Dialyzable leukocyte extract differentially regulates the production of TNFalpha, IL-6, and IL-8 in bacterial component-activated leukocytes and endothelial cells

OBJECTIVE: To investigate i) whether the Dialyzable Leukocyte Extract (DLE) modulates the production of proinflammatory cytokines in leukocytes activated by the bacterial cell wall components lipopolysaccharide (LPS), lipoteichoic acid (LTA), and peptidoglycan (PGN); ii) the effect of DLE on LPS-stimulated endothelial cells; and iii) whether the regulatory effect of DLE on inflammatory mediators is related to the modulation of Toll-like receptors (TLRs), NF-kappaB and cAMP signaling pathways. METHODS: Leukocytes were stimulated with LPS, LTA, and PGN in the presence of DLE. Endothelial cells were stimulated with LPS and treated with DLE. The levels of Tumor Necrosis Factor-alpha(TNFalpha), Interleukin-6 (IL-6), and IL-8 in culture supernatants were evaluated by ELISA. The expression of Toll-like receptor 2 (TLR2) and 4 (TLR4), NF-kappaB activity and cAMP levels were evaluated by flow cytometry, EMSA, and EIA, respectively. RESULTS: The addition of DLE to leukocytes stimulated with cell wall constituents suppressed the production of TNFalpha. However, DLE induced IL-8 release in monocytes and enhanced IL-6 and IL-8 production by activated monocytes and endothelial cells. Also, DLE induced TLR2 and TLR4 expression, and increased cAMP levels, whereas NF-kappaB activity was inhibited. CONCLUSIONS: The present data indicate the differential regulation by DLE of the production of TNFalpha, IL-6, and IL-8 cytokines, associated with effects on TLR2 and TLR4 expression and NF-kappaB and cAMP activities. We suggest a putative mechanism for the biological effects of DLE in activated leukocytes and endothelial cells.<br/

The specificity of Sushi peptides for endotoxin and anionic phospholipids: Potential application of POPG as an adjuvant for anti-LPS strategies

10.1042/BST20060270Biochemical Society Transactions342270-27

NMR structure of rALF-Pm3, an anti-lipopolysaccharide factor from shrimp: Model of the possible lipid A-binding site.

Correspondance auteur: Aumelas A. E-mail: [email protected] audienceThe anti-lipopolysaccharide factor ALF-Pm3 is a 98-residue protein identified in hemocytes from the black tiger shrimp Penaeus monodon. It was expressed in Pichia pastoris from the constitutive glyceraldehyde-3-phosphate dehydrogenase promoter as a folded and N-15 uniformly labeled rALF-Pm3 protein. Its 3D structure was established by NMR and consists of three alpha-helices packed against a four-stranded beta-sheet. The C-34-C-55 disulfide bond was shown to be essential for the structure stability. By using surface plasmon resonance, we demonstrated that rALF-Pm3 binds to LPS, lipid A and to OM(R)-174, a soluble analogue of lipid A. Biophysical studies of rALF-Pm3/LPS and rALF-Pm3/OM(R)-174 complexes indicated rather high molecular sized aggregates, which prevented us to experimentally determine by NMR the binding mode of these lipids to rALF-Pm3. However, on the basis of striking structural similarities to the FhuA/LPS complex, we designed an original model of the possible lipid A-binding site of ALF-Pm3. Such a binding site, located on the ALF-Pm3 beta-sheet and involving seven charged residues, is well conserved in ALF-L from Limulus polyphemus and in ALF-T from Tachypleus tridentatus. In addition, our model is in agreement with experiments showing that beta-hairpin synthetic peptides corresponding to ALF-L beta-sheet bind to LPS. Delineating lipid A-binding site of ALFs will help go further in the de novo design of new antibacterial or LPS-neutralizing drug

A 12-point recommendation framework to support advancement of the multidisciplinary care of psoriatic arthritis: a call to action

Objective: Making a differential diagnosis of psoriatic arthritis (PsA) is not straightforward. This is partly because of its heterogeneous presentation and partly because many patients with PsA are initially diagnosed with psoriasis and treated in primary care or by dermatologists, with referral to rheumatologists being delayed. Once diagnosed, optimal disease control requires frequent specialist monitoring, adjustment or switching of therapies, and management of comorbidities and concomitant diseases, as well as attention to patients’ overall well-being. Given the breadth of expertise that diagnosis and management of PsA requires, we sought to define a collaborative, structured framework that supports the optimisation of multidisciplinary care for patients with PsA in Europe. Methods: An expert panel comprising four rheumatologists, three dermatologists, two specialist nurses and one psychologist – from Spain, the United Kingdom, The Netherlands, Germany, France and Italy – met face-to-face to take part in a modified Delphi exercise. Results: The result of this exercise is a set of recommendations that are based on combining published evidence with the panel’s extensive clinical experience. Recommendations can be implemented in a number of ways, but the central call-to-action of this framework is the need for improved collaboration between dermatologists (or primary care physicians) and rheumatologists. This could occur in a variety of different formats: standard referral pathways, multidisciplinary physician meetings to discuss patient cases, or ‘one stop’, combined clinics. Conclusion: We anticipate that when the majority of patients with PsA receive regular multidisciplinary care, improved patient outcomes will follow, although robust research is needed to explore this assumption.</p