Kun-Ho Seo

Bio: Kun-Ho Seo is an academic researcher from Konkuk University. The author has contributed to research in topics: Campylobacter & Salmonella enteritidis. The author has an hindex of 26, co-authored 149 publications receiving 1756 citations.

Kefir alleviates obesity and hepatic steatosis in high-fat diet-fed mice by modulation of gut microbiota and mycobiota: targeted and untargeted community analysis with correlation of biomarkers.

Abstract: Kefir is a probiotic beverage containing over 50 species of lactic acid bacteria and yeast. In this study, the anti-obesity and anti-non-alcoholic fatty liver disease (NAFLD) effects of kefir were comprehensively addressed along with targeted and untargeted community analysis of the fecal microbiota in a high-fat diet (HFD)-induced obese mouse model. HFD-fed C57BL/6 mice were orally administrated either kefir or milk (control) once a day for 12 weeks, and body and organ weight, fecal microbiota and mycobiota, histopathology, blood cholesterol and cytokines and gene expressions were analyzed. Compared to the control, mice in the kefir group exhibited a significantly lower body weight (34.18 g vs. 40.24 g; p=0.00004) and histopathological liver lesion score (1.13 vs. 3.25; p=0.002). Remarkably, the kefir-fed mice also harbored more Lactobacillus/Lactococcus (7.01 vs. 6.32 log CFU/g), total yeast (6.07 vs. 5.01 log CFU/g) and Candida (5.56 vs. 3.88 log CFU/g). Kefir administration also up-regulated genes related to fatty acid oxidation, PPARα and AOX, in both the liver and adipose tissue (PPARα, 2.95- and 2.15-fold; AOX, 1.89- and 1.9-fold, respectively). The plasma concentration of IL-6, a proinflammatory marker, was significantly reduced following kefir consumption (50.39 pg/ml vs. 111.78 pg/ml; p=0.03). Strikingly, the populations of Lactobacillus/Lactococcus, total yeast and Candida were strongly correlated with PPARα gene expression in adipose and hepatic tissue (r=0.599, 0.580 and 0.562, respectively). These data suggest that kefir consumption modulates gut microbiota and mycobiota in HFD-fed mice, which prevents obesity and NAFLD via promoting fatty acid oxidation.

Dual function of Lactobacillus kefiri DH5 in preventing high-fat-diet-induced obesity: direct reduction of cholesterol and upregulation of PPAR-α in adipose tissue.

Abstract: cope Kefir consumption inhibits the development of obesity and non-alcoholic fatty liver disease in mice fed 60% high-fat diet (HFD). To identify the key contributor of this effect, we isolated lactic acid bacteria (LAB) from kefir and examined their anti-obesity properties from in vitro screening and in vivo validation. Methods and results Thirteen kefir LAB isolates were subjected to survivability test using artificial gastrointestinal environment and cholesterol-reducing assay. Lactobacillus kefiri DH5 showed 100% survivability in gastrointestinal environments and reduced 51.6% of cholesterol; thus, this strain was selected for in vivo experiment. Compared to the HFD-saline group, the HFD-DH5 group showed significantly lower body weight (34.68 vs. 31.10 g; p < 0.001), epididymal adipose tissue weight (1.39 vs. 1.05 g; p < 0.001), blood triglyceride (38.2 vs. 31.0 mg/dL; p < 0.01) and LDL-cholesterol levels (19.4 vs. 15.7 mg/dL; p < 0.01). In addition, L. kefiri DH5 administration significantly modulated gut microbiota of HFD-fed mice. The hepatic steatosis was significantly milder (Lesion score, 2.1 vs. 1.2; p < 0.001) and adipocyte diameter was significantly smaller (65.1 vs. 42.2 μm; p < 0.001) in the HFD-DH5 group. L. kefiri DH5 upregulated PPARα, FABP4, and CPT1 expression in the epididymal adipose tissues (2.29-, 1.77-, and 2.05-fold change, respectively), suggesting a reduction in adiposity by stimulating fatty acid oxidation. Conclusion L. kefiri DH5 exerts anti-obesity effects by direct reduction of cholesterol in the lumen and upregulation of PPARα gene in adipose tissues. This article is protected by copyright. All rights reserved

Antimicrobial Activity of Kefir against Various Food Pathogens and Spoilage Bacteria.

Abstract: Kefir is a unique fermented dairy product produced by a mixture of lactic acid bacteria, acetic acid bacteria, and yeast. Here, we compared the antimicrobial spectra of four types of kefirs (A, L, M, and S) fermented for 24, 36, 48, or 72 h against eight food-borne pathogens. Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Enterococcus faecalis, Escherichia coli, Salmonella Enteritidis, Pseudomonas aeruginosa, and Cronobacter sakazakii were used as test strains, and antibacterial activity was investigated by the spot on lawn method. The spectra, potencies, and onsets of activity varied according to the type of kefir and the fermentation time. The broadest and strongest antimicrobial spectrum was obtained after at least 36-48 h of fermentation for all kefirs, although the traditional fermentation method of kefir is for 18-24 h at 25℃. For kefir A, B. cereus, E. coli, S. Enteritidis, P. aeruginosa, and C. sakazakii were inhibited, while B. cereus, S. aureus, E. coli, S. Enteritidis, P. aeruginosa, and C. sakazakii were inhibited to different extents by kefirs L, M, and S. Remarkably, S. aureus, S. Enteritidis, and C. sakazakii were only inhibited by kefirs L, M, and S, and L. monocytogenes by kefir M after fermentation for specific times, suggesting that the antimicrobial activity is attributable not only to a low pH but also to antimicrobial substances secreted during the fermentation.

The gut–liver axis and the intersection with the microbiome

Abstract: In the past decade, an exciting realization has been that diverse liver diseases — ranging from nonalcoholic steatohepatitis, alcoholic steatohepatitis and cirrhosis to hepatocellular carcinoma — fall along a spectrum. Work on the biology of the gut–liver axis has assisted in understanding the basic biology of both alcoholic fatty liver disease and nonalcoholic fatty liver disease (NAFLD). Of immense importance is the advancement in understanding the role of the microbiome, driven by high-throughput DNA sequencing and improved computational techniques that enable the complexity of the microbiome to be interrogated, together with improved experimental designs. Here, we review gut–liver communications in liver disease, exploring the molecular, genetic and microbiome relationships and discussing prospects for exploiting the microbiome to determine liver disease stage and to predict the effects of pharmaceutical, dietary and other interventions at a population and individual level. Although much work remains to be done in understanding the relationship between the microbiome and liver disease, rapid progress towards clinical applications is being made, especially in study designs that complement human intervention studies with mechanistic work in mice that have been humanized in multiple respects, including the genetic, immunological and microbiome characteristics of individual patients. These ‘avatar mice’ could be especially useful for guiding new microbiome-based or microbiome-informed therapies.

Integrated Systems Approach to Study the Role of Omega-3 Long-Chain Polyunsaturated Fatty Acids in Health and Disease of the Retina

Abstract: In this work we advance the hypothesis that omega-3 (omega-3) long-chain polyunsaturated fatty acids (LCPUFAs) exhibit cytoprotective and cytotherapeutic actions contributing to a number of anti-angiogenic and neuroprotective mechanisms within the retina. omega-3 LCPUFAs may modulate metabolic processes and attenuate effects of environmental exposures that activate molecules implicated in pathogenesis of vasoproliferative and neurodegenerative retinal diseases. These processes and exposures include ischemia, chronic light exposure, oxidative stress, inflammation, cellular signaling mechanisms, and aging. A number of bioactive molecules within the retina affect, and are effected by such conditions. These molecules operate within complex systems and include compounds classified as eicosanoids, angiogenic factors, matrix metalloproteinases, reactive oxygen species, cyclic nucleotides, neurotransmitters and neuromodulators, pro-inflammatory and immunoregulatory cytokines, and inflammatory phospholipids. We discuss the relationship of LCPUFAs with these bioactivators and bioactive compounds in the context of three blinding retinal diseases of public health significance that exhibit both vascular and neural pathology. How is omega-3 LCPUFA status related to retinal structure and function? Docosahexaenoic acid (DHA), a major dietary omega-3 LCPUFA, is also a major structural lipid of retinal photoreceptor outer segment membranes. Biophysical and biochemical properties of DHA may affect photoreceptor membrane function by altering permeability, fluidity, thickness, and lipid phase properties. Tissue DHA status affects retinal cell signaling mechanisms involved in phototransduction. DHA may operate in signaling cascades to enhance activation of membrane-bound retinal proteins and may also be involved in rhodopsin regeneration. Tissue DHA insufficiency is associated with alterations in retinal function. Visual processing deficits have been ameliorated with DHA supplementation in some cases. What evidence exists to suggest that LCPUFAs modulate factors and processes implicated in diseases of the vascular and neural retina? Tissue status of LCPUFAs is modifiable by and dependent upon dietary intake. Certain LCPUFAs are selectively accreted and efficiently conserved within the neural retina. On the most basic level, omega-3 LCPUFAs influence retinal cell gene expression, cellular differentiation, and cellular survival. DHA activates a number of nuclear hormone receptors that operate as transcription factors for molecules that modulate reduction-oxidation-sensitive and proinflammatory genes; these include the peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and the retinoid X receptor. In the case of PPAR-alpha, this action is thought to prevent endothelial cell dysfunction and vascular remodeling through inhibition of: vascular smooth muscle cell proliferation, inducible nitric oxide synthase production, interleukin-1 induced cyclooxygenase (COX)-2 production, and thrombin-induced endothelin 1 production. Research on model systems demonstrates that omega-3 LCPUFAs also have the capacity to affect production and activation of angiogenic growth factors, arachidonic acid (AA)-based vasoregulatory eicosanoids, and MMPs. Eicosapentaenoic acid (EPA), a substrate for DHA, is the parent fatty acid for a family of eicosanoids that have the potential to affect AA-derived eicosanoids implicated in abnormal retinal neovascularization, vascular permeability, and inflammation. EPA depresses vascular endothelial growth factor (VEGF)-specific tyrosine kinase receptor activation and expression. VEGF plays an essential role in induction of: endothelial cell migration and proliferation, microvascular permeability, endothelial cell release of metalloproteinases and interstitial collagenases, and endothelial cell tube formation. The mechanism of VEGF receptor down-regulation is believed to occur at the tyrosine kinase nuclear factor-kappa B (NFkappaB). NFkappaB is a nuclear transcription factor that up-regulates COX-2 expression, intracellular adhesion molecule, thrombin, and nitric oxide synthase. All four factors are associated with vascular instability. COX-2 drives conversion of AA to a number angiogenic and proinflammatory eicosanoids. Our general conclusion is that there is consistent evidence to suggest that omega-3 LCPUFAs may act in a protective role against ischemia-, light-, oxygen-, inflammatory-, and age-associated pathology of the vascular and neural retina.

MicroRNAs: Target Recognition and Regulatory Functions

Abstract: MicroRNAs (miRNAs) are endogenous ∼23 nt RNAs that play important gene-regulatory roles in animals and plants by pairing to the mRNAs of protein-coding genes to direct their posttranscriptional repression. This review outlines the current understanding of miRNA target recognition in animals and discusses the widespread impact of miRNAs on both the expression and evolution of protein-coding genes.

Akkermansia muciniphila inversely correlates with the onset of inflammation, altered adipose tissue metabolism and metabolic disorders during obesity in mice.

Abstract: Recent evidence indicates that the gut microbiota plays a key role in the pathophysiology of obesity. Indeed, diet-induced obesity (DIO) has been associated to substantial changes in gut microbiota composition in rodent models. In the context of obesity, enhanced adiposity is accompanied by low-grade inflammation of this tissue but the exact link with gut microbial community remains unknown. In this report, we studied the consequences of high-fat diet (HFD) administration on metabolic parameters and gut microbiota composition over different periods of time. We found that Akkermansia muciniphila abundance was strongly and negatively affected by age and HFD feeding and to a lower extend Bilophila wadsworthia was the only taxa following an opposite trend. Different approaches, including multifactorial analysis, showed that these changes in Akkermansia muciniphila were robustly correlated with the expression of lipid metabolism and inflammation markers in adipose tissue, as well as several circulating parameters (i.e., glucose, insulin, triglycerides, leptin) from DIO mice. Thus, our data shows the existence of a link between gut Akkermansia muciniphila abundance and adipose tissue homeostasis on the onset of obesity, thus reinforcing the beneficial role of this bacterium on metabolism.

Salmonella: A review on pathogenesis, epidemiology and antibiotic resistance

Abstract: Salmonella is one of the most frequently isolated foodborne pathogens. It is a major worldwide public health concern, accounting for 93.8 million foodborne illnesses and 155,000 deaths per year. To date, over 2500 Salmonella serotypes have been identified and more than half of them belong to Salmonella enterica subsp. enterica, which accounts for the majority of Salmonella infections in humans. Salmonella infections that involve invasive serotypes are often life threatening, necessitating appropriate and effective antibiotic therapy. The emergence of multi-drug-resistant (MDR) Salmonella serotypes is having a great impact on the efficacy of antibiotic treatment, and an increasing prevalence of MDR strains may lead to an increase in mortality rates of Salmonella infections. Epidemiological studies indicate that MDR Salmonella serotypes are more virulent than susceptible strains, as reflected by increased severity and more prolonged disease in patients infected by MDR strains. Preventive measures have been ...