Laminarin Reduces Cholesterol Uptake and NPC1L1 Protein Expression in High-Fat Diet (HFD)-Fed Mice

Aberrantly high dietary cholesterol intake and intestinal cholesterol uptake lead to dyslipidemia, one of the risk factors for cardiovascular diseases (CVDs). Based on previous studies, laminarin, a polysaccharide found in brown algae, has hypolipidemic activity, but its underlying mechanism has not been elucidated. In this study, we investigated the effect of laminarin on intestinal cholesterol uptake in vitro, as well as the lipid and morphological parameters in an in vivo model of high-fat diet (HFD)-fed mice, and addressed the question of whether Niemann-Pick C1-like 1 protein (NPC1L1), a key transporter mediating dietary cholesterol uptake, is involved in the mechanistic action of laminarin. In in vitro studies, BODIPY-cholesterol-labeled Caco-2 cells were examined using confocal microscopy and a fluorescence reader. The results demonstrated that laminarin inhibited cholesterol uptake into Caco-2 cells in a concentration-dependent manner (EC50 = 20.69 μM). In HFD-fed C57BL/6J mice, laminarin significantly reduced the serum levels of total cholesterol (TC), total triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C). It also decreased hepatic levels of TC, TG, and total bile acids (TBA) while promoting the excretion of fecal cholesterol. Furthermore, laminarin significantly reduced local villous damage in the jejunum of HFD mice. Mechanistic studies revealed that laminarin significantly downregulated NPC1L1 protein expression in the jejunum of HFD-fed mice. The siRNA-mediated knockdown of NPC1L1 attenuated the laminarin-mediated inhibition of cholesterol uptake in Caco-2 cells. This study suggests that laminarin significantly improves dyslipidemia in HFD-fed mice, likely by reducing cholesterol uptake through a mechanism that involves the downregulation of NPC1L1 expression.

State of CD8+ T cells in progression from nonalcoholic steatohepatitis to hepatocellular carcinoma: From pathogenesis to immunotherapy

With the obesity epidemic, nonalcoholic steatohepatitis (NASH) is emerging as the fastest growing potential cause of hepatocellular carcinoma (HCC). NASH has been demonstrated to establish a tumor-prone liver microenvironment where both innate and adaptive immune systems are involved. As the most typical anti-tumor effector, the cell function of CD8+ T cells is remodeled by chronic inflammation, metabolic alteration, lipid toxicity and oxidative stress in the liver microenvironment along the NASH to HCC transition. Unexpectedly, NASH may blunt the effect of immune checkpoint inhibitor therapy against HCC due to the dysregulated CD8+ T cells. Growing evidence has supported that NASH is likely to facilitate the state transition of CD8+ T cells with changes in cell motility, effector function, metabolic reprogramming and gene transcription according to single-cell sequencing. However, the mechanistic insight of CD8+ T cell states in the NASH-driven HCC is not comprehensive. Herein, we focus on the characterization of state phenotypes of CD8+ T cells with both functional and metabolic signatures in NASH-driven fibrosis and HCC. The NASH-specific CD8+ T cells are speculated to mainly have a dualist effect, where its aberrant activated phenotype sustains chronic inflammation in NASH but subsequently triggers its exhaustion in HCC. As the exploration of CD8+ T cells on the distribution and phenotypic shifts will provide a new direction for the intervention strategies against HCC, we also discuss the implications for targeting different phenotypes of CD8+ T cells, shedding light on the personalized immunotherapy for NASH-driven HCC.

A diagnostic model for serious COVID-19 infection among older adults in Shanghai during the Omicron wave

Background

The Omicron variant is characterized by striking infectivity and antibody evasion. The analysis of Omicron variant BA.2 infection risk factors is limited among geriatric individuals and understanding these risk factors would promote improvement in the public health system and reduction in mortality. Therefore, our research investigated BA.2 infection risk factors for discriminating severe/critical from mild/moderate geriatric patients.

Methods

Baseline characteristics of enrolled geriatric patients (aged over 60 years) with Omicron infections were analyzed. A logistic regression analysis was conducted to evaluate factors correlated with severe/critical patients. A receiver operating characteristic (ROC) curve was constructed for predicting variables to discriminate mild/moderate patients from severe/critical patients.

Results

A total of 595 geriatric patients older than 60 years were enrolled in this study. Lymphocyte subset levels were significantly decreased, and white blood cells (WBCs) and D-dimer levels were significantly increased with disease progression from a mild/moderate state to a severe/critical state. Univariate and multivariate logistic regression analyses identified a panel of WBCs, CD4⁺ T cell, and D-dimer values that were correlated with good diagnostic accuracy for discriminating mild/moderate patients from severe/critical patients with an area under the curve of 0.962.

Conclusion

Some key baseline laboratory indicators change with disease development. A panel was identified for discriminating mild/moderate patients from severe/critical patients, suggesting that the panel could serve as a potential biomarker to enable physicians to provide timely medical services in clinical practice.

The effect of flaxseed oil consumtion on blood pressure among patients with metabolic syndrome and related disorders: A systematic review and meta-analysis of randomized clinical trials

We systematically reviewed randomized clinical trials (RCTs) to elucidate the overall effects of flaxseed oil consumption on blood pressure (BP) in patients with metabolic syndrome and related disorders. PubMed, Scopus, Cochrane Library, and ISI Web of Science databases were systematically searched until March 31, 2020, to find RCTs that examined the effect of flaxseed oil consumption on BP. Weighed mean difference (WMD) was pooled using a random-effects model. Standard methods were used for the assessment of heterogeneity, sensitivity analysis, and publication bias. Meta-analysis of five trials (6 arms) showed significant reductions in systolic (WMD: -3.86 mmHg, 95% CI: -7.59 to -0.13, p = .04) BP (SBP) after flaxseed oil consumption. However, the overall effect illustrated no significant change in diastolic (WMD: -1.71 mmHg, 95% CI: -3.67 to 0.26, p = .09) BP (DBP) in the intervention group compared with the control group. Our findings revealed that flaxseed oil consumption has favorable effects on SBP in patients with metabolic syndrome and related disorders. However, further investigations are needed to provide more reliable evidence.

Essential sufficiency of zinc, ω-3 polyunsaturated fatty acids, vitamin D and magnesium for prevention and treatment of COVID-19, diabetes, cardiovascular diseases, lung diseases and cancer

Despite the development of a number of vaccines for COVID-19, there remains a need for prevention and treatment of the virus SARS-CoV-2 and the ensuing disease COVID-19. This report discusses the key elements of SARS-CoV-2 and COVID-19 that can be readily treated: viral entry, the immune system and inflammation, and the cytokine storm. It is shown that the essential nutrients zinc, ω-3 polyunsaturated fatty acids (PUFAs), vitamin D and magnesium provide the ideal combination for prevention and treatment of COVID-19: prevention of SARS-CoV-2 entry to host cells, prevention of proliferation of SARS-CoV-2, inhibition of excessive inflammation, improved control of the regulation of the immune system, inhibition of the cytokine storm, and reduction in the effects of acute respiratory distress syndrome (ARDS) and associated non-communicable diseases. It is emphasized that the non-communicable diseases associated with COVID-19 are inherently more prevalent in the elderly than the young, and that the maintenance of sufficiency of zinc, ω-3 PUFAs, vitamin D and magnesium is essential for the elderly to prevent the occurrence of non-communicable diseases such as diabetes, cardiovascular diseases, lung diseases and cancer. Annual checking of levels of these essential nutrients is recommended for those over 65 years of age, together with appropriate adjustments in their intake, with these services and supplies being at government cost. The cost:benefit ratio would be huge as the cost of the nutrients and the testing of their levels would be very small compared with the cost savings of specialists and hospitalization.

Studying Adipocyte and Immune Cell Cross Talk Using a Co-culture System

The co-culture of adipocytes and immune cells, such as macrophages or T cells (CD4⁺ or CD8⁺ subsets), is a novel experimental approach used to study paracrine interactions (or the cross talk) between cultured cell types in isolation, in order to understand their role in obese adipose tissue (AT) inflammation and dysfunction. Here we describe the general methodologies required for the co-culture of mature adipocytes (differentiated 3T3-L1 pre-adipocyte cell line) with primary immune cell subsets purified from mouse splenic mononuclear cells using a magnetic MicroBead positive selection, wherein multiple immune cell populations can be purified sequentially from a single mouse spleen, thereby providing diversity in the types of immune cells that can be co-cultured with adipocytes. Additionally, we describe experimental procedures for co-culturing adipocytes and immune cells in two different co-culture systems, including a cell contact-dependent co-culture system, wherein the cells are in direct physical contact, and a cell contact-independent, soluble mediator-driven co-culture system wherein the cells are physically separated by a trans-well semipermeable membrane. Finally, we discuss how these co-culture models can be utilized to recapitulate the AT microenvironment in obesity by utilizing physiologically relevant ratios of adipocytes:immune cells (specifically CDllb⁺ macrophages, CD4⁺ T cells, or CD8⁺ T cells) and lipopolysaccharide stimulation that mimics endotoxin concentrations observed in obesity.

Phytochemicals affect T helper 17 and T regulatory cells and gut integrity: implications on the gut-bone axis

The pathology of osteoporosis is multifactorial, but a growing body of evidence supports an important role of the gut-bone axis, especially in bone loss associated with menopause, rheumatoid arthritis, and periodontal disease. Aberrant T cell responses favoring an increase in the ratio of T helper 17 cells to T regulatory cells play a critical role in the underlying etiology of this bone loss. Many of the dietary phytochemicals known to have osteoprotective activity such as flavonoids, organosulfur compounds, phenolic acids, as well as the oligosaccharides also improve gut barrier function and affect T cell differentiation and activation within gut-associated lymphoid tissues and at distal sites. Here, we examine the potential of these phytochemicals to act as prebiotics and immunomodulating agents, in part targeting the gut to mediate their effects on bone.

n-3 Polyunsaturated Fatty Acids Impede the TCR Mobility and the TCR-pMHC Interaction of Anti-Viral CD8+ T Cells

The immune-suppressive effects of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) on T cells have been observed via multiple in vitro and in vivo models. However, the precise mechanism that causes these effects is still undefined. In this study, we investigated whether n-3 PUFAs regulated T cell receptor (TCR) and peptide-major histocompatibility complex (pMHC) interactions. The expansion of anti-viral CD8⁺ T cells that endogenously synthesize n-3 PUFAs (FAT-1) dramatically decreased upon lymphocytic choriomeningitis virus (LCMV) infection in vivo. This decrease was not caused by the considerable reduction of TCR expression or the impaired chemotactic activity of T cells. Interestingly, a highly inclined and laminated optical sheet (HILO) microscopic analysis revealed that the TCR motility was notably reduced on the surface of the FAT-1 CD8⁺ T cells compared to the wild type (WT) CD8⁺ T cells. Importantly, the adhesion strength of the FAT-1 CD8⁺ T cells to the peptide-MHC was significantly lower than that of the WT CD8⁺T cells. Consistent with this result, treatment with docosahexaenoic acid (DHA), one type of n-3 PUFA, significantly decreased CD8⁺ T cell adhesion to the pMHC. Collectively, our results reveal a novel mechanism through which n-3 PUFAs decrease TCR-pMHC interactions by modulating TCR mobility on CD8⁺ T cell surfaces.

CD8+ T cell/adipocyte inflammatory cross talk and ensuing M1 macrophage polarization are reduced by fish-oil-derived n-3 polyunsaturated fatty acids, in part by a TNF-α-dependent mechanism

Obese visceral adipose tissue (AT) inflammation is driven by adipokine-mediated cross talk between CD8⁺ T cells and adipocytes, a process mitigated by long-chain (LC) n-3 polyunsaturated fatty acids (PUFA) but underlying mechanisms and ensuing effects on macrophage polarization status are unknown. Using an in vitro co-culture model that recapitulates the degree of CD8⁺ T cell infiltration reported in obese AT, 3T3-L1 adipocytes were co-cultured for 24 h with purified splenic CD8⁺ T cells from C57Bl/6 mice consuming either a 10% w/w safflower oil (control, CON) or 7% w/w safflower oil + 3% w/w fish oil (FO) diet for 4 weeks (n=8-10/diet). Co-cultured cells were in direct contact or in a contact-independent condition separated by a Transwell permeable membrane and stimulated with lipopolysaccharide (10 ng/ml) to mimic in vivo obese endotoxin levels. In contact-dependent co-cultures, FO reduced inflammatory (IL-6, TNFα, IFN-γ) and macrophage chemotactic (CCL2, CCL7, CCL3) mRNA expression and/or secreted protein, NF-κB p65 activation, ROS accumulation, NLRP3 inflammasome priming (Nlrp3, Il1β mRNA) and activation (caspase-1 activity) compared to CON (P<.05). The anti-inflammatory action of FO was reproduced by the addition of a TNF-α neutralizing antibody (1 μg/ml) to CON co-cultures (CON/anti-TNF-α), albeit to a lesser degree. Conditioned media from FO and CON/anti-TNF-α co-cultures, in turn, reduced RAW 264.7 macrophage mRNA expression of M1 polarization markers (iNos, Cd11c, Ccr2) and associated inflammatory cytokines (Il6, Tnfα, Il1β) compared to CON. These data suggest that inflammatory CD8⁺ T cell/adipocyte cross talk is partially attributable to TNF-α signaling, which can be mitigated by LC n-3 PUFA.

Omega-3 Polyunsaturated Fatty Acids Inhibit IL-17A Secretion through Decreased ICAM-1 Expression in T Cells Co-Cultured with Adipose-Derived Stem Cells Harvested from Adipose Tissues of Obese Subjects

SCOPE

Obese adipose tissue (AT) is infiltrated by inflammatory immune cells including IL-17A-producing-T (Th17) cells. It has been previously demonstrated that adipose-derived stem cells from obese (ob-ASCs), but not lean AT promote Th17 cells. Because n-3 PUFAs are known to inhibit obese AT inflammation, it is tested here whether they could inhibit ob-ASC-mediated IL-17A secretion.

METHODS AND RESULTS

The n-3 PUFA precursor, alpha-linolenic acid (ALA), or its derivatives, eicosapentaenoic, or docosahexaenoic acid, is added to co-cultures of human ob-ASCs and mononuclear cells (MNCs). All three inhibited IL-17A, but not IL-1β, IL-6, nor TNFα  secretion. As a control, palmitic acid (PA), a saturated fatty acid, did not inhibit IL-17A secretion. ALA also inhibited IL-17A secretion mediated by adipocytes differentiated from ob-ASCs. Toll-like-receptor 4 is shown to be involved in ob-ASC-mediated-IL-17A secretion, and to be inhibited by ALA, together with Cyclo-Oxygenase-2 and Signal-Transducer-and-Activator-of-transcription-3. In addition, ALA down-regulated Intercellular-Adhesion-Molecule-1 (ICAM-1) expression in both monocytes and ASCs, which resulted in decreased interactions between ob-ASCs and MNCs, and inhibition of IL-17A secretion.

CONCLUSION

It is demonstrated herein that ALA inhibits Th17 cell promotion, through decreased ICAM-1expression in both ob-ASCs and monocytes. This novel mechanism may contribute to explain the beneficial effects of n-3 PUFA in IL-17A-related inflammatory pathologies.

Integrated Immunomodulatory Mechanisms through which Long-Chain n-3 Polyunsaturated Fatty Acids Attenuate Obese Adipose Tissue Dysfunction

Obesity is a global health concern with rising prevalence that increases the risk of developing other chronic diseases. A causal link connecting overnutrition, the development of obesity and obesity-associated co-morbidities is visceral adipose tissue (AT) dysfunction, characterized by changes in the cellularity of various immune cell populations, altered production of inflammatory adipokines that sustain a chronic state of low-grade inflammation and, ultimately, dysregulated AT metabolic function. Therefore, dietary intervention strategies aimed to halt the progression of obese AT dysfunction through any of the aforementioned processes represent an important active area of research. In this connection, fish oil-derived dietary long-chain n-3 polyunsaturated fatty acids (PUFA) in the form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been demonstrated to attenuate obese AT dysfunction through multiple mechanisms, ultimately affecting AT immune cellularity and function, adipokine production, and metabolic signaling pathways, all of which will be discussed herein.

Dietary Flaxseed Oil Prevents Western-Type Diet-Induced Nonalcoholic Fatty Liver Disease in Apolipoprotein-E Knockout Mice

The prevalence of nonalcoholic fatty liver disease (NAFLD) has dramatically increased globally during recent decades. Intake of n-3 polyunsaturated fatty acids (PUFAs), mainly eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3), is believed to be beneficial to the development of NAFLD. However, little information is available with regard to the effect of flaxseed oil rich in α-linolenic acid (ALA, C18:3n-3), a plant-derived n-3 PUFA, in improving NAFLD. This study was to gain the effect of flaxseed oil on NAFLD and further investigate the underlying mechanisms. Apolipoprotein-E knockout (apoE-KO) mice were given a normal chow diet, a western-type high-fat and high-cholesterol diet (WTD), or a WTD diet containing 10% flaxseed oil (WTD + FO) for 12 weeks. Our data showed that consumption of flaxseed oil significantly improved WTD-induced NAFLD, as well as ameliorated impaired lipid homeostasis, attenuated oxidative stress, and inhibited inflammation. These data were associated with the modification effects on expression levels of genes involved in de novo fat synthesis (SREBP-1c, ACC), triacylglycerol catabolism (PPARα, CPT1A, and ACOX1), inflammation (NF-κB, IL-6, TNF-α, and MCP-1), and oxidative stress (ROS, MDA, GSH, and SOD).

Matrine alleviates lipopolysaccharide-induced intestinal inflammation and oxidative stress via CCR7 signal

The aim of this study was to investigate the protective effects of matrine on lipopolysaccharide (LPS)-induced inflammation and oxidative stress in vivo and in vitro. The results showed that matrine improved intestinal inflammatory status and oxidative balance and enhanced chemokine receptor 7 (CCR7) expression. In LPS-challenged mice and Caco-2 cells, matrine alleviated LPS-induced inflammation and oxidative stress via downregulating pro-inflammatory cytokines (IL-1β and IL-17) and malondialdehyde (MDA) production. CCR7-siRNA transfection blocked the protective effects of matrine on LPS-induced inflammation and oxidative stress and exacerbated LPS caused injury. In conclusion, matrine alleviates LPS-induced intestinal inflammation and oxidative stress in mice and Caco-2 cells, which may be associated with CCR7 signal.