The chemokines (or chemotactic cytokines) are a large family of small, secreted proteins that signal through cell surface G protein‐coupled heptahelical chemokine receptors. They are best known for their ability to stimulate the migration of cells, most notably white blood cells (leukocytes). Consequently, chemokines play a central role in the development and homeostasis of the immune system, and are involved in all protective or destructive immune and inflammatory responses. Classically viewed as inducers of directed chemotactic migration, it is now clear that chemokines can stimulate a variety of other types of directed and undirected migratory behavior, such as haptotaxis, chemokinesis, and haptokinesis, in addition to inducing cell arrest or adhesion. However, chemokine receptors on leukocytes can do more than just direct migration, and these molecules can also be expressed on, and regulate the biology of, many nonleukocytic cell types. Chemokines are profoundly affected by post‐translational modification, by interaction with the extracellular matrix (ECM), and by binding to heptahelical ‘atypical’ chemokine receptors that regulate chemokine localization and abundance. This guide gives a broad overview of the chemokine and chemokine receptor families; summarizes the complex physical interactions that occur in the chemokine network; and, using specific examples, discusses general principles of chemokine function, focusing particularly on their ability to direct leukocyte migration.

Mesenchymal stem cells (MSCs) are typically enriched from bone marrow via isolation of the plastic adherent, fibroblastoid cell fraction. However, plastic adherent cultures elaborated from murine bone marrow are an admixture of fibroblastoid and hematopoietic cell types. Here we report a reliable method based on immunodepletion to fractionate fibroblastoid cells from hematopoietic cells within plastic adherent murine marrow cultures. The immunodepleted cells expressed the antigens Sca-1, CD29, CD44, CD81, CD106, and the stem cell marker nucleostemin (NST) but not CD11b, CD31, CD34, CD45, CD48, CD90, CD117, CD135, or the transcription factor Oct-4. They were also capable of differentiating into adipocytes, chondrocytes, and osteoblasts in vitro as well as osteoblasts/osteocytes in vivo. Therefore, immunodepletion yields a cell population devoid of hematopoietic and endothelial cells that is phenotypically and functionally equivalent to MSCs. The immunodepleted cells exhibited a population doubling time of approximately 5-7 days in culture. Poor growth was due to the dramatic down regulation of many genes involved in cell proliferation and cell cycle progression as a result of immunodepletion. Exposure of immunodepleted cells to fibroblast growth factor 2 (FGF2) but not insulin-like growth factor (IGF), murine stem cell factor, or leukemia inhibitory factor (LIF) significantly increased their growth rate. Moreover, 82% of the transcripts down regulated by immunodepletion remain unaltered in the presence of FGF2. Exposure to the later also reversibly inhibited the ability of the immunodepleted cells to differentiate into adipocytes, chondrocytes, and osteoblasts in vitro. Therefore, FGF2 appears to function as a mitogen and self-maintenance factor for murine MSCs enriched from bone marrow by negative selection.

Summary Currently, we lack an understanding of the individual and combinatorial roles for chemokine receptors in the inflammatory process. We report studies on mice with a compound deletion of Ccr1 , Ccr2 , Ccr3 , and Ccr5 , which together control monocytic and eosinophilic recruitment to resting and inflamed sites. Analysis of resting tissues from these mice, and mice deficient in each individual receptor, provides clear evidence for redundant use of these receptors in establishing tissue-resident monocytic cell populations. In contrast, analysis of cellular recruitment to inflamed sites provides evidence of specificity of receptor use for distinct leukocyte subtypes and no indication of comprehensive redundancy. We find no evidence of involvement of any of these receptors in the recruitment of neutrophils or lymphocytes to resting or acutely inflamed tissues. Our data shed important light on combinatorial inflammatory chemokine receptor function and highlight Ccr2 as the primary driver of myelomonocytic cell recruitment in acutely inflamed contexts.

ABSTRACT.Purpose: This study investigates the clinical utility of the melanopsin-expressing intrinsically photosensitive retinal ganglion cell (ipRGC) controlled postillumination pupil response (PIPR) as a novel technique for documenting inner retinal function in patients with Type II diabetes without diabetic retinopathy. Methods: The PIPR was measured in seven patients with Type II diabetes, normal retinal nerve fibre thickness and no diabetic retinopathy compared to healthy age-similar controls. A 488-and 610-nm, 7.15-diameter stimulus was presented in Maxwellian view to the right eye and the left consensual pupil light reflex was recorded. Results: The group data for the blue PIPR (488 nm) identified a trend of reduced ipRGC function in patients with diabetes with no retinopathy. The transient pupil constriction was lower on average in the diabetic group. The relationship between duration of diabetes and the blue PIPR amplitude was linear, suggesting that ipRGC function decreases with increasing diabetes duration. Conclusion: This is the first report to show that the ipRGC-controlled PIPR may have clinical applications as a non-invasive technique for determining the progression of inner neuroretinal changes in patients with diabetes before they are ophthalmoscopically or anatomically evident. The lower transient pupil constriction amplitude indicates that outer retinal photoreceptor inputs to the pupil light reflex may also be affected in diabetes.

Tertiary lymphoid organs (TLOs) form in territorialized niches of peripheral tissues characterized by the presence of antigens; however, little is known about mechanism(s) of antigen handling by ectopic lymphoid structures. In this mini review, we will discuss the role of antigen-presenting cells and mechanisms of antigen presentation in TLOs, summarizing what is currently known about this facet of the formation and function of these tissues as well as identifying questions yet to be addressed.