Leukotriene B4, an activation product of mast cells, is a chemoattractant for their progenitors

Mast cells are tissue-resident cells with important functions in allergy and inflammation. Pluripotential hematopoietic stem cells in the bone marrow give rise to committed mast cell progenitors that transit via the blood to tissues throughout the body, where they mature. Knowledge is limited about the factors that release mast cell progenitors from the bone marrow or recruit them to remote tissues. Mouse femoral bone marrow cells were cultured with IL-3 for 2 wk and a range of chemotactic agents were tested on the c-kit+ population. Cells were remarkably refractory and no chemotaxis was induced by any chemokines tested. However, supernatants from activated mature mast cells induced pronounced chemotaxis, with the active principle identified as leukotriene (LT) B4. Other activation products were inactive. LTB4 was highly chemotactic for 2-wk-old cells, but not mature cells, correlating with a loss of mRNA for the LTB4 receptor, BLT1. Immature cells also accumulated in vivo in response to intradermally injected LTB4. Furthermore, LTB4 was highly potent in attracting mast cell progenitors from freshly isolated bone marrow cell suspensions. Finally, LTB4 was a potent chemoattractant for human cord blood–derived immature, but not mature, mast cells. These results suggest an autocrine role for LTB4 in regulating tissue mast cell numbers

The Calcitonin and Glucocorticoids Combination: Mechanistic Insights into Their Class-Effect Synergy in Experimental Arthritis

PMCID: PMC3564948This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Rheumatoid arthritis - treatment: 180. Utility of Body Weight Classified Low-Dose Leflunomide in Japanese Rheumatoid Arthritis

Background: In Japan, more than 20 rheumatoid arthritis (RA) patients died of interstitial pneumonia (IP) caused by leflunomide (LEF) were reported, but many of them were considered as the victims of opportunistic infection currently. In this paper, efficacy and safety of low-dose LEF classified by body weight (BW) were studied. Methods: Fifty-nine RA patients were started to administrate LEF from July 2007 to July 2009. Among them, 25 patients were excluded because of the combination with tacrolimus, and medication modification within 3 months before LEF. Remaining 34 RA patients administered 20 to 50 mg/week of LEF were followed up for 1 year and enrolled in this study. Dose of LEF was classified by BW (50 mg/week for over 50 kg, 40 mg/week for 40 to 50 kg and 20 to 30 mg/week for under 40 kg). The average age and RA duration of enrolled patients were 55.5 years old and 10.2 years. Prednisolone (PSL), methotrexate (MTX) and etanercept were used in 23, 28 and 2 patients, respectively. In case of insufficient response or adverse effect, dosage change or discontinuance of LEF were considered. Failure was defined as dosages up of PSL and MTX, or dosages down or discontinuance of LEF. Last observation carried forward method was used for the evaluation of failed patients at 1 year. Results: At 1 year after LEF start, good/ moderate/ no response assessed by the European League Against Rheumatism (EULAR) response criteria using Disease Activity Score, including a 28-joint count (DAS28)-C reactive protein (CRP) were showed in 14/ 10/ 10 patients, respectively. The dosage changes of LEF at 1 year were dosage up: 10, same dosage: 5, dosage down: 8 and discontinuance: 11 patients. The survival rate of patients in this study was 23.5% (24 patients failed) but actual LEF continuous rate was 67.6% (11 patients discontinued) at 1 year. The major reason of failure was liver dysfunction, and pneumocystis pneumonia was occurred in 1 patient resulted in full recovery. One patient died of sepsis caused by decubitus ulcer infection. DAS28-CRP score was decreased from 3.9 to 2.7 significantly. Although CRP was decreased from 1.50 to 0.93 mg/dl, it wasn't significant. Matrix metalloproteinase (MMP)-3 was decreased from 220.0 to 174.2 ng/ml significantly. Glutamate pyruvate transaminase (GPT) was increased from 19 to 35 U/l and number of leukocyte was decreased from 7832 to 6271 significantly. DAS28-CRP, CRP, and MMP-3 were improved significantly with MTX, although they weren't without MTX. Increase of GPT and leukopenia were seen significantly with MTX, although they weren't without MTX. Conclusions: It was reported that the risks of IP caused by LEF in Japanese RA patients were past IP history, loading dose administration and low BW. Addition of low-dose LEF is a potent safe alternative for the patients showing unsatisfactory response to current medicines, but need to pay attention for liver function and infection caused by leukopenia, especially with MTX. Disclosure statement: The authors have declared no conflicts of interes

An investigation into mechanisms underlying neutrophil-mediated oedema in vivo

Neutrophils play a crucial role in the acute immune response. Inflammatory stimuli recruit neutrophils into the tissues. Post-migratory neutrophils may then engage in pathogen killing and phagocytosis. Oedema-formation is associated with neutrophil transmigration, although evidence indicates that these are mechanistically distinct phenomena. Leukocyte-driven oedema is a feature of many inflammatory diseases including asthma, rheumatoid arthritis, and Crohn's disease, the mechanisms underlying neutrophil-mediated oedema are unclear.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Design and characterization of a cleavage-resistant Annexin A1 mutant to control inflammation in the microvasculature

Human polymorphonuclear leukocytes adhesion to endothelial cells during the early stage of inflammation leads to cell surface externalization of Annexin A1 (AnxA1), an effector of endogenous anti-inflammation. The antiadhesive properties of AnxA1 become operative to finely tune polymorphonuclear leukocytes transmigration to the site of inflammation. Membrane bound proteinase 3 (PR3) plays a key role in this microenvironment by cleaving the N terminus bioactive domain of AnxA1. In the present study, we generated a PR3-resistant human recombinant AnxA1-named superAnxA1 (SAnxA1)-and tested its in vitro and in vivo properties in comparison to the parental protein. SAnxA1 bound and activated formyl peptide receptor 2 in a similar way as the parental protein, while showing a resistance to cleavage by recombinant PR3. SAnxA1 retained anti-inflammatory activities in the murine inflamed microcirculation (leukocyte adhesion being the readout) and in skin trafficking model. When longer-lasting models of inflammation were applied, SAnxA1 displayed stronger anti-inflammatory effect over time compared with the parental protein. Together these results indicate that AnxA1 cleavage is an important process during neutrophilic inflammation and that controlling the balance between AnxA1/PR3 activities might represent a promising avenue for the discovery of novel therapeutic approaches

The combination elcatonin/Dexamethasone elicits a synergistic attenuation of MMP-2, TRAP-5b and CXCL5 expression.

<p>Rats were treated with collagen on Day 0 and then, from Day 11, received daily i.p. injections of elcatonin (eCT; 1.0 µg/kg) alone or together with a sub-therapeutic dose of Dexamethasone (D; 7.5 µg/kg) (Co-Tx, combination therapy). A positive control group of rats was treated with Dexamethasone (30 µg/kg). In all cases hind paw tissue extracts and plasma samples were taken at day 18. Protein levels of (A) metalloproteinase II (MMP-2) in tissue extracts, (B) plasma tartrate-resistant acid phosphatase (TRAP-5b), (C) tissue extract and (D) plasma CXCL5 were determined as described in Methods. Data are mean ± SEM of 10 rats per group. Statistical analyses by one-way ANOVA (Kruskal-Wallis test with Dunn’s post-test); *p<0.05, **p<0.01, and ***p<0.001 as compared to vehicle-treated group.</p

Elcatonin does not augment Dexamethasone-induced hyperglycaemia and ACTH suppression.

<p>Fasted rats were given a single dose of Dexamethasone (15 or 100 µg/kg i.p.) with or without 1.0 µg/kg elcatonin (eCT). Blood was collected by venepuncture and glucose was quantified: i) immediately prior to fasting, ii) prior to drug treatment, and iii) 5 h after drug treatment. Overnight fasting caused a fall in mean blood glucose from 6.19±0.10 to 4.80±0.13 mM. Blood glucose in the vehicle-treated group continued to drop, reaching 3.86±0.22 mM at the 5-hour time point. (A) Blood glucose data as measured 5 h post-treatment, and normalised for differing pre-fasting levels. (B) ACTH was assayed by EIA in blood collected by terminal cardiac puncture at 5 h post-treatment. ACTH suppression is expressed in relation to the levels quantified by ELISA in vehicle-treated animals (1.57±0.09 ng/ml). In both panels, data are mean ± SEM of 8 rats per group. Statistical analyses by one-way ANOVA (Kruskal-Wallis test with Dunn’s post-test); *p<0.05, **p<0.01, and ***p<0.001 as compared to vehicle-treated group, or by Mann-Whitney test; ^†p>0.05 in the indicated comparison.</p