Microbiota dictate T cell clonal selection to augment graft-versus-host disease after stem cell transplantation.

Allogeneic T cell expansion is the primary determinant of graft-versus-host disease (GVHD), and current dogma dictates that this is driven by histocompatibility antigen disparities between donor and recipient. This paradigm represents a closed genetic system within which donor T cells interact with peptide-major histocompatibility complexes (MHCs), though clonal interrogation remains challenging due to the sparseness of the T cell repertoire. We developed a Bayesian model using donor and recipient T cell receptor (TCR) frequencies in murine stem cell transplant systems to define limited common expansion of T cell clones across genetically identical donor-recipient pairs. A subset of donor CD4+ T cell clonotypes differentially expanded in identical recipients and were microbiota dependent. Microbiota-specific T cells augmented GVHD lethality and could target microbial antigens presented by gastrointestinal epithelium during an alloreactive response. The microbiota serves as a source of cognate antigens that contribute to clonotypic T cell expansion and the induction of GVHD independent of donor-recipient genetics.

An immunohistochemical method for identifying fibroblasts in formalin-fixed, paraffin-embedded tissue.

Fibroblasts are critical for tissue homeostasis, and their inappropriate proliferation and activation can result in common and debilitating conditions including fibrosis and cancer. We currently have a poor understanding of the mechanisms that control the growth and activation of fibroblasts in vivo, in part because of a lack of suitable fibroblast markers. We have taken advantage of an antibody previously shown to stain stromal cells in frozen tissues (TE-7) and identified conditions in which it can be used to stain fibroblasts and myofibroblasts in the paraffin-embedded tissue samples routinely collected for pathological analysis. We show that this antibody recognizes growing and quiescent fibroblasts and myofibroblasts by immunohistochemistry, immunofluorescence, and ELISA assays. We also present its staining patterns in normal tissue samples and in breast tumors.

Analysis of ROR1 Protein Expression in Human Cancer and Normal Tissues.

Purpose: This study examines cell surface ROR1 expression in human tumors and normal tissues. ROR1 is considered a promising target for cancer therapy due to putative tumor-specific expression, and multiple groups are developing antibodies and/or chimeric antigen receptor-modified T cells to target ROR1. On-target, off-tumor toxicity is a challenge for most nonmutated tumor antigens; however, prior studies suggest that ROR1 is absent on most normal tissues.Experimental Design: Our studies show that published antibodies lack sensitivity to detect endogenous levels of cell surface ROR1 by immunohistochemistry (IHC) in formalin-fixed, paraffin-embedded tissues. We developed a ROR1-specific monoclonal antibody (mAb) targeting the carboxy-terminus of ROR1 and evaluated its specificity and sensitivity in IHC.Results: The 6D4 mAb is a sensitive and specific reagent to detect cell surface ROR1 by IHC. The data show that ROR1 is homogenously expressed on a subset of ovarian cancer, triple-negative breast cancer, and lung adenocarcinomas. Contrary to previous findings, we found ROR1 is expressed on several normal tissues, including parathyroid; pancreatic islets; and regions of the esophagus, stomach, and duodenum. The 6D4 mAb recognizes rhesus ROR1, and ROR1 expression was similar in human and macaque tissues, suggesting that the macaque is a suitable model to evaluate safety of ROR1-targeted therapies.Conclusions: ROR1 is a promising immunotherapeutic target in many epithelial tumors; however, high cell surface ROR1 expression in multiple normal tissues raises concerns for on-target off-tumor toxicities. Clinical translation of ROR1-targeted therapies warrants careful monitoring of toxicities to normal organs and may require strategies to ensure patient safety. Clin Cancer Res; 23(12); 3061-71. ©2016 AACR.

A flexible mouse-on-mouse immunohistochemical staining technique adaptable to biotin-free reagents, immunofluorescence, and multiple antibody staining.

Immunohistochemistry on mouse tissue utilizing mouse monoclonal antibodies presents a challenge. Secondary antibodies directed against the mouse monoclonal primary antibody of interest will also detect endogenous mouse immunoglobulin in the tissue. This can lead to significant spurious staining. Therefore, a "mouse-on-mouse" staining strategy is needed to yield credible data. This paper presents a method that is easy to use and highly flexible to accommodate both an avidin-biotin detection system as well as a biotin-free polymer detection system. The mouse primary antibody is first combined with an Fab fragment of an anti-mouse antibody in a tube and allowed sufficient time to form an antibody complex. Any non-complexed secondary antibody is bound up with mouse serum. The mixture is then applied to the tissue. The flexibility of this method is confirmed with the use of different anti-mouse antibodies followed by a variety of detection reagents. These techniques can be used for immunohistochemistry (IHC), immunofluorescence (IF), as well as staining with multiple primary antibodies. This method has also been adapted to other models, such as using human antibodies on human tissue and using multiple rabbit antibodies in dual immunofluorescence.

Regulating the angiogenic balance in tissues.

A balance between angiogenesis inducers and inhibitors in the microenvironment controls the rate of new blood vessel formation. We hypothesized that fibroblasts, an important cellular constituent of the tissue stroma, secrete molecules that contribute to this balance. We further hypothesized that fibroblasts secrete molecules that promote angiogenesis when they are in a proliferative state and molecules that inhibit angiogenesis when they are not actively cycling (quiescent). Microarray analysis revealed that angiogenesis inducers and inhibitors are regulated as fibroblasts transition into a quiescent state and reenter the cell cycle in response to changes in serum. To assess whether changes in transcript levels result in changes in the levels of secreted proteins, we collected conditioned medium from proliferating and quiescent fibroblasts and performed immunoblotting for selected proteins. Secreted protein levels of the angiogenesis inhibitor pigment epithelium derived factor (PEDF) were higher in quiescent than proliferating fibroblasts. Conversely, proliferating fibroblasts secreted increased levels of the angiogenesis inducer vascular endothelial growth factor-C (VEGF-C). For the angiogenesis inhibitor thrombospondin-2, quiescent cells secreted a prominent 160 kDa form in addition to the 200 kDa form secreted by proliferating and restimulated fibroblasts. Using immunohistochemistry we discovered that fibroblasts surround blood vessels and that the angiogenesis inhibitor PEDF is expressed by quiescent fibroblasts in uterine tissue, supporting a role for PEDF in maintaining quiescence of the vasculature. This work takes a new approach to the study of angiogenesis by examining the expression of multiple angiogenesis regulators secreted from a key stromal cell, the fibroblast.

Expression of the fractalkine receptor (CX3CR1) in human kidney diseases.

BACKGROUND: CX3CL1 (fractalkine) is a membrane bound chemokine that can function as an adhesion molecule for cells expressing the receptor CX3CR1. This receptor is involved in the recruitment of inflammatory cells in a rat model of crescentic glomerulonephritis, where blockade of CX3CR1 has been shown to be of benefit. Here we describe the distribution of CX3CR1 positive cells in a variety of kidney diseases and renal development. METHODS: A total of 84 formalin-fixed, paraffin-embedded specimens including fetal kidneys (N = 12), normal areas of kidneys uninvolved by neoplasia from tumor nephrectomies (N = 4), renal transplant nephrectomies (N = 5), renal transplant biopsies (N = 19), and kidney biopsies from patients with crescentic glomerulonephritis (N = 7), membranous nephropathy (N = 7), membranoproliferative glomerulonephritis (N = 8), focal and segmental glomerulosclerosis (N = 10), collapsing glomerulopathy (N = 6), and minimal change disease (N = 6) were studied. Immunohistochemistry was performed on consecutive tissue sections for CD3 positive T cells, CD68 positive monocyte/macrophages, CCR5 positive cells and CX3CR1 positive cells. RESULTS: The majority of inflammatory leukocytes infiltrating the kidney expressed CX3CR1. The distribution pattern was consistent with expression by both T cells and monocytes/macrophages. In contrast to the distribution of CCR5, which was expressed on a subset of infiltrating cells predominantly localized in the interstitium, CX3CR1 was present on both interstitial and glomerular infiltrating leukocytes. In developing kidneys CX3CR1 positive cells formed a small, scattered population of cells, consistent with the distribution of infiltrating leukocytes. CONCLUSIONS: The high number of CX3CR1-positive inflammatory cells in various disease entities is consistent with its having a role in the accumulation of intrarenal inflammatory cells, but does not provide evidence of specificity of leukocytes bearing this receptor for specific types of injury. Other chemokine gradients, like those created by the ligands for the chemokine receptor CCR5, might subsequently guide leukocyte subsets to specific microenvironments.

Expression of the chemokine monocyte chemoattractant protein-1 and its receptor chemokine receptor 2 in human crescentic glomerulonephritis.

Crescents are morphologic manifestations of severe glomerular injury. Several chemokines and their receptors have been demonstrated to be involved in animal models of crescentic glomerulonephritis (cGN) and are potential targets for therapeutic interventions. Therefore, the expression of monocyte chemoattractant protein-1 (MCP-1), its receptor chemokine receptor 2B (CCR2B), and CCR5 in human cGN was studied. MCP-1 and CCR2B mRNA expression was evaluated, by in situ hybridization, in serial sections of 23 renal biopsies from patients with cGN. T cells, macrophages, and CCR5-expressing cells were examined by immunohistochemical analysis. MCP-1 mRNA was expressed by cells in crescents, parietal epithelium, and tubular epithelium, as well as by infiltrating leukocytes in the tubulointerstitium. The expression of CCR2B mRNA was observed in cells in glomeruli and crescents and in infiltrating leukocytes in the tubulointerstitium. CCR2B mRNA expression could not be clearly localized to intrinsic renal cells; evidence that most of the CCR2B-expressing cells were leukocytes is provided. CD3-positive T cells formed the major part of the interstitial cell infiltrates but were rare within the glomerular tufts. CD68-positive macrophages constituted a major population of infiltrating cells in crescents and contributed significantly to the interstitial infiltrates. The number of glomerular macrophages was associated with the number of MCP-1- and CCR2B-positive glomerular cells. Expression of CCR2B was significantly correlated with interstitial CD3-positive T cells. CCR5 expression was restricted to infiltrating leukocytes and was correlated quantitatively and by localization with interstitial CD3-positive T cells and CD68-positive macrophages. These first morphologic data on the distribution of CCR2-positive cells in human cGN suggest differential effects of chemokines and their receptors on the distribution of infiltrating leukocytes in different compartments of the kidney.

Platelet-derived growth factor-D expression in developing and mature human kidneys.

BACKGROUND: Platelet-derived growth factor (PDGF) is a family of growth regulatory molecules composed of sulfide-bonded dimeric structures. Two well-studied PDGF peptides (PDGF-A and PDGF-B) have been shown to mediate a wide range of biological effects. PDGF-D is a newly recognized member of the PDGF family. Initial studies of the PDGF-D gene found its expression in cells of the vascular wall, suggesting that it could participate in vascular development and pathology. However, its localization in human kidney tissues has never been studied. METHODS: PDGF-D expression in fetal (N = 30) and adult (N = 25) human kidney tissues was examined by immunohistochemistry using an affinity-purified antibody raised to human PDGF-D. Antibody absorption with the immunizing peptide was employed to confirm the specificity of this antibody. PDGF-D protein and gene expression in human kidneys also were demonstrated by Western blotting and reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: In the developing kidney, PDGF-D was first expressed by epithelial cells of comma- and S-shaped structures of the developing nephron, and most consistently in the visceral epithelial cells in the later stages of glomerular differentiation. In addition, PDGF-D could be found in mesenchymal, presumptively fibroblast cells in the interstitium of developing renal pelvis and in fetal smooth muscle cells in arterial vessels. In the adult normal kidney, PDGF-D was expressed by the visceral epithelial cells. There was persistent expression in arterial smooth muscle cells as well as in some neointimal smooth muscle cells of arteriosclerotic vessels, and expression in smooth muscle cells of vasa rectae in the medulla. PDGF-D could be identified at the basolateral membrane of some injured tubules in areas of chronic tubulointerstitial injury routinely encountered in aging kidneys. Western blotting of homogenates of adult kidneys demonstrated monospecific bands at 50 kD corresponding to previously established size parameter for this protein. RT-PCR of human kidney RNA resulted in a 918 basepair band, the sequence of which corresponded to human PDGF-D (Genbank number AF336376). CONCLUSIONS: To our knowledge, these are the first studies to localize PDGF-D in human kidneys and suggest that PDGF-D may have a role in kidney development. PDGF-D was shown to bind to PDGF beta receptor, which localizes to mesangial cells, parietal epithelial cells, and interstitial fibroblasts, suggesting potential paracrine interactions between those cells and the visceral epithelium.

Renal injury in apolipoprotein E-deficient mice.

Hyperlipidemia is thought to accelerate the progression of renal diseases, but the mechanisms by which hyperlipidemia exerts its deleterious effect is still poorly understood. The aim of this study was to describe the renal pathology in a hyperlipidemic mouse strain, the apolipoprotein E-deficient mice (apoE-/-). Renal specimens from a total of 34 mice were studied, including 19 apoE-/- females at the age of 36 weeks, 9 apoE-/- females at the age of 24 weeks, and 6 wild-type females (C57BL/6) as controls. Kidneys were evaluated by histologic examination, immunohistochemistry, and electron microscopy. Immunohistochemistry was used to detect MAC-2-expressing monocyte/macrophages, and the proliferation marker PCNA. Glomerular cell number, glomerular matrix area, and glomerular area were quantified by morphometry. Glomerular lesions in apoE-/- mice were characterized by macrophage accumulation, commonly with foam cell appearance, deposition of extracellular matrix, glomerular hyperplasia, and at times prominent mesangiolysis associated with capillary microaneurysms. Some cases demonstrated lipid deposits filling glomerular capillaries. Arterioles of the vascular pole demonstrated a "foamy" degeneration of smooth muscle cells. These lesions related to hyperlipidemia in this well-established mouse strain have not been previously described. Because this mouse strain is among the most widely studied for interventions aimed at altering hyperlipidemia and the progression of atherosclerosis, we believe that our observations may be of major importance for the accurate interpretation of interventional studies in this strain and offer a new opportunity to study mechanisms of hyperlipidemic renal injury.