Bacterial Mortality Research Articles

Incidence of Acute Cellular Rejection After Granulocyte Colony-Stimulating Factor in Lung Transplant Recipients

Background Neutropenia is a common complication in lung transplant recipients (LTRs). Filgrastim may be used to treat neutropenia in LTRs, but its consequences on acute cellular rejection (ACR) remain controversial. Objective: The purpose was to examine the association between filgrastim and incidence of ACR 6 months after filgrastim administration in LTRs. Secondary outcomes included burden of ACR, infections, chronic lung allograft dysfunction (CLAD), and survival. Methods: This was a matched cohort study of patients transplanted between January 2010 and October 2019. LTRs who received filgrastim for neutropenia were compared to a cohort who did not. LTRs were matched on transplant indication, sex, age, and time post-transplant and multivariable logistic regression models were used to evaluate the likelihood of ACR. Results: 212 patients were included in the analysis (106 in each group). 50 patients (47.2%) in the filgrastim group experienced ACR compared to 37 patients (34.9%) in the no filgrastim group (P = .070). In multivariable analysis, filgrastim use was not associated with ACR at 6 months (OR 1.409, 95% CI 0.772-2.571). Time to first ACR was shorter (P = .049) and 6-month ACR score was higher in the filgrastim group (.49 vs .33, P = .047). LTRs in the filgrastim group had higher incidence of bacterial pneumonia and 1-year mortality. Conclusions: Although not associated with increased likelihood of ACR at 6 months, our study found that filgrastim is associated with increased ACR burden and decreased time to ACR. This study can help inform clinicians of ACR risk after filgrastim use in LTRs.

Why Did Black Soldiers Historically Have More Pneumonia Than White Soldiers in the U.S. Army?

Black U.S. Army soldiers had four times as much bacterial pneumonia as White U.S. Army soldiers during both the U.S. Civil War and World War I (WWI). Pneumonia case fatality rates were a third greater in Black soldiers during the U.S. Civil War, but were the same between the racial groups by WWI. During WWII, the use of antibiotics decreased bacterial pneumonia mortality rates 100-fold and apparently erased racial differences. Similar differences in bacterial pneumonia rates by racial group were observed in African colonial soldiers of the French and British Armies during WWI. Pneumonia rates in Indian, Filipino, and Puerto Rican soldiers suggested that genetic polymorphisms were not a decisive factor determining Black pneumonia mortality. Postmeasles pneumonias did not suggest an immune deficit in Black soldiers. Geographic focus of pneumonia in Black soldiers from the southern U.S. states and other tropical regions raises the possibility that increased bacterial pneumonia rates were related indirectly to malaria infections. Malaria remains a difficult-to-measure but potentially important mortality risk factor in pneumonia.

Ascitic Fluid Calprotectin And Ratio Of Calprotectin To Total Protein In Spontaneous Bacterial Peritonitis.

To evaluate the diagnostic and prognostic role of ascitic fluid calprotectin and its ratio to total protein in spontaneous bacterial peritonitis cases. The prospective study was conducted at Kafrelsheikh University Hospital, Egypt, from November 2019 to December 2020, and comprised cirrhotic patients of either gender with ascites. Diagnostic abdominal paracentesis was performed for all patients and ascetic fluid calprotectin was measured. Patients were followed for development of spontaneous bacterial peritonitis or mortality. Data was analysed using SPSS 20. Of the 90 patients, 61(67.7%) were males and 29(32.2%) were females. There were 67(74.4%) patients with spontaneous bacterial peritonitis; 48(71.6%) males and 19(28.3%) females with mean age 60.42±8.3 years. The remaining 23(25.5%) did not have spontaneous bacterial peritonitis; 13(56.5%) males and 10(43.4%) females with mean age 59.7±7.4 years. The patients had significantly higher calprotectin, and calprotectin/total protein ratio (p<0.05). Logistic regression identified ascitic fluid calprotectin as a significant predictor of mortality (p=0.05). The non-survivors had significantly higher ascitic fluid calprotectin and calprotectin/total protein ratio compared to the survivors (p<0.05). Ascites calprotectin level and itsratio to total protein wasfound to be accurate diagnostic and predictive biomarkers for spontaneous bacterial peritonitis.

O-Polysaccharides of LPS Modulate E. coli Uptake by Acanthamoeba castellanii.

Protozoan grazing is a major cause of bacterial mortality and controls bacterial population size and composition in the natural environment. To enhance their survival, bacteria evolved many defense strategies to avoid grazing by protists. Cell wall modification is one of the defense strategies that helps bacteria escape from recognition and/or internalization by its predators. Lipopolysaccharide (LPS) is the major component of Gram-negative bacterial cell wall. LPS is divided into three regions: lipid A, oligosaccharide core and O-specific polysaccharide. O-polysaccharide as the outermost region of E. coli LPS provides protection against predation by Acanthamoeba castellanii; however, the characteristics of O-polysaccharide contribute to this protection remain unknown. Here, we investigate how length, structure and composition of LPS affect E. coli recognition and internalization by A. castellanii. We found that length of O-antigen does not play a significant role in regulating bacterial recognition by A. castellanii. However, the composition and structure of O-polysaccharide play important roles in providing resistance to A. castellanii predation.

Effectiveness of katuk leaf chlorophyll (Sauropus androgynus (L) Merr) with blue and red laser a ctivation to reduce Aggregatibacter actinomycetemcomitans and Enterococcus faecalis biofilm

In this study, the efficacy of using Sauropus androgynus (L) Merr, a katuk leaf chlorophyll photosensitizer, to reduce Aggregatibacter actinomycetemcomitans and Enterococcus faecalis biofilm was investigated. A red and blue diode laser is used as the light source. The sample was split into four groups: a negative control group, a positive control group, a blue laser treatment group (B), and a red laser treatment group (R), both with and without the addition of katuk leaf chlorophyll 1.6 mg/ml, and with varying densities of laser energy exposure of 2.5 J/cm2, 5 J/cm2, 7.5 J/cm2, and 10 J/cm2. Laser exposure and chlorophyll photosensitizer were tested using ELISA and ANOVA. At an energy density of 10 J/cm2, the optimal bacterial mortality rate was obtained in each treatment group. Namely, in the Aggregatibacter actinomycetemcomitans biofilm, the negative group, the number of deaths was 73.30% using a blue diode laser and 63.25% using a red diode laser. In the positive group, the number of deaths was 86.12% using a blue diode laser and 83.29% using a red diode laser. In the Enterococcus faecalis biofilm, in the negative group, the number of deaths was 67.78% using the blue diode laser and 75.33% using the red diode laser, and in the positive group, the number of deaths was 71.71% using the blue diode laser and 86.41 using a red diode laser. Exposure to blue and red diode lasers activates chlorophyll in katuk leaves, killing bacteria and reducing biofilms.

Prevalence of bacterial bloodstream infections and association between neutropenia and 30-day mortality among oncology inpatients at a university hospital in Saudi Arabia.

Cancer patients are highly prone to develop bacterial bloodstream infections (BSI) and are also at risk of neutropenia. Knowledge of the prevalence of these infections and whether neutropenia is associated with a change in mortality is important to more effective management and reducing mortality and morbidity. Estimate the prevalence of bacterial BSI among oncology inpatients and assess the associations of 30-day mortality with Gram stain results and neutropenia. Retrospective cross-sectional SETTING: University hospital in Saudi Arabia. We retrieved records of oncology inpatients at King Khalid University Hospital, excluding patients without malignancy and with non-bacterial BSI. The number of records included in the analysis was reduced based on a sample size calculation and systematic random sampling used to select patients to include in the study. Prevalence of bacterial BSI and association between neutropenia and 30-day mortality. 423. The prevalence of bacterial bloodstream infections was 18.9% (n=80). Gram-negative bacteria were more prevalent (n=48, 60.0%) than gram-positive bacteria, with the most common being Escherichia coli (n=20, 25.0%). The 23 patients (28.8%) who died included 16 (69.6%) with gram-negative infections and 7 (30.4%) with gram-positive infections. There was no statistically significant association of bacterial BSI-related 30-day mortality with Gram stain (P=.32). Of 18 patients (22.5%) who were neutropenic, only one (5.6%) died. Sixty-two (77.5%) patients were non-neutropenic, of whom 22 (35.50%) died. We found a statistically significant association between the presence of neutropenia and bacterial BSI-related 30-day mortality (P=.016), with mortality being lower among neutropenic patients. Gram-negative bacteria are more prevalent in bacterial BSI than gram-positive bacteria. No statistically significant association of Gram stain result with mortality was found. However, the 30-day mortality rate was lower among neutropenic patients than among non-neutropenic patients. We recommend further investigation with a larger sample size in multiple regions to further unravel the association of neutropenia with bacterial bloodstream infection-related 30-day mortality. Lack of regional data and sample size. None.

ZIP8 impacts protease activity in macrophages in response to Streptococcus pneumoniae

Abstract Zinc (Zn) is essential for immune function and Zn deficiency increases the incidence of community acquired pneumonia. The Zn transporter ZIP8 is required by myeloid cells to defend against pathogens. Previously, we reported that S. pneumoniae infected ZIP8 knockout mice (Zip8KO) have increased bacterial burden and mortality and that Zip8KO bone marrow derived macrophages (BMDMs) have reduced phagocytic activity. Others have shown that Zn induces cathepsin expression via the TFEB pathway. However, it is unknown whether ZIP8 impacts TFEB-dependent phagolysosomal processing in macrophages. Based on this, we hypothesized that ZIP8 facilitates phagolysosomal processing and eradication of bacteria via TFEB. BMDMs were derived from wild type and Zip8KO mice and then exposed to S. pneumoniae(MOI=10) for 1 hour. At 6–18 hours post challenge we assessed cathepsin B and L mRNA and protein levels as well as total protease, cathepsin B and L activity. In conjunction, we measured p-TFEB and total TFEB proteins levels. Active TFEB and cathepsin B protein levels were significantly lower in Zip8KO BMDMs with no difference in cathepsin L. Strikingly, Zip8KO BMDMs had significantly reduced total protease, cathepsin B and cathepsin L activity which also corresponded with decreased mRNA levels. Based on these findings we predict that ZIP8 loss in macrophages impairs phagolysosomal processing and bacterial eradication in a TFEB-dependent manner. Overall, this warrants future studies given the high incidence of Zn deficiency and the rs13107325 defective ZIP8 allele in humans. National Heart, Lung and Blood Institute #1R01HL156952-01-A1 (DLK)

How much do bacterial growth properties and biodegradable dissolved organic matter control water quality at low flow?

Abstract. The development of accurate water quality modeling tools is necessary for integrated water quality management of river systems. Even though some water quality models can simulate dissolved oxygen (DO) concentrations accurately during high-flow periods and phytoplankton blooms in rivers, significant discrepancies remain during low-flow periods, when the dilution capacity of the rivers is reduced. We use the C-RIVE biogeochemical model to evaluate the influence of controlling parameters on DO simulations at low flow. Based on a coarse model pre-analysis, three sensitivity analyses (SAs) are carried out using the Sobol method. The parameters studied are related to bacterial community (e.g., bacterial growth rate), organic matter (OM; partitioning and degradation of OM into constituent fractions), and physical factors (e.g., reoxygenation of the river due to navigation and wind). Bacterial growth and mortality rates are found to be by far the two most influential parameters, followed by bacterial growth yield. More refined SA results indicate that the biodegradable fraction of dissolved organic matter (BDOM) and the bacterial growth yield are the most influential parameters under conditions of a high net bacterial growth rate (= growth rate − mortality rate), while bacterial growth yield is independently dominant in low net growth situations. Based on the results of this study, proposals are made for in situ measurement of BDOM under an urban area water quality monitoring network that provides high-frequency data. The results also indicate the need for bacterial community monitoring in order to detect potential bacterial community shifts after transient events such as combined sewer overflows and modifications in internal processes of treatment plants. Furthermore, we discuss the inclusion of BDOM in statistical water quality modeling software for improvement in the estimation of organic matter inflow from boundary conditions.

Pyroptotic gasdermin exists in Mollusca and is vital to eliminating bacterial infection

Gasdermin (GSDM) is a family of proteins that execute pyroptosis in vertebrate. In invertebrate, pyroptotic GSDM was documented only in coral. Recent studies identified abundant GSDM structural homologs in Mollusca, but their functions are unclear. Herein, we report a functional GSDM from Pacific abalone Haliotis discus (HdGSDME). HdGSDME is specifically activated by abalone caspase 3 (HdCASP3) cleavage at two distinct sites, generating two active isoforms with pyroptotic and cytotoxic activities. HdGSDME possesses evolutionarily conserved residues that proved to be essential to the N-terminal pore-formation and C-terminal auto-inhibition capacities. Bacterial challenge activates the HdCASP3-HdGSDME pathway and induces pyroptosis and extracellular traps in abalone. Blockage of the HdCASP3-HdGSDME axis promotes bacterial invasion and host mortality. Collectively, this study reveals the existence of functionally conserved and yet distinct-featured GSDM in Mollusca and provides insights into the function and evolution of invertebrate GSDM.

Dissolved storage glycans shaped the community composition of abundant bacterioplankton clades during a North Sea spring phytoplankton bloom

BackgroundBlooms of marine microalgae play a pivotal role in global carbon cycling. Such blooms entail successive blooms of specialized clades of planktonic bacteria that collectively remineralize gigatons of algal biomass on a global scale. This biomass is largely composed of distinct polysaccharides, and the microbial decomposition of these polysaccharides is therefore a process of prime importance.ResultsIn 2020, we sampled a complete biphasic spring bloom in the German Bight over a 90-day period. Bacterioplankton metagenomes from 30 time points allowed reconstruction of 251 metagenome-assembled genomes (MAGs). Corresponding metatranscriptomes highlighted 50 particularly active MAGs of the most abundant clades, including many polysaccharide degraders. Saccharide measurements together with bacterial polysaccharide utilization loci (PUL) expression data identified β-glucans (diatom laminarin) and α-glucans as the most prominent and actively metabolized dissolved polysaccharide substrates. Both substrates were consumed throughout the bloom, with α-glucan PUL expression peaking at the beginning of the second bloom phase shortly after a peak in flagellate and the nadir in bacterial total cell counts.ConclusionsWe show that the amounts and composition of dissolved polysaccharides, in particular abundant storage polysaccharides, have a pronounced influence on the composition of abundant bacterioplankton members during phytoplankton blooms, some of which compete for similar polysaccharide niches. We hypothesize that besides the release of algal glycans, also recycling of bacterial glycans as a result of increased bacterial cell mortality can have a significant influence on bacterioplankton composition during phytoplankton blooms.A8iwHBb1oEC4q82u7HbzQ4Video

High rifampicin peak plasma concentrations accelerate the slow phase of bacterial decline in tuberculosis patients: Evidence for heteroresistance.

Antibiotic treatments are often associated with a late slowdown in bacterial killing. This separates the killing of bacteria into at least two distinct phases: a quick phase followed by a slower phase, the latter of which is linked to treatment success. Current mechanistic explanations for the in vitro slowdown are either antibiotic persistence or heteroresistance. Persistence is defined as the switching back and forth between susceptible and non-susceptible states, while heteroresistance is defined as the coexistence of bacteria with heterogeneous susceptibilities. Both are also thought to cause a slowdown in the decline of bacterial populations in patients and therefore complicate and prolong antibiotic treatments. Reduced bacterial death rates over time are also observed within tuberculosis patients, yet the mechanistic reasons for this are unknown and therefore the strategies to mitigate them are also unknown. We analyse a dose ranging trial for rifampicin in tuberculosis patients and show that there is a slowdown in the decline of bacteria. We show that the late phase of bacterial killing depends more on the peak drug concentrations than the total drug exposure. We compare these to pharmacokinetic-pharmacodynamic models of rifampicin heteroresistance and persistence. We find that the observation on the slow phase's dependence on pharmacokinetic measures, specifically peak concentrations are only compatible with models of heteroresistance and incompatible with models of persistence. The quantitative agreement between heteroresistance models and observations is very good ([Formula: see text]). To corroborate the importance of the slowdown, we validate our results by estimating the time to sputum culture conversion and compare the results to a different dose ranging trial. Our findings indicate that higher doses, specifically higher peak concentrations may be used to optimize rifampicin treatments by accelerating bacterial killing in the slow phase. It adds to the growing body of literature supporting higher rifampicin doses for shortening tuberculosis treatments.

Characterization of the pathogenicity of extraintestinal pathogenic Escherichia coli isolates from pneumonia-infected lung samples of dogs and cats in South Korea

This study aimed to investigate the pathogenicity of extraintestinal pathogenic Escherichia coli (ExPEC) isolated from dog and cat lung samples in South Korea. A total of 101 E. coli isolates were analyzed for virulence factors, phylogroups, and O-serogroups, and their correlation with bacterial pneumonia-induced mortality was elucidated. P fimbriae structural subunit (papA), hemolysin D (hlyD), and cytotoxic necrotizing factor 1 (cnf1) were highly prevalent in both species, indicating correlation with bacterial pneumonia. Phylogroups B1 and B2 were the most prevalent phylogroups (36.6% and 32.7%, respectively) and associated with high bacterial pneumonia-induced mortality rates. Isolates from both species belonging to phylogroup B2 showed high frequency of papA, hlyD, and cnf1. O-serogrouping revealed 21 and 15 serogroups in dogs and cats, respectively. In dogs, O88 was the most prevalent serogroup (n = 8), and the frequency of virulence factors was high for O4 and O6. In cats, O4 was the most prevalent serogroup (n = 6), and the frequency of virulence factors was high for O4 and O6. O4 and O6 serogroups were mainly grouped under phylogroup B2 and associated with high bacterial pneumonia-induced mortality. This study characterized the pathogenicity of ExPEC and described the probability of ExPEC pneumonia-induced mortality.

The Effect Of Corticosteroid Therapy on the Frequency of Secondary Bacterial Infections And Mortality in COVID-19 Patients in ICU

Objectives:There are recommendations and studies for the corticosteroid treatment of cytokine storm and ARDS in COVID-19 disease. The aim is to evaluate the rates of secondary infections and mortality in COVID-19 patients receiving various doses of corticosteroid treatment in the ICU.&#x0D; Methods: In a retrospective approach, 621 patients were analyzed and recorded in terms of age, gender, duration of mechanical ventilation, length of stay in intensive care, CRP, procalcitonin, LDH, IL-6, lymphocyte, D-dimer, ferritin values and corticosteroid doses as well as blood, urine, and tracheal aspiration growths. The patients were examined in 6 groups those who never took corticosteroids and those who took Methylprednisolone (MP) in doses of 250 mg, &gt;250 mg, 80 mg, 40 mg, and 6 mg dexamethasone. The data were evaluated to determine if there have been significant relationships between corticosteroid doses and the rates of secondary infection and mortality.&#x0D; Results: The mean hospital stay of the patients was 11.2 ± 7.71 days, and the mean of invasive mechanical ventilation was 7.5 days. There was no significant difference between patients who did not use corticosteroids and patients who received 40 mg MP for the length of hospital stay. The length of hospital stay was significantly longer in the corticosteroid groups (p

Nutrients strengthen density dependence of per-capita growth and mortality rates in the soil bacterial community.

Density dependence in an ecological community has been observed in many macro-organismal ecosystems and is hypothesized to maintain biodiversity but is poorly understood in microbial ecosystems. Here, we analyze data from an experiment using quantitative stable isotope probing (qSIP) to estimate per-capita growth and mortality rates of bacterial populations in soils from several ecosystems along an elevation gradient which were subject to nutrient addition of either carbon alone (glucose; C) or carbon with nitrogen (glucose + ammonium-sulfate; C + N). Across all ecosystems, we found that higher population densities, quantified by the abundance of genomes per gram of soil, had lower per-capita growth rates in C + N-amended soils. Similarly, bacterial mortality rates in C + N-amended soils increased at a significantly higher rate with increasing population size than mortality rates in control and C-amended soils. In contrast to the hypothesis that density dependence would promote or maintain diversity, we observed significantly lower bacterial diversity in soils with stronger negative density-dependent growth. Here, density dependence was significantly but weakly responsive to nutrients and was not associated with higher bacterial diversity.

Sensitivity and predictive value of dysentery in diagnosing shigellosis among under five children in Zambia.

Shigella is a leading cause of bacterial diarrhea morbidity and mortality affecting mainly children under five in the developing world. In Zambia, Shigella has a high prevalence of 34.7% in children with diarrhea and an attributable fraction of 6.7% in Zambian children with moderate to severe diarrhea. Zambian diarrhea management guidelines and the health ministry reporting tool Health Management Information System (HMIS) heavily rely on the WHO clinical classification of dysentery to potentially identify and estimate the burden of Shigella in children. This reliance on clinical dysentery as a proxy to shigellosis in under five children may be resulting in gross under-estimation of shigella disease burden in Zambia. We used existing laboratory and clinical data to examine the sensitivity and predictive value of dysentery to correctly identify Shigella infection in under five children with PCR confirmed Shigella infection in Lusaka and Ndola districts, Zambia. Clinical dysentery had a sensitivity of 8.5% (34/401) in identifying under five children with Shigella by stool PCR. Dysentery was able to correctly classify Shigella in 34 of 68 bloody stool samples giving a corresponding positive predictive value of 50%. Of the 1087 with non-bloody diarrhea, 720 did not have Shigella giving a negative predictive value of 66.2%. Use of clinical dysentery as a screening symptom for Shigella infection in children under five presenting with moderate to severe diarrhea has low sensitivity and low positive predictive value respectively. Clinical dysentery as a screening symptom for Shigella contributes to gross under diagnosis and reporting of Shigella infection among under five children in Zambia. Further research is required to better inform practice on more accurate methods or tools to use in support of routine diagnosis, particularly in low middle-income settings where laboratory diagnosis remains a challenge.

The Synergic Effect of Erythrosine and Gold Nanoparticles in Photodynamic Inactivation

Photodynamic inactivation (PDI) is a process that uses photosensitizing substances to produce reactive oxygen species. This is achieved by exposing photosensitizers to specific wavelengths of light and causing oxidative damage in cells. This sterilization technique is commonly utilized and has been extensively investigated owing to its environmentally friendly and inert characteristics. In this study, erythrosine was selected as the photosensitizer and a green light-emitting diode was used as the light source. Due to their excellent biocompatibility, gold nanoparticles were added; these acted as a carrier for erythrosine, linking it to Escherichia coli (E. coli) cells. Colony-forming unit plate counting and LIVE/DEAD bacterial viability tests were performed. A synergic PDI effect of the photosensitizer, light, and gold nanoparticles was demonstrated. After irradiation for 9 min, a bacterial death rate higher than 97% was achieved. Finally, to study the mechanism of E. coli death, we conducted reactive oxygen species tests by adding different scavengers, and concluded that the bacterial death was due to the production of singlet oxygen (Type II reaction).

MOF-Integrated Hierarchical Composite Fiber for Efficient Daytime Radiative Cooling and Antibacterial Protective Textiles.

Incorporating passive radiative cooling into textiles is an effective way to improve individual personalized thermophysiological comfort for the human body. Based on radiative cooling textile design, rational functionalization further facilitates practical applications, especially for medical protective products with customized requirements. Herein, we present a hierarchical polyurethane/metal-organic framework (MOF) composite nanofiber membrane with an integrated radiative cooling effect and photocatalytic antibacterial property. Fabricated by a scalable electrospinning method, the hierarchical nanofiber membrane shows high solar reflectance of 97% and improved thermal emissivity of 93% attributed to the abundant chemical bonds in ZIF-8 nanoparticles, rendering a temperature drop of ∼7.2 °C under direct sunlight and ∼5.5 °C at night. In addition, the photocatalytic activity of ZIF-8 ensures a 96% bacterial mortality rate for preventing bacterial infection. In practical application, our composite fabric can prevent superheating by 4.4 °C compared with the traditional protective suit under direct sunlight. Along with its anti-infection ability, the composite fabric is desirable for medical protective textiles. The innovative integration of passive radiative cooling design and functional MOFs breaks through the traditional cooling mode and provides huge substantial advantages for smart textiles and personal cooling applications.

Inhibition of sphingosine-1-phosphate receptor 3 suppresses ATP-induced NLRP3 inflammasome activation in macrophages via TWIK2-mediated potassium efflux.

Inhibition of sphingosine kinase 1 (SphK1), which catalyzes bioactive lipid sphingosine-1-phosphate (S1P), attenuates NLRP3 inflammasome activation. S1P exerts most of its function by binding to S1P receptors (S1PR1-5). The roles of S1P receptors in NLRP3 inflammasome activation remain unclear. The mRNA expressions of S1PRs in bone marrow-derived macrophages (BMDMs) were measured by real-time quantitative polymerase chain reaction (qPCR) assays. BMDMs were primed with LPS and stimulated with NLRP3 activators, including ATP, nigericin, and imiquimod. Interleukin-1β (IL-1β) in the cell culture supernatant was detected by enzyme-linked immunosorbent assay (ELISA). Intracellular potassium was labeled with a potassium indicator and was measured by confocal microscopy. Protein expression in whole-cell or plasma membrane fraction was measured by Western blot. Cecal ligation and puncture (CLP) was induced in C57BL/6J mice. Mortality, lung wet/dry ratio, NLRP3 activation, and bacterial loads were measured. Macrophages expressed all five S1PRs in the resting state. The mRNA expression of S1PR3 was upregulated after lipopolysaccharide (LPS) stimulation. Inhibition of S1PR3 suppressed NLRP3 and pro-IL-1β in macrophages primed with LPS. Inhibition of S1PR3 attenuated ATP-induced NLRP3 inflammasome activation, enhanced nigericin-induced NLRP3 activation, and did not affect imiquimod-induced NLRP3 inflammasome activation. In addition, inhibition of S1PR3 suppressed ATP-induced intracellular potassium efflux. Inhibition of S1PR3 did not affect the mRNA or protein expression of TWIK2 in LPS-primed BMDMs. ATP stimulation induced TWIK2 expression in the plasma membrane of LPS-primed BMDMs, and inhibition of S1PR3 impeded the membrane expression of TWIK2 induced by ATP. Compared with CLP mice treated with vehicle, CLP mice treated with the S1PR3 antagonist, TY52156, had aggravated pulmonary edema, increased bacterial loads in the lung, liver, spleen, and blood, and a higher seven-day mortality rate. Inhibition of S1PR3 suppresses the expression of NLRP3 and pro-IL-1β during LPS priming, and attenuates ATP-induced NLRP3 inflammasome activation by impeding membrane trafficking of TWIK2 and potassium efflux. Although inhibition of S1PR3 decreases IL-1β maturation in the lungs, it leads to higher bacterial loads and mortality in CLP mice.

Soil microbial legacies influence freeze–thaw responses of soil

Abstract Warmer winters with less snowfall are increasing the frequency of soil freeze–thaw cycles across temperate regions. Soil microbial responses to freeze–thaw cycles vary and some of this variation may be explained by microbial conditioning to prior winter conditions, yet such linkages remain largely unexplored. We investigated how differences in temperature history influenced microbial community composition and activity in response to freeze–thaw cycles. We collected soil microbial communities that developed under colder (high elevation) and warmer (low elevation) temperature regimes in spruce‐fir forests, then added each of these soil microbial communities to a sterile bulk‐soil in a laboratory microcosm experiment. The inoculated high‐elevation cold and low‐elevation warm microcosms were subjected to diurnal freeze–thaw cycles or constant above‐freezing temperature for 9 days. Then, all microcosms were subjected to a 7‐day above‐freezing recovery period. Overall, we found that the high‐elevation cold community had, relative to the low‐elevation warm community, a smaller reduction in microbial respiration (CO2 flux) during freeze–thaw cycles. Further, the high‐elevation cold community, on average, experienced lower freeze–thaw‐induced bacterial mortality than the warm community and may have partly acclimated to freeze–thaw cycles via increased lipid membrane fluidity. Respiration of both microbial communities quickly recovered following the end of the freeze–thaw treatment period and there were no changes in soil extractable carbon or nitrogen. Our results provide evidence that past soil temperature conditions may influence the responses of soil microbial communities to freeze–thaw cycles. The microbial community that developed under a colder temperature regime was more tolerant of freeze–thaw cycles than the community that developed under a warmer temperature regime, although both communities displayed some level of resilience. Taken together, our data suggest that microbial communities conditioned to less extreme winter soil temperatures may be most vulnerable to rapid changes in freeze–thaw regimes as winters warm, but they also may be able to quickly recover if mortality is low. Read the free Plain Language Summary for this article on the Journal blog.

The Effects of Reactive Oxygen and Nitrogen Species (RONS) Produced by Surface Dielectric Barrier Discharge (SDBD) Non-Thermal Plasma with Treatment Time and Distance Variations to Kill Escherichia coli

Research on the inactivation of Escherichia coli causing diarrheal disease using non-thermal plasma SDBD has been carried out. SDBD is a new technique for non-thermal plasma generation with several advantages: low power generation, comprehensive treatment area coverage, and reducing the potential effects of burning and drying tissue. This study aimed to analyze the effect of treatment time variations, namely 0 as control, 60, 75, 90, 105, and 120 seconds and treatment distance variations of 3, 6, 9, 12, and 15 mm of non-thermal plasma treatment of SDBD on E. coli. The results of the non-thermal plasma SDBD treatment with variations in time and distance showed that the longer the treatment time, the more bacterial cells died. Colony counts decreased to 4.33 x 107 CFU/mL compared to the control, 409 x 107 CFU/mL, with a treatment time variation of 120 seconds, yielding the best treatment results. At the same time, the results of the treatment for variations in the non-thermal plasma distance of SDBD showed that the smaller the treatment distance, the greater the bacterial death rate, with the best treatment results at a 3 mm treatment interval, with colony counts of 8 x 107 CFU/mL, compared to 409 x 107 CFU/mL in control. Based on these results, SDBD non-thermal plasma treatment can be used to inactivate or kill bacteria with effectiveness in killing bacteria depending on the length of treatment time and the distance of treatment.