed LysM-Cre;Ghsrf/f mice have significantly decreased monocyte/macrophage infiltration, pro-inflammatory activation, and lipid accumulation, showing elevated lipid-associated macrophages (LAMs) in eWAT and liver. Ex vivo, Ghsr-deficient macrophages protected against PA- or LPS-induced pro-inflammatory polarization, showing reduced glycolysis, increased fatty acid oxidation, and decreased NF-κB nuclear translocation. At molecular level, GHSR metabolically programs macrophage polarization through PKA-CREB-IRS2-AKT2 signaling pathway.

CONCLUSIONS

These novel results demonstrate that macrophage GHSR plays a key role in the pathogenesis of meta-inflammation, and macrophage GHSR promotes macrophage infiltration and induces pro-inflammatory polarization. These exciting findings suggest that GHSR may serve as a novel immunotherapeutic target for the treatment of obesity and its associated comorbidity.

ZnPP-laden nanoparticles improve glucose homeostasis and chronic inflammation during obesity

BACKGROUND AND PURPOSE

Chronic inflammation plays a pivotal role in the development of Type 2 diabetes mellitus (T2DM). Previous studies have shown that haem oxygenase-1 (HO-1) plays a proinflammatory role during metabolic stress, suggesting that HO-1 inhibition could be an effective strategy to treat T2DM. However, the application of HO-1 inhibitors is restricted due to solubility-limited bioavailability. In this study, we encapsulated the HO-1 inhibitor, zinc protoporphyrin IX (ZnPP), within nanoparticles and investigated their role in regulating glucose homeostasis and chronic inflammation during obesity.

EXPERIMENTAL APPROACH

We delivered DMSO-dissolved ZnPP (DMSO-ZnPP) and ZnPP-laden nanoparticles (Nano-ZnPP) to diet-induced obese male mice for 6 weeks. Glucose and insulin tolerance tests were carried out, liver and adipose tissue gene expression profiles analysed, and systemic inflammation analysed using flow cytometry.

KEY RESULTS

Nanoparticles significantly increased the delivery efficiency of ZnPP in both cells and mice. In mice with diet-induced obesity, inhibition of HO-1 by Nano-ZnPP significantly decreased adiposity, increased insulin sensitivity, and improved glucose tolerance. Moreover, Nano-ZnPP treatment attenuated both local and systemic inflammatory levels during obesity. Mechanistically, Nano-ZnPP significantly attenuated glucagon, TNF, and fatty acid synthesis signalling pathways in the liver. In white adipose tissue, the oxidative phosphorylation signalling pathway was enhanced and the inflammation signalling pathway diminished by Nano-ZnPP. Our results show that Nano-ZnPP has better effects on the improvement of glucose homeostasis and attenuation of chronic inflammation, than those of DMSO-dissolved ZnPP.

CONCLUSIONS AND IMPLICATIONS

These findings indicate that ZnPP-laden nanoparticles are potential therapeutic agents for treating T2DM.