Gut leakage enhances sepsis susceptibility in iron-overloaded β-thalassemia mice through macrophage hyperinflammatory responses

Differential gut microbiota composition in β-Thalassemia patients and its correlation with iron overload

Recent research highlights the significant impact of the gut microbiota on health and disease. Thalassemia, a hereditary blood disorder, requires regular blood transfusions, leading to an accumulation of iron in the body. Such changes could potentially alter the intestinal microbiota, thereby increasing the susceptibility of thalassemic patients to infection. In this study, we analyzed the fecal microbiota of 70 non-transfusion-dependent (NTDT) β-thalassemia/HbE patients and 30 healthy controls. Our findings indicate that iron chelation intervention had no detectable effect on the microbiome profile of thalassemic patients. However, the cross-sectional analysis revealed that the bacterial diversity and community structure in patients were significantly less diverse and distinct compared to those of healthy subjects. Using reference frames, we were also able to demonstrate that bacterial taxa that are known to produce short chain fatty acids, from the genera Alistipes, Coprococcus, and Oscillospira, and those from the family Ruminococcaceae, were less prevalent in the patients. In contrast, bacterial taxa associated with an unhealthy gut, including the genus Clostridium and those from the families Fusobacteriaceae, Enterobacteriaceae, and Peptostrptococcaceae, were more prevalent in patients and found to be correlated with higher levels of ferritin. Collectively, these changes in the microbiota could be regarded as markers of raised ferritin levels, and therefore, awareness should be exercised as they could interfere, albeit indirectly, with the treatment of the co-morbidities of thalassemia.

Evidences and perspectives on the association between gut microbiota and sepsis: A bibliometric analysis from 2003 to 2023

Background

In the last two decades, the role of the gut microbiome in the development, maintenance, and outcome of sepsis has received increased attention; however, few descriptive studies exist on its research focus, priorities, and future prospects. This study aimed to identify the current state, evolution, and emerging trends in the field of gut microbiota and sepsis using bibliometric analysis.

Methods

All publications on sepsis and gut microbiota were retrieved from the Web of Science Core Collection and included in this study. VOSviewer, CiteSpace, and the Web of Science online analysis platform were used to visualize trends based on publication country, institution, author, journal, and keywords.

Results

A total of 1,882 articles on sepsis-related gut microbiota were screened, mainly from 95 countries or regions and 2,581 institutions. The United States and China contributed the most to this research field, with 521 (27.683 %) and 376 (19.979 %) articles, respectively. Scientists from the University of California were the most prolific, publishing 63 (3.348 %) articles. Cani PD published papers with the highest H-index, establishing himself as a leader in the field. The most publications were published in the journals "Nutrients" and "PLOS One." The journals with the most co-citations were "PLOS One," "Nature," and "Gut." The most used keywords were prebiotics, gut microbiota, and sepsis. The keyword burst research analysis revealed that research on treatment strategies based on the intestinal microbiota, intestine-liver axis, and regulatory mechanisms of bacterial metabolites are currently hot directions.

Conclusion

This study presents a global overview of the current state and potential trends in the field of sepsis-related gut microbiota. This study identified hot research sub-directions and new trends through comparison and analysis, which will aid in the development of this field.

Gut permeability among Astronauts during Space missions

The space environment poses substantial challenges to human physiology, including potential disruptions in gastrointestinal health. Gut permeability has only recently become widely acknowledged for its potential to cause adverse effects on a systemic level, rendering it a critical factor to investigate in the context of spaceflight. Here, we propose that astronauts experience the onset of leaky gut during space missions supported by transcriptomic and metagenomic analysis of human and murine samples. A genetic map contributing to intestinal permeability was constructed from a systematic review of current literature. This was referenced against our re-analysis of three independent transcriptomic datasets which revealed significant changes in gene expression patterns associated with the gut barrier. Specifically, in astronauts during flight, we observed a substantial reduction in the expression genes that are crucial for intestinal barrier function, goblet cell development, gut microbiota modulation, and immune responses. Among rodent spaceflight studies, differential expression of cytokines, chemokines, and genes which regulate mucin production and post-translational modifications suggest a similar dysfunction of intestinal permeability. Metagenomic analysis of feces from two murine studies revealed a notable reduction probiotic, short chain fatty acid-producing bacteria and an increase in the Gram-negative pathogens, including Citrobacter rodentium, Enterobacter cloacea, Klebsiella aerogenes, and Proteus hauseri which promote LPS circulation, a recipe for barrier disruption and systemic inflammatory activation. These findings emphasize the critical need to understand the underlying mechanisms and develop interventions to maintain gastrointestinal health in space.

Excess iron intake induced liver injury: The role of gut-liver axis and therapeutic potential

Excessive iron intake is detrimental to human health, especially to the liver, which is the main organ for iron storage. Excessive iron intake can lead to liver injury. The gut-liver axis (GLA) refers to the bidirectional relationship between the gut and its microbiota and the liver, which is a combination of signals generated by dietary, genetic and environmental factors. Excessive iron intake disrupts the GLA at multiple interconnected levels, including the gut microbiota, gut barrier function, and the liver's innate immune system. Excessive iron intake induces gut microbiota dysbiosis, destroys gut barriers, promotes liver exposure to gut microbiota and its derived metabolites, and increases the pro-inflammatory environment of the liver. There is increasing evidence that excess iron intake alters the levels of gut microbiota-derived metabolites such as secondary bile acids (BAs), short-chain fatty acids, indoles, and trimethylamine N-oxide, which play an important role in maintaining homeostasis of the GLA. In addition to iron chelators, antioxidants, and anti-inflammatory agents currently used in iron overload therapy, gut barrier intervention may be a potential target for iron overload therapy. In this paper, we review the relationship between excess iron intake and chronic liver diseases, the regulation of iron homeostasis by the GLA, and focus on the effects of excess iron intake on the GLA. It has been suggested that probiotics, fecal microbiota transfer, farnesoid X receptor agonists, and microRNA may be potential therapeutic targets for iron overload-induced liver injury by protecting gut barrier function.

Polymeric Particle BAM15 Targeting Macrophages Attenuates the Severity of LPS-Induced Sepsis: A Proof of Concept for Specific Immune Cell-Targeted Therapy

Macrophage polarization requires different energy sources and metabolic processes. Therefore, cell energy interference to alter macrophage functions has been proposed as a treatment for severe inflammatory diseases, including sepsis. In this study, targeting cell energy using BAM15 (a mitochondrial uncoupling agent) in human THP-1 and mouse RAW264.7 macrophages prominently interfered with M1 but not M2 polarization. Free BAM15 (BAM15) and BAM15-loaded PLGA particles (BAM15 particles) reduced the inflammatory response of M1 macrophages and enhanced the expression of M2 signature genes with the restoration of mitochondrial activity (extracellular flux analysis) in RAW264.7 cells. Furthermore, BAM15 particles but not BAM15 showed specific effects on the inflammatory response of macrophages but not neutrophils, and the particles were actively captured by splenic and liver macrophages in vivo. Administration of BAM15 and BAM15 particles attenuated the severity of sepsis in LPS-induced sepsis mice. Interestingly, BAM15 particles but not BAM15 alleviated LPS-induced liver injury by reducing hepatic inflammation. Our findings substantiate the superior efficacy of macrophage-targeted therapy using a BAM15 particle-delivery system and provide further support for clinical development as a potential therapy for severe inflammatory diseases.

Acetylated Oligopeptide and N-acetyl cysteine Protected Against Oxidative Stress, Inflammation, Testicular-Blood Barrier Damage, and Testicular Cell Death in Iron-Overload Rat Model

Multiple organs, including the testes, are damaged by iron overload. It has been shown that N-acetyl cysteine (NAC) influences oxidative stress in iron overload. The present study aimed to evaluate the roles of acetylated peptide (AOP) and NAC in the inhibition of iron-overload induced-testicular damage. At the beginning of the experiment, NAC (150 mg /kg) was given for a week to all 40 rats. Then, four groups were formed by dividing the animals (10 rats/group). Group I included healthy control rats. Group II (iron overload) was given intraperitoneal iron dextran (60 mg/kg/day) 5 days a week for 4 weeks. Group III (NAC) was given NAC orally at a dose of 150 mg/kg/day for 4 weeks in addition to iron dextran. Group IV (AOP) was given AOP orally at a dose of 150 mg/kg/day for 4 weeks besides iron dextran. When the experiment time was over, testosterone serum level, testicular B cell lymphoma-2 (BCL-2) and protein kinase B (PKB) protein levels, nuclear factor kappa-B (NF-κB), and Beclin1 mRNA expression levels, and malondialdehyde (MDA), and reduced glutathione (GSH) were determined by ELISA, quantitative reverse transcription-PCR, and chemical methods. Finally, histopathological examinations and immunohistochemical detection of claudin-1 and CD68 were performed. The iron overload group exhibited decreased testosterone, BCL-2, PKB, claudin-1, and GSH and increased MDA, NF-κB, Beclin1, and CD68, while both NAC and AOP treatments protected against the biochemical and histopathological disturbances occurring in the iron overload model. We concluded that NAC and AOP can protect against testes damage by iron overload via their antioxidant, anti-inflammatory, antiapoptotic, and ant-autophagic properties. The NAC and AOP may be used as preventative measures against iron overload-induced testicular damage.

Intestinal barrier functions in hematologic and oncologic diseases

The intestinal barrier is a complex structure that not only regulates the influx of luminal contents into the systemic circulation but is also involved in immune, microbial, and metabolic homeostasis. Evidence implicating disruption in intestinal barrier functions in the development of many systemic diseases, ranging from non-alcoholic steatohepatitis to autism, or systemic complications of intestinal disorders has increased rapidly in recent years, raising the possibility of the intestinal barrier as a potential target for therapeutic intervention to alter the course and mitigate the complications associated with these diseases. In addition to the disease process being associated with a breach in the intestinal barrier functions, patients with hematologic and oncologic diseases are particularly at high risks for the development of increased intestinal permeability, due to the frequent use of broad-spectrum antibiotics and chemoradiation. They also face a distinct challenge of being intermittently severely neutropenic due to treatment of the underlying conditions. In this review, we will discuss how hematologic and oncologic diseases are associated with disruption in the intestinal barrier and highlight the complications associated with an increase in the intestinal permeability. We will explore methods to modulate the complication. To provide a background for our discussion, we will first examine the structure and appraise the methods of evaluation of the intestinal barrier.

High Fructose Causes More Prominent Liver Steatohepatitis with Leaky Gut Similar to High Glucose Administration in Mice and Attenuation by Lactiplantibacillus plantarum dfa1

High-sugar diet-induced prediabetes and obesity are a global current problem that can be the result of glucose or fructose. However, a head-to-head comparison between both sugars on health impact is still lacking, and Lactiplantibacillus plantarum dfa1 has never been tested, and has recently been isolated from healthy volunteers. The mice were administered with the high glucose or fructose preparation in standard mouse chaw with or without L. plantarum dfa1 gavage, on alternate days, and in vitro experiments were performed using enterocyte cell lines (Caco2) and hepatocytes (HepG2). After 12 weeks of experiments, both glucose and fructose induced a similar severity of obesity (weight gain, lipid profiles, and fat deposition at several sites) and prediabetes condition (fasting glucose, insulin, oral glucose tolerance test, and Homeostatic Model Assessment for Insulin Resistance (HOMA score)). However, fructose administration induced more severe liver damage (serum alanine transaminase, liver weight, histology score, fat components, and oxidative stress) than the glucose group, while glucose caused more prominent intestinal permeability damage (FITC-dextran assay) and serum cytokines (TNF-α, IL-6, and IL-10) compared to the fructose group. Interestingly, all of these parameters were attenuated by L. plantarum dfa1 administration. Because there was a subtle change in the analysis of the fecal microbiome of mice with glucose or fructose administration compared to control mice, the probiotics altered only some microbiome parameters (Chao1 and Lactobacilli abundance). For in vitro experiments, glucose induced more damage to high-dose lipopolysaccharide (LPS) (1 µg/mL) to enterocytes (Caco2 cell) than fructose, as indicated by transepithelial electrical resistance (TEER), supernatant cytokines (TNF-α and IL-8), and glycolysis capacity (by extracellular flux analysis). Meanwhile, both glucose and fructose similarly facilitated LPS injury in hepatocytes (HepG2 cell) as evaluated by supernatant cytokines (TNF-α, IL-6, and IL-10) and extracellular flux analysis. In conclusion, glucose possibly induced a more severe intestinal injury (perhaps due to LPS-glucose synergy) and fructose caused a more prominent liver injury (possibly due to liver fructose metabolism), despite a similar effect on obesity and prediabetes. Prevention of obesity and prediabetes with probiotics was encouraged.

Candida Administration in 5/6 Nephrectomized Mice Enhanced Fibrosis in Internal Organs: An Impact of Lipopolysaccharide and (1→3)-β-D-Glucan from Leaky Gut

Uremic toxins and gut dysbiosis in advanced chronic kidney disease (CKD) can induce gut leakage, causing the translocation of gut microbial molecules into the systemic circulation. Lipopolysaccharide (LPS) and (1→3)-β-D-glucan (BG) are the major gut microbial molecules of Gram-negative bacteria and fungi, respectively, and can induce inflammation in several organs. Here, the fibrosis in the kidney, liver, and heart was investigated in oral C. albicans-administered 5/6 nephrectomized (Candida-5/6 Nx) mice. At 20 weeks post 5/6 Nx, Candida-5/6 Nx mice demonstrated increased 24 h proteinuria, liver enzymes, and serum cytokines (TNF-α, IL-6, and IL-10), but not weight loss, systolic blood pressure, hematocrit, serum creatinine, or gut-derived uremic toxins (TMAO and indoxyl sulfate), compared to in 5/6 Nx alone. The gut leakage in Candida-5/6 Nx was more severe, as indicated by FITC-dextran assay, endotoxemia, and serum BG. The areas of fibrosis from histopathology, along with the upregulated gene expression of Toll-like receptor 4 (TLR-4) and Dectin-1, the receptors for LPS and BG, respectively, were higher in the kidney, liver, and heart. In vitro, LPS combined with BG increased the supernatant IL-6 and TNF-α, upregulated the genes of pro-inflammation and pro-fibrotic processes, Dectin-1, and TLR-4 in renal tubular (HK-2) cells and hepatocytes (HepG2), when compared with LPS or BG alone. This supported the pro-inflammation-induced fibrosis and the possible LPS-BG additive effects on kidney and liver fibrosis. In conclusion, uremia-induced leaky gut causes the translocation of gut LPS and BG into circulation, which activates the pro-inflammatory and pro-fibrotic pathways, causing internal organ fibrosis. Our results support the crosstalk among several organs in CKD through a leaky gut.

Mammary Leukocyte-Assisted Nanoparticle Transport Enhances Targeted Milk Trace Mineral Delivery

Nanoparticles are applied as versatile platforms for drug/gene delivery in many applications owing to their long-retention and specific targeting properties in living bodies. However, the delivery mechanism and the beneficial effect of nanoparticle-retention in many organisms remain largely uncertain. Here, the transport and metabolism of mineral nanoparticles in mammary gland during lactation are explored. It is shown that maternal intravenous administration of iron oxide nanoparticles (IONPs; diameter: ≈11.0 nm, surface charge: -29.1 mV, surface area: 1.05 m2 g-1 ) provides elevated iron delivery to mammary gland and increased iron secretion into breast milk, which is inaccessible by classical iron-ion transport approaches such as the transferrin receptor-mediated endocytic pathway. Mammary macrophages and neutrophils are found to play dominant roles in uptake and delivery of IONPs through an unconventional leukocyte-assisted iron secretion pathway. This pathway bypasses the tight iron concentration regulation of liver hepcidin-ferroportin axis and mammary epithelial cells to increase milk iron-ion content derived from IONPs. This work provides keen insight into the metabolic pathway of nanoparticles in mammary gland while offering a new scheme of nutrient delivery for neonate metabolism regulation by using nanosized nutrients.

Deferiprone has less benefits on gut microbiota and metabolites in high iron-diet induced iron overload thalassemic mice than in iron overload wild-type mice: A preclinical study

AIMS

This study aimed to investigate the changes in gut microbiota in iron-overload thalassemia and the roles of an iron chelator on gut dysbiosis/inflammation, and metabolites, including short-chain fatty acids (SCFAs) and trimethylamine N-oxide (TMAO).

MAIN METHODS

Adult male C57BL/6 mice both wild-type (WT: n = 15) and heterozygous β-thalassemia (BKO: n = 15) were fed on either a normal (ND: n = 5/group) or a high‑iron diet for four months (HFe: n = 10/group). HFe-treated WT and HFe-treated BKO groups were further subdivided into two subgroups and each subgroup given either vehicle (n = 5/subgroup) or deferiprone (n = 5/subgroup) during the last month. Gut microbiota profiles, gut barrier characteristics, levels of proinflammatory cytokines, and plasma SCFAs and TMAO were determined at the end of the study.

KEY FINDINGS

HFe-fed WT mice showed distinct gut microbiota profiles from those of ND-fed WT mice, whereas HFe-fed BKO mice showed slightly different gut microbiota profiles from ND-fed BKO. Gut inflammation and barrier disruption were found only in HFe-fed BKO mice, however, an increase in plasma TMAO levels and decreased levels of SCFAs were observed in both WT and BKO mice with HFe-feeding. Treatment with deferiprone, gut dysbiosis and disturbance of metabolites were attenuated in HFe-fed WT mice, but not in HFe-fed BKO mice. Increased Verrucomicrobia and Ruminococcaceae were associated with the beneficial effects of deferiprone.

SIGNIFICANCE

Iron-overload leads to gut dysbiosis/inflammation and disturbance of metabolites, and deferiprone alleviates those conditions more effectively in WT than in those that are thalassemic.

Association of Gut Microbiota Enterotypes with Blood Trace Elements in Women with Infertility

Infertility is defined as failure to achieve pregnancy within 12 months of unprotected intercourse in women. Trace elements, a kind of micronutrient that is very important to female reproductive function, are affected by intestinal absorption, which is regulated by gut microbiota. Enterotype is the classification of an intestinal microbiome based on its characteristics. Whether or not Prevotella-enterotype and Bacteroides-enterotype are associated with blood trace elements among infertile women remains unclear. The study aimed to explore the relationship between five main whole blood trace elements and these two enterotypes in women with infertility. This retrospective cross-sectional study recruited 651 Chinese women. Whole blood copper, zinc, calcium, magnesium, and iron levels were measured. Quantitative real-time PCR was performed on all fecal samples. Patients were categorized according to whole blood trace elements (low levels group, <5th percentile; normal levels group, 5th‒95th percentile; high levels group, >95th percentile). There were no significant differences in trace elements between the two enterotypes within the control population, while in infertile participants, copper (P = 0.033), zinc (P < 0.001), magnesium (P < 0.001), and iron (P < 0.001) in Prevotella-enterotype was significantly lower than in Bacteroides-enterotype. The Chi-square test showed that only the iron group had a significant difference in the two enterotypes (P = 0.001). Among infertile patients, Prevotella-enterotype (Log(P/B) > −0.27) predicted the low levels of whole blood iron in the obesity population (AUC = 0.894; P = 0.042). For the high levels of iron, Bacteroides-enterotype (Log(P/B) <−2.76) had a predictive power in the lean/normal group (AUC = 0.648; P = 0.041) and Log(P/B) <−3.99 in the overweight group (AUC = 0.863; P = 0.013). We can infer that these two enterotypes may have an effect on the iron metabolism in patients with infertility, highlighting the importance of further research into the interaction between enterotypes and trace elements in reproductive function.

Helicobacter pylori, Protected from Antibiotics and Stresses Inside Candida albicans Vacuoles, Cause Gastritis in Mice

Due to (i) the simultaneous presence of Helicobacter pylori (ulcer-induced bacteria) and Candida albicans in the stomach and (ii) the possibility of prokaryotic-eukaryotic endosymbiosis (intravacuolar H. pylori in the yeast cells) under stresses, we tested this symbiosis in vitro and in vivo. To that end, intravacuolar H. pylori were induced by the co-incubation of C. albicans with H. pylori under several stresses (acidic pH, non-H. pylori-enrichment media, and aerobic environments); the results were detectable by direct microscopy (wet mount) and real-time polymerase chain reaction (PCR). Indeed, intravacuolar H. pylori were predominant under all stresses, especially the lower pH level (pH 2-3). Interestingly, the H. pylori (an amoxicillin-sensitive strain) inside C. albicans were protected from the antibiotic (amoxicillin), while extracellular H. pylori were neutralizable, as indicated by the culture. In parallel, the oral administration of intravacuolar H. pylori in mice caused H. pylori colonization in the stomach resulting in gastritis, as indicated by gastric histopathology and tissue cytokines, similar to the administration of free H. pylori (extra-Candida bacteria). In conclusion, Candida protected H. pylori from stresses and antibiotics, and the intravacuolar H. pylori were able to be released from the yeast cells, causing gastric inflammation with neutrophil accumulations.

Critical roles of sepsis-reshaped fecal virota in attenuating sepsis severity

Because studies on all fecal organisms (bacteria, fungi, and viruses) in sepsis are rare and bacteriophages during sepsis might have adapted against gut bacteria with possible pathogenicity, cecal ligation and puncture (CLP; a sepsis mouse model) was evaluated. In fecal bacteriome, sepsis increased Bacteroides and Proteobacteria but decreased Firmicutes, while fecal virome demonstrated increased Podoviridae when compared with sham feces. There was no difference in the fungal microbiome (predominant Ascomycota in both sham and CLP mice) and the abundance of all organisms between sepsis and control groups. Interestingly, the transfers of feces from CLP mice worsened sepsis severity when compared with sham fecal transplantation, as evaluated by mortality, renal injury (serum creatinine and histology), liver damage (liver enzyme and histology), spleen apoptosis, serum cytokines, endotoxemia, and bacteremia. In contrast, the transfers of fecal viral particles from sepsis mice, but not from sham mice, attenuated inflammation in CLP sepsis possibly through the decrease in several fecal pathogenic bacteria (such as Proteobacteria, Gammaproteobacteria, and Prevotellaceae) as evaluated by fecal microbiome analysis. Perhaps the isolation of favorable bacteriophages in sepsis feces and increased abundance ex vivo before oral treatment in a high concentration are beneficial.

Genetic Deletion of LRP5 and LRP6 in Macrophages Exacerbates Colitis-Associated Systemic Inflammation and Kidney Injury in Response to Intestinal Commensal Microbiota

Extraintestinal manifestations are common in inflammatory bowel disease and involve several organs, including the kidney. However, the mechanisms responsible for renal manifestation in inflammatory bowel disease are not known. In this study, we show that the Wnt-lipoprotein receptor-related proteins 5 and 6 (LRP5/6) signaling pathway in macrophages plays a critical role in regulating colitis-associated systemic inflammation and renal injury in a murine dextran sodium sulfate-induced colitis model. Conditional deletion of the Wnt coreceptors LRP5/6 in macrophages in mice results in enhanced susceptibility to dextran sodium sulfate colitis-induced systemic inflammation and acute kidney injury (AKI). Furthermore, our studies show that aggravated colitis-associated systemic inflammation and AKI observed in LRP5/6^LysM mice are due to increased bacterial translocation to extraintestinal sites and microbiota-dependent increased proinflammatory cytokine levels in the kidney. Conversely, depletion of the gut microbiota mitigated colitis-associated systemic inflammation and AKI in LRP5/6^LysM mice. Mechanistically, LRP5/6-deficient macrophages were hyperresponsive to TLR ligands and produced higher levels of proinflammatory cytokines, which are associated with increased activation of MAPKs. These results reveal how the Wnt-LRP5/6 signaling in macrophages controls colitis-induced systemic inflammation and AKI.

Candida Worsens Klebsiella pneumoniae Induced-Sepsis in a Mouse Model with Low Dose Dextran Sulfate Solution through Gut Dysbiosis and Enhanced Inflammation

Klebsiella pneumoniae is an opportunistic pathogen and a commensal organism that is possibly enhanced in several conditions with gut dysbiosis, and frequently detectable together with Candida overgrowth. Here, K. pneumoniae with or without Candida albicans was daily orally administered for 3 months in 0.8% dextran sulfate solution-induced mucositis mice and also tested in vitro. As such, Candida worsened Klebsiella-DSS-colitis as demonstrated by mortality, leaky gut (FITC-dextran assay, bacteremia, endotoxemia, and serum beta-glucan), gut dysbiosis (increased Deferribacteres from fecal microbiome analysis), liver pathology (histopathology), liver apoptosis (activated caspase 3), and cytokines (in serum and in the internal organs) when compared with Klebsiella-administered DSS mice. The combination of heat-killed Candida plus Klebsiella mildly facilitated inflammation in enterocytes (Caco-2), hepatocytes (HepG2), and THP-1-derived macrophages as indicated by supernatant cytokines or the gene expression. The addition of heat-killed Candida into Klebsiella preparations upregulated TLR-2, reduced Occludin (an intestinal tight junction molecule), and worsened enterocyte integrity (transepithelial electrical resistance) in Caco-2 and enhanced casp8 and casp9 (apoptosis genes) in HepG2 when compared with heat-killed Klebsiella alone. In conclusion, Candida enhanced enterocyte inflammation (partly through TLR-2 upregulation and gut dysbiosis) that induced gut translocation of endotoxin and beta-glucan causing hyper-inflammatory responses, especially in hepatocytes and macrophages.

Macrophage depletion alters bacterial gut microbiota partly through fungal overgrowth in feces that worsens cecal ligation and puncture sepsis mice

Because macrophage dysfunction from some emerging therapies might worsen gut-derived sepsis, cecal ligation and puncture (CLP) sepsis are performed in mice with clodronate-induced macrophage depletion. Macrophage depletion (non-sepsis) increased fecal Ascormycota, with a subtle change in bacterial microbiota, that possibly induced gut-barrier defect as Candida pintolopesii and Enterococcus faecalis were identified from blood. Sepsis in macrophage-depleted mice was more severe than sepsis control as indicated by mortality, cytokines, organ injury (liver, kidney, and spleen), gut-leakage (FITC-dextran), fecal Proteobacteria, and blood organisms (bacteria and fungi). Lysate of C. pintolopesii or purified (1 → 3)-β-d-glucan (BG; a major component of fungal cell wall) enhanced growth of Klebsiella pneumoniae and Escherichia coli that were isolated from the blood of macrophage-depleted CLP mice implying a direct enhancer to some bacterial species. Moreover, the synergy of LPS and BG on enterocytes (Caco-2) (Transepithelial electrical resistance) and neutrophils (cytokines) also supported an influence of gut fungi in worsening sepsis. In conclusion, macrophage depletion enhanced sepsis through the selectively facilitated growth of some bacteria (dysbiosis) from increased fecal fungi that worsened gut-leakage leading to the profound systemic responses against gut-translocated LPS and BG. Our data indicated a possible adverse effect of macrophage-depleted therapies on enhanced sepsis severity through spontaneous elevation of fecal fungi.

High phosphate intake induces bone loss in nephrectomized thalassemic mice

Although patients with either β-thalassemia or chronic kidney disease (CKD) clinically correlate with severe osteoporosis, the mechanism by which CKD exposed to high phosphate affects bone turnover has not been characterized in β-thalassemia. We aimed to determine the effects of renal insufficiency on high phosphate intake induced changes in bone metabolism after 5/6th nephrectomy in hemizygous β-globin knockout (BKO) mice. Male BKO mice manifested severe anemia and osteopenia. Nephrectomy induced renal fibrosis and reduced renal function as assessed by increased serum urea nitrogen levels. Moreover, nephrectomy increased bone turnover leading to bone loss in wild type (WT) but not BKO mice. In nephrectomized BKO, PBS in drinking water induced hyperphosphatemia, and hypercalcemia along with osteopenia in both cancellous and cortical bone. Histomorphometric analysis confirmed reduced cancellous bone volume due to decreased bone formation rate, osteoblast number and osteoclast number. The mRNA levels for Alpl, Sp7, Kl, Tnfsf11, and Tnfsf11/Tnfrsf11b were decreased in nephrectomized BKO mice drinking PBS. Interestingly, Fgf23, a bone-derived hormone produced by osteocytes and osteoblasts in response to hyperphosphatemia, were remarkably increased in nephrectomized BKO mice following PBS intake. Serum FGF23 and erythropoietin levels were markedly elevated in BKO mice. Nephrectomy decreased serum erythropoietin but not FGF23 levels. Hyperphosphatemia in BKO mice increased serum erythropoietin, FGF23, and PTH levels, nominating these factors as candidate mediators of bone loss in thalassemic mice with CKD during phosphate retention.

Sepsis Encephalopathy Is Partly Mediated by miR370-3p-Induced Mitochondrial Injury but Attenuated by BAM15 in Cecal Ligation and Puncture Sepsis Male Mice

BAM15 (a mitochondrial uncoupling agent) was tested on cecal ligation and puncture (CLP) sepsis mice with in vitro experiments. BAM15 attenuated sepsis as indicated by survival, organ histology (kidneys and livers), spleen apoptosis (activated caspase 3), brain injury (SHIRPA score, serum s100β, serum miR370-3p, brain miR370-3p, brain TNF-α, and apoptosis), systemic inflammation (cytokines, cell-free DNA, endotoxemia, and bacteremia), and blood-brain barrier (BBB) damage (Evan's blue dye and the presence of green fluorescent E. coli in brain after an oral administration). In parallel, brain miR arrays demonstrated miR370-3p at 24 h but not 120 h post-CLP, which was correlated with metabolic pathways. Either lipopolysaccharide (LPS) or TNF-α upregulated miR370-3p in PC12 (neuron cells). An activation by sepsis factors (LPS, TNF-α, or miR370-3p transfection) damaged mitochondria (fluorescent color staining) and reduced cell ATP, possibly through profound mitochondrial activity (extracellular flux analysis) that was attenuated by BAM15. In bone-marrow-derived macrophages, LPS caused mitochondrial injury, decreased cell ATP, enhanced glycolysis activity (extracellular flux analysis), and induced pro-inflammatory macrophages (iNOS and IL-1β) which were neutralized by BAM15. In conclusion, BAM15 attenuated sepsis through decreased mitochondrial damage, reduced neuronal miR370-3p upregulation, and induced anti-inflammatory macrophages. BAM15 is proposed to be used as an adjuvant therapy against sepsis hyperinflammation.

More Prominent Inflammatory Response to Pachyman than to Whole-Glucan Particle and Oat-β-Glucans in Dextran Sulfate-Induced Mucositis Mice and Mouse Injection through Proinflammatory Macrophages

(1→3)-β-D-glucans (BG) (the glucose polymers) are recognized as pathogen motifs, and different forms of BGs are reported to have various effects. Here, different BGs, including Pachyman (BG with very few (1→6)-linkages), whole-glucan particles (BG with many (1→6)-glycosidic bonds), and Oat-BG (BG with (1→4)-linkages), were tested. In comparison with dextran sulfate solution (DSS) alone in mice, DSS with each of these BGs did not alter the weight loss, stool consistency, colon injury (histology and cytokines), endotoxemia, serum BG, and fecal microbiome but Pachyman-DSS-treated mice demonstrated the highest serum cytokine elicitation (TNF-α and IL-6). Likewise, a tail vein injection of Pachyman together with intraperitoneal lipopolysaccharide (LPS) induced the highest levels of these cytokines at 3 h post-injection than LPS alone or LPS with other BGs. With bone marrow-derived macrophages, BG induced only TNF-α (most prominent with Pachyman), while LPS with BG additively increased several cytokines (TNF-α, IL-6, and IL-10); inflammatory genes (iNOS, IL-1β, Syk, and NF-κB); and cell energy alterations (extracellular flux analysis). In conclusion, Pachyman induced the highest LPS proinflammatory synergistic effect on macrophages, followed by WGP, possibly through Syk-associated interactions between the Dectin-1 and TLR-4 signal transduction pathways. Selection of the proper form of BGs for specific clinical conditions might be beneficial.

Neutrophil Extracellular Traps in Severe SARS-CoV-2 Infection: A Possible Impact of LPS and (1→3)-β-D-glucan in Blood from Gut Translocation

Due to limited data on the link between gut barrier defects (leaky gut) and neutrophil extracellular traps (NETs) in coronavirus disease 2019 (COVID-19), blood samples of COVID-19 cases—mild (upper respiratory tract symptoms without pneumonia; n = 27), moderate (pneumonia without hypoxia; n = 28), and severe (pneumonia with hypoxia; n = 20)—versus healthy control (n = 15) were evaluated, together with in vitro experiments. Accordingly, neutrophil counts, serum cytokines (IL-6 and IL-8), lipopolysaccharide (LPS), bacteria-free DNA, and NETs parameters (fluorescent-stained nuclear morphology, dsDNA, neutrophil elastase, histone–DNA complex, and myeloperoxidase–DNA complex) were found to differentiate COVID-19 severity, whereas serum (1→3)-β-D-glucan (BG) was different between the control and COVID-19 cases. Despite non-detectable bacteria-free DNA in the blood of healthy volunteers, using blood bacteriome analysis, proteobacterial DNA was similarly predominant in both control and COVID-19 cases (all severities). In parallel, only COVID-19 samples from moderate and severe cases, but not mild cases, were activated in vitro NETs, as determined by supernatant dsDNA, Peptidyl Arginine Deiminase 4, and nuclear morphology. With neutrophil experiments, LPS plus BG (LPS + BG) more prominently induced NETs, cytokines, NFκB, and reactive oxygen species, when compared with the activation by each molecule alone. In conclusion, pathogen molecules (LPS and BG) from gut translocation along with neutrophilia and cytokinemia in COVID-19-activated, NETs-induced hyperinflammation.

Uremia-Induced Gut Barrier Defect in 5/6 Nephrectomized Mice Is Worsened by Candida Administration through a Synergy of Uremic Toxin, Lipopolysaccharide, and (1➔3)-β-D-Glucan, but Is Attenuated by Lacticaseibacillus rhamnosus L34

A chronic kidney disease (CKD) causes uremic toxin accumulation and gut dysbiosis, which further induces gut leakage and worsening CKD. Lipopolysaccharide (LPS) of Gram-negative bacteria and (1➔3)-β-D-glucan (BG) of fungi are the two most abundant gut microbial molecules. Due to limited data on the impact of intestinal fungi in CKD mouse models, the influences of gut fungi and Lacticaseibacillus rhamnosus L34 (L34) on CKD were investigated using oral C. albicans-administered 5/6 nephrectomy (5/6Nx) mice. At 16 weeks post-5/6Nx, Candida-5/6Nx mice demonstrated an increase in proteinuria, serum BG, serum cytokines (tumor necrotic factor-α; TNF-α and interleukin-6), alanine transaminase (ALT), and level of fecal dysbiosis (Proteobacteria on fecal microbiome) when compared to non-Candida-5/6Nx. However, serum creatinine, renal fibrosis, or gut barrier defect (FITC-dextran assay and endotoxemia) remained comparable between Candida- versus non-Candida-5/6Nx. The probiotics L34 attenuated several parameters in Candida-5/6Nx mice, including fecal dysbiosis (Proteobacteria and Bacteroides), gut leakage (fluorescein isothiocyanate (FITC)-dextran), gut-derived uremic toxin (trimethylamine-N-oxide; TMAO) and indoxyl sulfate; IS), cytokines, and ALT. In vitro, IS combined with LPS with or without BG enhanced the injury on Caco-2 enterocytes (transepithelial electrical resistance and FITC-dextran permeability) and bone marrow-derived macrophages (supernatant cytokines (TNF-α and interleukin-1 β; IL-1β) and inflammatory genes (TNF-α, IL-1β, aryl hydrocarbon receptor, and nuclear factor-κB)), compared with non-IS activation. These injuries were attenuated by the probiotics condition media. In conclusion, Candida administration worsens kidney damage in 5/6Nx mice through systemic inflammation, partly from gut dysbiosis-induced uremic toxins, which were attenuated by the probiotics. The additive effects on cell injury from uremic toxin (IS) and microbial molecules (LPS and BG) on enterocytes and macrophages might be an important underlying mechanism.

Enhanced Bacteremia in Dextran Sulfate-Induced Colitis in Splenectomy Mice Correlates with Gut Dysbiosis and LPS Tolerance

Because both endotoxemia and gut dysbiosis post-splenectomy might be associated with systemic infection, the susceptibility against infection was tested by dextran sulfate solution (DSS)-induced colitis and lipopolysaccharide (LPS) injection models in splenectomy mice with macrophage experiments. Here, splenectomy induced a gut barrier defect (FITC-dextran assay, endotoxemia, bacteria in mesenteric lymph nodes, and the loss of enterocyte tight junction) and gut dysbiosis (increased Proteobacteria by fecal microbiome analysis) without systemic inflammation (serum IL-6). In parallel, DSS induced more severe mucositis in splenectomy mice than sham-DSS mice, as indicated by mortality, stool consistency, gut barrier defect, serum cytokines, and blood bacterial burdens. The presence of green fluorescent-producing (GFP) E. coli in the spleen of sham-DSS mice after an oral gavage supported a crucial role of the spleen in the control of bacteria from gut translocation. Additionally, LPS administration in splenectomy mice induced lower serum cytokines (TNF-α and IL-6) than LPS-administered sham mice, perhaps due to LPS tolerance from pre-existing post-splenectomy endotoxemia. In macrophages, LPS tolerance (sequential LPS stimulation) demonstrated lower cell activities than the single LPS stimulation, as indicated by the reduction in supernatant cytokines, pro-inflammatory genes (iNOS and IL-1β), cell energy status (extracellular flux analysis), and enzymes of the glycolysis pathway (proteomic analysis). In conclusion, a gut barrier defect after splenectomy was vulnerable to enterocyte injury (such as DSS), which caused severe bacteremia due to defects in microbial control (asplenia) and endotoxemia-induced LPS tolerance. Hence, gut dysbiosis and gut bacterial translocation in patients with a splenectomy might be associated with systemic infection, and gut-barrier monitoring or intestinal tight-junction strengthening may be useful.

Hemochromatosis drives acute lethal intestinal responses to hyperyersiniabactin-producing Yersinia pseudotuberculosis

Hemachromatosis (iron-overload) increases host susceptibility to siderophilic bacterial infections that cause serious complications, but the underlying mechanisms remain elusive. The present study demonstrates that oral infection with hyperyersiniabactin (Ybt) producing Yersinia pseudotuberculosis Δfur mutant (termed Δfur) results in severe systemic infection and acute mortality to hemochromatotic mice due to rapid disruption of the intestinal barrier. Transcriptome analysis of Δfur-infected intestine revealed up-regulation in cytokine-cytokine receptor interactions, the complement and coagulation cascade, the NF-κB signaling pathway, and chemokine signaling pathways, and down-regulation in cell-adhesion molecules and Toll-like receptor signaling pathways. Further studies indicate that dysregulated interleukin (IL)-1β signaling triggered in hemachromatotic mice infected with Δfur damages the intestinal barrier by activation of myosin light-chain kinases (MLCK) and excessive neutrophilia. Inhibiting MLCK activity or depleting neutrophil infiltration reduces barrier disruption, largely ameliorates immunopathology, and substantially rescues hemochromatotic mice from lethal Δfur infection. Moreover, early intervention of IL-1β overproduction can completely rescue hemochromatotic mice from the lethal infection.

Intestinal mycobiota composition and changes in children with thalassemia who underwent allogeneic hematopoietic stem cell transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) alters the diversity of the intestinal bacterial microbiota. This study aimed to evaluate human mycobiota composition pre-HSCT and post-HSCT in children with thalassemia.

METHOD

Ten children with thalassemia undergoing allogeneic HSCT were enrolled. The stool samples were collected before the transplantation regimen, before the transplant day, and +15, +30 days, and three months after transplantation. Stool samples were also collected from the donor and the patient's caregivers. Gut mycobiota composition was evaluated with metagenomic analysis.

RESULTS

Pretransplant mycobiota of children with thalassemia (the predominant genus was Saccharomyces, 64.1%) has been shown to approximate the diverse mycobiota compositions of healthy adult donors but becomes altered (lower diversity) following transplant procedures. Three months after HSCT, phyla Ascomycota and Basidiomycota were 83.4% and 15.6%, respectively. The predominant species were Saccaharomyces_uc and Saccharomyces cerevisiae (phylum Ascomycota); we also observed Malassezia restricta and Malassezia globosa (phylum Basidiomycota) (∼13%). On day 90 after HSCT, we observed 65.3% M. restricta and 18.4% M. globosa predominance at the species level in a four-year-old boy with acute graft-versus-host disease (GVHD) (skin and gut involvement) 19 days after transplantation included.

CONCLUSION

The mycobiota composition of children with thalassemia altered after HSCT. We observed Malassezia predominance in a child with GVHD. Further studies in children with GVHD will identify this situation.

Lactiplantibacillus plantarum dfa1 Outperforms Enterococcus faecium dfa1 on Anti-Obesity in High Fat-Induced Obesity Mice Possibly through the Differences in Gut Dysbiosis Attenuation, despite the Similar Anti-Inflammatory Properties

Fat reduction and anti-inflammation are commonly claimed properties of probiotics. Lactiplantibacillus plantarum and Enterococcus faecium were tested in high fat-induced obesity mice and in vitro experiments. After 16 weeks of probiotics, L. plantarum dfa1 outperforms E. faecium dfa1 on the anti-obesity property as indicated by body weight, regional fat accumulation, serum cholesterol, inflammatory cytokines (in blood and colon tissue), and gut barrier defect (FITC-dextran assay). With fecal microbiome analysis, L. plantarum dfa1 but not E. faecium dfa1 reduced fecal abundance of pathogenic Proteobacteria without an alteration in total Gram-negative bacteria when compared with non-probiotics obese mice. With palmitic acid induction, the condition media from both probiotics similarly attenuated supernatant IL-8, improved enterocyte integrity and down-regulated cholesterol absorption-associated genes in Caco-2 cell (an enterocyte cell line) and reduced supernatant cytokines (TNF-α and IL-6) with normalization of cell energy status (extracellular flux analysis) in bone-marrow-derived macrophages. Due to the anti-inflammatory effect of the condition media of both probiotics on palmitic acid-activated enterocytes was neutralized by amylase, the active anti-inflammatory molecules might, partly, be exopolysaccharides. As L. plantarum dfa1 out-performed E. faecium dfa1 in anti-obesity property, possibly through the reduced fecal Proteobacteria, with a similar anti-inflammatory exopolysaccharide; L. plantarum is a potentially better option for anti-obesity than E. faecium.

Lactobacillus rhamnosus attenuates Thai chili extracts induced gut inflammation and dysbiosis despite capsaicin bactericidal effect against the probiotics, a possible toxicity of high dose capsaicin

Because of a possible impact of capsaicin in the high concentrations on enterocyte injury (cytotoxicity) and bactericidal activity on probiotics, Lactobacillus rhamnosus L34 (L34) and Lactobacillus rhamnosus GG (LGG), the probiotics derived from Thai and Caucasian population, respectively, were tested in the chili-extract administered C57BL/6 mice and in vitro experiments. In comparison with placebo, 2 weeks administration of the extract from Thai chili in mice caused loose feces and induced intestinal permeability defect as indicated by FITC-dextran assay and the reduction in tight junction molecules (occludin and zona occludens-1) using fluorescent staining and gene expression by quantitative real-time polymerase chain reaction (qRT-PCR). Additionally, the chili extracts also induced the translocation of gut pathogen molecules; lipopolysaccharide (LPS) and (1→3)-β-d-glucan (BG) and fecal dysbiosis (microbiome analysis), including reduced Firmicutes, increased Bacteroides, and enhanced total Gram-negative bacteria in feces. Both L34 and LGG attenuated gut barrier defect (FITC-dextran, the fluorescent staining and gene expression of tight junction molecules) but not improved fecal consistency. Additionally, high concentrations of capsaicin (0.02-2 mM) damage enterocytes (Caco-2 and HT-29) as indicated by cell viability test, supernatant cytokine (IL-8), transepithelial electrical resistance (TEER) and transepithelial FITC-dextran (4.4 kDa) but were attenuated by Lactobacillus condition media (LCM) from both probiotic-strains. The 24 h incubation with 2 mM capsaicin (but not the lower concentrations) reduced the abundance of LGG (but not L34) implying a higher capsaicin tolerance of L34. However, Lactobacillus rhamnosus fecal abundance, using qRT-PCR, of L34 or LGG after 3, 7, and 20 days of the administration in the Thai healthy volunteers demonstrated the similarity between both strains. In conclusion, high dose chili extracts impaired gut permeability and induced gut dysbiosis but were attenuated by probiotics. Despite a better capsaicin tolerance of L34 compared with LGG in vitro, L34 abundance in feces was not different to LGG in the healthy volunteers. More studies on probiotics with a higher intake of chili in human are interesting.

Causal Effects of Genetically Predicted Iron Status on Sepsis: A Two-Sample Bidirectional Mendelian Randomization Study

Background/Aim: Several observational studies showed a significant association between elevated iron status biomarkers levels and sepsis with the unclear direction of causality. A two-sample bidirectional mendelian randomization (MR) study was designed to identify the causal direction between seven iron status traits and sepsis. Methods: Seven iron status traits were studied, including serum iron, ferritin, transferrin saturation, transferrin, hemoglobin, erythrocyte count, and reticulocyte count. MR analysis was first performed to estimate the causal effect of iron status on the risk of sepsis and then performed in the opposite direction. The multiplicative random-effects and fixed-effects inverse-variance weighted, weighted median-based method and MR-Egger were applied. MR-Egger regression, MR pleiotropy residual sum and outlier (MR-PRESSO), and Cochran's Q statistic methods were used to assess heterogeneity and pleiotropy. Results: Genetically predicted high levels of serum iron (OR = 1.21, 95%CI = 1.13-1.29, p = 3.16 × 10^-4), ferritin (OR = 1.32, 95%CI = 1.07-1.62, p =0.009) and transferrin saturation (OR = 1.14, 95%CI = 1.06-1.23, p = 5.43 × 10^-4) were associated with an increased risk of sepsis. No significant causal relationships between sepsis and other four iron status biomarkers were observed. Conclusions: This present bidirectional MR analysis suggested the causal association of the high iron status with sepsis susceptibility, while the reverse causality hypothesis did not hold. The levels of transferrin, hemoglobin, erythrocytes, and reticulocytes were not significantly associated with sepsis. Further studies will be required to confirm the potential clinical value of such a prevention and treatment strategy.

A Comparison Between 1 Day versus 7 Days of Sepsis in Mice with the Experiments on LPS-Activated Macrophages Support the Use of Intravenous Immunoglobulin for Sepsis Attenuation

Background

Because survival and death after sepsis are partly due to a proper immune adaptation and immune dysregulation, respectively, survivors and moribund mice after cecal ligation and puncture (CLP) sepsis surgery and in vitro macrophage experiments were explored.

Methods

Characteristics of mice at 1-day and 7-days post-CLP, the representative of moribund mice (an innate immune hyper-responsiveness) and survivors (a successful control on innate immunity), respectively. In parallel, soluble heat aggregated immunoglobulin (sHA-Ig), a representative of immune complex, was tested in lipopolysaccharide (LPS)-activated macrophages together with a test of intravenous immunoglobulin (IVIG), a molecule of adaptive immunity, on CLP sepsis mice.

Results

Except for a slight increase in alanine transaminase (liver injury), IL-10, endotoxemia, and gut leakage (FITC-dextran assay), most of the parameters in survivors (7-days post-CLP) were normalized, with enhanced adaptive immunity, including serum immunoglobulin (using serum protein electrophoresis) and activated immune cells in spleens (flow cytometry analysis). The addition of sHA-Ig in LPS-activated macrophages reduced supernatant cytokines, cell energy (extracellular flux analysis), reactive oxygen species (ROS), several cell activities (proteomic analysis), and Fc gamma receptors (FcgRs) expression. The loss of anti-inflammatory effect of sHA-Ig in LPS-activated macrophages from mice with a deficiency on Fc gamma receptor IIb (FcgRIIb-/-), the only inhibitory signaling of FcgRs family, when compared with wild-type macrophages, implying the FcgRIIb-dependent mechanism. Moreover, IVIG attenuated sepsis severity in CLP mice as evaluated by serum creatinine, liver enzyme (alanine transaminase), serum cytokines, spleen apoptosis, and abundance of dendritic cells in the spleen (24-h post-CLP) and survival analysis.

Conclusion

Immunoglobulin attenuated LPS-activated macrophages, partly, through the reduced cell energy of macrophages and might play a role in sepsis immune hyper-responsiveness. Despite the debate over IVIG’s use in sepsis, IVIG might be beneficial in sepsis with certain conditions.

Interference on Cytosolic DNA Activation Attenuates Sepsis Severity: Experiments on Cyclic GMP-AMP Synthase (cGAS) Deficient Mice

Although the enhanced responses against serum cell-free DNA (cfDNA) in cases of sepsis—a life-threatening organ dysfunction due to systemic infection—are understood, the influence of the cytosolic DNA receptor cGAS (cyclic guanosine monophosphate–adenosine monophosphate (GMP–AMP) synthase) on sepsis is still unclear. Here, experiments on cGAS deficient (cGAS^-/-) mice were conducted using cecal ligation and puncture (CLP) and lipopolysaccharide (LPS) injection sepsis models and macrophages. Severity of CLP in cGAS^-/- mice was less severe than in wildtype (WT) mice, as indicated by mortality, serum LPS, cfDNA, leukopenia, cytokines (TNF-α, IL-6 and IL-10), organ histology (lung, liver and kidney) and spleen apoptosis. With the LPS injection model, serum cytokines in cGAS^-/- mice were lower than in WT mice, despite the similar serum cfDNA level. Likewise, in LPS-activated WT macrophages, the expression of several mitochondria-associated genes (as revealed by RNA sequencing analysis) and a profound reduction in mitochondrial parameters, including maximal respiration (determined by extracellular flux analysis), DNA (mtDNA) and mitochondrial abundance (revealed by fluorescent staining), were demonstrated. These data implied the impact of cfDNA resulting from LPS-induced cell injury. In parallel, an additive effect of bacterial DNA on LPS, seen in comparison with LPS alone, was demonstrated in WT macrophages, but not in cGAS^-/- cells, as indicated by supernatant cytokines (TNF-α and IL-6), M1 proinflammatory polarization (iNOS and IL-1β), cGAS, IFN-γ and supernatant cyclic GMP–AMP (cGAMP). In conclusion, cGAS activation by cfDNA from hosts (especially mtDNA) and bacteria was found to induce an additive proinflammatory effect on LPS-activated macrophages which was perhaps responsible for the more pronounced sepsis hyperinflammation observed in WT mice compared with the cGAS^-/- group.

Acute Kidney Injury Induced Lupus Exacerbation Through the Enhanced Neutrophil Extracellular Traps (and Apoptosis) in Fcgr2b Deficient Lupus Mice With Renal Ischemia Reperfusion Injury

Renal ischemia is the most common cause of acute kidney injury (AKI) that might be exacerbate lupus activity through neutrophil extracellular traps (NETs) and apoptosis. Here, the renal ischemia reperfusion injury (I/R) was performed in Fc gamma receptor 2b deficient (Fcgr2b-/-) lupus mice and the in vitro experiments. At 24 h post-renal I/R injury, NETs in peripheral blood neutrophils and in kidneys were detected using myeloperoxidase (MPO), neutrophil elastase (NE) and citrullinated histone H3 (CitH3), as well as kidney apoptosis (activating caspase-3), which were prominent in Fcgr2b-/- mice more compared to wild-type (WT). After 120 h renal-I/R injury, renal NETs (using MPO and NE) were non-detectable, whereas glomerular immunoglobulin (Ig) deposition and serum anti-dsDNA were increased in Fcgr2b-/- mice. These results imply that renal NETs at 24 h post-renal I/R exacerbated the lupus nephritis at 120 h post-renal I/R injury in Fcgr2b-/- lupus mice. Furthermore, a Syk inhibitor attenuated NETs, that activated by phorbol myristate acetate (PMA; a NETs activator) or lipopolysaccharide (LPS; a potent inflammatory stimulator), more prominently in Fcgr2b-/- neutrophils than the WT cells as determined by dsDNA, PAD4 and MPO. In addition, the inhibitors against Syk and PAD4 attenuated lupus characteristics (serum creatinine, proteinuria, and anti-dsDNA) in Fcgr2b-/- mice at 120 h post-renal I/R injury. In conclusion, renal I/R in Fcgr2b-/- mice induced lupus exacerbation at 120 h post-I/R injury partly because Syk-enhanced renal NETs led to apoptosis-induced anti-dsDNA, which was attenuated by a Syk inhibitor.

Increased susceptibility to dextran sulfate-induced mucositis of iron-overload β-thalassemia mice, another endogenous cause of septicemia in thalassemia

Enterocyte damage and gut dysbiosis are caused by iron-overload in thalassemia (Thl), possibly making the gut vulnerable to additional injury. Hence, iron-overload in the heterozygous β-globin deficient (Hbb^th3/+) mice were tested with 3% dextran sulfate solution (DSS).

With 4 months of iron-gavage, iron accumulation, gut-leakage (fluorescein isothiocyanate dextran (FITC-dextran), endotoxemia, and tight junction injury) in Thl mice were more prominent than WT mice. Additionally, DSS-induced mucositis in iron-overloaded mice from Thl group was also more severe than the WT group as indicated by mortality, liver enzyme, colon injury (histology and tissue cytokines), serum cytokines, and gut-leakage (FITC-dextran, endotoxemia, bacteremia, and the detection of Green-Fluorescent Producing Escherichia coli in the internal organs after an oral administration). However, Lactobacillus rhamnosus GG attenuated the disease severity of DSS in iron-overloaded Thl mice as indicated by mortality, cytokines (colon tissue and serum), gut-leakage (FITC-dextran, endotoxemia, and bacteremia) and fecal dysbiosis (microbiome analysis). Likewise, Lactobacillus conditioned media (LCM) decreased inflammation (supernatant IL-8 and cell expression of TLR-4, nuclear factor κB (NFκB), and cyclooxygenase-2 (COX-2)) and increased transepithelial electrical resistance (TEER) in enterocytes (Caco-2 cells) stimulated by lipopolysaccharide (LPS) and LPS plus ferric ion.

In conclusion, in the case of iron-overloaded Thl, there was a pre-existing intestinal injury that wask more vulnerable to DSS-induced bacteremia (gut translocation). Hence, the prevention of gut-derived bacteremia and the monitoring on gut-leakage might be beneficial in patients with thalassemia.

Non-Thermal Atmospheric Pressure Argon-Sourced Plasma Flux Promotes Wound Healing of Burn Wounds and Burn Wounds with Infection in Mice through the Anti-Inflammatory Macrophages

Plasma medicine is the utilization of gas ionization that might be beneficial for the treatment of burn wounds, a healthcare problem with a significant mortality rate. Due to a lack of information on the impact of plasma flux in immune cells and a high prevalence of bacterial infection in burn wounds, non-thermal argon-based plasma flux was tested on macrophages (RAW246.7) and in mouse models of burn wounds with or without Staphylococcus aureus infection. Accordingly, plasma flux enhanced reactive oxygen species (ROS), using dihydroethidium assay, and decreased abundance of NF-κB-p65 (Western blot analysis) in non-stimulating macrophages. In parallel, plasma flux upregulated IL-10 gene expression (an anti-inflammatory cytokine) in lipopolysaccharide (LPS)-induced inflammatory macrophages, while downregulating the pro-inflammatory cytokines (IL-1β and IL-6). Additionally, plasma flux improved the migratory function of fibroblasts (L929) (fibroblast scratch assay) but not fibroblast proliferation. Moreover, once daily plasma flux administration for 7 days promoted the healing process in burn wounds with or without infection (wound area and wound rank score). Additionally, plasma flux reduced tissue cytokines (TNF-α and IL-6) in burn wounds with infection and promoted collagen in burn wounds without infection. In conclusion, plasma flux induced anti-inflammatory macrophages and promoted the burn-wound healing process partly through the decrease in macrophage NF-κB. Hence, plasma flux treatment should be tested in patients with burn wounds.

EnvIRONmental Aspects in Myelodysplastic Syndrome

Systemic iron overload is multifactorial in patients suffering from myelodysplastic syndrome (MDS). Disease-immanent ineffective erythropoiesis together with chronic red blood cell transfusion represent the main underlying reasons. However, like the genetic heterogeneity of MDS, iron homeostasis is also diverse in different MDS subtypes and can no longer be generalized. While a certain amount of iron and reactive oxygen species (ROS) are indispensable for proper hematological output, both are harmful if present in excess. Consequently, iron overload has been increasingly recognized as an important player in MDS, which is worth paying attention to. This review focuses on iron- and ROS-mediated effects in the bone marrow niche, their implications for hematopoiesis and their yet unclear involvement in clonal evolution. Moreover, we provide recent insights into hepcidin regulation in MDS and its interaction between erythropoiesis and inflammation. Based on Tet methylcytosine dioxygenase 2 (TET2), representing one of the most frequently mutated genes in MDS, leading to disturbances in both iron homeostasis and hematopoiesis, we highlight that different genetic alteration may have different implications and that a comprehensive workup is needed for a complete understanding and development of future therapies.

Candida Administration in Bilateral Nephrectomy Mice Elevates Serum (1→3)-β-D-glucan That Enhances Systemic Inflammation Through Energy Augmentation in Macrophages

Systemic inflammation, from gut translocation of organismal molecules, might worsen uremic complications in acute kidney injury (AKI). The monitoring of gut permeability integrity and/or organismal molecules in AKI might be clinically beneficial. Due to the less prominence of Candida albicans in human intestine compared with mouse gut, C. albicans were orally administered in bilateral nephrectomy (BiN) mice. Gut dysbiosis, using microbiome analysis, and gut permeability defect (gut leakage), which was determined by fluorescein isothiocyanate-dextran and intestinal tight-junction immunofluorescent staining, in mice with BiN-Candida was more severe than BiN without Candida. Additionally, profound gut leakage in BiN-Candida also resulted in gut translocation of lipopolysaccharide (LPS) and (1→3)-β-D-glucan (BG), the organismal components from gut contents, that induced more severe systemic inflammation than BiN without Candida. The co-presentation of LPS and BG in mouse serum enhanced inflammatory responses. As such, LPS with Whole Glucan Particle (WGP, a representative BG) induced more severe macrophage responses than LPS alone as determined by supernatant cytokines and gene expression of downstream signals (NFκB, Malt-1 and Syk). Meanwhile, WGP alone did not induced the responses. In parallel, WGP (with or without LPS), but not LPS alone, accelerated macrophage ATP production (extracellular flux analysis) through the upregulation of genes in mitochondria and glycolysis pathway (using RNA sequencing analysis), without the induction of cell activities. These data indicated a WGP pre-conditioning effect on cell energy augmentation. In conclusion, Candida in BiN mice accelerated gut translocation of BG that augmented cell energy status and enhanced pro-inflammatory macrophage responses. Hence, gut fungi and BG were associated with the enhanced systemic inflammation in acute uremia.

Iron Reshapes the Gut Microbiome and Host Metabolism

Compelling studies have established that the gut microbiome is a modifier of metabolic health. Changes in the composition of the gut microbiome are influenced by genetics and the environment, including diet. Iron is a potential node of crosstalk between the host-microbe relationship and metabolic disease. Although iron is well characterized as a frequent traveling companion of metabolic disease, the role of iron is underappreciated because the mechanisms of iron's influence on host metabolism are poorly characterized. Both iron deficiency and excessive amounts leading to iron overload can have detrimental effects on cardiometabolic health. Optimal iron homeostasis is critical for regulation of host immunity and metabolism in addition to regulation of commensal and pathogenic enteric bacteria. In this article we review evidence to support the notion that altering composition of the gut microbiome may be an important route via which iron impacts cardiometabolic health. We discuss reshaping of the microbiome by iron, the physiological significance and the potential for therapeutic interventions.

Pterostilbene Ameliorates DSS-Induced Intestinal Epithelial Barrier Loss in Mice via Suppression of the NF-κB-Mediated MLCK-MLC Signaling Pathway

The integrity of the intestinal barrier is critical for homeostasis. In this study, we investigated the protective effect of pterostilbene (PTE) on the intestinal epithelium barrier. In vitro results of transepithelial electrical resistance (TEER) in Caco-2 cells indicated that PTE counteracted tumor necrosis factor α (TNFα)-induced barrier damage. In vivo PTE pretreatment markedly ameliorated intestinal barrier dysfunction induced by dextran sulfate sodium (DSS). Notably, intestinal epithelial tight junction (TJ) molecules were restored by PTE in mice exposed to DSS. The mechanism study revealed that PTE prevented myosin light-chain kinase (MLCK) from driving phosphorylation of MLC (p-MLC), which is crucial for maintaining intestinal TJ stability. Furthermore, PTE blunted translocation of NF-κB subunit p65 into the nucleus to downregulate MLCK expression and then to safeguard TJs and barrier integrity. These findings suggest that PTE protected the intestinal epithelial barrier through the NF-κB- MLCK/p-MLC signal pathway.

Lactobacillus acidophilus LA5 improves saturated fat-induced obesity mouse model through the enhanced intestinal Akkermansia muciniphila

Obesity, a major healthcare problem worldwide, induces metabolic endotoxemia through the gut translocation of lipopolysaccharides (LPS), a major cell wall component of Gram-negative bacteria, causing a chronic inflammatory state. A combination of several probiotics including Lactobacillus acidophilus 5 (LA5), a potent lactic acid-producing bacterium, has previously been shown to attenuate obesity. However, data on the correlation between a single administration of LA5 versus microbiota alteration might be helpful for the probiotic adjustment. LA5 was administered daily together with a high-fat diet (HFD) for 8 weeks in mice. Furthermore, the condition media of LA5 was also tested in a hepatocyte cell-line (HepG2 cells). Accordingly, LA5 attenuated obesity in mice as demonstrated by weight reduction, regional fat accumulation, lipidemia, liver injury (liver weight, lipid compositions, and liver enzyme), gut permeability defect, endotoxemia, and serum cytokines. Unsurprisingly, LA5 improved these parameters and acidified fecal pH leads to the attenuation of fecal dysbiosis. The fecal microbiome analysis in obese mice with or without LA5 indicated; (i) decreased Bacteroidetes (Gram-negative anaerobes that predominate in non-healthy conditions), (ii) reduced total fecal Gram-negative bacterial burdens (the sources of gut LPS), (iii) enhanced Firmicutes (Gram-positive bacteria with potential benefits) and (iv) increased Verrucomycobia, especially Akkermansia muciniphila, a bacterium with the anti-obesity property. With LA5 administration, A. muciniphila in the colon were more than 2,000 folds higher than the regular diet mice as determined by 16S rRNA. Besides, LA5 produced anti-inflammatory molecules with a similar molecular weight to LPS that reduced cytokine production in LPS-activated HepG2 cells. In conclusion, LA5 attenuated obesity through (i) gut dysbiosis attenuation, partly through the promotion of A. muciniphila (probiotics with the difficulty in preparation processes), (ii) reduced endotoxemia, and (iii) possibly decreased liver injury by producing the anti-inflammatory molecules.

Prominent Indomethacin-Induced Enteropathy in Fcgriib Defi-cient lupus Mice: An Impact of Macrophage Responses and Immune Deposition in Gut

A high dose of NSAIDs, a common analgesic, might induce lupus activity through several NSAIDs adverse effects including gastrointestinal permeability defect (gut leakage) and endotoxemia. Indomethacin (25 mg/day) was orally administered for 7 days in 24-wk-old Fc gamma receptor IIb deficient (FcgRIIb-/-) mice, an asymptomatic lupus model (increased anti-dsDNA without lupus nephritis), and age-matched wild-type (WT) mice. Severity of indomethacin-induced enteropathy in FcgRIIb-/- mice was higher than WT mice as demonstrated by survival analysis, intestinal injury (histology, immune-deposition, and intestinal cytokines), gut leakage (FITC-dextran assay and endotoxemia), serum cytokines, and lupus characteristics (anti-dsDNA, renal injury, and proteinuria). Prominent responses of FcgRIIb-/- macrophages toward lipopolysaccharide (LPS) compared to WT cells due to the expression of only activating-FcgRs without inhibitory-FcgRIIb were demonstrated. Extracellular flux analysis indicated the greater mitochondria activity (increased respiratory capacity and respiratory reserve) in FcgRIIb-/- macrophages with a concordant decrease in glycolysis activity when compared to WT cells. In conclusion, gut leakage-induced endotoxemia is more severe in indomethacin-administered FcgRIIb-/- mice than WT, possibly due to the enhanced indomethacin toxicity from lupus-induced intestinal immune-deposition. Due to a lack of inhibitory-FcgRIIb expression, mitochondrial function, and cytokine production of FcgRIIb-/- macrophages were more prominent than WT cells. Hence, lupus disease-activation from NSAIDs-enteropathy-induced gut leakage is possible.

Candida Administration Worsens Uremia-Induced Gut Leakage in Bilateral Nephrectomy Mice, an Impact of Gut Fungi and Organismal Molecules in Uremia

The impact of gut fungi and (1→3)-β-d-glucan (BG), a major fungal cell wall component, on uremia was explored by Candida albicans oral administration in bilateral nephrectomy (BiNx) mice because of the prominence of C. albicans in the human intestine but not in mice. As such, BiNx with Candida administration (BiNx-Candida) enhanced intestinal injury (colon cytokines and apoptosis), gut leakage (fluorescein isothiocyanate [FITC]-dextran assay, endotoxemia, serum BG, and bacteremia), systemic inflammation, and liver injury at 48 h postsurgery compared with non-Candida BiNx mice. Interestingly, uremia-induced enterocyte apoptosis was severe enough for gut translocation of viable bacteria, as indicated by culture positivity for bacteria in blood, mesenteric lymph nodes (MLNs), and other organs, which was more severe in BiNx-Candida than in non-Candida BiNx mice. Candida induced alterations in the gut microbiota of BiNx mice as indicated by (i) the higher fungal burdens in the feces of BiNx-Candida mice than in sham-Candida mice by culture methods and (ii) increased Bacteroides with decreased Firmicutes and reduced bacterial diversity in the feces of BiNx-Candida mice compared with non-Candida BiNx mice by fecal microbiome analysis. In addition, lipopolysaccharide plus BG (LPS+BG), compared with each molecule alone, induced high supernatant cytokine levels, which were enhanced by uremic mouse serum in both hepatocytes (HepG2 cells) and macrophages (RAW264.7 cells). Moreover, LPS+BG, but not each molecule alone, reduced the glycolysis capacity and mitochondrial function in HepG2 cells as determined by extracellular flux analysis. Additionally, a probiotic, Lactobacillus rhamnosus L34 (L34), attenuated disease severity only in BiNx-Candida mice but not in non-Candida BiNx mice, as indicated by liver injury and serum cytokines through the attenuation of gut leakage, the fecal abundance of fungi, and fecal bacterial diversity but not fecal Gram-negative bacteria. In conclusion, Candida enhanced BiNx severity through the worsening of gut leakage and microbiota alterations that resulted in bacteremia, endotoxemia, and glucanemia.IMPORTANCE The impact of fungi in the intestine on acute uremia was demonstrated by the oral administration of Candida albicans in mice with the removal of both kidneys. Because fungi in the mouse intestine are less abundant than in humans, a Candida-administered mouse model has more resemblance to patient conditions. Accordingly, acute uremia, without Candida, induced intestinal mucosal injury, which resulted in the translocation of endotoxin, a major molecule of gut bacteria, from the intestine into blood circulation. In acute uremia with Candida, intestinal injury was more severe due to fungi and the alteration in intestinal bacteria (increased Bacteroides with decreased Firmicutes), leading to the gut translocation of both endotoxin from gut bacteria and (1→3)-β-d-glucan from Candida, which synergistically enhanced systemic inflammation in acute uremia. Both pathogen-associated molecules were delivered to the liver and induced hepatocyte inflammatory responses with a reduced energy production capacity, resulting in acute uremia-induced liver injury. In addition, Lactobacillus rhamnosus attenuated intestinal injury through reduced gut Candida and improved intestinal bacterial conditions.

Pathogen-Associated Molecules from Gut Translocation Enhance Severity of Cecal Ligation and Puncture Sepsis in Iron-Overload β-Thalassemia Mice

Introduction

Systemic inflammation induced by gut translocation of lipopolysaccharide (LPS), a major component of Gram-negative bacteria, in thalassemia with iron-overload worsens sepsis. However, the impact of (1→3)-β-D-glucan (BG), a major fungal molecule, in iron-overload thalassemia is still unclear. Hence, the influence of BG was explored in 1) iron-overload mice with sepsis induced by cecal ligation and puncture (CLP) surgery; and 2) in bone marrow-derived macrophages (BMMs).

Methods

The heterozygous β-globin-deficient mice, Hbb^th3/+ mice, were used as representative thalassemia (TH) mice. Iron overload was generated by 6 months of oral iron administration before CLP surgery- induced sepsis in TH mice and wild-type (WT) mice. Additionally, BMMs from both mouse strains were used to explore the impact of BG.

Results

Without sepsis, iron-overload TH mice demonstrated more severe intestinal mucosal injury (gut leakage) with higher LPS and BG in serum, from gut translocation, when compared with WT mice. With CLP in iron-overload mice, sepsis severity in TH mice was more severe than WT as determined by survival analysis, organ injury (kidney and liver), bacteremia, endotoxemia, gut leakage (FITC-dextran) and serum BG. Activation by LPS plus BG (LPS+BG) in BMMs and in peripheral blood-derived neutrophils (both WT and TH cells) demonstrated more prominent cytokine production when compared with LPS activation alone. In parallel, LPS+BG also prominently induced genes expression of M1 macrophage polarization (iNOS, TNF-α and IL-1β) in both WT and TH cells in comparison with LPS activation alone. In addition, LPS+BG activated macrophage cytokine production was enhanced by a high dose of ferric ion (800 mM), more predominantly in TH macrophages compared with WT cells. Moreover, LPS+BG induced higher glycolysis activity with similar respiratory capacity in RAW264.7 (a macrophage cell line) compared with LPS activation alone. These data support an additive pro-inflammatory effect of BG upon LPS.

Conclusion

The enhanced-severity of sepsis in iron-overload TH mice was due to 1) increased LPS and BG in serum from iron-induced gut-mucosal injury; and 2) the pro-inflammatory amplification by ferric ion on LPS+BG activation.