Aberrant TNF secretion by whole blood in healthy subjects with a history of reactive arthritis: time course in adherent and non-adherent cultures

The mechanical and biochemical properties of tail tendon in a rat model of obesity: Effect of moderate exercise and prebiotic fibre supplementation

The worldwide trajectory of increasing obesity rates is a major health problem precipitating a rise in the prevalence of a variety of co-morbidities and chronic diseases. Tendinopathy, in weight and non-weight bearing tendons, in individuals with overweight or obesity has been linked to metabolic dysfunction resulting from obesity. Exercise and dietary fibre supplementation (DFS) are common countermeasures to combat obesity and therefore it seems reasonable to assume that they might protect tendons from structural and mechanical damage in a diet-induced obesity (DIO) model. The purpose of this study was to determine the effects of a DIO, DIO combined with moderate exercise, DIO combined with DFS (prebiotic oligofructose), and DIO combined with moderate exercise and DFS on the mechanical and biochemical properties of the rat tail tendon. Twenty-four male Sprague-Dawley rats, fed a high-fat/high-sucrose diet were randomized into a sedentary, a moderate exercise, a DFS, or a moderate exercise combined with DFS group for 12 weeks. Additionally, six lean age-matched animals were included as a sedentary control group. DIO in combination with exercise alone and with exercise and DFS reduced the Young's Modulus but not the collagen content of the rat tail tendons compared to lean control animals. However, no differences in the mechanical and biochemical properties of the rat tail tendon were detected between the DIO and the lean control group, suggesting that DIO by itself did not impact the tail tendon. It seems that longer DIO exposure periods may be needed to develop overt differences in our DIO model.

The Importance of HLA-B27 in the Evolution of Reactive Arthritis

Reactive arthritis is an inflammatory joint disease which develops after 1-4 weeks following an enteral, genital or ORL infection, with a higher frequency in HLA-B27 positive patients.

AIMS

The objective of this paper is to study the importance of HLA-B27 antigen in the development of reactive arthritis.

PATIENTS AND METHODS

The transversal, observational study was conducted in the Rheumatology Clinic of the University of Medicine and Pharmacy of Craiova during the period 2012-2015 and included 112 patients. They were divided into three groups, as follows: group I (52 reactive arthritis cases), group II (30 other spondyloarthritis cases), group III (40 osteoarthritis cases). ELISA and PCR techniques were used to determine the antigen.

RESULTS

Those whom had this genetic marker present, the number of enthesitis almost doubled highlighting a possible correlation between the antigen and these imaging changes. We can confirm the same thing for the erosions as well. Unlike enthesitis, erosions occurred also in group III (37.5%), but if we refer to the first two groups, we will observe a significant relationship regarding HLA-B27. More specifically, in HLA-B27 positive patients (68.97%), erosions were found to be twice as numerous than in HLA-B27 negative patients (31.03%). In group I we identified stage 2 sacroiliitis in 68% of HLA-B27 positive patients and 32% in HLA-B27 negative, which shows another link to this antigen with both joint destruction and a possible unfavorable evolution of reactive arthritis.

CONCLUSIONS

This antigen specific to the seronegative group of spondyloarthritis determines the acceleration of articular destruction, translated by erosion, and the evolution of sacroiliitis to a more advanced stage.

Strategies for the development of an electrochemical bioassay for TNF-alpha detection by using a non-immunoglobulin bioreceptor

TNF-α is an inflammatory cytokine produced by the immune system. Serum TNF-α level is elevated in some pathological states such as septic shock, graft rejection, HIV infection, neurodegenerative diseases, rheumatoid arthritis and cancer. Detecting trace amount of TNF-α is, also, very important for the understanding of tumor biological processes. Detection of this key biomarker is commonly achieved by use of ELISA or cytofluorimetric based methods. In this study the traditional optical detection was replaced by differential pulse voltammetry (DPV) and an affinity molecule, produced by evolutionary approaches, has been tested as capture bioreceptor. This molecule, namely a combinatorial non-immunoglobulin protein (Affibody®) interacts with TNF-α selectively and was here tested in a sandwich assay format. Moreover magnetic beads were used as support for bioreceptor immobilization and screen printed carbon electrodes were used as transducers. TNF-α calibration curve was performed, obtaining the detection limit of 38pg/mL, the quantification range of 76-5000pg/mL and RSD%=7. Preliminary results of serum samples analysis were also reported.

Immunopathogenesis of reactive arthritis: Role of the cytokines

Reactive arthritis (ReA), also known as sterile postinfectious arthritis, belongs to the group of related arthropathies known as spondyloarthritis (SpA). ReA can arise 1-4 wk after a gastrointestinal or genitourinary infection, but once arthritis develops, the microorganism is not found in the joint. The classical microbes associated with ReA development include Gram-negative aerobic or microaerophilic bacteria containing LPS in their outer membrane. The immunopathogenic mechanisms involved in ReA development are still unknown. A hypothesis suggested that the bacteria probably persist outside the joint, at sites such as gut mucosa or lymph nodes, and bacterial antigens might then be transported to the joints. On the other hand, an altered immune response and the unbalanced production of cytokines have been reported in subjects with ReA. Currently, there is increased evidence to suggest that both mechanisms would operate in the immunopathogenesis of ReA. In this review we highlight recent advances on the role of cytokines in the ReA. Particularly, we discuss the roles of some pro- and anti-inflammatory cytokines involved in the immunopathogenesis of ReA.

An aptasensor for electrochemical detection of tumor necrosis factor in human blood

Electrochemical aptasensors can detect disease markers such as cytokines to provide point-of-care diagnosis that is low-cost, rapid, specific and sensitive. Herein, we describe the development of an aptamer-based electrochemical sensor for detection and analysis of tumor necrosis factor-alpha (TNF-α) - a key inflammatory cytokine - in whole human blood. When testing spiked blood, a TNF-α detection limit of 58 pM (10 ng mL(-1)) and a linear range of 6 nM (100 ng mL(-1)) could be achieved. Furthermore, detection of TNF-α in mitogen stimulated whole blood was demonstrated.

Normal inflammasome activation and low production of IL-23 by monocyte-derived macrophages from subjects with a history of reactive arthritis

OBJECTIVES

The pathogenesis of reactive arthritis (ReA) is incompletely understood but may involve aberration(s) in the host's innate immune response towards infecting microbes. We therefore studied the production of interleukin (IL)-1β, a marker of inflammasome activation, and of IL-6, IL-12, IL-23, and tumour necrosis factor (TNF)-α, promoters of T-cell differentiation, by peripheral blood mononuclear cells (PBMNs) and monocyte-derived macrophages from healthy subjects with a history of ReA.

METHOD

The study included 10 human leucocyte antigen (HLA)-B27-positive healthy subjects with previous ReA triggered by Yersinia enterocolitica O:3 infection and 20 healthy reference subjects, of whom 10 were HLA-B27 positive. PBMNs and macrophages were cultured for 18 h with bacterial lipopolysaccharide (LPS), muramyl dipeptide (MDP), Yersinia, or their appropriate combinations. PBMNs were also stimulated with monosodium urate (MSU) crystals. Cytokine levels were measured using an enzyme-linked immunosorbent assay (ELISA) and the Luminex system.

RESULTS

IL-1β secretion was similar from cells of the ReA group and from the HLA-B27-positive and -negative reference groups. TNF-α production from macrophages upon co-stimulation of LPS and MDP increased in the order ReA group < HLA-B27-positive reference group < HLA-B27-negative reference group (p for a trend = 0.027). Similarly, Yersinia-induced TNF-α and IL-23 production increased in the same order (p for trend for TNF-α = 0.036; p for trend for IL-23 = 0.026).

CONCLUSIONS

PBMNs and macrophages from healthy subjects with previous ReA show normal inflammasome activation and low TNF-α and IL-23 production. This low cytokine production may impair bacterial elimination and thereby contribute to the triggering of ReA.

Signalling profiles of circulating leucocytes in patients recovered from reactive arthritis

OBJECTIVES

Reactive arthritis (ReA) is a sterile joint inflammation triggered by a remote infection and associated with human leucocyte antigen (HLA)-B27. Its pathogenesis is unknown, but abnormal response to microbial structures or endogenous inflammatory mediators may be involved. We studied responses in leucocyte signalling profiles in patients with previous ReA after a full recovery.

METHOD

The study comprised 10 HLA-B27-positive healthy subjects with a history of Yersinia enterocolitica-triggered ReA (B27+ReA+) and 20 healthy reference subjects, of whom 10 carried HLA-B27 (B27+ReA-) and 10 did not (B27-ReA-). Phosphospecific fluorescent monoclonal antibodies and flow cytometry were used to determine activation of nuclear factor kappa B (NF-κB), signal transducers and activators of transcription (STATs) 1, 3, 5, and 6, and two mitogen-activated protein (MAP) kinases, p38 and extracellular signal-regulated kinase (ERK)1/2, in monocytes, lymphocytes, lymphocyte subsets, and neutrophils. B27+ReA+ and B27-ReA- whole-blood samples were incubated with Yersinia with or without infliximab to study the role of tumour necrosis factor (TNF) in lymphocyte subset activation. Samples of the three subject groups were studied using soluble bacterial or endogenous stimuli. Fluorescence levels were determined as relative fluorescence units (RFU) and the proportion of positively fluorescing cells.

RESULTS

The intracellular activation of circulating leucocytes in response to soluble stimuli was consistently comparable in B27+ReA+, B27+ReA-, and B27-ReA- subjects. Infliximab inhibited Yersinia-induced lymphocyte NF-κB phosphorylation similarly in B27+ReA+ and B27-ReA- groups.

CONCLUSIONS

ReA susceptibility is not reflected in leucocyte signalling profiles elicited by phlogistic stimuli. However, the possibility remains that aberrations occur in response to combinations of stimuli, such as those associated with leucocyte adhesion.

Lack of TNFR p55 results in heightened expression of IFN-γ and IL-17 during the development of reactive arthritis

Reactive arthritis (ReA) is a type of arthritis originating from certain gastrointestinal or genitourinary infections. In previous studies, we reported the development of progressive Yersinia enterocolitica-induced ReA in mice lacking TNFR p55; however, the mechanisms underlying this effect are still uncertain. In this study, we investigated the impact of TNFR p55 deficiency in modulating Ag-specific Th1 and Th17 responses during this arthritogenic process. We found more severe ReA in TNFRp55(-/-) mice compared with their wild-type (WT) counterparts. This effect was accompanied by increased levels of Yersinia LPS in the joints of knockout mice. Analysis of the local cytokine profile revealed greater amounts of IFN-γ and IL-17 in arthritic joints of TNFRp55(-/-) mice compared with WT mice at day 21 postinfection. Moreover, altered IL-17 and IFN-γ production was observed in mesenteric and inguinal lymph nodes of Yersinia-infected TNFRp55(-/-) mice, as well as in spleen cells obtained from infected mice and restimulated ex vivo with bacterial Ags. Increased levels of cytokine secretion were associated with a greater frequency of CD4(+)IL-17(+), CD4(+)IFN-γ(+), and IL-17(+)IFN-γ(+) cells in TNFRp55(-/-) mice compared with WT mice. Remarkably, Ab-mediated blockade of IL-17 and/or IFN-γ resulted in reduced joint histological scores in TNFRp55(-/-) mice. A mechanistic analysis revealed the involvement of p40, a common subunit of heterodimeric IL-12 and IL-23, in the generation of augmented IFN-γ and IL-17 production under TNFR p55 deficiency. Taken together, these data indicate that, in the absence of TNFR p55 signaling, Th1 and Th17 effector cells may act in concert to sustain the inflammatory response in bacterial-induced arthritogenic processes.

Mechanisms of disease: infection and spondyloarthritis

There is compelling evidence that some infections can initiate a chronic nonseptic arthritis. This has proved to be an important area of investigation into gene-environment interactions, particularly since HLA-B27 confers increased susceptibility to reactive arthritis. This research has investigated the microbiology of these events, and the strategies used by pathogens to induce chronic joint inflammation. Insights into the HLA-orchestrated immune response in this context have also shed light on the impact of HLA-B27 on immunity, which might provide insights into the mechanism of other HLA-B27-associated diseases. Despite the genetic link to reactive arthritis, there is no proven relationship between ankylosing spondylitis and an inciting infection. In general, most trials have found antibiotics to be ineffective in modifying the course of spondyloarthritis.