Permeability Damage Research Articles

Characterization and Performance Evaluation of Modified Apatite Ore as a New Acid-Soluble Weighting Agent for Drilling Fluids

Summary Drilling in oil and gas reservoir formations requires the solid weighting agent used in drilling fluids to have good acid solubility to facilitate plugging removal in subsequent operations. Limestone is the most commonly used acid-soluble weighting agent, but its low density and significant thickening effect lead to a low weighting limit. To achieve control of drilling fluid density, rheology, sag stability, and acid solubility, the feasibility of using apatite (AP) ore as an acid-soluble weighting agent for drilling fluids has been discussed after it was modified by the nitrogen-containing organic polybasic phosphonic acid sodium salt. The basic characteristics of AP and modified AP (MAP) were analyzed. After that, the rheological, filtration, and sag stability properties of MAP-weighted water-based drilling fluids with densities of 1.2 g/cm3 and 1.6 g/cm3 were evaluated, and acid solubility, filter-cake permeability, core permeability damage, and plugging removal tests by acid solutions were performed to evaluate the formation protection effect. The results show that the density of AP is 2.98 g/cm3, and the main component is hydroxyapatite. Its negative electricity and hydrophilicity were enhanced after surface modification, so its dispersion stability in water was enhanced, thereby improving the rheology, filtration, and sag stability properties of the MAP-weighted drilling fluid. The solubility of MAP in 10% HCl solution reached 90.13%, and the core contamination experiments show that after being soaked in HCl solution, the return permeability of contaminated cores reached higher than 90%, indicating that the MAP invading the core can be efficiently dissolved and removed in the acidic working fluids used in the subsequent completion and stimulation operations, thus effectively protecting the reservoir formation. The properties of MAP are superior to those of limestone, and it can be used as a new acid-soluble weighting agent for drilling fluids, considering both drilling fluid performance regulation and reservoir formation protection.

Continuous measurement of gas permeability in non-homogeneous hydrate reservoirs under effective pressure via a novel apparatus

Gas permeability is a key physical parameter to determine the exploitation efficiency of natural gas hydrate (NGH). However, the relevant research mainly focuses on the permeability of homogeneous hydrate reservoirs, there have been no studies of non-homogeneous hydrate reservoirs. Therefore, a novel permeability measurement apparatus was designed in this study, which used two core holders in parallel to achieve the spatio-temporal continuous measurements of gas permeability for non-homogeneous reservoirs. Marine soils obtained from the South China Sea were used to remold the non-homogeneous hydrate reservoirs, including two homogeneous hydrate reservoirs with water saturation of 40% (reservoir A) and 80% (reservoir B), respectively. The constant gas flow of 0.5 ml/s and constant back pressure of 3 MPa was carried out to measure the gas permeability. The experimental results showed that the gas permeability measured in this work had similar regularities with other literature data. When the effective pressure increased from 1 MPa to 6 MPa, the permeability of reservoir A, reservoir B, and non-homogeneous hydrate reservoir decreased from 15.2 mD to 10.9 mD, 10.5 mD to 4.6 mD, and 12.5 mD to 8.5 mD, respectively. In addition, the variation in the non-homogeneous coefficient showed three stages: 1–2 MPa stage, 2–3 MPa stage, and 3–6 MPa stage. What's more, the permeability damage rate of non-homogeneous reservoirs increased by nearly 35% with the increase of effective pressure. These findings obtained by this apparatus will enhance the understanding of gas permeability in the non-homogeneous hydrate reservoirs, and guide further field exploitation of hydrate reservoirs.

Multi-Sized Granular Suspension Transport Modeling for the Control of Lost Circulation and Formation Damage in Fractured Oil and Gas Reservoirs

Transport and retention of multi-sized suspended granules are common phenomena in fracture media of oil, gas and geothermal reservoirs. It can lead to severe permeability damage and productivity decline, which has a significant impact on the efficient development of underground resources. However, the granule transport and retention behaviors remain not well understood and quantified. The novel stochastic model is proposed for the multi-sized suspended granule transport in naturally fractured reservoirs accounting for granule retention and fracture clogging kinetics. A percolation fracture network is proposed considering fracture connectivity evolution during suspended granule transport. Granule retention and fracture clogging dynamics equations are proposed to account for incomplete fracture clogging by retained granules. The microscale stochastic model is allowed for upscaling to predict the multi-sized granule transport behavior in naturally fractured reservoirs. The model solution exhibits preferential plugging of fractures with sizes equal to or below the granule size. Multi-sized suspended granule shows great advantages over mono-sized suspended granule in the control of permeability damage induced by granule retention and fracture clogging. The retained granule concentration and permeability damage rate decrease with fracture network connectivity improvement. The experimental investigation on size-exclusion suspended granule flow has been performed. The model-based prediction of the retained granule concentration and permeability variation history shows good agreement with the experimental data, which verifies the developed model.

Porous Asphalt Mixture with Improved Fatigue Resistance and Stormwater Pollutant Reduction in Urban Road Pavement

One alternative measure to minimise the stormwater runoff volume and its pollutants and reduce impervious areas is to use permeable pavement. However, due to weak mechanical performance under heavy-load traffic related to fatigue resistance, porous mixtures and permeable pavements have restricted applications, i.e., parking lots and low-traffic roads. This work aims to evaluate the fatigue resistance of a porous asphalt mixture produced with highly modified asphalt (HiMA) and its potential contribution to reducing stormwater runoff and pollutants. In order to estimate the capability of runoff pollutants and stormwater flood reduction, a case study was performed on an urban road. A permeable pavement was designed using the porous mixture as a surface layer. The mixture volumetric parameters and asphalt content were established using the Marshall method, considering the void content, interconnected voids, permeability, Cantabro test, and moisture damage test evaluation. The resilient modulus and fatigue resistance tests were performed on a diametral compression device. The mixture design resulted in an asphalt content of 5.1% and a void content of 21.5%. The resilient modulus was 2764 MPa, and the porous mixture obtained excellent fatigue performance, allowing its application in diverse traffic conditions. The porous mixture efficiency infiltration capacity was 90%, and some runoff pollutants could be reduced after being filtered by the pavement surface, contributing to minimizing environmental contamination. This work filled part of a gap in predicting porous mixtures’ fatigue performance, collaborating to popularise and expand its use for various purposes.

Evaluation method for reservoir damage of cementing slurry

The damage of cement slurry to the reservoir is directly related to the production of oil and gas wells, and is a problem that must be solved for the efficient and economic development of oil and gas reservoirs. According to the characteristics and field conditions of reservoir damage caused by cement slurry, this paper analyzes the main factors affecting the degree of reservoir damage, puts forward the technical index requirements of the evaluation device, and establishes the evaluation method of reservoir damage caused by cement slurry in case of loss of injection. The results show that the influence of temperature on the damage of the cement slurry layer is small, and the influence of pressure difference on the damage to the cement slurry layer is large; When the pressure difference is 22 Mpa, the penetration damage rate caused by cement slurry to the pore center without mud cake attachment is about 43%. After a day of core maintenance, the permeability damage rate will reach 61.2%; The damage of cement slurry to the pore micro-fractured core is very serious. After 1 day of maintenance, the damage to the core permeability after cement slurry solidification is as high as 83%, with an average of 76.5%; When the risk of leakage is low, the cement slurry system with low density and low water loss can be used for cementing operation. The filtrate of cement slurry should be better matched with the formation clay minerals, formation water, and drilling fluid filtrate. When the risk of leakage is high, high-density cement slurry, balanced pressure cementing, pressure control cementing, and other technologies to avoid leakage can be used for cementing operations. When the cementing conditions are more difficult, the cementing slurry system can be used to dissolve the cementing slurry system at a later stage. The research results provide theoretical data support for the study of reducing the damage of cement slurry to the reservoir.

A numerical model for gas CO 2 migration in a fault zone

Understanding whether fractures and faults impact the CO 2 migration through the overburden is critical in the evaluation and monitoring of CO 2 geological storage sites. We present a numerical model and workflow to describe the hydraulic behaviour of a fault located in the shallow part of the overburden. This helps to evaluate the sealing potential of the system in case of unwanted CO 2 migration toward the surface and to design an efficient monitoring plan. The model configuration is representative of several experiments performed at real sites under quite shallow conditions (50–500 m). The model results, applied to a selected fault outcropping in the Apennines (Italy), show that most of the gas migrates through the high permeable footwall damage zone. A significant amount of gas then dissolves into the water, emphasizing the importance of accurate modelling to assess the hazard of CO 2 leakage into near-surface aquifers or to the surface. The occurrence of pressure buildup close to the fault core points out that detailed modelling of the migration conditions is required to predict gas path through a fault zone. Thematic collection: This article is part of the Fault and top seals 2022 collection available at: https://www.lyellcollection.org/topic/collections/fault-and-top-seals-2022

Permeability variation and sensitivity of CO2 injection into coals under the control of effective stress and temperature

ABSTRACT The injection of CO2 into coal reservoirs offers a promising approach for reducing CO2 emissions and enhancing coalbed methane production. An inadequate understanding of the CO2 permeability variation in coals under the coupled constraints of temperature and effective stress limits the accurate evaluation of the CO2 injection potential. To address this issue, coal samples of different ranks were collected from the Sihe, Zhangjiamao, and Dahebian coal mines in China (designated as SH-1, ZJM-1, and DHB-1, respectively). These samples were used to investigate the characteristics of permeability variation and sensitivity to coal rank, temperature, and effective stress. The coal samples ZJM-1, DHB-1, and SH-1 had absolute permeability of 0.01355, 0.03953, and 0.00064mD, respectively. The SH-1 sample had the lowest absolute permeability due to its high coal rank, and the DHB-1 sample had the highest absolute permeability due to its tectonically deformed and fractured coal structure. The association of permeability to effective stress can be more accurately described by the permeability model with variable pore compression coefficient than that with constant pore compression coefficient. The CO2 permeability of the coal samples decreased exponentially with increasing effective stress, while the permeability damage rate increased exponentially and the permeability curvature decreased exponentially. Based on the fitted curve of the permeability damage rate to effective stress, three stages of stress sensitivity were identified: rapidly increasing stage, slowly increasing stage, and approximately stable stage. The permeability and temperature sensitivity coefficient exhibited a decreasing trend with increasing temperature, following a power function relationship. Among the undisturbed coal samples, the SH-1 sample showed higher sensitivity to stress and temperature compared to the ZJM-1 sample. The DHB-1 sample, characterized by a fractured coal structure, exhibited the lowest temperature sensitivity and the highest stress sensitivity. The temperature sensitivity of different coal samples tended to be consistent at temperatures above 70°C. Predictive models for CO2 permeability under the dual constraints of temperature and effective stress were constructed for the three samples using the surface fitting method. These models can assist in evaluating the feasibility of CO2 injection into coal reservoirs at various depths in associated areas.

Particle blockage mechanism of a weakly consolidated sandstone geothermal reservoir during tailwater recharge

Weakly consolidated sandstone geothermal reservoirs (WCSGR) are widely distributed, highly developed and utilized, with tremendous potential to meet enormous energy needs. However, this kind of geothermal reservoir (GR) suffer from permeability damage during tailwater recharge, primarily due to particle blockage (PB). The exact impact of PB on the permeability of GRs during tailwater recharge remains unclear. Therefore, an experimental study investigating PB in WCSGR tailwater recharge was conducted, considering the comprehensive effects of multiple factors. The study aimed to understand the mechanism of PB and its effect on GR permeability by observing the migration of fluorescent particles in sandstone core. Through analysis of microsphere migration/blockage properties, theoretical calculations, and empirical criteria, the PB mechanism during tailwater recharge in weakly consolidated sandstone was revealed. A physical model of particle movement was developed to explain the permeability attenuation phenomena in the experimental cores, describing the occurrence and development process of PB in real recharge operations. Finally, the theoretical computation were integrated with the experimental findings, and the chemical and dynamic conditions of geothermal tailwater recharge in the WCSGR were optimized. This study provides theoretical guidance for further numerical simulations and field tests.

CircRNA SCAR Improves High-Glucose-Induced Mitochondrial Dysfunction and Permeability Damage in Retinal Microvascular Endothelial Cells.

This study was designed to assess the role and mechanism of circRNA SCAR in human retinal microvascular endothelial cells (hRMVECs) treated with high glucose. Quantitative real-time polymerase chain reaction (qRT-PCR) and cell counting kit 8 (CCK-8) were used to detect the effects of different concentrations of glucose on circRNA SCAR expression and cell proliferation in hRMVECs. Cell viability, levels of oxygen species (ROS), malondialdehyde (MDA) and adenosine triphosphate (ATP), as well as activities of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the transfected hRMVECs in each group were detected using CCK-8 and their corresponding detection kits. Changes in mtDNA copy number in high-glucose-induced hRMVECs were observed by qRT-PCR. Additionally, western blot was applied to detect effect of overexpressing circRNA SCAR on the expression levels of mitochondrial function-related proteins (Drp1 and Fis1) and cell permeability-related proteins (claudin-5, occludin and ZO-1) in hRMVECs under high-glucose concentration. According to experimental results, high glucose significantly downregulated circRNA SCAR expression and inhibited cell proliferation in hRMVECs. Instead, overexpression of this circRNA SCAR promoted cell proliferation, reduced levels of ROS, MDA and ATP, and increased SOD and CAT activities in hRMVECs under high-glucose concentration. Also, circRNA SCAR overexpression reversed the high-glucose-induced decrease in mtDNA copy number as well as, high-glucose-induced upregulation of Drp1 and Fis1 protein expression and downregulation of claudin-5, occludin and ZO-1 protein expression in hRMVECs. In summary, circRNA SCAR promotes the proliferation of hRMVECs under high-glucose concentration, alleviates oxidative stress induced by high glucose, and improves mitochondrial function and permeability damage.

Experimental Investigation on Deformation and Permeability of Clayey–Silty Sediment during Hydrate Dissociation by Depressurization

The sediments in the South China sea are mainly composed of clayey silt, characterized by weak cementation, low strength, and poor permeability. These characteristics lead to slow gas and water transport and low gas production efficiency in the production process, which is not conducive to reservoir stability. Therefore, this paper studied the influence of different factors on the displacement and permeability of hydrate-bearing sediments by using remolded cores from the South China Sea. It was found that, when the depressurization method was used for hydrate decomposition, the displacement change in sediments could be divided into three stages: depressurization stage, decomposition stage, and creep stage. During the decompression stage, sediment deformation was rapid and displacement was small. During the decomposition process of hydrates, sediment deformation was slow and displacement was maximum. The creep stage had the slowest deformation and the smallest displacement. The displacement increased with the increase in initial porosity, hydrate saturation, effective pressure, and depressurization amplitude. The permeability of the sediments was lower than that of the original sediments after hydrate decomposition. This permeability damage increased with the increase in the sediment porosity, hydrate saturation, depressurization range and effective pressure. Furthermore, the displacement of sediments was positively correlated with the permeability damage.

Effect of Carbon Dioxide Injection on Limestone Permeability Damage Induced by Alumina Nanoparticles for Enhanced Oil Recovery Applications

Enhanced oil recovery using nanoparticles is a promising method. However, when injected into a reservoir, nanoparticles can block pores and cause permeability damage. Therefore, enhancing their performance to lower the permeability damage effect is crucial. This study investigated the effect of pH alteration through carbon dioxide (CO2) injection on the permeability damage of limestone caused by an aluminum oxide (α-Al2O3) nanofluid. The methodology involved nanofluid alternating CO2 core flooding experiments by using nanofluids with a pH of 4.5 and 2.8. After core flooding, the permeability damage was calculated as a percentage of the reduction in the original permeability. The results revealed that the permeability damage in the case of nanofluid alternating CO2 injection was 23.23%. In the nanofluid with a pH of 4.5 injection case, the permeability damage was 47.53%. In the 2.8 pH nanofluid injection case, the permeability damage was 31.01%. The retention of nanoparticles was confirmed through scanning electron microscopy and energy dispersive X-ray analysis. Permeability damage could be attributed to the large nanoparticles’ agglomeration size, roughness of pore surfaces, and nanoparticle sedimentation. The results of the study revealed that altering pH through the α-Al2O3 nanofluid alternating CO2 injection can effectively reduce the permeability damage of limestone.

Permeability damage and hydrate dissociation barrier caused by invaded fracturing fluid during hydrate reservoir stimulation

Hydraulic fracturing is a promising stimulation technology for enhancing the gas productivity and energy efficiency of low-permeability hydrate reservoirs. Presently, most studies focus on the fracturing feasibility of hydrate-bearing sediments and recovery efficiency after fracturing. Although the fracturing fluid inevitably invades the hydrate reservoirs during fracturing, the effects of invaded fracturing fluid on sediment permeability and hydrate dissociation have not been investigated yet. In this study, the invasion of water-based fracturing fluid into hydrate-bearing sediments was experimentally studied to clarify the dynamic characteristics of the fracturing fluid invasion, including its effects on sediment permeability and hydrate dissociation. The results revealed that the fracturing fluid loss rate was initially high but abruptly became extremely small, potentially because of the filter cake deposition on the fracture surface and the secondary hydrate formation in the invaded zone. However, the invaded fracturing fluid increased the dissociated gas flow resistance and inhibited the hydrate dissociation and gas production that yielded a two-stage gas production process, including slow hydrate dissociation in the invaded zone followed by relatively fast hydrate dissociation in the uninvaded zone. Furthermore, the degree of permeability damage in the invaded zone gradually decreased with the increasing invasion distance that was caused by the variations in the microscopic filtrate–sediment reactions. Interestingly, the water saturation measured by NMR gradually decreased from about 90% to 60% (initial water saturation) along the invasion distance. This phenomenon indicates that water sensitivity and water lock acted as the primary sources of permeability damage to the clayey–silty sediments after fracturing fluid invasion, suggesting that inhibiting clay swelling and increasing the flowback rate of the invaded fluid were essential for reducing permeability damage. Noted that using the fracturing fluid with breaker and KCl exhibited the lowest degree (25%) and shortest distance (<15 cm) of sediment permeability damage. The present results are vital for applying hydraulic fracturing in the field tests of hydrate reservoirs to optimize the fracturing fluid and improve the fracturing stimulation effect.

Permeability Damage Mechanism and Evolution of Gas-Bearing Coal Seams Induced by Drilling Fluid

Permeability Damage Mechanism and Evolution of Gas-Bearing Coal Seams Induced by Drilling Fluid

Experimental study on the degree and damage-control mechanisms of fuzzy-ball-induced damage in single and multi-layer commingled tight reservoirs

Fuzzy-ball working fluids (FBWFs) have been successfully applied in different development phases of tight reservoirs. Field reports revealed that FBWFs satisfactorily met all the operational and reservoir damage control requirements during their application. However, the damage-control mechanisms and degree of formation damage caused by fuzzy-ball fluids have not been investigated in lab-scale studies so far. In this study, the degree of fuzzy-ball-induced damage in single-and double-layer reservoirs was evaluated through core flooding experiments that were based on permeability and flow rate indexes. Additionally, its damage mechanisms were observed via scanning electron microscope and energy-dispersive spectroscopy tests. The results show that: (1) For single-layer reservoirs, the FBWF induced weak damage on coals and medium-to-weak damage on sandstones, and the difference of the damage in permeability or flow rate index on coals and sandstones is below 1%. Moreover, the minimum permeability recovery rate was above 66%. (2) For double-layer commingled reservoirs, the flow rate index revealed weak damage and the overall damage in double-layer was lower than the single-layer reservoirs. (3) There is no significant alteration in the microscopic structure of fuzzy-ball saturated cores with no evidence of fines migration. The dissolution of lead and sulfur occurred in coal samples, while tellurium in sandstone, aluminum, and magnesium in carbonate. However, the precipitation of aluminum, magnesium, and sodium occurred in sandstone but no precipitates found in coal and carbonate. The temporal plugging and dispersion characteristics of the FBWFs enable the generation of reservoir protection layers that will minimize formation damage due to solid and fluid invasion.

Role of Imaging Modalities and N-Acetylcysteine Treatment in Sepsis-Associated Encephalopathy.

Sepsis-associated encephalopathy is a severe systemic infection complication. Although early stages involve pathophysiological changes, detection using conventional imaging is challenging. Glutamate chemical exchange saturation transfer and diffusion kurtosis imaging can noninvasively investigate cellular and molecular events in early disease stages using magnetic resonance imaging (MRI). N-Acetylcysteine, an antioxidant and precursor of glutathione, regulates neurotransmitter glutamate metabolism and participates in neuroinflammation. We investigated the protective role of n-acetylcysteine in sepsis-associated encephalopathy using a rat model and monitored changes in brain using magnetic resonance (MR) molecular imaging. Bacterial lipopolysaccharide was injected intraperitoneally to induce a sepsis-associated encephalopathy model. Behavioral performance was assessed using the open-field test. Tumor necrosis factor α and glutathione levels were detected biochemically. Imaging was performed using a 7.0-T MRI scanner. Protein expression, cellular damage, and changes in blood-brain barrier permeability were assessed using western blotting, pathological staining, and Evans blue staining, respectively. Lipopolysaccharide-induced rats showed reduced anxiety and depression after treatment with n-acetylcysteine. MR molecular imaging can identify pathological processes at different disease stages. Furthermore, rats treated with n-acetylcysteine showed increased glutathione levels and decreased tumor necrosis factor α, suggesting enhanced antioxidant capacity and inhibition of inflammatory processes, respectively. Western blot analysis showed reduced expression of nuclear factor kappa B (p50) protein after treatment, suggesting that n-acetylcysteine inhibits inflammation via this signaling pathway. Finally, n-acetylcysteine-treated rats showed reduced cellular damage by pathology and reduced extravasation of their blood-brain barrier by Evans Blue staining. Thus, n-acetylcysteine might be a therapeutic option for sepsis-associated encephalopathy and other neuroinflammatory diseases. Furthermore, noninvasive "dynamic visual monitoring" of physiological and pathological changes related to sepsis-associated encephalopathy was achieved using MR molecular imaging for the first time, providing a more sensitive imaging basis for early diagnosis, identification, and prognosis.

Knockdown of SHP2 attenuated LPS-induced ferroptosis via downregulating ACSL4 expression in acute lung injury.

Acute lung injury (ALI) is a complex disease with a high mortality. Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2) is a protein tyrosine phosphatase that participates in pathogenesis of multiple diseases. Nevertheless, the role of SHP2 in ALI remains unknown. The in vivo and in vitro lipopolysaccharide (LPS)-induced ALI models were successfully established. The histopathological changes were evaluated by hematoxylin and eosin staining. The vascular permeability of lungs was assessed by Evans blue assay. The expression of ACSL4 and SHP2 was detected by western blot and qRT-PCR assay. The lactate dehydrogenase (LDH) activity, malondialdehyde (MDA), iron, and glutathione (GSH) levels were measured by commercial kits. The SHP2 was upregulated in LPS-induced ALI mice and LPS-stimulated MLE-12 cells. In loss-of function experiment, the knockdown of SHP2 attenuated LPS-induced lung injury, microvessels damage, pulmonary edema, and increase of lung vascular permeability in vivo. Mechanically, shSHP2-rescued LPS induced increase in LDH activity, MDA, and iron levels, and decrease in GSH levels, as well as the accumulation of reactive oxygen species in vivo and in vitro, leading to an alleviation of LPS-induced ferroptosis. Notably, shSHP2 reduced the expression of Acyl-CoA synthetase long-chain 4 (ACSL4). In the rescued experiments, overexpression of ACSL4 abolished the shSHP2-induced reduction of LDH activity, MDA, and iron levels, and increase in GSH levels, thereby aggravating the LPS-induced ferroptosis. These findings concluded that the knockdown of SHP2 attenuated LPS-induced ferroptosis via downregulation of ACSL4 expression in ALI, providing a novel sight for ALI treatment.

Tingli Dazao Xiefei Decoction ameliorates asthma in vivo and in vitro from lung to intestine by modifying NO–CO metabolic disorder mediated inflammation, immune imbalance, cellular barrier damage, oxidative stress and intestinal bacterial disorders

Ethnopharmacological relevanceAsthma is a chronic airway inflammatory disease. Current treatment of mainstream medications has significant side effects. There is growing evidence that the refractoriness of asthma is closely related to common changes in the lung and intestine. The lungs and intestines, as sites of frequent gas exchange in the body, are widely populated with gas signaling molecules NO and CO, which constitute NO–CO metabolism and may be relevant to the pathogenesis of asthma in the lung and intestine. The Chinese herbal formula Tingli Dazao Xiefei Decoction (TD) is commonly used in clinical practice to treat asthma with good efficacy, but there are few systematic evaluations of the efficacy of asthma on NO–CO metabolism, and the mode of action of its improving effect on the lung and intestine is unclear. Aim of the studyTo investigate the effect of TD on the lung and intestine of asthmatic rats based on NO–CO metabolism. Materials and methodsIn vivo, we established a rat asthma model by intraperitoneal injection of sensitizing solution with OVA atomization, followed by intervention by gavage administration of TD. We simultaneously examined alterations in basal function, pathology, NO–CO metabolism, inflammation and immune cell homeostasis in the lungs and intestines of asthmatic rats, and detected changes in intestinal flora by macrogenome sequencing technology, with a view to multi-angle evaluation of the treatment effects of TD on asthmatic rats. In vitro, lung cells BEAS-2B and intestinal cells NCM-460 were used to establish a model of lung injury causing intestinal injury using LPS and co-culture chambers, and lung cells or intestinal cells TD-containing serum was administered to intervene. Changes in inflammatory, NO–CO metabolism-related, cell barrier-related and oxidative stress indicators were measured in lung cells and intestinal cells to evaluate TD on intestinal injury by way of amelioration and in-depth mechanism. ResultsIn vivo, our results showed significant basal functional impairment in the lung and intestine of asthmatic rats, and an inflammatory response, immune cell imbalance and intestinal flora disturbance elicited by NO–CO metabolic disorders were observed (P < 0.05 or 0.01). The administration of TD was shown to deliver a multidimensional amelioration of the impairment induced by NO–CO metabolic disorders (P < 0.05 or 0.01). In vitro, the results showed that LPS-induced lung cells BEAS-2B injury could cause NO–CO metabolic disorder-induced inflammatory response, cell permeability damage and oxidative stress damage in intestinal cells NCM-460 (P < 0.01). The ameliorative effect on intestinal cells NCM-460 could only be exerted when TD-containing serum interfered with lung cells BEAS-2B (P < 0.01), suggesting that the intestinal ameliorative effect of TD may be exerted indirectly through the lung. ConclusionTD can ameliorate NO–CO metabolism in the lung and thus achieve the indirectly amelioration of NO–CO metabolism in the intestine, ultimately achieving co-regulation of lung and intestinal inflammation, immune imbalance, cellular barrier damage, oxidative stress and intestinal bacterial disorders in asthma in vivo and in vitro. Targeting lung and intestinal NO–CO metabolic disorders in asthma may be a new therapeutic idea and strategy for asthma.

Complex probiotics alleviate ampicillin-induced antibiotic-associated diarrhea in mice.

Antibiotic-associated diarrhea (AAD) is a common side effect during antibiotic treatment, which can cause dysbacteriosis of the gut microbiota. Previous studies have shown beneficial effects in AAD treatment with Bifidobacterium lactis XLTG11, Lactobacillus casei Zhang, Lactobacillus plantarum CCFM8661, and Lactobacillus rhamnosus Probio-M9. However, no studies have been conducted on the immunomodulatory effects and protective intestinal barrier function of four complex probiotics. The aim of our study is to investigate the alleviation effects of complex probiotics on ampicillin-induced AAD. Thirty-six BALB/c mice were randomly divided into six groups: normal control group (NC), model control group (MC), low-, medium-, and high-dose probiotics groups (LD, MD, and HD), and positive drug (Bifico, 1 × 107 cfu) control group (PDC; Bifico, also known as Bifidobacterium Triple Live Capsule, is composed of Bifidobacterium longum, Lactobacillus acidophilus, and Enterococcus faecalis). An AAD model was established by intragastric administration of ampicillin, by gavage of different doses of complex probiotics and Bifico. The weight gain, fecal water content, loose stool grade, intestinal permeability, total protein and albumin levels, intestinal barrier, cytokine levels, and gut microbiota were determined. The results showed that complex probiotics significantly decreased the fecal water content, loose stool grade, intestinal permeability, and ileum tissue damage. Their application increased the weight gain, SIgA, TP, and ALB levels. Additionally, complex probiotics significantly decreased the levels of pro-inflammatory cytokines and increased those of anti-inflammatory cytokines. Meanwhile, the mRNA expression levels of ZO-1, occludin, claudin-1, and MUC2 were significantly upregulated in the probiotic-treated group. Furthermore, the complex probiotics increased the gut microbiota diversity and modulated the changes in the gut microbiota composition caused by ampicillin. At the phylum level, the abundance of Proteobacteria in the HD group was lower than that in the MC group, whereas that of Bacteroidetes was higher. At the genus level, the abundances of Klebsiella and Parabacteroides in the HD group were lower, whereas those of Bacteroides, Muribaculaceae, and Lactobacillus were higher than those in the MC group. Moreover, Spearman's correlation analysis also found that several specific gut microbiota were significantly correlated with AAD-related indicators. We found that complex probiotics improved the diarrhea-related indexes, regulated gut microbiota composition and diversity, increased the expression levels of intestinal protective barrier-related genes, preserved the intestinal barrier function, and relieved inflammation and intestinal injury, thereby effectively improving AAD-associated symptoms. Graphical Abstract.

Alterations of the intestinal mucus layer correlate with dysbiosis and immune dysregulation in human Type 1 Diabetes

In preclinical models of Type 1 Diabetes (T1D) the integrity of the gut barrier (GB) is instrumental to avoid dysregulated crosstalk between the commensal microbiota and immune cells and to prevent autoimmunity. The GB is composed of the intestinal epithelial barrier (IEB) and of the mucus layer containing mucins and antimicrobial peptides (AMPs) that are crucial to maintain immune tolerance. In preclinical models of T1D the alterations of the GB primarily affect the mucus layer. In human T1D increased gut permeability and IEB damage have been demonstrated but the integrity of the mucus layer was never assessed. We evaluated GB integrity by measuring serological markers of IEB damage (serological levels of zonulin) and bacterial translocation such as lipopolysaccharide binding protein (LBP) and myeloid differentiation protein 2 (MD2), and mRNA expression of tight junction proteins, mucins and AMPs in intestinal tissue of T1D patients and healthy controls (HC). Simultaneously, we performed immunological profiling on intestinal tissue and 16S rRNA analysis on the mucus-associated gut microbiota (MAGM). Our data show a GB damage with mucus layer alterations and reduced mRNA expression of several mucins (MUC2, MUC12, MUC13, MUC15, MUC20, MUC21) and AMPs (HD4 and HD5) in T1D patients. Mucus layer alterations correlated with reduced relative abundance of short chain fatty acids (SCFA)-producing bacteria such as Bifidobacterium dentium, Clostridium butyricum and Roseburia intestinalis that regulate mucin expression and intestinal immune homeostasis. In T1D patients we also found intestinal immune dysregulation with higher percentages of effector T cells such as T helper (Th) 1, Th17 and TNF-α+ T cells. Our data show that mucus layer alterations are present in T1D subjects and associated with dysbiosis and immune dysregulation. Research Grants from the Juvenile Diabetes Foundation (Grant 1-INO-2018-640-A-N to MF and 2-SRA-2019-680-S-B to JD) and from the Italian Ministry of Health (Grant RF19-12370721 to MF).

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.