Promising Anti-Inflammatory Tools: Biomedical Efficacy of Lipoxins and Their Synthetic Pathways.

Lipoxins (LXs) have attracted widespread attention as a class of anti-inflammatory lipid mediators that are produced endogenously by the organism. LXs are arachidonic acid (ARA) derivatives that include four different structures: lipoxin A4 (LXA4), lipoxin B4 (LXB4), and the aspirin-induced differential isomers 15-epi-LXA4 and 15-epi-LXB4. Because of their unique biological activity of reducing inflammation in the body, LXs have great potential for neuroprotection, anti-inflammatory treatment of COVID-19, and other related diseases. The synthesis of LXs in vivo is achieved through the action of lipoxygenase (LO). As a kind of important enzyme, LO plays a major role in the physiological processes of living organisms in mammals and functions in some bacteria and fungi. This suggests new options for the synthesis of LXs in vitro. Meanwhile, there are other chemical and biochemical methods to synthesize LXs. In this review, the recent progress on physiological activity and synthetic pathways of LXs is summarized, and new insights into the synthesis of LXs in vitro are provided.

Protective Immunity against Listeria monocytogenes in Rats, Provided by HCl- and NaOH-Induced Listeria monocytogenes Bacterial Ghosts (LMGs) as Vaccine Candidates.

Listeria monocytogenes (Lm) bacterial ghosts (LMGs) were produced by the minimum inhibitory concentration (MIC) of HCl, H2SO4, and NaOH. Acid and alkali effects on the LMGs were compared by in vitro and in vivo analyses. Scanning electron microscope showed that all chemicals form lysis pores on the Lm cell envelopes. Real-time qPCR revealed a complete absence of genomic DNA in HCl- and H2SO4-induced LMGs but not in NaOH-induced LMGs. HCl-, H2SO4- and NaOH-induced LMGs showed weaker or missing protein bands on SDS-PAGE gel when compared to wild-type Lm. Murine macrophages exposed to the HCl-induced LMGs showed higher cell viability than those exposed to NaOH-induced LMGs or wild-type Lm. The maximum level of cytokine expression (TNF-α, iNOS, IFN-γ, and IL-10 mRNA) was observed in the macrophages exposed to NaOH-induced LMGs, while that of IL-1ß mRNA was observed in the macrophages exposed to HCl-induced LMGs. To investigate LMGs as a vaccine candidate, mice were divided into PBS buffer-injected, HCl- and NaOH-induced LMGs immunized groups. Mice vaccinated with HCl- and NOH-induced LMGs, respectively, significantly increased in specific IgG antibodies, bactericidal activities of serum, and CD4+ and CD8+ T-cell population. Antigenic Lm proteins reacted with antisera against HCl- and NOH-induced LMGs, respectively. Bacterial loads in HCl- and NaOH-induced LMGs immunized mice were significantly lower than PBS-injected mice after virulent Lm challenges. It suggested that vaccination with LMGs induces both humoral and cell-mediated immune responses and protects against virulent challenges.

How well does qSOFA correspond to underlying systemic inflammatory response?

Need for prompt recognition and management of sepsis recently led to the introduction of qSOFA score. However, its association with underlying host inflammatory response remains unclear, while previous studies have challenged its performance in non - intensive care unit (ICU) patients comparing to previously used systemic inflammatory response syndrome (SIRS) criteria. Between June 2016 and April 2017, we performed a prospective observational study in the medical ward of a tertiary hospital to explore the relation of qSOFA ≥ 2 and <2 to underlying inflammatory response, as this is mirrored in levels of serum pro- and anti-inflammatory mediators i.e. IL-6, IL-10 and TNF-α. A total of 100 consecutive patients were finally included in this study. Comparable levels [(pg/ml) median (IQR)] of IL-6 [200 (53-200) vs 65.1 (17.3-200)], IL-10 [ 7 (2.3-170.6) vs 2.3 (2.3-27.7)], and TNF-α [4 (4-46.1) vs 46.06 (4-227.2)] were noted between group of patients with qSOFA ≥ 2 or <2. Nevertheless, prognosis was worse in patients with qSOFA ≥ 2 showing longer length of stay [10 (7-25) vs 5 (3-7) days, p = .03] and lower recovery rates (41 vs 93%, p < .0001). Our results underline the need for prompt management of critically ill patients in presence of systemic inflammatory response regardless of qSOFA score, partly reflecting its low sensitivity comparing to previously used SIRS criteria.

Resolvin D1 primes the resolution process initiated by calorie restriction in obesity-induced steatohepatitis.

Insulin resistance and nonalcoholic steatohepatitis (NASH), characterized by hepatic steatosis combined with inflammation, are major sequelae of obesity. Currently, lifestyle modification (i.e., weight loss) is the first-line therapy for NASH. However, weight loss resolves steatosis but not inflammation. In this study, we tested the ability of resolvin D1 (RvD1), an anti-inflammatory and proresolving molecule, to promote the resolution initiated by calorie restriction in obese mice with NASH. Calorie restriction reduced adipose and liver weight (-56 and -13%, respectively; P<0.001), serum leptin and resistin levels, hepatic steatosis, and insulin resistance. In addition to these, mice receiving RvD1 during the dietary intervention showed increased adiponectin expression at both the mRNA and protein levels and reduced liver macrophage infiltration (-15%, P<0.01). Moreover, RvD1 skewed macrophages from an M1- to an M2-like anti-inflammatory phenotype, induced a specific hepatic miRNA signature (i.e., miR-219-5p and miR-199a-5p), and reduced inflammatory adipokine mRNA and protein expression and macrophage innate immune response. In precision-cut liver slices (PCLSs), which override the influence of circulating factors, RvD1 attenuated hypoxia-induced mRNA and protein expression of COX-2, IL-1ß, IL-6, and CCR7. Of note, RvD1 anti-inflammatory actions were absent in macrophage-depleted PCLSs. In summary, RvD1 acts as a facilitator of the hepatic resolution process by reducing the inflammatory component of obesity-induced NASH.

Serial changes in plasma annexin A1 and cortisol levels in sepsis patients.

Annexin A1 (AnxA1), originally identified as a glucocorticoid-regulated protein, is an impor- tant endogenous anti-inflammatory mediator during the resolution phase of inflammation, and its cir- culating level has been rarely studied in sepsis patients. Glucocorticoid has been extensively used in treating patients with sepsis. However, it is unclear whether endogenous cortisol or exogenous glucocor- ticoid contributes to the regulation of AnxA1 levels in peripheral blood of sepsis patients. The aim of this study was to investigate: [1] serial changes over time in the plasma levels of AnxA1 and cortisol in sepsis patients; and [2] prognostic value of AnxA1 level in the survival of sepsis patients. Fifty-eight adult sepsis patients admitted to an intensive care unit (ICU) were enrolled. The plasma levels of cortisol and AnxA1 were determined by specific enzyme-link immunosorbent assay. Results show that the median daily levels of cortisol at the 1st, 3rd, 5th and 7th day after admission to ICU were signifi- cantly elevated over the cortisol level of the control subjects. However, the AnxA1 level was elevated in only thirty-three patients (56%) over the observation period. There was no significant correlation between cortisol levels and AnxA1 levels. Further analysis indicated that steroid treatment resulted in significant elevation of the cortisol level over time, but did not affect the AnxA1 level. AnxA1 levels were also not statistically different between surviving and non-surviving patients. In conclusions, the circu- lating level of AnxA1 is elevated in a subgroup of sepsis patients, and the AnxA1 level does not correlate with the cortisol level in the peripheral blood of sepsis patients.

The impact of short-chain fatty acid-producing bacteria of the gut microbiota in hyperuricemia and gout diagnosis.

INTRODUCTION/OBJECTIVES: Persistent hyperuricemia is a key factor in gout; however, only 13.5% of hyperuricemic individuals manifest the disease. The gut microbiota could be one of the many factors underlying this phenomenon. We aimed to assess the difference in taxonomic and predicted functional profiles of the gut microbiota between asymptomatic hyperuricemia (AH) individuals and gout patients. METHODS: The V3-V4 region of the 16S rRNA gene of the gut microbiota of AH individuals, gout patients, and controls was sequenced. Bioinformatic analyses were carried out with QIIME2 and phyloseq to determine the difference in the relative abundance of bacterial genera among the study groups. Tax4fun2 was used to predict the functional profile of the gut microbiota. RESULTS: AH individuals presented a higher abundance of butyrate- and propionate-producing bacteria than gout patients; however, the latter had more bacteria capable of producing acetate. The abundance of Prevotella genus bacteria was not significantly different between the patients but was higher than that in controls. This result was corroborated by the functional profile, in which AH individuals had less pyruvate oxidase abundance than gout patients and less abundance of an enzyme that regulates glutamate synthetase activation than controls. CONCLUSION: We observed a distinctive taxonomic profile in AH individuals characterized by a higher abundance of short-chain fatty acid-producing bacteria in comparison to those observed in gout patients. Furthermore, we provide scientific evidence that indicates that the gut microbiota of AH individuals could provide anti-inflammatory mediators, which prevent the appearance of gout flares. Key Points • AH and gout patients both have a higher abundance of Prevotella genus bacteria than controls. • AH individuals' gut microbiota had more butyrate- and propionate-producing bacteria than gout patients. • The gut microbiome of AH individuals provides anti-inflammatory mediators that could prevent gout flares.

Exposure to low-dose bisphenol A during the juvenile period of development disrupts the immune system and aggravates allergic airway inflammation in mice.

Bisphenol A (BPA) is used in the production of polycarbonate plastics and epoxy resins and found in many consumer products. Previous studies have reported that perinatal exposure to BPA through the oral route promotes the development of allergic airway inflammation. We investigated the effects of exposure to low-dose BPA during the juvenile period of development on allergic airway inflammation. Six-week-old male C3H/HeJ mice were intratracheally administered ovalbumin (OVA, 1 µg) every 2 weeks and/or BPA (0, 0.0625, 1.25, and 25 pmol/animal/week) once per week for 6 weeks. Following the final intratracheal instillation, we examined the cellular profile of the bronchoalveolar lavage fluid, histological changes and expression of inflammatory/anti-inflammatory mediators in the lungs, OVA-specific immunoglobulin (Ig) production, serum corticosterone levels, and changes in the lymphoid tissues (mediastinal lymph node (MLN) and spleen). Exposure to OVA + BPA enhanced inflammatory cell infiltration and protein expression of Th2 cytokines/chemokines (e.g. interleukin (IL)-13 and IL-33) in the lungs, OVA-specific immunoglobulin E (IgE) production, the numbers of total cells and activated antigen-presenting cells (MHC class II+ CD86+, CD11c+), as well as the production of Th2 cytokines (i.e. IL-4 and IL-5) and stromal cell-derived factor-1α in MLN cells compared to OVA exposure alone. These effects were more prominent with 0.0625 or 1.25 pmol/animal/week of BPA. Furthermore, exposure to OVA + BPA altered serum levels of anti-inflammatory corticosterone, estrogen receptor 2 messenger RNA (mRNA) expression in the lungs and spleen functionality. These findings suggest that low-dose BPA exposure may aggravate allergic airway inflammation by enhancing Th2 responses via disruption of the immune system.