Expression of specific inflammasome gene modules stratifies older individuals into two extreme clinical and immunological states

Low-grade, chronic inflammation has been associated with many diseases of aging, but the mechanisms responsible for producing this inflammation remain unclear. Inflammasomes can drive chronic inflammation in the context of an infectious disease or cellular stress, and they trigger the maturation of interleukin-1β (IL-1β). Here we find that the expression of specific inflammasome gene modules stratifies older individuals into two extremes: those with constitutive expression of IL-1β, nucleotide metabolism dysfunction, elevated oxidative stress, high rates of hypertension and arterial stiffness; and those without constitutive expression of IL-1β, who lack these characteristics. Adenine and N4-acetylcytidine, nucleotide-derived metabolites that are detectable in the blood of the former group, prime and activate the NLRC4 inflammasome, induce the production of IL-1β, activate platelets and neutrophils and elevate blood pressure in mice. In individuals over 85 years of age, the elevated expression of inflammasome gene modules was associated with all-cause mortality. Thus, targeting inflammasome components may ameliorate chronic inflammation and various other age-associated conditions

Interaction of a poly(dimethylsiloxane) with triglycerides in monomolecular films and application to lipase kinetics

NRC publication: Ye

Interfacial and/or molecular recognition by lipases of mixed monomolecular films of 1,2-dicaprin and chiral organophosphorus glyceride analogues?

International audienc

Biochemical properties and three-dimensional structures of two extracellular lipolytic enzymes from Bacillus subtilis

This article reviews our present knowledge on the extracellular lipolytic enzymes LipA and LipB from Bacillus subtilis. Growth of B. subtilis to the late logarithmic growth phase results in a total lipolytic activity of 12–18 units per liter of culture supernatant. Immunodetection with LipA- and LipB-specific antibodies indicated a differential expression of both lipolytic enzymes depending on the composition of the growth medium. LipA was produced in rich and in minimal medium, whereas LipB was present only in rich medium. The lipA and lipB genes were cloned and overexpressed in B. subtilis and Escherichia coli, the corresponding proteins purified to electrophoretic homogeneity and their substrate specificities, pH- and temperature stabilities were determined. The active site residue Ser78 of LipB is located in the consensus sequence Ala–X–Ser–X–Gly where the alanine replaces a glycine found in most of the bacterial lipases. The role of this Ala-residue was investigated by constructing LipB variant A76G thereby restoring the canonical lipase consensus motif. When compared with wild-type LipB this variant showed a markedly reduced thermostability at pH 11 but an increased stability at pH 5–7. These findings were rationalized by building a three-dimensional structural model of LipB using the atomic coordinates of the LipA crystal structure, which was solved recently. The LipB model structure revealed that 43 out of 45 residues, which are different from LipA, were located on the surface of LipB. The surface-exposed amino acids including those located at the rim of the active site cleft may cause the differences in specific activities between LipA and LipB.

Potential role of Mycoplasma hominis in Interleukin (IL)–17–Producing CD4+ T-Cell generation via induction of IL-23 secretion by human dendritic cells

Background. Mycoplasma hominis, a human urogenital pathogen, is involved in genital and extragenital infections and arthritis, particularly in immunocompromised patients. The interleukin (IL) 23/T helper (Th) 17 axis is associated with inflammatory and autoimmune diseases. The aim of this study was to assess the IL-23 response to M. hominis in human dendritic cells (DCs) and the CD4+ T-cell differentiation in response to M. hominis–infected DCs. Methods. Human monocyte–derived DCs were cultured with phosphate-buffered saline, lipopolysaccharide, or M. hominis PG21. Cocultures with heterologous T cells were performed. Extracts from M. hominis were separated and incubated with DCs. Isolates from different clinical syndromes were tested. Results. M. hominis induced the maturation of human DCs with predominant IL-23 secretion in a Toll-like receptor 2–dependent manner. The in vitro immunomodulatory capacity of M. hominis was contained in a lipoprotein-enriched fraction from the mycoplasma. M. hominis–activated DCs induced IL-17–producing CD4+ T cells. Interestingly, clinical isolates differed in their ability to promote IL-23 secretion by DCs. Conclusions. Taken together, our findings demonstrate a major role for the IL-23/Th17 axis in the defense against M. hominis and indicate a potential role for these bacteria in inflammatory and autoimmune diseases

Clusterin Neutralizes the Inflammatory and Cytotoxic Properties of Extracellular Histones in Sepsis

Rationale: Extracellular histones, released into the surrounding environment during extensive cell death, promote inflammation and cell death, and these deleterious roles have been well documented in sepsis. Clusterin (CLU) is a ubiquitous extracellular protein that chaperones misfolded proteins and promotes their removal. Objectives: We investigated whether CLU could protect against the deleterious properties of histones. Methods: We assessed CLU and histone expression in patients with sepsis and evaluated the protective role of CLU against histones in in vitro assays and in vivo models of experimental sepsis. Measurements and Main Results: We show that CLU binds to circulating histones and reduces their inflammatory, thrombotic, and cytotoxic properties. We observed that plasma CLU levels decreased in patients with sepsis and that the decrease was greater and more durable in nonsurvivors than in survivors. Accordingly, CLU deficiency was associated with increased mortality in mouse models of sepsis and endotoxemia. Finally, CLU supplementation improved mouse survival in a sepsis model. Conclusions: This study identifies CLU as a central endogenous histone-neutralizing molecule and suggests that, in pathologies with extensive cell death, CLU supplementation may improve disease tolerance and host survival

Platelets Induce Thymic Stromal Lymphopoietin Production by Endothelial Cells: Contribution to Fibrosis in Human Systemic Sclerosis.

OBJECTIVE: To investigate the relationship between vascular damage and fibrosis in systemic sclerosis (SSc) by testing the hypothesis that platelets contribute to skin fibrosis via the activation of human dermal microvascular endothelial cells (HDMECs) and subsequent production of profibrotic mediators. METHODS: A total of 203 SSc patients and 30 healthy donors were prospectively enrolled between 2012 and 2015 at the University Hospital of Bordeaux. Immunohistochemistry and immunofluorescence analyses were performed on skin biopsy sections from 18 SSc patients and 5 healthy donors. Serum thymic stromal lymphopoietin (TSLP) levels were measured by enzyme-linked immunosorbent assay in the entire cohort. HDMECs and fibroblasts were purified from biopsy sections. Extracellular matrix production by cultured fibroblasts was assessed by real-time quantitative polymerase chain reaction. RESULTS: Serum TSLP levels were significantly increased in SSc patients compared to healthy donors (P < 0.0001) and were associated with a higher frequency of vasculopathy (P = 0.02). The proportion of TSLP-positive dermal cells was increased in the skin of SSc patients compared with healthy donors (P < 0.0001) and was correlated with fibrosis (modified Rodnan skin thickness score) (r = 0.6146, P = 0.0001). In SSc dermis, TSLP was mainly expressed by CD31-positive endothelial cells. In vitro, activated platelets induced TSLP production by HDMECs in an interleukin-1β-dependent manner. SSc fibroblasts responded differently according to their original TSLP environment. CONCLUSION: Taken together, these results identify HDMECs as contributors to TSLP production in SSc and suggest a potential mechanism by which platelets may profoundly affect the fibrotic process in SSc