The effect of polyamines on the binding of anti-DNA antibodies from patients with SLE and normal human subjects

Gut Microbial Metabolites on Host Immune Responses in Health and Disease

Intestinal microorganisms interact with various immune cells and are involved in gut homeostasis and immune regulation. Although many studies have discussed the roles of the microorganisms themselves, interest in the effector function of their metabolites is increasing. The metabolic processes of these molecules provide important clues to the existence and function of gut microbes. The interrelationship between metabolites and T lymphocytes in particular plays a significant role in adaptive immune functions. Our current review focuses on 3 groups of metabolites: short-chain fatty acids, bile acids metabolites, and polyamines. We collated the findings of several studies on the transformation and production of these metabolites by gut microbes and explained their immunological roles. Specifically, we summarized the reports on changes in mucosal immune homeostasis represented by the Tregs and Th17 cells balance. The relationship between specific metabolites and diseases was also analyzed through latest studies. Thus, this review highlights microbial metabolites as the hidden treasure having potential diagnostic markers and therapeutic targets through a comprehensive understanding of the gut-immune interaction.

Metabolomic profile in patients with primary warm autoimmune haemolytic anaemia

Autoimmune haemolytic anaemia (AIHA) is a rare clinical condition with immunoglobulin fixation on the surface of erythrocytes, with or without complement activation. The pathophysiology of AIHA is complex and multifactorial, presenting functional abnormalities of T and B lymphocytes that generate an imbalance between lymphocyte activation, immunotolerance and cytokine production that culminates in autoimmune haemolysis. In AIHA, further laboratory data are needed to predict relapse and refractoriness of therapy, and thus, prevent adverse side-effects and treatment-induced toxicity. The metabolomic profile of AIHA has not yet been described. Our group developed a cross-sectional study with follow-up to assess the metabolomic profile in these patients, as well as to compare the metabolites found depending on the activity and intensity of haemolysis. We analysed the plasma of 26 patients with primary warm AIHA compared to 150 healthy individuals by mass spectrometry. Of the 95 metabolites found in the patients with AIHA, four acylcarnitines, two phosphatidylcholines (PC), asymmetric dimethylarginine (ADMA) and three sphingomyelins were significantly increased. There was an increase in PC, spermine and spermidine in the AIHA group with haemolytic activity. The PC ae 34:3/PC ae 40:2 ratio, seen only in the 12-month relapse group, was a predictor of relapse with 81% specificity and 100% sensitivity. Increased sphingomyelin, ADMA, PC and polyamines in patients with warm AIHA can interfere in autoantigen and autoimmune recognition mechanisms in a number of ways (deficient action of regulatory T lymphocytes on erythrocyte recognition as self, negative regulation of macrophage nuclear factor kappa beta activity, perpetuation of effector T lymphocyte and antibody production against erythrocyte antigens). The presence of PC ae 34:3/PC ae 40:2 ratio as a relapse predictor can help in identifying cases that require more frequent follow-up or early second-line therapies.

The Binding of Monoclonal and Polyclonal Anti-Z-DNA Antibodies to DNA of Various Species Origin

DNA is a polymeric macromolecule that can display a variety of backbone conformations. While the classical B-DNA is a right-handed double helix, Z-DNA is a left-handed helix with a zig-zag orientation. The Z conformation depends upon the base sequence, base modification and supercoiling and is considered to be transient. To determine whether the presence of Z-DNA can be detected immunochemically, the binding of monoclonal and polyclonal anti-Z-DNA antibodies to a panel of natural DNA antigens was assessed by an ELISA using brominated poly(dG-dC) as a control for Z-DNA. As these studies showed, among natural DNA tested (Micrococcus luteus, calf thymus, Escherichiacoli, salmon sperm, lambda phage), micrococcal (MC) DNA showed the highest binding with both anti-Z-DNA preparations, and E. coli DNA showed binding with the monoclonal anti-DNA preparation. The specificity for Z-DNA conformation in MC DNA was demonstrated by an inhibition binding assay. An algorithm to identify propensity to form Z-DNA indicated that DNA from Mycobacterium tuberculosis could form Z-DNA, a prediction confirmed by immunoassay. Together, these findings indicate that anti-Z-DNA antibodies can serve as probes for the presence of Z-DNA in DNA of various species origin and that the content of Z-DNA varies significantly among DNA sources.

Polyamine patterns in plasma of patients with systemic lupus erythematosus and fever

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with various clinical manifestations and serologic markers. In this study, we analyzed nine polyamine (PA) profiles of plasma from patients with SLE and healthy controls (HCs), and the relationship between the PA profiles and disease activity. PA alterations in plasma of 44 patients with SLE and fever were investigated using gas chromatography mass spectrometry (GC-MS) in selected ion monitoring mode using N-ethoxycarbonyl/ N-pentafluoropropionyl derivatives, and compared with those of 43 HCs. Patients with SLE and HCs showed differences in five of nine PA profiles. Among five changed PA levels, four PAs, namely N¹-acetylcadaverine, spermidine, N¹-acetylspermidine, and spermine, were dramatically decreased. However, the level of cadaverine was increased in patients with SLE. In the partial correlation with PA profiles and disease activity markers of SLE, several disease activity markers and nutritional markers were correlated with cadaverine, spermidine, and N ⁸-acetylspermidine. Thus, our results provide a comprehensive understanding of the relationship between PA metabolomics and disease activity markers in patients with SLE.

Suppression of interleukin 17 contributes to the immunomodulatory effects of adipose-derived stem cells in a murine model of systemic lupus erythematosus

Due to roles in immunoregulation and low immunogenicity, mesenchymal stem cells have been suggested to be potent regulators of the immune response and may represent promising treatments for autoimmune disease. Adipose-derived stem cells (ADSCs), stromal cells derived from adipose tissue, were investigated with allogeneic ADSCs in B6.MRL/lpr mice, a murine model of systemic lupus erythematosus (SLE). We intravenously injected allogeneic ADSCs into SLE mice after disease onset and report that ADSCs reduced anti-ds DNA antibodies in serum and proteinuria in SLE mice. Also, ADSCs decreased IL-17 and IL-6 expression in serum of SLE mice. ADSCs alleviated renal damage and inflammatory cell infiltration and edema of the renal interstitium. Furthermore, ADSCs significantly downregulated renal IL-17 and CD68 expression, suggesting that ADSCs suppressed renal inflammation. ADSCs also decreased IL-17 mRNA expression and increased Foxp3, ROR-γt and miR-23b mRNA expression in renal tissue in SLE mice. ADSCs reduced renal protein expression of TAB 2 and IKK-α in SLE mice. Thus, ADSCs may be a novel potential therapy for treating SLE.

The role of monogamous bivalency and Fc interactions in the binding of anti-DNA antibodies to DNA antigen

Antibodies to DNA (anti-DNA) are the serological hallmark of systemic lupus erythematosus. These antibodies can bind DNA avidly by monogamous bivalency, a mechanism which requires the interaction of both Fab combining regions with antigenic determinants on the same polynucleotide. To explore further this mechanism, we tested Fab and F(ab')2 fragments prepared from IgG from patient plasmas in an ELISA with native DNA antigen, detecting antibody with a peroxidase conjugated anti-Fab reagent. These studies showed that Fab fragments, which can only bind monovalently, had negligible activity. Although bivalent F(ab')2 fragments would be predicted to bind DNA, these fragments also showed poor anti-DNA activity. Control studies showed that the fragments retained antibody activity to tetanus toxoid and an EBV antigen preparation. Together, these findings suggest that anti-DNA avidity depends on monogamous bivalency, with the antibody Fc portion also influencing DNA binding, in a mechanism which can be termed Fc-dependent monogamous bivalency.

Anti-DNA antibodies--quintessential biomarkers of SLE

Antibodies that recognize and bind to DNA (anti-DNA antibodies) are serological hallmarks of systemic lupus erythematosus (SLE) and key markers for diagnosis and disease activity. In addition to common use in the clinic, anti-DNA antibody testing now also determines eligibility for clinical trials, raising important questions about the nature of the antibody-antigen interaction. At present, no 'gold standard' for serological assessment exists, and anti-DNA antibody binding can be measured with a variety of assay formats, which differ in the nature of the DNA substrates and in the conditions for binding and detection of antibodies. A mechanism called monogamous bivalency--in which high avidity results from simultaneous interaction of IgG Fab sites with a single polynucleotide chain--determines anti-DNA antibody binding; this mechanism might affect antibody detection in different assay formats. Although anti-DNA antibodies can promote pathogenesis by depositing in the kidney or driving cytokine production, they are not all alike, pathologically, and anti-DNA antibody expression does not necessarily correlate with active disease. Levels of anti-DNA antibodies in patients with SLE can vary over time, distinguishing anti-DNA antibodies from other pathogenic antinuclear antibodies. Elucidation of the binding specificities and the pathogenic roles of anti-DNA antibodies in SLE should enable improvements in the design of informative assays for both clinical and research purposes.