No abstract

More than one-half of the ~50 human chemokines have been associated with or implicated in the pathogenesis of type 1 diabetes, yet their actual expression patterns in the islet environment of type 1 diabetic patients remain, at present, poorly defined. Here, we have integrated a human islet culture system, murine models of virus-induced and spontaneous type 1 diabetes, and the histopathological examination of pancreata from diabetic organ donors with the goal of providing a foundation for the informed selection of potential therapeutic targets within the chemokine/receptor family. Chemokine (C-C motif) ligand (CCL) 5 (CCL5), CCL8, CCL22, chemokine (C-X-C motif) ligand (CXCL) 9 (CXCL9), CXCL10, and chemokine (C-X3-C motif) ligand (CX3CL) 1 (CX3CL1) were the major chemokines transcribed (in an inducible nitric oxide synthase–dependent but not nuclear factor-κB–dependent fashion) and translated by human islet cells in response to in vitro inflammatory stimuli. CXCL10 was identified as the dominant chemokine expressed in vivo in the islet environment of prediabetic animals and type 1 diabetic patients, whereas CCL5, CCL8, CXCL9, and CX3CL1 proteins were present at lower levels in the islets of both species. Of importance, additional expression of the same chemokines in human acinar tissues emphasizes an underappreciated involvement of the exocrine pancreas in the natural course of type 1 diabetes that will require consideration for additional type 1 diabetes pathogenesis and immune intervention studies.

NK cells are innate lymphoid cells important for immune surveillance, identifying and responding to stress, infection, and/or transformation. While conventional NK (cNK) cells circulate systemically, many NK cells reside in tissues where they appear to be poised to locally regulate tissue function. Here we tested the contribution of tissue-resident NK (trNK) cells to tissue homeostasis by studying ischemic injury in the mouse kidney. Parabiosis experiments demonstrate that the kidney contains a significant fraction of trNK cells under homeostatic conditions. Kidney trNK cells developed independent of NFIL3 and Tbet, and expressed a distinct cell surface phenotype as compared to cNK cells. Among these, trNK cells had reduced asialo-GM1 (AsGM1) expression relative to cNK cells, a phenotype observed in trNK cells across multiple organs and mouse strains. Strikingly, anti-AsGM1 antibody treatment, commonly used as NK cell-depleting regimen, resulted in a robust and selective depletion of cNKs, leaving trNKs largely intact. Using this differential depletion, we tested the relative contribution of cNK and trNK cells in ischemic kidney injury. Whereas anti-NK1.1 antibody effectively depleted both trNK and cNK cells and protected against ischemic-reperfusion injury, anti-AsGM1 antibody preferentially depleted cNK cells and failed to protect against injury. These data demonstrate unanticipated specificity of anti-AsGM1 antibody depletion on NK cell subsets and reveal a new approach to study the contributions of cNK and trNK cells in vivo. In total, these data demonstrate that trNK cells play a key role in modulating local responses to ischemic tissue injury in the kidney and potentially other organs.

The chemokines are a large family of mainly secreted molecules involved in the regulation of numerous physiological and pathophysiological processes. Despite many years of investigation, the precise cellular sources of most chemokines have remained incompletely defined as a consequence of the limited availability of suitable reagents to visualize the expression of chemokine proteins at the single-cell level. Here, we developed a simple flow cytometry-based assay using commercially available chemokine-specific antibodies for efficient cell-associated detection of 37 of 39 murine chemokines. To demonstrate the utility of this methodology, we used it to reevaluate the nature of homeostatic chemokines in the hematopoietic compartment, to delineate the complete chemokine profiles of NK cells and B cells in response to major polyclonal stimuli, and to assess the chemokine response of DCs to bacterial infection. The versatility of this analytical methodology was further demonstrated by its application to selected human chemokines and should greatly facilitate any future investigation into chemokine biology at large.