Effects of gallic acid on signaling kinases in murine macrophages and immune modulation against Brucella abortus 544 infection in mice

Recent advances on the regulation of bacterial biofilm formation by herbal medicines

Biofilm formation is a fundamental part of life cycles of bacteria which affects various aspects of bacterial-host interactions including the development of drug resistance and chronic infections. In clinical settings, biofilm-related infections are becoming increasingly difficult to treat due to tolerance to antibiotics. Bacterial biofilm formation is regulated by different external and internal factors, among which quorum sensing (QS) signals and nucleotide-based second messengers play important roles. In recent years, different kinds of anti-biofilm agents have been discovered, among which are the Chinese herbal medicines (CHMs). CHMs or traditional Chinese medicines have long been utilized to combat various diseases around the world and many of them have the ability to inhibit, impair or decrease bacterial biofilm formation either through regulation of bacterial QS system or nucleotide-based second messengers. In this review, we describe the research progresses of different chemical classes of CHMs on the regulation of bacterial biofilm formation. Though the molecular mechanisms on the regulation of bacterial biofilm formation by CHMs have not been fully understood and there are still a lot of work that need to be performed, these studies contribute to the development of effective biofilm inhibitors and will provide a novel treatment strategy to control biofilm-related infections.

Serum Metabolomics Analysis of the Anti-Inflammatory Effects of Gallic Acid on Rats With Acute Inflammation

Background: Gallic acid (GA) is a natural small-molecule polyphenol having a wide range of pharmacological activities. Until now, some works have studied the effect and the mechanisms of GA against inflammation. However, whether or how gallic acid regulates the downstream metabolic disorder against acute inflammation remains unclear. The present study explored the protective effect and the potential mechanism of GA on acute inflammation through the metabolomics approach.

Methods: An acute inflammation rat model was induced by local injection of carrageenin. Local swelling on paw and serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) were assessed in Control, Model and Gallic acid groups, respectively. Serum metabolomics based on high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) was also established to collect rats’ metabolic profiles and explore the metabolic changes related to GA pretreatment.

Results: Compared to the Modal group, local pain, redness, and swelling induced by carrageenin were significantly alleviated in GA groups in addition to the dose-dependent decreases of TNF-α and IL-6. Metabolomics analysis found significant alterations in metabolic signatures between the carrageenin-induced inflammation and control groups. Twelve potential biomarkers were further identified in acute inflammation by principal component analysis (PCA) and partial least squares discrimination analysis (PLS-DA). In addition, when rats were pretreated with gallic acid, serum levels of eleven biomarkers were observed to restore partially. Metabolic pathway and networks analysis revealed that GA might invert the pathological process of acute inflammation by regulating the key biomarkers involved in linoleic acid metabolism, ascorbate and aldarate metabolism, pentose and glucuronate interconversions, and arachidonic acid (AA) metabolism pathways.

Conclusion: The study elucidates the protective effect of gallic acid against acute inflammation and its possible regulating mechanism from a metabolomic perspective. These results could provide a theoretical basis for clarifying gallic acid’s mechanism and potential medicinal value in curing inflammation disorder in the clinic.

Phenolic profile and in vitro anti-inflammatory activity of Mimosa scabrella Bentham honeydew honey in RAW 264.7 murine macrophages

The anti-inflammatory activity is mainly attributed to the phenolic compounds. Once the geographical location affects the phenolic content of honeys, a relationship between the collection spot and the anti-inflammatory effect of bracatinga (Mimosa scabrella Bentham) honeydew honeys was hypothesized. The inhibitory effect of 14 honey samples on NOx, TNF-α, IL-6, IL-12p70, MCP-1, INF-γ, and IL-10 in RAW 264.7 macrophages inflamed by LPS was evaluated. Fourteen phenolic compounds were identified, mainly syringic acid and rutin. Ten honeys inhibited nitrite production; at least six downregulated TNF-α, IL-12p70, MCP-1, and IFN-γ; only four honey samples inhibited IL-6; and one honey sample inhibited IL-10 levels, showing their variable effects on the inflammatory markers. Principal component analysis grouped samples according to the phenolic content and downregulation of specific inflammatory markers. The bracatinga honeydew honey effectiveness was associated with geographical location, as samples from areas with higher density and diversity of plants had a more significant anti-inflammatory effect. PRACTICAL APPLICATIONS: The present research study investigated the anti-inflammatory potential of bracatinga honeydew honey samples collected from regions with different vegetation coverages. Honey samples collected from locations presenting greater forest diversity and density inhibited inflammatory markers more efficiently. This study reinforces the role of the bracatinga honeydew honey in preventing inflammatory processes and the importance of preserving forests so that products with a greater diversity of compounds and consequently more active can be obtained.

Combination of natural antivirals and potent immune invigorators: A natural remedy to combat COVID-19

The flare‐up in severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) that emerged in December 2019 in Wuhan, China, and spread expeditiously worldwide has become a health challenge globally. The rapid transmission, absence of anti‐SARS‐CoV‐2 drugs, and inexistence of vaccine are further exacerbating the situation. Several drugs, including chloroquine, remdesivir, and favipiravir, are presently undergoing clinical investigation to further scrutinize their effectiveness and validity in the management of COVID‐19. Natural products (NPs) in general, and plants constituents specifically, are unique sources for various effective and novel drugs. Immunostimulants, including vitamins, iron, zinc, chrysin, caffeic acid, and gallic acid, act as potent weapons against COVID‐19 by reinvigorating the defensive mechanisms of the immune system. Immunity boosters prevent COVID‐19 by stimulating the proliferation of T‐cells, B‐cells, and neutrophils, neutralizing the free radicals, inhibiting the immunosuppressive agents, and promoting cytokine production. Presently, antiviral therapy includes several lead compounds, such as baicalin, glycyrrhizin, theaflavin, and herbacetin, all of which seem to act against SARS‐CoV‐2 via particular targets, such as blocking virus entry, attachment to host cell receptor, inhibiting viral replication, and assembly and release.

Impact of Gallic Acid on Gut Health: Focus on the Gut Microbiome, Immune Response, and Mechanisms of Action

Gallic acid (GA) is a naturally occurring polyphenol compound present in fruits, vegetables, and herbal medicines. According to previous studies, GA has many biological properties, including antioxidant, anticancer, anti-inflammatory, and antimicrobial properties. GA and its derivatives have multiple industrial uses, such as food supplements or additives. Additionally, recent studies have shown that GA and its derivatives not only enhance gut microbiome (GM) activities, but also modulate immune responses. Thus, GA has great potential to facilitate natural defense against microbial infections and modulate the immune response. However, the exact mechanisms of GA acts on the GM and immune system remain unclear. In this review, first the physicochemical properties, bioavailability, absorption, and metabolism of GA are introduced, and then we summarize recent findings concerning its roles in gastrointestinal health. Furthermore, the present review attempts to explain how GA influences the GM and modulates the immune response to maintain intestinal health.

Astragalus polysaccharide strengthens the inflammatory and immune responses of Brucella suis S2-infected mice and macrophages

Brucella infection is one of the most serious zoonoses worldwide, affecting humans and domestic and wild animals. Astragalus polysaccharide (APS) is extracted from astragalus, which exhibits bioactive properties, including immunomodulation and anti-tumour and antiviral activity. The present study revealed that APS treatment promoted macrophage activation, the production of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-12 and interferon-γ, and Brucella clearance in murine macrophages and spleens. APS treatment was also demonstrated to protect the integrity of macrophages during infection with live attenuated Brucella suis strain 2 (B. suis S2). The results from in vitro experiments were consistent with the findings from the in vivo study, showing the elevated secretion of TNF-α and nitric oxide in APS-treated murine peritoneal macrophages following B. suis S2 infection. The current study demonstrated the potential of APS in the control and treatment of Brucella infection, and the enhancement of host inflammatory and immune responses.

Gallic acid attenuates allergic airway inflammation via suppressed interleukin-33 and group 2 innate lymphoid cells in ovalbumin-induced asthma in mice

BACKGROUND

Asthma is an inflammatory disease characterized by airway hyperresponsiveness. Gallic acid is a powerful anti-inflammatory agent. In this study we aimed to investigate the efficacy of gallic acid in asthma treatment and its mechanisms.

METHODS

An ovalbumin-induced asthma mouse model was generated. Pro-inflammatory cell infiltration and T helper (Th2)-associated cytokine release in the bronchoalveolar lavage fluid (BALF) were analyzed to reflect the severity of asthma in mice. An interleukin-33 (IL-33)-induced asthma mouse model was also generated to study the mechanism by which gallic acid could improve asthma. Group 2 lymphoid cells (ILC2s) were identified using flow cytometry. Proteins were detected using Western blotting.

RESULTS

Ovalbumin significantly increased the infiltration of pro-inflammatory cells, including eosinophils, macrophages, lymphocytes, and neutrophils, accompanied by enhanced airway hyperesponsiveness. Gallic acid reduced pro-inflammatory cell infiltration and improved airway hyperresponsiveness. Meanwhile, gallic acid reduced IL-5 and IL-13 levels in BALF and decreased expression of IL-33 in the lungs. Mechanistically, gallic acid inhibited MyD88 expression and downregulated nuclear factor (NF)-κB signaling to decrease IL-33 expression.

CONCLUSIONS

Gallic acid can mollify ovalbumin-induced asthma in mice, possibly by inhibiting IL-33-mediated ILC2 activation and subsequent Th2 cytokine release via downregulation of the MyD88/NF-κB signaling pathway. ©2018 ARSAAOA, LLC.