Lactobacillus acidophilus KBL409 protects against kidney injury via improving mitochondrial function with chronic kidney disease

PURPOSE

Recent advances have led to greater recognition of the role of mitochondrial dysfunction in the pathogenesis of chronic kidney disease (CKD). There has been evidence that CKD is also associated with dysbiosis. Here, we aimed to evaluate whether probiotic supplements can have protective effects against kidney injury via improving mitochondrial function.

METHODS

An animal model of CKD was induced by feeding C57BL/6 mice a diet containing 0.2% adenine. KBL409, a strain of Lactobacillus acidophilus, was administered via oral gavage at a dose of 1 × 109 CFU daily. To clarify the underlying mechanisms by which probiotics exert protective effects on mitochondria in CKD, primary mouse tubular epithelial cells stimulated with TGF-β and p-cresyl sulfate were administered with butyrate.

RESULTS

In CKD mice, PGC-1α and AMPK, key mitochondrial energy metabolism regulators, were down-regulated. In addition, mitochondrial dynamics shifted toward fission, the number of fragmented cristae increased, and mitochondrial mass decreased. These alterations were restored by KBL409 administration. KBL409 supplementation also improved defects in fatty acid oxidation and glycolysis and restored the suppressed enzyme levels involved in TCA cycle. Accordingly, there was a concomitant improvement in mitochondrial respiration and ATP production assessed by mitochondrial function assay. These favorable effects of KBL409 on mitochondria ultimately decreased kidney fibrosis in CKD mice. In vitro analyses with butyrate recapitulated the findings of animal study.

CONCLUSIONS

This study demonstrates that administration of the probiotic Lactobacillus acidophilus KBL409 protects against kidney injury via improving mitochondrial function.

Fermented Milk Containing Lacticaseibacillus rhamnosus SNU50430 Modulates Immune Responses and Gut Microbiota in Antibiotic-Treated mice

Antibiotics are used to control infectious diseases. However, adverse effects of antibiotics, such as devastation of the gut microbiota and enhancement of the inflammatory response, have been reported. Health benefits of fermented milk are established and can be enhanced by the addition of probiotic strains. In this study, we evaluated effects of fermented milk containing Lacticaseibacillus rhamnosus (L. rhamnosus) SNUG50430 in a mouse model with antibiotic treatment. Fermented milk containing 2 × 105 colony-forming units of L. rhamnosus SNUG50430 was administered to six week-old female BALB/c mice for 1 week. Interleukin (IL)-10 levels in colon samples were significantly increased (P < 0.05) compared to water-treated mice, whereas interferon-gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) were decreased, of mice treated with fermented milk containing L. rhamnosus SNUG50430- antibiotics-treated (FM+LR+Abx-treated) mice. Phylum Firmicutes composition in the gut was restored and the relative abundances of several bacteria, including the genera Coprococcus and Lactobacillus, were increased in FM+LR+Abx-treated mice compared to PBS+Abx-treated mice. Interestingly, abundances of genus Coprococcus and Lactobacillus were positively correlated with IL5 and IL-10 levels (P < 0.05) in colon samples and negative correlated with IFN-γ and TNF-α levels in serum samples (P < 0.001). Acetate and butyrate were increased in mice with fermented milk and fecal microbiota of FM+LR+Abx-treated mice were highly enriched with butyrate metabolism pathway compared to water-treated mice (P < 0.05). Thus, fermented milk containing L. rhamnosus SNUG50430 was shown to ameliorate adverse health effects caused by antibiotics through modulating immune responses and the gut microbiota.

Strain-Specific Anti-Inflammatory Effects of Faecalibacterium prausnitzii Strain KBL1027 in Koreans

Faecalibacterium prausnitzii is one of the most dominant commensal bacteria in the human gut, and certain anti-inflammatory functions have been attributed to a single microbial anti-inflammatory molecule (MAM). Simultaneously, substantial diversity among F. prausnitzii strains is acknowledged, emphasizing the need for strain-level functional studies aimed at developing innovative probiotics. Here, two distinct F. prausnitzii strains, KBL1026 and KBL1027, were isolated from Korean donors, exhibiting notable differences in the relative abundance of F. prausnitzii. Both strains were identified as the core Faecalibacterium amplicon sequence variant (ASV) within the healthy Korean cohort, and their MAM sequences showed a high similarity of 98.6%. However, when a single strain was introduced to mice with dextran sulfate sodium (DSS)-induced colitis, KBL1027 showed the most significant ameliorative effects, including alleviation of colonic inflammation and restoration of gut microbial dysbiosis. Moreover, the supernatant from KBL1027 elevated the secretion of IL-10 cytokine more than that of KBL1026 in mouse bone marrow-derived macrophage (BMDM) cells, suggesting that the strain-specific, anti-inflammatory efficacy of KBL1027 might involve effector compounds other than MAM. Through analysis of the Faecalibacterium pan-genome and comparative genomics, strain-specific functions related to extracellular polysaccharide biosynthesis were identified in KBL1027, which could contribute to the observed morphological disparities. Collectively, our findings highlight the strain-specific, anti-inflammatory functions of F. prausnitzii, even within the same core ASV, emphasizing the influence of their human origin.

Lactobacillus acidophilus KBL409 Ameliorates Atopic Dermatitis in a Mouse Model

Atopic dermatitis (AD) is a chronic inflammatory skin disease with repeated exacerbations of eczema and pruritus. Probiotics can prevent or treat AD appropriately via modulation of immune responses and gut microbiota. In this study, we evaluated effects of Lactobacillus acidophilus (L. acidophilus) KBL409 using a house dust mite (Dermatophagoides farinae)-induced in vivo AD model. Oral administration of L. acidophilus KBL409 significantly reduced dermatitis scores and decreased infiltration of immune cells in skin tissues. L. acidophilus KBL409 reduced in serum immunoglobulin E and mRNA levels of T helper (Th)1 (Interferon-γ), Th2 (Interleukin [IL]-4, IL-5, IL-13, and IL-31), and Th17 (IL-17A) cytokines in skin tissues. The anti-inflammatory cytokine IL-10 was increased and Foxp3 expression was up-regulated in AD-induced mice with L. acidophilus KBL409. Furthermore, L. acidophilus KBL409 significantly modulated gut microbiota and concentrations of short-chain fatty acids and amino acids, which could explain its effects on AD. Our results suggest that L. acidophilus KBL409 is the potential probiotic for AD treatment by modulating of immune responses and gut microbiota of host.

Lactobacillus rhamnosus KBL2290 Ameliorates Gut Inflammation in a Mouse Model of Dextran Sulfate Sodium-Induced Colitis

Ulcerative colitis, a major form of inflammatory bowel disease (IBD) associated with chronic colonic inflammation, may be induced via overreactive innate and adaptive immune responses. Restoration of gut microbiota abundance and diversity is important to control the pathogenesis. Lactobacillus spp., well-known probiotics, ameliorate IBD symptoms via various mechanisms, including modulation of cytokine production, restoration of gut tight junction activity and normal mucosal thickness, and alterations in the gut microbiota. Here, we studied the effects of oral administration of Lactobacillus rhamnosus (L. rhamnosus) KBL2290 from the feces of a healthy Korean individual to mice with DSS-induced colitis. Compared to the dextran sulfate sodium (DSS) + phosphate-buffered saline control group, the DSS + L. rhamnosus KBL2290 group evidenced significant improvements in colitis symptoms, including restoration of body weight and colon length, and decreases in the disease activity and histological scores, particularly reduced levels of pro-inflammatory cytokines and an elevated level of anti-inflammatory interleukin-10. Lactobacillus rhamnosus KBL2290 modulated the levels of mRNAs encoding chemokines and markers of inflammation; increased regulatory T cell numbers; and restored tight junction activity in the mouse colon. The relative abundances of genera Akkermansia, Lactococcus, Bilophila, and Prevotella increased significantly, as did the levels of butyrate and propionate (the major short-chain fatty acids). Therefore, oral L. rhamnosus KBL2290 may be a useful novel probiotic.

Secreted Akkermansia muciniphila threonyl-tRNA synthetase functions to monitor and modulate immune homeostasis

Commensal bacteria are critically involved in the establishment of tolerance against inflammatory challenges, the molecular mechanisms of which are just being uncovered. All kingdoms of life produce aminoacyl-tRNA synthetases (ARSs). Thus far, the non-translational roles of ARSs have largely been reported in eukaryotes. Here, we report that the threonyl-tRNA synthetase (AmTARS) of the gut-associated bacterium Akkermansia muciniphila is secreted and functions to monitor and modulate immune homeostasis. Secreted AmTARS triggers M2 macrophage polarization and orchestrates the production of anti-inflammatory IL-10 via its unique, evolutionary-acquired regions, which mediates specific interactions with TLR2. This interaction activates the MAPK and PI3K/AKT signaling pathways, which converge on CREB, leading to an efficient production of IL-10 and suppression of the central inflammatory mediator NF-κB. AmTARS restores IL-10-positive macrophages, increases IL-10 levels in the serum, and attenuates the pathological effects in colitis mice. Thus, commensal tRNA synthetases can act as intrinsic mediators that maintain homeostasis.

Chemokine CCL6 Plays Key Role in the Inhibitory Effect of Vitamin A on Norovirus Infection

Norovirus (NoV) is the most common viral cause of acute gastroenteritis worldwide. Vitamin A has demonstrated the potential to protect against gastrointestinal infections. However, the effects of vitamin A on human norovirus (HuNoV) infections remain poorly understood. This study aimed to investigate how vitamin A administration affects NoV replication. We demonstrated that treatment with retinol or retinoic acid (RA) inhibited NoV replication in vitro based on their effects on HuNoV replicon-bearing cells and murine norovirus-1 (MNV-1) replication in murine cells. MNV replication in vitro showed significant transcriptomic changes, which were partially reversed by retinol treatment. RNAi knockdown of CCL6, a chemokine gene that was downregulated by MNV infection but upregulated by retinol administration, resulted in increased MNV replication in vitro. This suggested a role of CCL6 in the host response to MNV infections. Similar gene expression patterns were observed in the murine intestine after oral administration of RA and/or MNV-1.CW1. CCL6 directly decreased HuNoV replication in HG23 cells, and might indirectly regulate the immune response against NoV infection. Finally, relative replication levels of MNV-1.CW1 and MNV-1.CR6 were significantly increased in CCL6 knockout RAW 264.7 cells. This study is the first to comprehensively profile transcriptomes in response to NoV infection and vitamin A treatment in vitro, and thus may provide new insights into dietary prophylaxis and NoV infections.

Catecholamine induces Kupffer cell apoptosis via growth differentiation factor 15 in alcohol-associated liver disease

Chronic alcohol consumption often induces hepatic steatosis but rarely causes severe inflammation in Kupffer cells (KCs) despite the increased hepatic influx of lipopolysaccharide (LPS), suggesting the presence of a veiled tolerance mechanism. In addition to LPS, the liver is affected by several gut-derived neurotransmitters through the portal blood, but the effects of catecholamines on KCs have not been clearly explored in alcohol-associated liver disease (ALD). Hence, we investigated the regulatory roles of catecholamine on inflammatory KCs under chronic alcohol exposure. We discovered that catecholamine levels were significantly elevated in the cecum, portal blood, and liver tissues of chronic ethanol-fed mice. Increased catecholamines induced mitochondrial translocation of cytochrome P450 2E1 in perivenous hepatocytes expressing the β2-adrenergic receptor (ADRB2), leading to the enhanced production of growth differentiation factor 15 (GDF15). Subsequently, GDF15 profoundly increased ADRB2 expression in adjacent inflammatory KCs to facilitate catecholamine/ADRB2-mediated apoptosis. Single-cell RNA sequencing of KCs confirmed the elevated expression of Adrb2 and apoptotic genes after chronic ethanol intake. Genetic ablation of Adrb2 or hepatic Gdf15 robustly decreased the number of apoptotic KCs near perivenous areas, exacerbating alcohol-associated inflammation. Consistently, we found that blood and stool catecholamine levels and perivenous GDF15 expression were increased in patients with early-stage ALD along with an increase in apoptotic KCs. Our findings reveal a novel protective mechanism against ALD, in which the catecholamine/GDF15 axis plays a critical role in KC apoptosis, and identify a unique neuro-metabo-immune axis between the gut and liver that elicits hepatoprotection against alcohol-mediated pathogenic challenges.

Bacteroides vulgatus SNUG 40005 Restores Akkermansia Depletion by Metabolite Modulation

BACKGROUND & AIMS

Weight loss and exercise intervention have been reported to increase the interaction between Bacteroides spp and Akkermansiamuciniphila (Am), although the underlying mechanisms and consequences of the interaction remain unknown.

METHODS

Using a healthy Korean twin cohort (n = 582), we analyzed taxonomic associations with host body mass index. B vulgatus strains were isolated from mice and human subjects to investigate the strain-specific effect of B vulgatus SNUG 40005 (Bvul) on obesity. The mechanisms underlying Am enrichment by Bvul administration were investigated by multiple experiments: (1) in vitro cross-feeding experiments, (2) construction of Bvul mutants with the N-acetylglucosaminidase gene knocked out, and (3) in vivo validation cohorts with different metabolites. Finally, metabolite profiling in mouse and human fecal samples was performed.

RESULTS

An interaction between Bvul and Am was observed in lean subjects but was disrupted in obese subjects. The administration of Bvul to mice fed a high-fat diet decreased body weight, insulin resistance, and gut permeability. In particular, Bvul restored the abundance of Am, which decreased significantly after a long-term high-fat diet. A cross-feeding analysis of Am with cecal contents or Bvul revealed that Am enrichment was attributed to metabolites produced during mucus degradation by Bvul. The metabolome profile of mouse fecal samples identified N-acetylglucosamine as contributing to Am enrichment, which was confirmed by in vitro and in vivo experiments. Metabolite network analysis of the twin cohort found that lysine serves as a bridge between N-acetylglucosamine, Bvul, and Am.

CONCLUSIONS

Strain-specific microbe-microbe interactions modulate the mucosal environment via metabolites produced during mucin degradation in the gut.

Distinct Changes in Microbiota-Mediated Intestinal Metabolites and Immune Responses Induced by Different Antibiotics

The cocktails of antibiotics are utilized to study the functions of microbiota. There have been studies on the alteration of not only the microbiota composition but also the host's metabolism or immunity. However, the bacterial species associated with these altered physiologic markers are still unclear. Therefore, we supplied mice with drinking water containing ampicillin (AMP), vancomycin (VAN), neomycin (NEO), or metronidazole (MET) to observe the effect of each antibiotic on helper T cells and inflammation-related gene expression and metabolism, including amino acid metabolism and changes in gut microbiota. We observed major changes in gut microbiota in mice treated with AMP and VAN, respectively, immediately after administration. The abundance of the genera Parabacteroides and Akkermansia increased in the AMP and VAN groups, while Prevotella almost disappeared from both groups. The compositional changes in intestinal metabolites in the AMP and VAN groups were more distinct than those in the NEO and MET groups, which was similar to the microbiome results. In particular, the most distinct changes were observed in amino acid related metabolism in AMP and VAN groups; the amounts of phenylalanine and tyrosine were increased in the AMP group while those were decreased in the VAN group. The changed amounts of intestinal amino acids in each of the AMP and VAN groups were correlated with increases in the abundance of the genera Parabacteroides and Akkermansia in the AMP and VAN groups, respectively. The most distinctive changes in intestinal gene expression were observed in the ileum, especially the expression Th17-related genes such as rorgt, il17a, and il17f, which decreased dramatically in the guts of most of the antibiotic-treated groups. These changes were also associated with a significant decrease in Prevotella in both the AMP and VAN groups. Taken together, these findings indicate that changes in gut microbiota as well as host physiology, including host metabolism and immunity, differ depending on the types of antibiotics, and the antibiotic-induced gut microbiota alteration has a correlation with host physiology such as host metabolic or immunological status. Thus, the immune and metabolic status of the host should be taken into account when administering antibiotics.

Wnt-activating human skin organoid model of atopic dermatitis induced by Staphylococcus aureus and its protective effects by Cutibacterium acnes

A recently developed human PSC-derived skin organoid model has opened up new avenues for studying skin development, diseases, and regeneration. The current model has limitations since the generated organoids are enclosed, circular aggregates with an inside-out morphology with unintended off-target development of cartilage. Here, we first demonstrated that Wnt signaling activation resulted in larger organoids without off-target cartilage. We optimized further using an air-liquid interface (ALI) culture method to recapitulate structural features representative of human skin tissue. Finally, we used the ALI-skin organoid platform to model atopic dermatitis by Staphylococcus aureus (SA) colonization and infection. SA infection led to a disrupted skin barrier and increased production of epidermal- and dermal-derived inflammatory cytokines. Additionally, we found that pre-treatment with Cutibacterium acnes had a protective effect on SA-infected organoids. Thus, this ALI-skin organoid platform may be a useful tool for modeling human skin diseases and evaluating the efficacy of novel therapeutics.

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Wnt signaling activation results in larger organoids without off-target cartilage

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Air-liquid interface culture is used to recapitulate human skin tissue structure

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S. aureus infection damaged the skin barrier and elevated inflammatory cytokines

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Pre-treated Cutibacterium acnes had a protective effect on Staphylococcus aureus-infected organoids

Codiversification of gut microbiota with humans

The gut microbiomes of human populations worldwide have many core microbial species in common. However, within a species, some strains can show remarkable population specificity. The question is whether such specificity arises from a shared evolutionary history (codiversification) between humans and their microbes. To test for codiversification of host and microbiota, we analyzed paired gut metagenomes and human genomes for 1225 individuals in Europe, Asia, and Africa, including mothers and their children. Between and within countries, a parallel evolutionary history was evident for humans and their gut microbes. Moreover, species displaying the strongest codiversification independently evolved traits characteristic of host dependency, including reduced genomes and oxygen and temperature sensitivity. These findings all point to the importance of understanding the potential role of population-specific microbial strains in microbiome-mediated disease phenotypes.

Lactobacillus acidophilus KBL409 reduces kidney fibrosis via immune modulatory effects in mice with chronic kidney disease

SCOPE

Intestinal dysbiosis has been reported to play an important role in the pathogenesis of various diseases, including chronic kidney disease (CKD). Here, we aimed to evaluate whether probiotic supplements can have protective effects against kidney injury in an animal model of CKD.

METHODS AND RESULTS

An animal model of CKD was established by feeding C57BL/6 mice a diet containing 0.2% adenine. These model mice were administered Lactobacillus acidophilus KBL409 daily for 4 weeks. Features of adenine-induce CKD (Ade-CKD) mice, such as prominent kidney fibrosis and higher levels of serum creatinine and albuminuria were improved by administration of KBL409. Ade-CKD mice also exhibited a disrupted intestinal barrier and elevated levels of TNF-α, IL-6, and 8-hydroxy-2'-deoxyguanosine. These changes were attenuated by KBL409. Administration of KBL409 significantly reduced macrophage infiltration and promoted a switch to the M2 macrophage phenotype and increasing regulatory T cells. Notably, the NLRP3 inflammasome pathway was activated in the kidneys of Ade-CKD and decreased by KBL409. In primary kidney tubular epithelial cells treated with p-cresyl sulfate, short-chain fatty acids significantly increased M2 macrophage polarization factors and decreased profibrotic markers.

CONCLUSIONS

These results demonstrate that supplementation with the probiotic KBL409 has beneficial immunomodulating effects and protects against kidney injury. This article is protected by copyright. All rights reserved.

Interaction effect between NAFLD severity and high carbohydrate diet on gut microbiome alteration and hepatic de novo lipogenesis

Nonalcoholic fatty liver disease (NAFLD) is associated with high carbohydrate (HC) intake. We investigated whether the relationship between carbohydrate intake and NAFLD is mediated by interactions between gut microbial modulation, impaired insulin response, and hepatic de novo lipogenesis (DNL). Stool samples were collected from 204 Korean subjects with biopsy-proven NAFLD (n = 129) and without NAFLD (n = 75). The gut microbiome profiles were analyzed using 16S rRNA amplicon sequencing. Study subjects were grouped by the NAFLD activity score (NAS) and percentage energy intake from dietary carbohydrate. Hepatic DNL-related transcripts were also analyzed (n = 90). Data from the Korean healthy twin cohort (n = 682), a large sample of individuals without NAFLD, were used for comparison and validation. A HC diet rather than a low carbohydrate diet was associated with the altered gut microbiome diversity according to the NAS. Unlike individuals from the twin cohort without NAFLD, the abundances of Enterobacteriaceae and Ruminococcaceae were significantly different among the NAS subgroups in NAFLD subjects who consumed an HC diet. The addition of these two microbial families, along with Veillonellaceae, significantly improved the diagnostic performance of the predictive model, which was based on the body mass index, age, and sex to predict nonalcoholic steatohepatitis in the HC group. In the HC group, two crucial regulators of DNL (SIRT1 and SREBF2) were differentially expressed among the NAS subgroups. In particular, kernel causality analysis revealed a causal effect of the abundance of Enterobacteriaceae on SREBF2 upregulation and of the surrogate markers of insulin resistance on NAFLD activity in the HC group. Consuming an HC diet is associated with alteration in the gut microbiome, impaired glucose homeostasis, and upregulation of hepatic DNL genes, altogether contributing to NAFLD pathogenesis.

Revisiting the role of Akkermansia muciniphila as a therapeutic bacterium

Despite a short history since its first isolation, Akkermansia muciniphila has been extensively studied in relation to its effects on human metabolism. A recent human intervention study also demonstrated that the bacterium is safe to use for therapeutic purposes. The best-known effects of A. muciniphila in human health and disease relate to its ability to strengthen gut integrity, modulate insulin resistance, and protect the host from metabolic inflammation. A further molecular mechanism, induction of GLP-1 secretion through ICAM-2 receptor, was recently discovered with the identification of a new bacterial protein produced by A. muciniphila. However, other studies have suggested a detrimental role for A. muciniphila in specific host immune settings. Here, we evaluate the molecular, mechanistic effects of A. muciniphila in host health and suggest some of the missing links to be connected before the organism should be considered as a next-generation biotherapeutic agent.

Bactericidal activity of immobilized silver nanoparticles on silica substrates with different sizes

Hybrid particles with immobilized silver nanoparticles (AgNPs) receive a lot of attention due to their excellent antibacterial activity with the prevention of inherent aggregation of AgNPs. In this study, serial sized silica substrate particles (231, 401, and 605 nm) and their corresponding hybrid particles with AgNPs (~ 30 nm) are prepared, with detailed bactericidal images of the corresponding particles at various times. Their bactericidal activity is elucidated for both Gram-positive Streptococcus agalactiae and Gram-negative Escherichia coli CN13, which show the size of 0.8 μm × 0.9 μm and 1.3 μm × 1.8 μm, respectively. There is a large difference in the bactericidal activity between the smallest (231 nm, 3-log₁₀ reduction) and larger (401 and 605 nm, 6-log₁₀ reduction) silica substrates, whereas there is hardly a difference between the latter. Their effective total surface area (ETSA) is considered important for their bactericidal activity, based on the nearly equal large ETSA of the well-dispersed two larger silica substrates and the much smaller ETSA of the agglomerated smallest substrates. Submicron-sized pits appear on the bacterial membrane by direct contact with the hybrid particles, implicating the importance of ETSA. Still, further research is needed with much different silica substrate sizes to fully elucidate the impact of the silica substrate on the bactericidal activity of immobilized AgNPs.

Activation of ectopic olfactory receptor 544 induces GLP-1 secretion and regulates gut inflammation

Olfactory receptors are ectopically expressed in extra-nasal tissues. The gut is constantly exposed to high levels of odorants where ectopic olfactory receptors may play critical roles. Activation of ectopic olfactory receptor 544 (Olfr544) by azelaic acid (AzA), an Olfr544 ligand, reduces adiposity in mice fed a high-fat diet (HFD) by regulating fuel preference to fats. Herein, we investigated the novel function of Olfr544 in the gut. In GLUTag cells, AzA induces the cAMP-PKA-CREB signaling axis and increases the secretion of GLP-1, an enteroendocrine hormone with anti-obesity effects. In mice fed a HFD and orally administered AzA, GLP-1 plasma levels were elevated in mice. The induction of GLP-1 secretion was negated in cells with Olfr544 gene knockdown and in Olfr544-deficient mice. Gut microbiome analysis revealed that AzA increased the levels of Bacteroides acidifaciens and microbiota associated with antioxidant pathways. In fecal metabolomics analysis, the levels of succinate and trehalose, metabolites correlated with a lean phenotype, were elevated by AzA. The function of Olfr544 in gut inflammation, a key feature in obesity, was further investigated. In RNA sequencing analysis, AzA suppressed LPS-induced activation of inflammatory pathways and reduced TNF-α and IL-6 expression, thereby improving intestinal permeability. The effects of AzA on the gut metabolome, microbiome, and colon inflammation were abrogated in Olfr544-KO mice. These results collectively demonstrated that activation of Olfr544 by AzA in the gut exerts multiple effects by regulating GLP-1 secretion, gut microbiome and metabolites, and colonic inflammation in anti-obesogenic phenotypes and, thus, may be applied for obesity therapeutics.

Gut microbiome signatures distinguish type 2 diabetes mellitus from non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is closely associated with type 2 diabetes mellitus (T2D), and these two metabolic diseases demonstrate bidirectional influences. The identification of microbiome profiles that are specific to liver injury or impaired glucose metabolism may assist understanding of the role of the gut microbiota in the relationship between NAFLD and T2D. Here, we studied a biopsy-proven Asian NAFLD cohort (n = 329; 187 participants with NAFLD, 101 with NAFLD and T2D, and 41 with neither) and identified Enterobacter, Romboutsia, and Clostridium sensu stricto as the principal taxa associated with the severity of NAFLD and T2D, whereas Ruminococcus and Megamonas were specific to NAFLD. In particular, the taxa that were associated with both severe liver pathology and T2D were also significantly associated with markers of diabetes, such as fasting blood glucose and Hb1Ac. Enterotype analysis demonstrated that participants with NAFLD had a significantly higher proportion of Bacteroides and a lower proportion of Ruminococcus than a Korean healthy twin cohort (n = 756). However, T2D could not be clearly distinguished from NAFLD. Analysis of an independent T2D cohort (n = 185) permitted us to validate the T2D-specific bacterial signature identified in the NAFLD cohort. Functional inference analysis revealed that endotoxin biosynthesis pathways were significantly enriched in participants with NAFLD and T2D, compared with those with NAFLD alone. These findings may assist with the development of effective therapeutic approaches for metabolic diseases that are associated with specific bacterial signatures.

Improved real-time quantitative reverse transcription PCR detection of norovirus following removal of inhibitors

Human norovirus (HuNoV) is an important enteric virus that can cause large gastroenteritis outbreaks via the fecal-oral route from contaminated water and produce. Real-time quantitative reverse transcription PCR (RT-qPCR) is the only method to apply the routine detection of HuNoV in various samples, however, inhibitors present in the samples can affect the accuracy and sensitivity of RT-qPCR results. Here, we suggest an inhibitor-removal treatment for two types of noroviruses using two commercial kits. Two types of water sample (surface and seawater) and four types of produce (green onions, lettuces, radishes, and strawberries) were evaluated. The recovery efficiencies of noroviruses in water samples clearly increased in surface and seawater samples with the inhibitor-removal treatment compared to untreated samples. Moreover, murine norovirus-1 was well recovered from the four types of produce with the inhibitor-removal treatment. The mean recovery efficiencies of HuNoV genogroup II genotype 4 in lettuces and strawberries were also increased in the treated samples. Therefore, we suggest that the inhibitor-removal treatment could be useful for improving the accuracy and sensitivity of RT-qPCR methods for noroviruses in water and produce.

Synthetic gut microbiome: Advances and challenges

An exponential rise in studies regarding the association among human gut microbial communities, human health, and diseases is currently attracting the attention of researchers to focus on human gut microbiome research. However, even with the ever-growing number of studies on the human gut microbiome, translation into improved health is progressing slowly. This hampering is due to the complexities of the human gut microbiome, which is composed of >1,000 species of microorganisms, such as bacteria, archaea, viruses, and fungi. To overcome this complexity, it is necessary to reduce the gut microbiome, which can help simplify experimental variables to an extent, such that they can be deliberately manipulated and controlled. Reconstruction of synthetic or established gut microbial communities would make it easier to understand the structure, stability, and functional activities of the complex microbial community of the human gut. Here, we provide an overview of the developments and challenges of the synthetic human gut microbiome, and propose the incorporation of multi-omics and mathematical methods in a better synthetic gut ecosystem design, for easy translation of microbiome information to therapies.

Alleviation of DSS-induced colitis via Lactobacillus acidophilus treatment in mice

Gut microbiota play a major role in host physiology and immunity. Inflammatory bowel diseases (IBDs), the important immune-related diseases, can occur through immune system malfunction originating due to dysregulation of the gut microbiota. The aim of this study was to investigate the capabilities and mechanisms of Lactobacillus acidophilus (L. acidophilus) KBL402 and KBL409 treatment in the alleviation of colitis using the in vivo dextran sodium sulfate (DSS)-induced colitis mice model. Various colitis symptoms of mice, including disease activity index score [4.55 ± 0.99 (P < 0.001) and 5.12 ± 0.94 (P < 0.001), respectively], colon length [6.18 ± 0.43 mm (P < 0.001) and 6.62 ± 0.47 mm (P < 0.001), respectively], and colon histological score [(5.33 ± 1.03 (P < 0.001) and 4.00 ± 0.89 (P < 0.01), respectively)], were significantly restored with L. acidophilus KBL402 or KBL409 administration (1 × 10⁹ colony-forming units) for 8 days. Moreover, inflammatory cytokines, chemokines, and myeloperoxidase were downregulated in mice with L. acidophilus treatment. Upregulation of anti-inflammatory cytokine IL-10 or regulatory T cells were discovered with L. acidophilus KBL402 (12.90 ± 7.87 pg mL^-1) (P < 0.05) or L. acidophilus KBL409 treatment (10.63 ± 2.70%) (P < 0.05), respectively. Expressions of inflammation-related micro-RNAs (miRs) were also significantly altered in mice with L. acidophilus. Finally, L. acidophilus treatment could restore the diversity of the gut microbiota. Mice with L. acidophilus KBL402 treatment showed a high relative abundance of the genus Akkermansia (0.022 ± 0.017) and Prevotella (0.010 ± 0.006) (P < 0.01). Butyrate and propionate, the major short-chain fatty acids, in the ceca of DSS + KBL402-treated mice were significantly higher than in that of the mice with DSS-induced colitis (0.03 ± 0.02 ng mg^-1 and 0.03 ± 0.01 ng mg^-1, respectively) (P < 0.05). Our study suggests that L. acidophilus KBL402 and KBL409 could be useful for the prevention or treatment of IBDs in various ways including the modulation of immune responses and miR expression, restoration of the gut microbiota, and production of metabolites.

Clostridium fessum sp. nov., isolated from human faeces

An obligately anaerobic, Gram-stain-positive and spore-forming strain, SNUG30386^T was isolated from a faecal sample of a healthy Korean subject. The strain formed a round ivory-coloured colony and cells were chained rods with tapered ends, approximately 2.0-2.5×0.6-0.8 μm in size. The taxonomic analysis indicated that strain SNUG30386^T was within the family Lachnospiraceae. According to the 16S rRNA gene sequence similarity, the closest species to strain SNUG30386^T was Clostridium symbiosum (95.6 %), followed by Enterocloster asparagiformis (94.8 %), Enterocloster clostridioformis (94.8 %) and Enterocloster lavalensis (94.6 %). The evolutionary tree based on 16S rRNA gene sequences demonstrated that strain SNUG30386^T had split apart at a unique branch point far from other close relatives. Its DNA G+C content was 48.3 mol% calculated from the whole genome sequence. The major cellular fatty acids were C_16 : 0 and C_14 : 0. Compared to those of the closely related species, strain SNUG30386^T showed distinct biochemical activities such as being unable to utilize most of carbon sources except d-glucose and l-arabinose. As a result, based on its unique phylogenetic clade and taxonomic characteristics, we conclude that strain SNUG30386^T represents a novel species within the genus Clostridium, for which the name Clostridium fessum sp. nov. is proposed. The type strain of the novel species is SNUG30386^T (=KCTC 15633^T= JCM 32258^T).

Lactobacillus paracasei KBL382 administration attenuates atopic dermatitis by modulating immune response and gut microbiota

Administration of probiotics has been linked to immune regulation and changes in gut microbiota composition, with effects on atopic dermatitis (AD). In this study, we investigated amelioration of the symptoms of AD using Lactobacillus paracasei KBL382 isolated from the feces of healthy Koreans. Mice with Dermatophagoides farinae extract (DFE)-induced AD were fed 1 × 10⁹ CFU d^-1 of L. paracasei KBL382 for 4 weeks. Oral administration of L. paracasei KBL382 significantly reduced AD-associated skin lesions, epidermal thickening, serum levels of immunoglobulin E, and immune cell infiltration. L. paracasei KBL382-treated mice showed decreased production of T helper (Th)1-, Th2-, and Th17-type cytokines, including thymic stromal lymphopoietin, thymus, and activation-regulated chemokine, and macrophage-derived chemokine, and increased production of the anti-inflammatory cytokine IL-10 and transforming growth factor-β in skin tissue. Intake of L. paracasei KBL382 also increased the proportion of CD4+ CD25+ Foxp3+ regulatory T cells in mesenteric lymph nodes. In addition, administration of L. paracasei KBL382 dramatically changed the composition of gut microbiota in AD mice. Administration of KBL382 significantly ameliorates AD-like symptoms by regulating the immune response and altering the composition of gut microbiota.

Lactobacillus paracasei KBL382 administration attenuates atopic dermatitis by modulating immune response and gut microbiota

Administration of probiotics has been linked to immune regulation and changes in gut microbiota composition, with effects on atopic dermatitis (AD). In this study, we investigated amelioration of the symptoms of AD using Lactobacillus paracasei KBL382 isolated from the feces of healthy Koreans. Mice with Dermatophagoides farinae extract (DFE)-induced AD were fed 1 × 10⁹ CFU d^-1 of L. paracasei KBL382 for 4 weeks. Oral administration of L. paracasei KBL382 significantly reduced AD-associated skin lesions, epidermal thickening, serum levels of immunoglobulin E, and immune cell infiltration. L. paracasei KBL382-treated mice showed decreased production of T helper (Th)1-, Th2-, and Th17-type cytokines, including thymic stromal lymphopoietin, thymus, and activation-regulated chemokine, and macrophage-derived chemokine, and increased production of the anti-inflammatory cytokine IL-10 and transforming growth factor-β in skin tissue. Intake of L. paracasei KBL382 also increased the proportion of CD4+ CD25+ Foxp3+ regulatory T cells in mesenteric lymph nodes. In addition, administration of L. paracasei KBL382 dramatically changed the composition of gut microbiota in AD mice. Administration of KBL382 significantly ameliorates AD-like symptoms by regulating the immune response and altering the composition of gut microbiota.

Distinct signatures of gut microbiome and metabolites associated with significant fibrosis in non-obese NAFLD

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity but also found in non-obese individuals. Gut microbiome profiles of 171 Asians with biopsy-proven NAFLD and 31 non-NAFLD controls are analyzed using 16S rRNA sequencing; an independent Western cohort is used for external validation. Subjects are classified into three subgroups according to histological spectra of NAFLD or fibrosis severity. Significant alterations in microbiome diversity are observed according to fibrosis severity in non-obese, but not obese, subjects. Ruminococcaceae and Veillonellaceae are the main microbiota associated with fibrosis severity in non-obese subjects. Furthermore, stool bile acids and propionate are elevated, especially in non-obese subjects with significant fibrosis. Fibrosis-related Ruminococcaceae and Veillonellaceae species undergo metagenome sequencing, and four representative species are administered in three mouse NAFLD models to evaluate their effects on liver damage. This study provides the evidence for the role of the microbiome in the liver fibrosis pathogenesis, especially in non-obese subjects.

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity but also found in individuals without obesity. Here, gut microbiome analysis using a biopsy-proven NAFLD cohort reveal distinct signatures of microbiome-metabolites associated with significant fibrosis in patients with NAFLD without obesity.

Male-Specific and Somatic Coliphage Profiles from Major Aquaculture Areas in Republic of Korea

Human and animal feces are important sources of various types of microbial contamination in water. Especially, enteric viruses, the major agents of waterborne infection, can attain long-term survival in water environments due to their strong resistance to various environmental factors including pH, salinity, and temperature. Coliphages are promising viral indicators for fecal contamination in water environments. Here, we investigated the seasonal and spatial distribution of male-specific and somatic coliphages in surface water and seawater at three major aquaculture areas, including Goseong Bay, Aphae Island, and Gomso Bay, in Republic of Korea over a period of 1 year. We selected 6 surface water and 14 seawater sampling sites for each study area and collected a total of 480 water samples from March 2014 to February 2015. Overall, surface water samples contained higher occurrences of coliphages than seawater samples. The high coliphage concentrations were detected in spring (March to May 2014). The differences in geographical features and patterns in land usage of the three aquaculture areas may have affected the coliphage concentration and occurrence. Moreover, environmental factors such as cumulative precipitation were strongly correlated with coliphage concentrations. Therefore, we suggest that further longitudinal studies on coliphage concentrations and distributions should be performed to support the application of coliphages in tracking fecal contamination in water.

Lactobacillus paracasei treatment modulates mRNA expression in macrophages

Macrophage metabolic pathways show changes in response to various external stimuli. Especially, increased lipopolysaccharide, an important bacterial component and Toll-like receptor 4 agonist, can induce activity in various macrophage metabolic pathways, including energy production and biosynthesis, as well as high immune responses due to increase in differentiated M1 macrophages. In this study, we confirmed that Lactobacillus paracasei (L. paracasei) KBL382, KBL384 and KBL385, isolated from the feces of healthy Koreans, can modulate various enzymes and membrane transporters related to glycolysis or macrophage polarization including hypoxia-inducible factor 1-alpha (HIF1A), inducible nitric oxide synthase (iNOS) and arginase in stimulated macrophages at the mRNA level, using the in vitro rodent bone-marrow-derived macrophage (BMDM) model. All L. paracasei exhibited significant down-regulatory effects on mRNAs for glycolysis-related enzymes, including lactate dehydrogenase A, solute carrier family 2 member 1, and triosephosphate isomerase. Moreover, L. paracasei treatment could lead to significant reductions in HIF1A or iNOS mRNA, and induced arginase mRNA in the BMDM model. Therefore, further extensive studies should be performed to support the application of L. paracasei, such as in probiotics or therapeutics, in controlling abnormal immune responses related to macrophage.

Preparing for the renaissance: treating breast cancer during the COVID-19 pandemic and planning for a safe re-emergence to routine surgical care within a universal health care system

The evolving covid-19 pandemic is placing tremendous pressure on health systems. [...]

Administration of Lactobacillus fermentum KBL375 Causes Taxonomic and Functional Changes in Gut Microbiota Leading to Improvement of Atopic Dermatitis

Gut microbiota play an important role in immune responses and energy metabolism. In this study, we evaluated whether administration of Lactobacillus fermentum (L. fermentum) KBL375 isolated from healthy Korean feces improves the atopic dermatitis using the house dust mite (Dermatophagoides farinae)-induced atopic dermatitis (AD) mouse model. Administration of L. fermentum KBL375 significantly decreased dermatitis score, ear and dorsal thickness, and serum immunoglobulin E level in AD-induced mice. Significant reductions in mast cells and eosinophils were discovered in skin tissues from L. fermentum KBL375-treated mice. T helper 2 cell-related cytokines interleukin (IL)-4, IL-5, IL-13, and IL-31 significantly decreased, and anti-inflammatory cytokine IL-10 or transforming growth factor-β increased in skin tissues from L. fermentum KBL375-treated mice. In addition to phenotypic changes in skin tissues, L. fermentum KBL375 treatment induced an increase in the CD4+CD25+Foxp3+ cell population in mesenteric lymph nodes. Taxonomic and functional analyses of gut microbiota showed significantly higher cecum bacterial diversities and abundances including genus Bilophila, Dorea, and Dehalobacterium in L. fermentum KBL375-treated mice. Metabolic analysis of the cecum also showed significant changes in the levels of various amino acids including methionine, phenylalanine, serine, and tyrosine, as well as short chain fatty acids such as acetate, butyrate, and propionate in AD-induced mice due to L. fermentum KBL375 treatment. These altered metabolites in AD-induced mice returned to the levels similar to those in control mice when treated with L. fermentum KBL375. Therefore, L. fermentum KBL375 could be useful for AD treatment by modulating the immune system and inducing various metabolites.

A systematic review of outcomes after salvage abdominoperineal resection for persistent or recurrent anal squamous cell cancer

AIM

Up to 30% of patients with squamous cell cancer of the anus (SCCA) will require a salvage abdominoperineal resection (APR) for either persistent or recurrent disease. The objective of this study was to assess cancer-related outcomes in patients with (i) persistent or (ii) recurrent SCCA.

METHOD

Embase and MEDLINE were searched. Publications were included if they assessed overall survival (OS), disease-free survival (DFS) and locoregional recurrence or metastatic disease after salvage APR for persistent or recurrent SCCA.

RESULTS

A total of 28 retrospective case series (study size ranged from nine to 111) met our inclusion criteria. The median time to salvage APR was 2.6 months [interquartile range (IQR) 2.6-5.0 months, six studies] for persistent disease and 27.6 months (IQR 15.0-32.7 months, five studies) for recurrent disease. The median 5-year OS from the time of salvage APR was 45.0% (IQR 32.0%-52.3%, 10 studies) for persistent disease and 51.0% (IQR 36.0%-60.9%, 11 studies) for recurrent disease. The median 5-year DFS following salvage APR was 44.0% (IQR 29.5%-53.0%, 10 studies) for all patients. Following salvage APR, the median locoregional recurrence rate was 23.5% (IQR 15.8%- 46.9%, 19 studies) and 9.0% (IQR 6.4%-13.3%, 16 studies) of patients developed metastatic disease after salvage APR.

CONCLUSION

Our review characterizes the best evidence for outcomes following salvage APR for patients with persistent or recurrent SCCA. The evidence is limited by the quality of included studies, as many were single centre case series.

Faecalibacillus intestinalis gen. nov., sp. nov. and Faecalibacillus faecis sp. nov., isolated from human faeces

Two long-rod-shaped, Gram-stain-positive, obligately anaerobic and non-spore-forming strains, SNUG30099^T and SNUG30370^T, were isolated from faecal samples of healthy Korean subjects. The strains formed circular ivory-coloured colonies on Brain-heart infusion medium supplemented with 0.5% Difco yeast extract (YBHI) agar and cells were approximately 3.5-4.5×0.3-0.4 µm in size. Taxonomic analyses based on 16S rRNA gene sequences distinguished the strains from other species within the family Erysipelotrichaceae. The closest relative of strains SNUG30099^T and SNUG30370^T was Longibaculum muris (92.9 % and 93.6 % similarity, respectively), followed by Clostridium saccharogumia (92.3 % and 92.2 %). Phylogenetic inference also divided the strains into a unique branch that differed from other related strains that belong to the family Erysipelotrichaceae. DNA G+C contents based on the whole genome sequences of strains SNUG30099^T and SNUG30370^T were 29.2 and 30.2 mol%, respectively. Both novel strains possessed meso-diaminopimelic acid as the peptidoglycan, and phosphatidylethanolamine was observed as one of the major polar lipids. The major cellular fatty acid composition was different from those of other related taxa. In addition, the profile of biochemical activities advocated that the strains have distinct characteristics in comparison to other strains. Taken together, a novel genus, named Faecalibacillus gen. nov., is proposed, which includes the type species Faecalibacillus intestinalis sp. nov. for strain SNUG30099^T and Faecalibacillus faecis sp. nov. for strain SNUG30370^T. The type strains of these novel species are SNUG30099^T (=KCTC 15631^T=JCM 32256^T) and SNUG30370^T (=KCTC 15632^T=JCM 32257^T).

Comparison of Swab Sampling Methods for Norovirus Recovery on Surfaces

Human noroviruses (HuNoVs) can be easily transferred by the contacts of humans or fomites. Swab sampling methods are widely used for recovering HuNoVs from small surfaces of various fomites or hard-to-reach locations and swab sampling conditions are important for the accurate detection of HuNoVs, which have a low infectious dose and relatively long persistence under a range of environmental conditions. Therefore, to determine the suitable swab sampling method for recovering HuNoVs from various surfaces, we evaluated combinations of four swab materials (cotton, microdenier polyester [a type of microfiber], polyurethane foam, and rayon) and three elution buffer solutions (phosphate-buffered saline [PBS], PBS with 0.2% Tween-80, and 3% beef extract-50 mM glycine [pH 9.5]). First, we inoculated HuNoVs or murine noroviruses (MuNoVs), the surrogate of HuNoVs, onto test coupons (10 × 10 cm) consisting of three common surface materials (high-density polyethylene, stainless steel, and wood). Coupons were swabbed using a combination of each swab material and elution buffer, and the viral recovery was measured by real-time reverse transcription quantitative polymerase chain reaction (RT-qPCR) or plaque assay. By RT-qPCR, we confirmed that the cotton swab-PBS and microdenier polyester-PBS combinations had recovery efficiencies greater than 80% for viruses on plastic and stainless steel surfaces. The cotton swab-PBS combination had the highest recovery efficiency on all surface materials via the plaque assay. Therefore, a cotton or a microdenier polyester swab with PBS could be a useful method for sampling HuNoVs on various surfaces.

Use of coliphages to investigate norovirus contamination in a shellfish growing area in Republic of Korea

A number of severe norovirus outbreaks due to the consumption of contaminated shellfish have been reported recently. In this study, we evaluated the distribution of coliphage densities to determine their efficacy as fecal indicators of enteric viruses, including noroviruses, in water samples collected from a shellfish growing area in Republic of Korea over a period of approximately 1 year. Male-specific and somatic coliphages in water samples were analyzed using the single agar layer method, and norovirus genogroups I and II, which infect mainly humans, were analyzed using duplex reverse transcription quantitative PCR. Male-specific and somatic coliphages were detected widely throughout the study area. Several environmental parameters, including salinity, precipitation, temperature, and wind speed were significantly correlated with coliphage concentrations (P < 0.05). Moreover, the concentrations of male-specific coliphages were positively correlated with the presence of human noroviruses (r = 0.443; P < 0.01). The geospatial analysis with coliphage concentrations using a geographic information system revealed that densely populated residential areas were the major source of fecal contamination. Our results indicate that coliphage monitoring in water could be a useful approach to prevent norovirus contamination in shellfish.

Inactivation of influenza A virus via exposure to silver nanoparticle-decorated silica hybrid composites

Influenza A virus (IFV-A) is one of the main cause of seasonal flu and can infect various of host species via the reassortment of segmented RNA genomes. Silver nanoparticles (AgNPs) have been known as excellent antiviral agent against IFV. However, the use of free AgNPs has several major drawbacks, including the inherent aggregation among AgNPs and unwanted cytotoxic or genotoxic damages for human body via inhalation or ingestion. In this study, we assessed the efficacy of our novel ~ 30-nm-diameter AgNP-decorated silica hybrid composite (Ag30-SiO₂; ~ 400 nm in diameter) for IFV-A inactivation. Ag30-SiO₂ particles can inhibit IFV-A effectively in a clear dose-dependent manner. However, when real-time RT-PCR assay was used, merely 0.5-log₁₀ reduction of IFV-A was observed at both 5 and 20 °C. Moreover, even after 1 h of exposure to Ag30-SiO₂ particles, more than 80% of hemagglutinin (HA) damage and 20% of neuraminidase (NA) activities had occurred, and the infection of Madin-Darby Canine Kidney (MDCK) cells by IFV-A was reduced. The results suggested that the major antiviral mechanism of Ag30-SiO₂ particles is the interaction with viral components located at the membrane. Therefore, Ag30-SiO₂ particles can cause nonspecific damage to various IFV-A components and be used as an effective method for inactivating IFV-A.

Host-Specific Bacteroides Markers-Based Microbial Source Tracking in Aquaculture Areas

Various waterborne pathogens originate from human or animal feces and may cause severe gastroenteric outbreaks. Bacteroides spp. that exhibit strong host- or group-specificities are promising markers for identifying fecal sources and their origins. In the present study, 240 water samples were collected from two major aquaculture areas in Republic of Korea over a period of approximately 1 year, and the concentrations and occurrences of four host-specific Bacteroides markers (human, poultry, pig, and ruminant) were evaluated in the study areas. Host-specific Bacteroides markers were detected widely in the study areas, among which the poultry-specific Bacteroides marker was detected at the highest concentration (1.0-1.2 log₁₀ copies L^-1). During the sampling period, high concentrations of host-specific Bacteroides markers were detected between September and December 2015. The host-specific Bacteroides marker-combined geospatial map revealed the up-to-downstream gradient of fecal contamination, as well as the effects of land-use patterns on host-specific Bacteroides marker concentrations. In contrast to traditional bacterial indicators, the human-specific Bacteroides marker correlated with human specific pathogens, such as noroviruses (r=0.337; P<0.001). The present results indicate that host-specific Bacteroides genetic markers with an advanced geospatial analysis are useful for tracking fecal sources and associated pathogens in aquaculture areas.

Disinfection of waterborne viruses using silver nanoparticle-decorated silica hybrid composites in water environments

Silver nanoparticles (AgNPs) have been reported as an effective alternative for controlling a broad-spectrum of pathogenic viruses. We developed a micrometer-sized silica hybrid composite decorated with AgNPs (AgNP-SiO₂) to prevent the inherent aggregation of AgNPs, and facilitated their recovery from environmental media after use. The production process had a high-yield, and fabrication was cost-effective. We evaluated the antiviral capabilities of Ag30-SiO₂ particles against two model viruses, bacteriophage MS2 and murine norovirus (MNV), in four different types of water (deionized, tap, surface, and ground). MNV was more susceptible to Ag30-SiO₂ particles in all four types of water compared to MS2. Furthermore, several water-related factors, including temperature and organic matter content, were shown to affect the antimicrobial capabilities of Ag30-SiO₂ particles. The modified Hom model was the best-fit disinfection model for MNV disinfection in the different types of water. Additionally, this study demonstrated that the effects of a certain level of physical obstacles in water were negligible in regards to the use of Ag30-SiO₂ particles. Thus, effective use of AgNPs in water disinfection processes can be achieved using our novel hybrid composites to inactivate various waterborne viruses.

Effects of fermented milk treatment on microbial population and metabolomic outcomes in a three-stage semi-continuous culture system

We investigated the impact of a fermented milk product on gut microbiota and their metabolism in 3 different conditions of the colon with a systemic viewpoint. An in vitro semi-continuous anaerobic cultivation was used to assess the colon compartment-specific influence of fermented milk, followed by a multiomics approach combining 16S rDNA amplicon sequencing and nuclear magnetic resonance (NMR) spectroscopy. The microbiome profiling and metabolomic features were significantly different across three colon compartments and after fermented milk treatment. Integrative correlation analysis indicated that the alteration of butyrate-producing microbiota (Veillonella, Roseburia, Lachnospira, and Coprococcus) and some primary metabolites (butyrate, ethanol, lactate, and isobutyrate) in the treatment group had a strong association with the fermented milk microorganisms. Our findings suggested that fermented milk treatment significantly affected microbial population in an in vitro cultivation system as well as the colonic metabolome in different ways in each of colon compartment.

Disinfection of various bacterial pathogens using novel silver nanoparticle-decorated magnetic hybrid colloids

Silver nanoparticles (AgNPs) have long been considered a powerful disinfectant for controlling pathogenic microorganisms. However, AgNPs might have adverse effects on both human health and our ecosystems due to their potential cytotoxicity and the difficulty in recovering them after their release into the environment. In this study, we characterized the antimicrobial efficacy caused by a novel micrometer-sized magnetic hybrid colloid (MHC) containing 7, 15, or 30nm sized monodispersed AgNPs (AgNP-MHCs), which can be re-collected from the environment using simple procedures, such as a magnet or centrifugation. We evaluated the antibacterial capabilities of AgNP-MHCs against target bacteria (Legionella pneumophila, Bacillus subtilis, Escherichia coli, and Clostridium perfringens) and compared them with the inactivation efficacy of AgNPs ~30nm in diameter (nAg30s). Among the different AgNP-MHCs composites evaluated, Ag30-MHCs had the greatest antibacterial effect. After 1h of exposure, more than a 4-log₁₀ reduction of L. pneumophila and 6-log₁₀ reduction of B. subtilis was achieved by 4.6×10⁹particles/mL of Ag30-MHCs and Ag30-MHC-Ls. In addition, Ag30-MHC-Ls maintained their strong antibacterial capabilities under anaerobic conditions. Our results indicate that AgNP-MHCs can be considered excellent tools for controlling waterborne bacterial pathogens, with a minimal risk of release into the environment.

Oral Microbiota: Microbial Biomarkers of Metabolic Syndrome Independent of Host Genetic Factors

The oral microbiota plays a critical role in both local and systemic inflammation. Metabolic syndrome (MetS) is characterized by low-grade inflammation, and many studies have been conducted on the gut microbiota from stool specimens. However, the etiological role of the oral microbiota in the development of MetS is unclear. In this study, we analyzed the oral and gut microbiome from 228 subgingival plaque and fecal samples from a Korean twin-family cohort with and without MetS. Significant differences in microbial diversity and composition were observed in both anatomical niches. However, a host genetic effect on the oral microbiota was not observed. A co-occurrence network analysis showed distinct microbiota clusters that were dependent on the MetS status. A comprehensive analysis of the oral microbiome identified Granulicatella and Neisseria as bacteria enriched in subjects with MetS and Peptococcus as bacteria abundant in healthy controls. Validation of the identified oral bacteria by quantitative PCR (qPCR) showed that healthy controls possessed significantly lower levels of G. adiacens (p = 0.023) and a higher ratio of Peptococcus to Granulicatella (p < 0.05) than MetS subjects. Our results support that local oral microbiota can be associated with systemic disorders. The microbial biomarkers identified in this study would aid in determination of which individuals develop chronic diseases from their MetS and contribute to strategic disease management.

Bile salt hydrolase-mediated inhibitory effect of Bacteroides ovatus on growth of Clostridium difficile

Clostridium difficile infection (CDI) is one of the most common nosocomial infections. Dysbiosis of the gut microbiota due to consumption of antibiotics is a major contributor to CDI. Recently, fecal microbiota transplantation (FMT) has been applied to treat CDI. However, FMT has important limitations including uncontrolled exposure to pathogens and standardization issues. Therefore, it is necessary to evaluate alternative treatment methods, such as bacteriotherapy, as well as the mechanism through which beneficial bacteria inhibit the growth of C. difficile. Here, we report bile acid-mediated inhibition of C. difficile by Bacteroides strains which can produce bile salt hydrolase (BSH). Bacteroides strains are not commonly used to treat CDI; however, as they comprise a large proportion of the intestinal microbiota, they can contribute to bile acid-mediated inhibition of C. difficile. The inhibitory effect on C. difficile growth increased with increasing bile acid concentration in the presence of Bacteroides ovatus SNUG 40239. Furthermore, this inhibitory effect on C. difficile growth was significantly attenuated when bile acid availability was reduced by cholestyramine, a bile acid sequestrant. The findings of this study are important due to the discovery of a new bacterial strain that in the presence of available bile acids inhibits growth of C. difficile. These results will facilitate development of novel bacteriotherapy strategies to control CDI.

Evaluation of Various Real-Time Reverse Transcription Quantitative PCR Assays for Norovirus Detection

Human noroviruses are widespread and contagious viruses causing nonbacterial gastroenteritis. Real-time reverse transcription quantitative PCR (real-time RT-qPCR) is currently the gold standard for the sensitive and accurate detection of these pathogens and serves as a critical tool in outbreak prevention and control. Different surveillance teams, however, may use different assays, and variability in specimen conditions may lead to disagreement in results. Furthermore, the norovirus genome is highly variable and continuously evolving. These issues necessitate the re-examination of the real-time RT-qPCR's robustness in the context of accurate detection as well as the investigation of practical strategies to enhance assay performance. Four widely referenced real-time RT-qPCR assays (Assays A-D) were simultaneously performed to evaluate characteristics such as PCR efficiency, detection limit, and sensitivity and specificity with RT-PCR, and to assess the most accurate method for detecting norovirus genogroups I and II. Overall, Assay D was evaluated to be the most precise and accurate assay in this study. A ZEN internal quencher, which decreases nonspecific fluorescence during the PCR, was added to Assay D's probe, which further improved the assay performance. This study compared several detection assays for noroviruses, and an improvement strategy based on such comparisons provided useful characterizations of a highly optimized real-time RT-qPCR assay for norovirus detection.

Sensitive, Quantitative Naked-Eye Biodetection with Polyhedral Cu Nanoshells

One of the most heavily used methods in chemical and biological labeling, detection, and imaging is based on silver shell-based enhancement on Au nanoparticles (AuNPs) that is useful for amplifying Rayleigh scattering, colorimetric signal, surface-enhanced Raman scattering, and electrical signal, but poor structural controllability and nonspecific growth of silver shells have limited its applications, especially with respect to signal reproducibility and quantification. Here, a highly specific, well-defined Cu nanopolyhedral shell overgrowth chemistry is developed with the aid of polyethyleneimine (PEI) on AuNPs, and the use of this PEI-mediated Cu polyhedral nanoshell (CuP) chemistry is shown as a means of light-scattering signal enhancement for the development of naked-eye-based highly sensitive and quantitative detections of DNA and viruses. Remarkably, these CuPs are exclusively formed on AuNPs in a controllable manner, with no noticeable nonspecific CuP growth. The findings enable to acquire clearly visible signals without analytic instrumentation, detectable down to 8 × 10^-15 m of DNA (anthrax sequence) and 2700 copies of viruses (noroviruses in clinical stool samples) with broad dynamic ranges on archetypal assay platforms. This new method provides a general platform in controlling Cu shell nanostructures and their optical signals, and opens up revenues for highly reliable, quantitative onsite naked-eye biodetection.

New perspectives regarding the antiviral effect of vitamin A on norovirus using modulation of gut microbiota

Gut microbiota has been revealed to play an important role in various health conditions, and recent studies have suggested the modulation of gut microbiota as a therapeutic strategy. There is no effective treatment of norovirus infection, though vitamin A has been suggested to have an antiviral effect in an epidemiological study. We demonstrated that vitamin A significantly inhibited murine norovirus replication. Vitamin A supplementation significantly increased the abundance of Lactobacillus sp. during norovirus infection, which played a crucial role in antiviral efficacy, inhibiting murine norovirus. Therefore, we elaborated the antiviral effect of vitamin A via modulation of gut microbiota. Furthermore, we suggest a novel strategy, using potential probiotics, as having a protective and therapeutic effect on noroviral infection.

The effect of heritability and host genetics on the gut microbiota and metabolic syndrome

OBJECTIVE

Metabolic syndrome (MetS) arises from complex interactions between host genetic and environmental factors. Although it is now widely accepted that the gut microbiota plays a crucial role in host metabolism, current knowledge on the effect of host genetics on specific gut microbes related to MetS status remains limited. Here, we investigated the links among host genetic factors, gut microbiota and MetS in humans.

DESIGN

We characterised the gut microbial community composition of 655 monozygotic (n=306) and dizygotic (n=74) twins and their families (n=275), of which approximately 18% (121 individuals) had MetS. We evaluated the association of MetS status with the gut microbiota and estimated the heritability of each taxon. For the MetS-related and heritable taxa, we further investigated their associations with the apolipoprotein A-V gene (APOA5) single nucleotide polymorphism (SNP) rs651821, which is known to be associated with triglyceride levels and MetS.

RESULTS

Individuals with MetS had a lower gut microbiota diversity than healthy individuals. The abundances of several taxa were associated with MetS status; Sutterella, Methanobrevibacter and Lactobacillus were enriched in the MetS group, whereas Akkermansia, Odoribacter and Bifidobacterium were enriched in the healthy group. Among the taxa associated with MetS status, the phylum Actinobacteria, to which Bifidobacterium belongs, had the highest heritability (45.7%). Even after adjustment for MetS status, reduced abundances of Actinobacteria and Bifidobacterium were significantly linked to the minor allele at the APOA5 SNP rs651821.

CONCLUSIONS

Our results suggest that an altered microbiota composition mediated by a specific host genotype can contribute to the development of MetS.

Modeling environmental risk factors of autism in mice induces IBD-related gut microbial dysbiosis and hyperserotonemia

Autism spectrum disorder (ASD) is a range of neurodevelopmental conditions that are sharply increasing in prevalence worldwide. Intriguingly, ASD is often accompanied by an array of systemic aberrations including (1) increased serotonin, (2) various modes of gastrointestinal disorders, and (3) inflammatory bowel disease (IBD), albeit the underlying cause for such comorbidities remains uncertain. Also, accumulating number of studies report that the gut microbial composition is significantly altered in children with ASD or patients with IBD. Surprisingly, when we analyzed the gut microbiota of poly I:C and VPA-induced mouse models of ASD, we found a distinct pattern of microbial dysbiosis that highly recapitulated those reported in clinical cases of ASD and IBD. Moreover, we report that such microbial dysbiosis led to notable perturbations in microbial metabolic pathways that are known to negatively affect the host, especially with regards to the pathogenesis of ASD and IBD. Lastly, we found that serum level of serotonin is significantly increased in both poly I:C and VPA mice, and that it correlates with increases of a bacterial genus and a metabolic pathway that are implicated in stimulation of host serotonin production. Our results using animal model identify prenatal environmental risk factors of autism as possible causative agents of IBD-related gut microbial dysbiosis in ASD, and suggest a multifaceted role of gut microbiota in the systemic pathogenesis of ASD and hyperserotonemia.