bims-traimu 2022-10-16 papers

Issue of 2022–10–16
five papers selected by
Yantong Wan, Southern Medical University

Front Immunol. 2022 ;13 977235

Proline metabolism reprogramming of trained macrophages induced by early respiratory infection combined with allergen sensitization contributes to development of allergic asthma in childhood of mice.

Hanglin Li, Linyan Ma, Wenjian Li, Boyang Zheng, Junhai Wang, Shunyan Chen, Yang Wang, Fei Ge, Beibei Qin, Xiaoqing Zheng, Yuqing Deng, Ruihong Zeng.

Background: Infants with respiratory syncytial virus (RSV)-associated bronchiolitis are at increased risk of childhood asthma. Recent studies demonstrated that certain infections induce innate immune memory (also termed trained immunity), especially in macrophages, to respond more strongly to future stimuli with broad specificity, involving in human inflammatory diseases. Metabolic reprogramming increases the capacity of the innate immune cells to respond to a secondary stimulation, is a crucial step for the induction of trained immunity. We hypothesize that specific metabolic reprogramming of lung trained macrophages induced by neonatal respiratory infection is crucial for childhood allergic asthma.
Objective: To address the role of metabolic reprogramming in lung trained macrophages induced by respiratory virus infection in allergic asthma.
Methods: Neonatal mice were infected and sensitized by the natural rodent pathogen Pneumonia virus of mice (PVM), a mouse equivalent strain of human RSV, combined with ovalbumin (OVA). Lung CD11b+ macrophages in the memory phase were re-stimulated to investigate trained immunity and metabonomics. Adoptive transfer, metabolic inhibitor and restore experiments were used to explore the role of specific metabolic reprogramming in childhood allergic asthma.
Results: PVM infection combined with OVA sensitization in neonatal mice resulted in non-Th2 (Th1/Th17) type allergic asthma following OVA challenge in childhood of mice. Lung CD11b+ macrophages in the memory phage increased, and showed enhanced inflammatory responses following re-stimulation, suggesting trained macrophages. Adoptive transfer of the trained macrophages mediated the allergic asthma in childhood. The trained macrophages showed metabolic reprogramming after re-stimulation. Notably, proline biosynthesis remarkably increased. Inhibition of proline biosynthesis suppressed the development of the trained macrophages as well as the Th1/Th17 type allergic asthma, while supplement of proline recovered the trained macrophages as well as the allergic asthma.
Conclusion: Proline metabolism reprogramming of trained macrophages induced by early respiratory infection combined with allergen sensitization contributes to development of allergic asthma in childhood. Proline metabolism could be a well target for prevention of allergic asthma in childhood.

Keywords: allergic asthma; innate immune memory; proline metabolism reprogramming; respiratory virus infection; trained macrophages

DOI: https://doi.org/10.3389/fimmu.2022.977235

Infect Dis Ther. 2022 Oct 15.

Efficacy of Bacillus Calmette-Guérin (BCG) Vaccination in Reducing the Incidence and Severity of COVID-19 in High-Risk Population (BRIC): a Phase III, Multi-centre, Quadruple-Blind Randomised Control Trial.

INTRODUCTION: Universal coverage of vaccines alone cannot be relied upon to protect at-risk populations in lower- and middle-income countries against the impact of the coronavirus disease 2019 (COVID-19) pandemic and newer variants. Live vaccines, including Bacillus Calmette-Guérin (BCG), are being studied for their effectiveness in reducing the incidence and severity of COVID-19 infection.
METHODS: In this multi-centre quadruple-blind, parallel assignment randomised control trial, 495 high-risk group adults (aged 18-60 years) were randomised into BCG and placebo arms and followed up for 9 months from the date of vaccination. The primary outcome was the difference in the incidence of COVID-19 infection at the end of 9 months. Secondary outcomes included the difference in the incidence of severe COVID-19 infections, hospitalisation rates, intensive care unit stay, oxygen requirement and mortality at the end of 9 months. The primary analysis was done on an intention-to-treat basis, while safety analysis was done per protocol.
RESULTS: There was no significant difference in the incidence rates of cartridge-based nucleic acid amplification test (CB-NAAT) positive COVID-19 infection [odds ratio (OR) 1.08, 95% confidence interval (CI) 0.54-2.14] in the two groups, but the BCG arm showed a statistically significant decrease in clinically diagnosed (symptomatic) probable COVID-19 infections (OR 0.38, 95% CI 0.20-0.72). Compared with the BCG arm, significantly more patients developed severe COVID-19 pneumonia (CB-NAAT positive) and required hospitalisation and oxygen in the placebo arm (six versus none; p = 0.03). One patient belonging to the placebo arm required intensive care unit (ICU) stay and died. BCG had a protective efficacy of 62% (95% CI 28-80%) for likely symptomatic COVID-19 infection.
CONCLUSIONS: BCG is protective in reducing the incidence of acute respiratory illness (probable symptomatic COVID-19 infection) and severity of the disease, including hospitalisation, in patients belonging to the high-risk group of COVID-19 infection, and the antibody response persists for quite a long time. A multi-centre study with a larger sample size will help to confirm the findings in this study.
CLINICAL TRIALS REGISTRY: Clinical Trials Registry India (CTRI/2020/07/026668).

Keywords: BCG vaccination; Incidence of COVID-19; Severe COVID-19; Symptomatic COVID-19; Vaccine efficacy

DOI: https://doi.org/10.1007/s40121-022-00703-y

Fish Shellfish Immunol. 2022 Oct 06. pii: S1050-4648(22)00630-1. [Epub ahead of print]

Poly I:C promotes malate to enhance innate immune response against bacterial infection.

Chang Guo, Jing-Zhou Ye, Min Song, Xuan-Xian Peng, Hui Li.

Polyinosinic-polycytidylic acid (poly I:C) is a synthetic analog of double-stranded RNA (dsRNA) that activates anti-infective innate immunity. The underlying mechanisms are identified as targeting pattern recognition receptors and Th1-inducing. However, whether poly I:C manipulates metabolism to implement this anti-infective function is unknown. Here, GC-MS based metabolomics was used to characterize metabolic profiles induced by different doses of poly I:C. Analysis on the dose-dependent metabolomes shows that elevation of the TCA cycle and malate with the increasing dose of ploy I:C forms the most characteristic feature of the poly I:C stimulation. Exogenous malate activates the TCA cycle and elevates survival of zebrafish infected with Vibrio alginolyticus, which is related to the elevated expression of il-1b, il-6, il-8, tnf-a, and c3b. These results reveal a previously unknown regulation of poly I:C that boosts the TCA cycle to enhance innate immunity against bacterial infection.

Keywords: Bacteria; Infection; Innate immunity; Malate; Poly I:C; The TCA cycle; Vibrio alginolyticus

DOI: https://doi.org/10.1016/j.fsi.2022.09.064

J Inflamm Res. 2022 ;15 5635-5648

Sustained Inflammation Induced by LPS Leads to Tolerable Anorexia and Fat Loss via Tlr4 in Mice.

Yale Yang, Wuling Zhong, Yali Zhang, Yalan Cheng, Hejin Lai, Huimin Yu, Ning Feng, Yumo Han, Rui Huang, Qiwei Zhai.

Background: Sustained inflammation is implicated in a variety of pathological conditions like infection, obesity and type 2 diabetes. Lipid metabolism is crucial to support immune response during infection of bacteria. However, how sustained inflammation affects lipid metabolism, especially in white adipose tissue remains largely unknown.
Methods: Sustained inflammation was induced by daily injection of Lipopolysaccharide (LPS). Tlr4 knockout mice were used to study the mechanism. Inflammation and lipid metabolism were evaluated by quantitative PCR, white blood cell counting, nuclear magnetic resonance, fat cell size quantification, lipolysis and fatty acid uptake assays, respiratory exchange ratio, and energy expenditure.
Results: Here, we found that sustained inflammation leads to fat loss in mice with a quick loss and gradual increase manner. Moreover, LPS injection leads to inflammation, anorexia, decreased lipid anabolism, and increased lipid catabolism. Mechanically, we show that LPS induces fat loss, inflammation, anorexia, and alteration of lipid metabolism mainly dependent on Tlr4. Interestingly, sustained inflammation induces less fat loss, especially in epididymal white adipose tissue, than pair-feeding, and pair-feeding has no significant effect on inflammation and leads to less fatty acid uptake, more lipid catabolism and energy expenditure than LPS injection. In addition, we demonstrate that short-term sustained inflammation leads to relative long-term tolerance for LPS-induced anorexia, inflammation and altered lipid metabolism.
Conclusion: These findings demonstrate that sustained inflammation induced by LPS leads to tolerable anorexia and fat loss via Tlr4 in mice, and provide new insights into the effect of sustained inflammation on lipid metabolism and subsequent tolerance.

Keywords: lipid metabolism; lipopolysaccharide; sustained inflammation; tolerance; white adipose tissue

DOI: https://doi.org/10.2147/JIR.S358518

Front Immunol. 2022 ;13 947213

Post-transcriptional regulatory feedback encodes JAK-STAT signal memory of interferon stimulation.

Eirini Kalliara, Malgorzata Kardynska, James Bagnall, David G Spiller, Werner Müller, Dominik Ruckerl, Jarosław Śmieja, Subhra K Biswas, Pawel Paszek.

Immune cells fine tune their responses to infection and inflammatory cues. Here, using live-cell confocal microscopy and mathematical modelling, we investigate interferon-induced JAK-STAT signalling in innate immune macrophages. We demonstrate that transient exposure to IFN-γ stimulation induces a long-term desensitisation of STAT1 signalling and gene expression responses, revealing a dose- and time-dependent regulatory feedback that controls JAK-STAT responses upon re-exposure to stimulus. We show that IFN-α/β1 elicit different level of desensitisation from IFN-γ, where cells refractory to IFN-α/β1 are sensitive to IFN-γ, but not vice versa. We experimentally demonstrate that the underlying feedback mechanism involves regulation of STAT1 phosphorylation but is independent of new mRNA synthesis and cognate receptor expression. A new feedback model of the protein tyrosine phosphatase activity recapitulates experimental data and demonstrates JAK-STAT network's ability to decode relative changes of dose, timing, and type of temporal interferon stimulation. These findings reveal that STAT desensitisation renders cells with signalling memory of type I and II interferon stimulation, which in the future may improve administration of interferon therapy.

Keywords: JAK-STAT network; STAT1 kinetics; interferons; live-cell microscopy; mathematical modelling; pathway desensitisation; signal memory

DOI: https://doi.org/10.3389/fimmu.2022.947213