Role and species-specific expression of colon T cell homing receptor GPR15 in colitis.

Lymphocyte recruitment maintains intestinal immune homeostasis but also contributes to inflammation. The orphan chemoattractant receptor GPR15 mediates regulatory T cell homing and immunosuppression in the mouse colon. We show that GPR15 is also expressed by mouse TH17 and TH1 effector cells and is required for colitis in a model that depends on the trafficking of these cells to the colon. In humans GPR15 is expressed by effector cells, including pathogenic TH2 cells in ulcerative colitis, but is expressed poorly or not at all by colon regulatory T (Treg) cells. The TH2 transcriptional activator GATA-3 and the Treg-associated transcriptional repressor FOXP3 robustly bind human, but not mouse, GPR15 enhancer sequences, correlating with receptor expression. Our results highlight species differences in GPR15 regulation and suggest it as a potential therapeutic target for colitis.

Transcriptional programs of lymphoid tissue capillary and high endothelium reveal control mechanisms for lymphocyte homing.

Lymphocytes are recruited from blood by high-endothelial venules (HEVs). We performed transcriptomic analyses and identified molecular signatures that distinguish HEVs from capillary endothelium and that define tissue-specific HEV specialization. Capillaries expressed gene programs for vascular development. HEV-expressed genes showed enrichment for genes encoding molecules involved in immunological defense and lymphocyte migration. We identify capillary and HEV markers and candidate mechanisms for regulated recruitment of lymphocytes, including a lymph node HEV-selective transmembrane mucin; transcriptional control of functionally specialized carbohydrate ligands for lymphocyte L-selectin; HEV expression of molecules for transendothelial migration; and metabolic programs for lipid mediators of lymphocyte motility and chemotaxis. We also elucidate a carbohydrate-recognition pathway that targets B cells to intestinal lymphoid tissues, defining CD22 as a lectin-homing receptor for mucosal HEVs.

Absence of Nkx2-3 homeodomain transcription factor reprograms the endothelial addressin preference for lymphocyte homing in Peyer's patches.

Although the homing of lymphocytes to GALT has been extensively studied, little is known about how high endothelial venules (HEVs) within Peyer's patches (PPs) are patterned to display dominantly mucosal addressin cell adhesion molecule 1 (MAdCAM-1). In this study, we report that Nkx2-3-deficient mice show gradual loss of MAdCAM-1 in PPs postnatally and increased levels of mRNA for peripheral lymph node addressin (PNAd) backbone proteins as well as enhanced expression of MECA79 sulfated glycoepitope at the luminal aspect of HEVs, thus replacing MAdCAM-1 with PNAd. Induction of PNAd in mutant PPs requires lymphotoxin ß receptor activity, and its upregulation needs the presence of mature T and B cells. Furthermore, treatment with MECA-79 anti-PNAd mAb in vivo effectively blocks lymphocyte homing to mutant PPs. Despite the replacement of MAdCAM-1 by PNAd in HEV endothelia, lymphocytes could efficiently home to PPs in mutant mice. We conclude that although Nkx2-3 activity controls the addressin balance of HEVs in GALT, the general HEV functionality is preserved independently from Nkx2-3, indicating a substantial plasticity in the specification of GALT HEV endothelium.

Expression, regulation, and function of atypical chemerin receptor CCRL2 on endothelial cells.

Chemokine (CC motif) receptor-like 2 (CCRL2) binds leukocyte chemoattractant chemerin and can regulate local levels of the attractant, but does not itself support cell migration. In this study, we show that CCRL2 and VCAM-1 are upregulated on cultured human and mouse vascular endothelial cells (EC) and cell lines by proinflammatory stimuli. CCRL2 induction is dependent on NF-κB and JAK/STAT signaling pathways, and activated endothelial cells specifically bind chemerin. In vivo, CCRL2 is constitutively expressed at high levels by lung endothelial cells and at lower levels by liver endothelium; and liver but not lung EC respond to systemic LPS injection by further upregulation of the receptor. Plasma levels of total chemerin are elevated in CCRL2(-/-) mice and are significantly enhanced after systemic LPS treatment in CCRL2(-/-) mice compared with wild-type mice. Following acute LPS-induced pulmonary inflammation in vivo, chemokine-like receptor 1 (CMKLR1)(+) NK cell recruitment to the airways is significantly impaired in CCRL2(-/-) mice compared with wild-type mice. In vitro, chemerin binding to CCRL2 on endothelial cells triggers robust adhesion of CMKLR1(+) lymphoid cells through an α(4)ß(1) integrin/VCAM-1-dependent mechanism. In conclusion, CCRL2 is expressed by EC in a tissue- and activation-dependent fashion, regulates circulating chemerin levels and its bioactivity, and enhances chemerin- and CMKLR1-dependent lymphocyte/EC adhesion in vitro and recruitment to inflamed airways in vivo. Its expression and/or induction on EC by proinflammatory stimuli provide a novel and specific mechanism for the local enrichment of chemerin at inflammatory sites, regulating the recruitment of CMKLR1(+) cells.

Harvey Cushing's experience with cranial deformity.

Surgery for cranial deformity was associated with significant surgical morbidity during the early part of the 20th century. For this reason, Harvey Cushing was initially not in favor of surgical treatment of craniosynostosis. Later in his career, Cushing began to operate on these children, although it never became a major focus of his practice. Several examples of his patients with cranial deformity are presented, and his limited role in the development of this field is discussed.

Prevalence of Burnout in Occupational and Environmental Medicine Physicians in the United States.

OBJECTIVE: To determine prevalence and key drivers of burnout in Occupational and Environmental Medicine physicians in the United States. METHODS: A nationwide survey of Occupational Medicine physicians was conducted using the Qualtrics® platform. Burnout, measured by the Maslach Burnout Inventory®, Social Support, and Job Satisfaction were assessed. RESULTS: The response rate was 46%, the overall burnout prevalence 38%, and most respondents were men (69%). The mean age and mean years in practice were 56 years and 20 years respectively. Physicians working in government/military (48%) and private medical center group settings (46%) were significantly more likely to report burnout, with consultants (15%) reporting the lowest rate. CONCLUSIONS: Although the overall burnout prevalence is lower in Occupational Medicine physicians compared with most specialties, the rate varies significantly by practice setting (15% to 48%) affirming the impact of organizational factors.

A molecular map of murine lymph node blood vascular endothelium at single cell resolution.

Blood vascular endothelial cells (BECs) control the immune response by regulating blood flow and immune cell recruitment in lymphoid tissues. However, the diversity of BEC and their origins during immune angiogenesis remain unclear. Here we profile transcriptomes of BEC from peripheral lymph nodes and map phenotypes to the vasculature. We identify multiple subsets, including a medullary venous population whose gene signature predicts a selective role in myeloid cell (vs lymphocyte) recruitment to the medulla, confirmed by videomicroscopy. We define five capillary subsets, including a capillary resident precursor (CRP) that displays stem cell and migratory gene signatures, and contributes to homeostatic BEC turnover and to neogenesis of high endothelium after immunization. Cell alignments show retention of developmental programs along trajectories from CRP to mature venous and arterial populations. Our single cell atlas provides a molecular roadmap of the lymph node blood vasculature and defines subset specialization for leukocyte recruitment and vascular homeostasis.

Emergency suboccipital decompression for respiratory arrest during supratentorial surgery: the untold story of a surgeon's courage in times of despair.

The odyssey leading to the discovery of herniation syndromes was prolonged due to a lack of early understanding of the underlying pathophysiology. In 1896, Leonard Hill documented transtentorial pressure gradients as the intervening phenomenon involved in uncal herniation. In 1904, James Collier became the first to describe cerebellar tonsillar herniation as a "false localizing sign" often associated with intracranial tumors. During the infancy of neurological surgery, management of increased intracranial pressure and an improved understanding of brain herniation syndromes were of the utmost importance in achieving a safe technique. Harvey Cushing provided seminal contributions in understanding the pathophysiology of increased intracranial pressure and resulting cardiopulmonary effects. Cushing believed that tonsillar herniation was a cause of acute cardiorespiratory compromise in patients with intracranial tumors. In this vignette, we describe the untold story of Cushing's heroic attempt to treat respiratory arrest operatively during supratentorial tumor surgery with an emergency suboccipital craniectomy to relieve the medullary dysfunction that he believed was caused by compression from tonsillar herniation. This case illustrates a surgeon's determination and courage in fighting for his patient's life in the most desperate of times.

Nonaccidental head injury in children. Historical vignette.

Our current understanding of nonaccidental head injury in children is the result of decades of effort and the tireless work of numerous physicians. In 1860 Auguste Ambroise Tardieu, a French forensics expert, recognized important patterns of injury in children and identified nonaccidental trauma as the cause of these injuries. His work was ignored. In the years that followed, physicians continued to report these patterns of injury but were unable to identify the etiology. A fundamental misunderstanding of the usual cause of subdural hematoma (SDH) contributed to the confusion at that time. Early in the 20th century, neurosurgeons such as Wilfred Trotter recognized that SDHs were traumatic in origin. However, even Trotter's efforts to expose faults in the theories that SDHs primarily resulted from inflammatory or infectious processes were not accepted immediately. Eventually, the pattern of injuries in children was again recognized both by neurosurgeons, who began to identify an association between trauma-induced SDHs and retinal hemorrhages, and by radiologists, who began to note SDHs in conjunction with osseous lesions. Not until the 1950s and 1960s, however, did physicians begin to routinely identify nonaccidental trauma as the cause of these injuries. Following the recognition of child abuse, a pattern of injuries in conjunction with shaking was identified and is currently known as shaken baby syndrome. Since its identification, our understanding of this syndrome has been modified as a result of new medical research, legal challenges, and popular media forces.

Multiplexed serum measurement of IgG, IgA, IgM, and IgE antibody responses to therapeutic biologicals.

Analytical methods characterizing the immunogenicity of therapeutic proteins are useful for monitoring, characterizing and predicting reactions to biopharmaceuticals. A multiplexed assay capable of isotyping the specific IgG, IgA, IgM and IgE (IgGAME) antibody responses against a biotherapeutic was demonstrated in a hyper-immunized cynomolgus monkey, over a 15-month period. The quantitative range of the antibody measurements was determined to be 15 ng/ml to 50 ng/ml in 10% serum. By the use of any biotinylated or fluorescently tagged therapeutic as a detector, this multiplexed isotyping assay can be broadly applied to human and non-human primate IgG, IgA, IgM and IgE immunogenicity studies.

Modified representational difference analysis: isolation of differentially expressed mRNAs from rare cell populations.

Representational difference analysis of cDNAs (cDNA-RDA) is a sensitive subtractive hybridization technique capable of isolating rare mRNAs differentially expressed in two cell populations. cDNA-RDA can detect sequences represented at 0.0001% in the starting mRNA. By using reverse transcriptase polymerase chain reaction (PCR), cDNA-RDA also lends itself to studies in which samples are derived from limited numbers of cells. Standard cDNA-RDA protocols depend upon the presence of specific restriction enzyme sites in each cDNA, typically enzymes with four base recognition sequences. These sites are used to reduce the cDNA size range and provide primer sites for subsequent PCR amplification. Consequently, transcripts containing fewer than two of the chosen restriction sites are undetectable by cDNA-RDA. We have developed a restriction enzyme site-independent cDNA-RDA protocol called modified RDA (MRDA). We constructed MRDA test sequences from random hexamer-primed cDNA, thereby increasing the representation of mRNAs which are excluded by cDNA-RDA protocols. MRDA is also more efficient than cDNA-RDA at removing highly expressed housekeeping genes during the subtractive hybridization process, thereby allowing more efficient isolation of preferentially expressed mRNAs. Using MRDA, we isolated cDNAs differentially expressed between limited numbers of human CD4(+) naive and memory T lymphocyte subsets and skin- and gut-homing memory T cell subsets.