The macrophage-TCRαß is a cholesterol-responsive combinatorial immune receptor and implicated in atherosclerosis.

Recent evidence indicates constitutive expression of a recombinatorial TCRαß immune receptor in mammalian monocytes and macrophages. Here, we demonstrate in vitro that macrophage-TCRß repertoires are modulated by atherogenic low density cholesterol (LDL) and high-density cholesterol (HDL). In vivo, analysis of freshly obtained artery specimens from patients with severe carotid atherosclerosis reveals massive abundance of TCRαß(+) macrophages within the atherosclerotic lesions. Experimental atherosclerosis in mouse carotids induces accumulation of TCR bearing macrophages in the vascular wall and TCR deficient rag(-/-) mice have an altered macrophage-dependent inflammatory response. We find that the majority of TCRαß bearing macrophages are localized in the hot spot regions of the atherosclerotic lesions. Advanced carotid artery lesions express highly restricted TCRαß repertoires that are characterized by a striking usage of the Vß22 and Vß16 chains. This together with a significant degree of interindividual lesion repertoire sharing suggests the existence of atherosclerosis-associated TCRαß signatures. Our results implicate the macrophage-TCRαß combinatorial immunoreceptor in atherosclerosis and thus identify an as yet unknown adaptive component in the innate response-to-injury process that underlies this macrophage-driven disease.

A TNF-regulated recombinatorial macrophage immune receptor implicated in granuloma formation in tuberculosis.

Macrophages play a central role in host defense against mycobacterial infection and anti- TNF therapy is associated with granuloma disorganization and reactivation of tuberculosis in humans. Here, we provide evidence for the presence of a T cell receptor (TCR) αß based recombinatorial immune receptor in subpopulations of human and mouse monocytes and macrophages. In vitro, we find that the macrophage-TCRαß induces the release of CCL2 and modulates phagocytosis. TNF blockade suppresses macrophage-TCRαß expression. Infection of macrophages from healthy individuals with mycobacteria triggers formation of clusters that express restricted TCR Vß repertoires. In vivo, TCRαß bearing macrophages abundantly accumulate at the inner host-pathogen contact zone of caseous granulomas from patients with lung tuberculosis. In chimeric mouse models, deletion of the variable macrophage-TCRαß or TNF is associated with structurally compromised granulomas of pulmonary tuberculosis even in the presence of intact T cells. These results uncover a TNF-regulated recombinatorial immune receptor in monocytes/macrophages and demonstrate its implication in granuloma formation in tuberculosis.

The neutrophil recombinatorial TCR-like immune receptor is expressed across the entire human life span but repertoire diversity declines in old age.

Recent evidence has revealed the existence of T cell receptor (TCR) αß-based recombinatorial immune receptors in phagocytes. Here, we performed a systematic survey of the variable ß-chain repertoires of the neutrophil TCR-like αß immunoreceptor (referred to as TCRL(n)αß) in defined cohorts of young and old individuals. Peripheral blood CD15(+) neutrophils from young adults (age 30 ± 7 years, n=12) expressed an average number of 13 ± 6 distinct TCRL(n) Vß-chains from the total pool of 25 human Vß-chains. Neutrophils from aged subjects (age 76 ± 6 years, n=12) also consitutively express the TCRL(n), however, only a small number of Vß-chains is used (4 ± 2). Consistent with this, the average number of expressed CDR3 Vß length variants was fourfold higher in young individuals than in aged subjects (33 ± 24 vs. 8 ± 3). Young adults showed broad usage of all TCRL(n) Vß-chains. In contrast, >70years individuals displayed a striking repertoire polarization towards the TCRL(n) Vß1 and Vß5b chains and a high degree of Vß5b clonotype sharing. Our study reveals broad TCRL(n) repertoire diversity in young adults and demonstrates that the neutrophil variable immune receptor is expressed throughout the entire human life span. The marked decline in TCRL(n) repertoire diversity in old age identifies a novel mechanism of immunosenescence in neutrophils.

Gastrointestinal stromal tumors.

INTRODUCTION: The gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the intestinal tract, known to be refractory to conventional chemotherapy or radiation. Its pathogenesis is defined by mutations within the KIT and PDGFRA gene, which constitutively activate KIT and PDGFRA oncoproteins, and serve as crucial diagnostic and therapeutic targets. DISCUSSION: Besides surgery, therapy with imatinib mesylate, which inhibits KIT kinase activity, represents the other cornerstone for the treatment of GIST. Still, the only curative option for GIST is given after complete surgical removal even in a metastatic setting, but recurrence is common, and the risk can be defined by surgical factors like incomplete resection, intraperitoneal rupture, or bleeding and tumor associated factors like tumor size, mitotic index, or localization. CONCLUSION: Consequently, adjuvant therapy with imatinib mesylate or other tyrosine kinase inhibitors is recommended for high-risk patients after complete resection. For unresectable and advanced GIST, a partial response or stable disease can be achieved in about 80% of patients with imatinib mesylate.

Trilineage Sequencing Reveals Complex TCRß Transcriptomes in Neutrophils and Monocytes Alongside T Cells.

Recent findings indicate the presence of T cell receptor (TCR)-based combinatorial immune receptors beyond T cells in neutrophils and monocytes/macrophages. In this study, using a semiquantitative trilineage immune repertoire sequencing approach as well as under rigorous bioinformatic conditions, we identify highly complex TCRß transcriptomes in human circulating monocytes and neutrophils that separately encode repertoire diversities one and two orders of magnitude smaller than that of T cells. Intraindividual transcriptomic analyses reveal that neutrophils, monocytes, and T cells express distinct TCRß repertoires with less than 0.1% overall trilineage repertoire sharing. Interindividual comparison shows that in all three leukocyte lineages, the vast majority of the expressed TCRß variants are private. We also find that differentiation of monocytes into macrophages induces dramatic individual-specific repertoire shifts, revealing a surprising degree of immune repertoire plasticity in the monocyte lineage. These results uncover the remarkable complexity of the two phagocyte-based flexible immune systems which until now has been hidden in the shadow of T cells.

Immediate Neutrophil-Variable-T Cell Receptor Host Response in Bacterial Meningitis.

Bacterial meningitis is a life-threatening disease that evokes an intense neutrophil-dominated host response to microbes invading the subarachnoid space. Recent evidence indicates the existence of combinatorial V(D)J immune receptors in neutrophils that are based on the T cell receptor (TCR). Here, we investigated expression of the novel neutrophil TCRαß-based V(D)J receptors in cerebrospinal fluid (CSF) from human patients with acute-phase bacterial meningitis using immunocytochemical, genetic immunoprofiling, cell biological, and mass spectrometric techniques. We find that the human neutrophil combinatorial V(D)J receptors are rapidly induced in CSF neutrophils during the first hours of bacterial meningitis. Immune receptor repertoire diversity is consistently increased in CSF neutrophils relative to circulating neutrophils and phagocytosis of baits directed to the variable immunoreceptor is enhanced in CSF neutrophils during acute-phase meningitis. Our results reveal that a flexible immune response involving neutrophil V(D)J receptors which enhance phagocytosis is immediately initiated at the site of acute bacterial infection.

Expression of combinatorial immunoglobulins in macrophages in the tumor microenvironment.

Recent evidence indicates the presence of macrophage subpopulations that express the TCRαß in chronic inflammatory diseases such as tuberculosis and atherosclerosis and in the tumor microenvironment. Here, we demonstrate that a second subpopulation of macrophages expresses rearranged heavy and light chain immunoglobulins. We identify immunoglobulin expression in human and murine monocytes, in ex vivo differentiated macrophages and macrophages from the tumor microenvironment of five randomly selected distinct human tumor entities. The immunoglobulin heavy and light chains are expressed in a small macrophage subfraction (~3-5%) as combinatorial and individual-specific immune receptors. Using Sanger sequencing and deep sequencing, we routinely find markedly restricted Ig repertoires in monocytes/macrophages compared to normal B cells. Furthermore, we report the complete Ig heavy and light chain sequences of a fully functional immunoglobulin from a single tumor-associated macrophage. These results demonstrate that Ig expression is a defining feature of monocytes and also macrophages in the tumor microenvironment and thus reveal an as yet unrecognized modus operandi of host defense in professional phagocytes.

A combinatorial αß T cell receptor expressed by macrophages in the tumor microenvironment.

Recent evidence indicates the presence of macrophage subpopulations that express the TCRαß in two major inflammatory diseases, tuberculosis and atherosclerosis. Inflammation is also a well-established attribute of cancer progression and macrophages are one of the major immune cells that infiltrate tumors. Here, we demonstrate that the macrophage-TCRαß is expressed in the tumor microenvironment of human and murine malignancies. We identify TCRαß+ macrophages in each case of four randomly selected distinct human tumor entities. In human tumor tissues, the TCRαß expressed by macrophages in the tumor microenvironment is a combinatorial and individual-specific immune receptor. Furthermore, we routinely find TCRαß+ macrophage subpopulations in experimental tumors (TS/A, mammary adenocarcinoma) which we induced both in normal mice and mice deficient in the macrophage receptor stabilin-1. Expression of the combinatorial murine tumor macrophage TCRαß is individual-specific and independent of stabilin-1. These results demonstrate that TCRαß expression is a characteristic feature of macrophages in the tumor microenvironment and identify an as yet unrecognized flexible element in the macrophage-based host response to tumors.

Pelvic intraoperative neuromonitoring during robotic-assisted low anterior resection for rectal cancer.

While the oncological outcome of patients with rectal cancer has been considerably improved within the last decades, anorectal, urinary and sexual functions remained impaired at high levels, regardless of whether radical surgery was performed open or laparoscopically. Consequently, intraoperative monitoring of the autonomic pelvic nerves with simultaneous electromyography of the internal anal sphincter and manometry of the urinary bladder has been introduced to advance nerve-sparing surgery and to improve functional outcome. Initial results suggested that pelvic neuromonitoring may result in better functional outcomes. Very recently, it has also been demonstrated that minimally invasive neuromonitoring is technically feasible. Because, to the best of our knowledge, pelvic neuromonitoring has not been performed during robotic surgery, we report the first case of robotic-assisted low anterior rectal resection combined with intraoperative monitoring of the autonomic pelvic nerves.

Diagnosis of Gastroesophageal Reflux Disease Using Real-time Magnetic Resonance Imaging.

A small angle (His angle) between the oesophagus and the fundus of the stomach is considered to act as flap valve and anti-reflux barrier. A wide angle results in dysfunction of the oesophagogastric junction and subsequently in gastroesophageal reflux disease (GERD). Here, we used real-time magnetic resonance imaging (MRI) at 50 ms resolution (20 frames per second) in 12 volunteers and 12 patients with GERD to assess transport of pineapple juice through the oesophagogastric junction and reflux during Valsalva. We found that the intra-abdominal part of the oesophagus was bended towards the left side resulting in an angle of 75.3 ± 17.4, which was significantly larger during Valsava (P = 0.017). Reflux and several underlying pathologies were detected in 11 out of 12 patients. Our data visualize oesophagogastric junction physiology and disprove the flap valve hypothesis. Further, non-invasive real-time MRI has considerable potential for the diagnosis of causative pathologies leading to GERD.

On the horizon: flexible immune recognition outside lymphocytes.

Since decades there is consensus among immunologists that in jawless and jawed vertebrates flexible immune recognition is strictly confined to the lymphoid lineage. In jawed vertebrates the adaptive immune system is represented by two lineages of lymphocytes, B cells and T cells that express recombinatorial antigen receptors of enormous diversity known as immunoglobulins and the T cell receptor (TCR). The recent identification of recombined immune receptors that are structurally based on the TCR in subpopulations of neutrophils and eosinophils (referred to here as TCR-like immunoreceptors, "TCRL") provides unexpected evidence for the existence of flexible host defense mechanisms beyond the realm of lymphocytes. Consistent with this, subpopulations of monocytes and macrophages from humans and mice now have also been shown to constitutively express recombined TCR-like immunoreceptors. Available in vitro evidence suggests that the TCRL in macrophages may exert functions as facilitators of phagocytosis and self-recruitment. More importantly, our recent findings that the macrophage-TCRL is implicated in granuloma formation in tuberculosis and the neutrophil-TCRL is associated with autoimmune hemolytic anemia establish for the first time a link between myeloid recombinatorial immune receptors and clinical disease. The discovery of recombined TCR-like immune receptors in granulocytes and macrophages extends the principle of combinatorial immune recognition to phagocytic cells. Conceptually, this unifies the two hitherto disparate cardinal features of innate and adaptive immunity, phagocytic capacity and recombinatorial immune recognition on a common cellular platform. Moreover, it strongly suggests that flexible host defense in vertebrates may operate on a broader cellular basis than currently thought.

A second combinatorial immune receptor in monocytes/macrophages is based on the TCRγδ.

Recent evidence indicates that monocytes and macrophages express T cell receptor (TCR)αß-like combinatorial immune receptors. Here, we demonstrate the presence of a second recombinatorial immunoreceptor, which is structurally based on the TCR γ- and δ-chains, in human and murine monocytes and differentially activated macrophages (referred to here as TCRL(m)γδ). In vitro, infection of macrophages with mycobacteria and gram positive or gram negative bacteria induced expression of donor-specific and differential TCRL(m)Vδ repertoires indicating that the novel immunoreceptor represents a dynamic flexible host defense system that responds to bacterial challenge. In vivo, we find that TCRL(m)γδ bearing macrophages, which express highly restricted repertoires of the antigen-binding Vδ chain, accumulate in the cerebrospinal fluid in acute bacterial meningitis and in advanced lesions of atherosclerosis. These results identify an as yet unrecognized monocyte/macrophage subpopulation that bears combinatorial TCRL(m)γδ immune receptors, and is associated with both acute and chronic inflammatory diseases. Moreover, they indicate that the monocytic lineage uses the same bipartite system of TCRαß/TCRγδ-based combinatorial immune receptors that is present in T cells. Our findings suggest specific roles of monocytes/macrophages in various inflammatory conditions and lend further evidence that flexible immune recognition in higher vertebrates operates on a broader cellular basis than previously thought.

Extralymphocytic flexible immune recognition: a new angle on inflammation and aging.

Longstanding immunological dogma holds that flexible immune recognition, which forms the mechanistic basis of adaptive immunity, is strictly confined to the lymphocyte lineage. In higher vertebrates, flexible immune recognition is represented by recombinatorial antigen receptors of enormous diversity known as immunoglobulins, expressed by B lymphocytes, and the T cell receptor (TCR), expressed by T lymphocytes. The recent discovery of recombinatorial immune receptors that are structurally based on the TCR (referred to as TCR-like immunoreceptors, "TCRL") in myeloid phagocytes such as neutrophils and monocytes/macrophages now challenges the lymphocentric paradigm of flexible immunity. Here, we introduce the emerging concept of "extralymphocytic flexible immune recognition" and discuss its implications for inflammation and aging.

A variable immunoreceptor in a subpopulation of human neutrophils.

Neutrophils are thought to rely solely on nonspecific immune mechanisms. Here we provide molecular biological, immunological, ultrastructural, and functional evidence for the presence of a T cell receptor (TCR)-based variable immunoreceptor in a 5-8% subpopulation of human neutrophils. We demonstrate that these peripheral blood neutrophils express variable and individual-specific TCRalphabeta repertoires and the RAG1/RAG2 recombinase complex. The proinflammatory cytokine granulocyte colony-stimulating factor regulates expression of the neutrophil immunoreceptor and RAG1/RAG2 in vivo. Specific engagement of the neutrophil TCR complex protects from apoptosis and stimulates secretion of the neutrophil-activating chemokine IL-8. Our results, which also demonstrate the presence of the TCR in murine neutrophils, suggest the coexistence of a variable and an innate host defense system in mammalian neutrophils.