Two physically, functionally, and developmentally distinct peritoneal macrophage subsets

The peritoneal cavity (PerC) is a unique compartment within which a variety of immune cells reside, and from which macrophages (Mempty set) are commonly drawn for functional studies. Here we define two Mempty set subsets that coexist in PerC in adult mice. One, provisionally called the large peritoneal Mempty set (LPM), contains approximately 90% of the PerC Mempty set in unstimulated animals but disappears rapidly from PerC following lipopolysaccharide (LPS) or thioglycolate stimulation. These cells express high levels of the canonical Mempty set surface markers, CD11b and F4/80. The second subset, referred to as small peritoneal Mempty set (SPM), expresses substantially lower levels of CD11b and F4/80 but expresses high levels of MHC-II, which is not expressed on LPM. SPM, which predominates in PerC after LPS or thioglycolate stimulation, does not derive from LPM. Instead, it derives from blood monocytes that rapidly enter the PerC after stimulation and differentiate to mature SPM within 2 to 4 d. Both subsets show clear phagocytic activity and both produce nitric oxide (NO) in response to LPS stimulation in vivo. However, their responses to LPS show key differences: in vitro, LPS stimulates LPM, but not SPM, to produce NO; in vivo, LPS stimulates both subsets to produce NO, albeit with different response patterns. These findings extend current models of Mempty set heterogeneity and shed new light on PerC Mempty set diversity, development, and function. Thus, they introduce a new context for interpreting (and reinterpreting) data from ex vivo studies with PerC Mempty set.

Prospective ultramorphological characterization of human hair by optical coherence tomography

Background/purpose The continuous advancement in cosmetic science has led to an increasing demand for the development of non-invasive, reliable scientific techniques directed toward claim substantiation, which is of utmost relevance, to obtain data regarding the efficacy and safety of cosmetic products. Methods In this work, we used the optical coherence tomography (OCT) technique to produce in vitro transversal section-images of human hair. We also compared the OCT signal before and after chemical treatment with an 18% w/w ammonium thioglycolate solution. Results The mean diameter of the medulla was 29 +/- 7 mu m and the hair diameter was 122 +/- 16 mu m in our samples of standard Afro-ethnic hair. A three-dimensional (3D) image was constructed starting from 601 cross-sectional images (slices). Each slice was taken in steps of 6.0 mu m at eight frames per second, and the entire 3D image was constructed in 60 s. Conclusion It was possible to identify, using the A-scan protocol, the principal structures: the cuticle, cortex and medulla. After chemical treatment, it was not possible to identify the main structures of hair fiber due to index matching promoted by deleterious action of the chemical agent.

Regulation of chemokine receptor by Toll-like receptor 2 is critical to neutrophil migration and resistance to polymicrobial sepsis

Patients with sepsis have a marked defect in neutrophil migration. Here we identify a key role of Toll-like receptor 2 (TLR2) in the regulation of neutrophil migration and resistance during polymicrobial sepsis. We found that the expression of the chemokine receptor CXCR2 was dramatically down-regulated in circulating neutrophils from WT mice with severe sepsis, which correlates with reduced chemotaxis to CXCL2 in vitro and impaired migration into an infectious focus in vivo. TLR2 deficiency prevented the down-regulation of CXCR2 and failure of neutrophil migration. Moreover, TLR2(-/-) mice exhibited higher bacterial clearance, lower serum inflammatory cytokines, and improved survival rate during severe sepsis compared with WT mice. In vitro, the TLR2 agonist lipoteichoic acid (LTA) down-regulated CXCR2 expression and markedly inhibited the neutrophil chemotaxis and actin polymerization induced by CXCL2. Moreover, neutrophils activated ex vivo by LTA and adoptively transferred into naive WT recipient mice displayed a significantly reduced competence to migrate toward thioglycolate-induced peritonitis. Finally, LTA enhanced the expression of G protein-coupled receptor kinases 2 (GRK2) in neutrophils; increased expression of GRK2 was seen in blood neutrophils from WT mice, but not TLR2(-/-) mice, with severe sepsis. Our findings identify an unexpected detrimental role of TLR2 in polymicrobial sepsis and suggest that inhibition of TLR2 signaling may improve survival from sepsis.

Pharmacological analysis of the neutrophil migration induced by D. rostrata lectin: Involvement of cytokines and nitric oxide

In the present study, we investigated the involvement of resident cell and inflammatory mediators in the neutrophil migration induced by chemotactic activity of a glucose/mannose-specific lectin isolated from Dioclea rostrata seeds (DrosL). Rats were injected i.p. with DrosL (125-1000 mu g/cavity), and at 2-96 h thereafter the leukocyte counts in peritoneal fluid were determined. DrosL-induced a dose-dependent neutrophil migration accumulation, which reached maximal response at 24 h after injection and declines thereafter. The carbohydrate ligand nearly abolished the neutrophil influx. Pre-treatment of peritoneal cavities with thioglycolate which increases peritoneal macrophage numbers, enhanced neutrophil migration induced by DrosL by 303%. However, the reduction of peritoneal mast cell numbers by treatment of the cavities with compound 48/80 did not modify DrosL-induced neutrophil migration. The injection into peritoneal cavities of supernatants from macrophage cultures stimulated with DrosL (125, 250 and 500 mu g/ml) induced neutrophil migration. In addition, DrosL treatment induced cytokines (TNF-alpha, IL-1 beta and CINC-1) and NO release into the peritoneal cavity of rats. Finally, neutrophil chemotaxis assay in vitro showed that the lectin (15 and 31 mu g/ml) induced neutrophil chemotaxis by even 180%. In conclusion, neutrophil migration induced by D. rostrata lectin occurs by way of the release of NO and cytokines such as IL-1 beta, TNF-alpha and CINC-1. (C) 2009 Elsevier Ltd. All rights reserved.