High-throughput characterization of lipopolysaccharide-binding proteins using mass spectrometry

Lipopolysaccharide and the gut microbiota: Considering structural variation

Systemic inflammation is associated with chronic disease and is purported to be a main pathogenic mechanism underlying metabolic conditions. Microbes harbored in the host gastrointestinal tract release signaling byproducts from their cell wall, such as lipopolysaccharides (LPS), which can act locally and, after crossing the gut barrier and entering circulation, also systemically. Defined as metabolic endotoxemia, elevated concentrations of LPS in circulation are associated with metabolic conditions and chronic disease. As such, measurement of LPS is highly prevalent in animal and human research investigating these states. Indeed, LPS can be a potent stimulant of host immunity but this response depends on the microbial species' origin, a parameter often overlooked in both preclinical and clinical investigations. Indeed, the lipid A portion of LPS is mutable and comprises the main virulence and endotoxic component, thus contributing to the structural and functional diversity among LPSs from microbial species. In this review, we discuss how such structural differences in LPS can induce differential immunological responses in the host.

Identification of nuclear factor-κB inhibitors and β2 adrenergic receptor agonists in Chinese medicinal preparation Fuzilizhong pills using UPLC with quadrupole time-of-flight MS

INTRODUCTION

Fuzilizhong Pills (FZLZ), a modified form of a famous traditional Chinese medicine (TCM) Lizhong Wan in Treatise on Febrile Diseases and consisting of Panax ginseng C.A.Mey. (Ren Shen), Aconitum carmichaelii Debx. (Fu Zi, Zhi), Glycyrrhiza uralensis Fisch., Glycyrrhiza inflata Bat. or Glycyrrhiza glabra L. (Gan Cao), Atractylodes macrocephala Koidz. (Bai Zhu) and Zingiber offcinale Rosc. (Gan Jiang), show strong clinical therapeutic effects for dyspnea and pulmonary oedema. However, the bioactive compounds are still unclear. In this study, FZLZ was analysed using a rapid detection method to identify its anti-inflammatory and spasmolytic constituents.

OBJECTIVE

To develop a simple screening method to detect the anti-inflammatory and spasmolytic constituents of FZLZ.

METHODS

Ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry combined with dual-bioactive (NF-κB and β2 -adrenergic receptor) luciferase reporter assay systems was employed.

RESULTS

Two β2 -adrenergic receptor agonists (salsolinol and higeramine) and three terpenoidal analogues of NF-κB inhibitors such as ginsenosides derivatives, triperpenoids derivatives and diester-diterpenoid aconitum alkaloid derivatives were characterised. Mesaconitine, flaconitine, ginsenosides Rb2, Rf, Rg2, F1 and Ro were considered to be new NF-κB inhibitors. Furthermore, IL-8 detection by enzyme linked immunosorbent assay confirmed the anti-inflammatory effects of the potential NF-κB inhibitors.

CONCLUSION

Compared with conventional fingerprints, activity-integrated fingerprints that contain both chemical and bioactive details offer a more comprehensive understanding of the chemical composition of plant materials. This strategy clearly demonstrated that dual bioactivity-integrated fingerprinting is a powerful tool for the improved screening and identification of potential dual-target lead compounds in complex herbal medicines.

Bioactivity-integrated ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry for the identification of nuclear factor-κB inhibitors and β2 adrenergic receptor agonists in Chinese medicinal preparation Chuanbeipipa dropping pills

A simple and dual-target method based on ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry combined with dual-bioactive [nuclear factor-κB (NF-κB) and β2 -adrenergic receptor] luciferase reporter assay systems was developed to rapidly characterize the chemical structure of various bioactive compounds of TCM preparations. Chuanbeipipa dropping pills, a traditional Chinese medicine preparation used for the clinical therapy of chronic obstructive lung disease and cough caused by bronchial catarrh, was analyzed with this method. Potential anti-inflammatory and spasmolytic constituents were screened using NF-κB and β2 -adrenergic receptor activity luciferase reporter assay systems and simultaneously identified according to the time-of-flight mass spectrometry data. One β2-adrenergic receptor agonist (ephedrine) and two structural types of NF-κB inhibitors (platycosides derivatives and ursolic acid derivatives) were characterized. Platycodin D3 and E were considered new NF-κB inhibitors. Further cytokine and chemokine detection confirmed the anti-inflammatory effects of the potential NF-κB inhibitors. Compared with conventional fingerprints, activity-integrated fingerprints that contain both chemical and bioactive details offer a more comprehensive understanding of the chemical makeup of plant materials. This strategy clearly demonstrated that multiple bioactivity-integrated fingerprinting is a powerful tool for the improved screening and identification of potential multi-target lead compounds in complex herbal medicines.

Innate immunity probed by lipopolysaccharides affinity strategy and proteomics

Lipopolysaccharides (LPSs) are ubiquitous and vital components of the cell surface of Gram-negative bacteria that have been shown to play a relevant role in the induction of the immune-system response. In animal and plant cells, innate immune defenses toward microorganisms are triggered by the perception of pathogen associated molecular patterns. These are conserved and generally indispensable microbial structures such as LPSs that are fundamental in the Gram-negative immunity recognition. This paper reports the development of an integrated strategy based on lipopolysaccharide affinity methodology that represents a new starting point to elucidate the molecular mechanisms elicited by bacterial LPS and involved in the different steps of innate immunity response. Biotin-tagged LPS was immobilized on streptavidin column and used as a bait in an affinity capture procedure to identify protein partners from human serum specifically interacting with this effector. The complex proteins/lipopolysaccharide was isolated and the protein partners were fractionated by gel electrophoresis and identified by mass spectrometry. This procedure proved to be very effective in specifically binding proteins functionally correlated with the biological role of LPS. Proteins specifically bound to LPS essentially gathered within two functional groups, regulation of the complement system (factor H, C4b, C4BP, and alpha 2 macroglobulin) and inhibition of LPS-induced inflammation (HRG and Apolipoproteins). The reported strategy might have important applications in the elucidation of biological mechanisms involved in the LPSs-mediated molecular recognition and anti-infection responses.