Genomic interval engineering of mice identifies a novel modulator of triglyceride production

To accelerate the biological annotation of novel genes discovered in sequenced regions of mammalian genomes, we are creating large deletions in the mouse genome targeted to include clusters of such genes. Here we describe the targeted deletion of a 450-kb region on mouse chromosome 11, which, based on computational analysis of the deleted murine sequences and human 5q orthologous sequences, codes for nine putative genes. Mice homozygous for the deletion had a variety of abnormalities, including severe hypertriglyceridemia, hepatic and cardiac enlargement, growth retardation, and premature mortality. Analysis of triglyceride metabolism in these animals demonstrated a several-fold increase in hepatic very-low density lipoprotein triglyceride secretion, the most prevalent mechanism responsible for hypertriglyceridemia in humans. A series of mouse BAC and human YAC transgenes covering different intervals of the 450-kb deleted region were assessed for their ability to complement the deletion induced abnormalities. These studies revealed that OCTN2, a gene recently shown to play a role in carnitine transport, was able to correct the triglyceride abnormalities. The discovery of this previously unappreciated relationship between OCTN2, carnitine, and hepatic triglyceride production is of particular importance because of the clinical consequence of hypertriglyceridemia and the paucity of genes known to modulate triglyceride secretion.     

Contrasting effects of recombinant human granulocyte-macrophage colony- stimulating factor (CSF) and granulocyte CSF treatment on the cycling of blood elements in childhood-onset cyclic neutropenia

Recombinant human granulocyte colony-stimulating factor (G-CSF) treatment has been shown to increase average neutrophil counts substantially in patients with childhood-onset cyclic neutropenia (or "cyclic hematopoiesis"), but not to eliminate the cyclic oscillations of neutrophil counts or those of other blood elements (monocytes, platelets, eosinophils, and reticulocytes) that are characteristic of this hematopoietic disorder. Indeed, oscillations of neutrophil counts are amplified during G-CSF treatment. We have compared the effects of recombinant granulocyte-macrophage-CSF (GM-CSF) with those of G-CSF in three patients with this disease (2 men and 1 woman, 17, 30, and 32 years of age). These patients were treated with GM-CSF (2.1 micrograms/kg/day, subcutaneously) for 6 weeks, preceded and followed by 6 to 13 weeks of detailed observation to document changes in the cyclic oscillations of blood neutrophils and other blood elements; two of the patients were subsequently treated with G-CSF (5.0 micrograms/kg/d, subcutaneously) and observed for comparable periods of time. Unlike G-CSF treatment, which increased average neutrophil counts more than 20-fold, GM-CSF increased neutrophil counts only modestly, from 1.6- to 3.9-fold, although eosinophilia of varying prominence was induced in each patient. However, at the same time, GM-CSF treatment dampened or eliminated the multilineage oscillations of circulating blood elements (neutrophils, monocytes, platelets, and/or reticulocytes) in each of the patients. In contrast, G-CSF treatment of the same patients markedly amplified the oscillations of neutrophil counts and caused the cycling of other blood elements (monocytes in particular) to become more distinct. These findings support the conclusion that the distinctive cycling of blood cell production in childhood-onset cyclic neutropenia results from abnormalities in the coordinate regulation of both GM-CSF-responsive, multipotential progenitor cells and G-CSF-responsive, lineage-restricted, neutrophil progenitors.     

Scavenging of soluble and immobilized CCL21 by ACKR4 regulates peripheral dendritic cell emigration

Leukocyte homing driven by the chemokine CCL21 is pivotal for adaptive immunity because it controls dendritic cell (DC) and T cell migration through CCR7. ACKR4 scavenges CCL21 and has been shown to play an essential role in DC trafficking at the steady state and during immune responses to tumors and cutaneous inflammation. However, the mechanism by which ACKR4 regulates peripheral DC migration is unknown, and the extent to which it regulates CCL21 in steady-state skin and lymph nodes (LNs) is contested. Specifically, our previous findings that CCL21 levels are increased in LNs of ACKR4-deficient mice [I. Comerford et al., Blood 116, 4130–4140 (2010)] were refuted [M. H. Ulvmar et al., Nat. Immunol. 15, 623–630 (2014)], and no differences in CCL21 levels in steady-state skin of ACKR4-deficient mice were reported despite compromised CCR7-dependent DC egress in these animals [S. A. Bryce et al., J. Immunol. 196, 3341–3353 (2016)]. Here, we resolve these issues and reveal that two forms of CCL21, full-length immobilized and cleaved soluble CCL21, exist in steady-state barrier tissues, and both are regulated by ACKR4. Without ACKR4, extracellular CCL21 gradients in barrier sites are saturated and nonfunctional, DCs cannot home directly to lymphatic vessels, and excess soluble CCL21 from peripheral tissues pollutes downstream LNs. The results identify the mechanism by which ACKR4 controls DC migration in barrier tissues and reveal a complex mode of CCL21 regulation in vivo, which enhances understanding of functional chemokine gradient formation.

CCL21 is a chemokine that mediates recruitment of multiple leukocyte subsets through CCR7-mediated signaling during the steady state and inflammation. CCL21 plays crucial roles in priming adaptive immunity via governing egress of dendritic cells (DCs) from barrier tissues and T cell entry and positioning in secondary lymphoid organs (1–5). A well-characterized site of CCL21 gradient formation is the skin, where CCL21 is secreted by lymphatic endothelial cells (LECs) and immobilized on extracellular heparan sulfate moieties via interactions with the charged, elongated C-terminal tail of CCL21 (6–8). Here, immobilized CCL21 gradients are essential for interstitial DC trafficking toward lymphatic vessels (LVs) (8), after which CCL21 further contributes to LV attachment (9), infiltration (10), downstream luminal migration (11), and migration from the lymph node (LN) subcapsular sinus (SCS) to the paracortex (12). In-vitro studies have shown that the C-terminal tail of CCL21 can also be proteolytically cleaved by mature DCs to generate solubilized CCL21 (13), with signaling properties distinct from another soluble CCR7 ligand, CCL19 (14, 15). While CCL19 is dispensable for steady-state DC migration (16), important questions regarding the in vivo processing and function of cleaved CCL21 remain.Both forms of CCL21 are also ligands for the atypical chemokine receptor ACKR4 (17), which regulates chemokine bioavailability rather than directly mediating cell migration. ACKR4 expression has been identified in multiple barrier tissues (18–20) and lymphoid tissues (12, 21) where expression is largely restricted to stromal cell populations, with the exception of germinal-center B cells (22). Despite clear evidence of ACKR4 scavenging of CCL21 in vitro, the extent to which it regulates CCL21 in vivo is disputed. We have shown increased CCL21 in the LNs of Ackr4^−/− mice, which was associated with exacerbated Th17 responses in autoimmunity (23) and an ACKR4-dependent increase in CCL21 in tumors that promotes antitumor immunity (24). However, no differences in dermal CCL21 abundance were previously reported in steady-state Ackr4^−/− mice despite steady-state CCR7-dependent DC migratory defects being independent of CCL19 (19), and the contribution of ACKR4 in regulating LN CCL21 abundance has been disputed despite a clear role for ACKR4 in maintaining interfollicular CCL21 gradients in LN (12). These discrepancies have remained unresolved but point to previously unrecognized complexity in ACKR4-dependent regulation of CCL21 in both barrier and lymphoid tissues.     

Management of biliary tract complications following liver transplantation.

BACKGROUND: A review of biliary tract complications was performed in 32 patients who underwent liver transplantation by the Western Australian Liver Transplantation Service during a 2-year period. METHODS: A review was made of patient data collected prospectively, and confirmed by retrospective casenote review. RESULTS: A total of 30 patients (31 grafts) survived more than 2 days after transplantation, and of these 28 had an end-to-end biliary anastomosis. Analysis of these 28 patients found that eight of 17 patients with T-tubes had complications: three leaks at T-tube removal; two strictures and leaks; and three strictures. Six of 11 patients without a T-tube had complications: one leak; three strictures and leaks; and two strictures. Predisposing factors were present in eight of the 14 patients with biliary tract complications: hepatic artery stenosis in three; and one each with hepatic artery thrombosis; biliary calculi; donor-recipient bile duct mismatch; severe cellular rejection: and prolonged postoperative hypotension. Acute rejection, steroid-resistant rejection and cytomegalovirus infection were all significantly more common in those patients with biliary tract complications compared with those without. There was no difference in cold ischaemic time or donor age. Twelve of the 14 patients with biliary complications required endoscopic stenting with or without balloon dilation, and eight patients required radiological percutaneous drainage of bile collections. Only one patient required biliary reconstruction and two patients required re-transplantation. One patient died of uncontrolled infection. Of three patients who underwent choledochojejunostomy, biliary leak developed in two patients, both of whom required operative biliary and hepatic repair. One of the three patients died from disseminated Aspergillus infection. The median total hospital stay of patients with biliary complications was 61 days (range: 30-180 days) compared with 33.5 days (range: 22-70 days) for patients without. Of patients with end-to-end biliary anastomosis, 50% had biliary tract complications and more than half of these had predisposing factors. The majority of biliary complications were managed without the need for surgery. CONCLUSION: A total of 50% of patients with end-to-end biliary anastomosis had biliary tract complications. Biliary strictures presented later than leaks, and the majority of these complications were managed without the need for surgery.     

Steroids Alone or as Adjunctive Therapy with Doxycycline Fail To Improve Oviduct Damage in Mice Infected with Chlamydia muridarum

In women, Chlamydia trachomatis can ascend from the cervix to the fallopian tubes, where an overly aggressive host inflammatory response can cause scarring that leads to chronic pelvic pain, infertility, or ectopic pregnancy. Although screening and treatment programs for women have resulted in decreased rates of sequelae, morbidities associated with oviduct scarring continue to occur. Since corticosteroids have anti-inflammatory and antifibrotic effects, we tested the ability of dexamethasone to inhibit inflammation and prevent oviduct scarring in mice genitally infected with Chlamydia muridarum. The administration of 1 or 2.5 mg/kg of body weight of dexamethasone on days 7 to 21 of infection resulted in reduced accumulation of inflammatory cells in the oviducts compared to that in controls. However, a concomitant increase in bacterial burden was observed, and chronic oviduct disease was not reduced. Adjunctive administration of a prolonged (21-day) or short (3-day) course of dexamethasone in combination with the antibiotic doxycycline also failed to reduce chronic oviduct pathology compared to antibiotic treatment alone. Steroids administered alone or adjunctively with antibiotics failed to prevent oviduct damage in this murine model of C. trachomatis infection.     

Percutaneous fluoroscopic removal of a knotted Swan–Ganz catheter in a patient with a persistent left‐sided superior vena cava

Knotting of intravascular catheters is an uncommon but a well‐recognized occurrence. The Swan–Ganz catheter (SGC) is the one that knots most commonly. A case of a knotted SGC is described in a patient with a persistent left‐sided superior vena cava, and we propose that the presence of a left‐sided superior vena cava is a risk factor for knot formation not previously reported. We review the published work on the risk factors for knot formation and on the techniques used to remove knotted SGC. We describe a technique using a gooseneck snare and Omni Flush catheter (Angiodynamics, Queensbury, NY, USA) to loosen and untie a knotted SGC.     

Immune responses induced by BCG recombinant for human papillomavirus L1 and E7 proteins

Recombinant bacille Calmette-Guerin (BCG) based vaccine delivery systems could potentially share the safety and effectiveness of BCG. We therefore prepared recombinant BCG vaccines which expressed the L1 late protein of the human papillomavirus (HPV) 6b or the E7 early protein of the HPV 16. The two recombinants were evaluated as immunogens in C57BL/6J and BALB/c mice, and compared with a conventional protein/adjuvant system using E7 or L1 mixed with Quil-A adjuvant. rBCG6bL1 and rBCG16E7 primed specific immune responses, represented by DTH, T-proliferation and antibody, and rBCG16E7 induced cytotoxic immune response to E7 protein. The magnitude of the observed responses were less than those elicited by protein/adjuvant vaccine. As recombinant BCG vaccines expressing HPV6bL1 or HPV16E7 persist at low levels in the immunised host, they may be beneficial to prime or retain memory responses to antigens, but are unlikely to be useful as a single component vaccine strategy.     

人乳头瘤病毒6b型病毒样颗粒免疫活性的研究

目的：了解人乳头瘤病毒（HPV）6b型病毒样颗粒（VLP）的免疫活性及其诱导的保护性抗体对HPV11型VLP和牛乳头瘤病毒1型（BPV1）VLP的交叉免疫反应。方法：将HPV6b、HPV11和BPV1晚期基因L1的开放读码框架（ORFs）分别重组到杆状病毒中,该重组病毒在感染的昆虫细胞（Sf9细胞）中表达,表达的L1蛋白可自行组装成HPV6b、HPV11和BPV1 VLP。取50μg纯化的HPV6bVLP分别在第0天和第21天经肌肉免疫Balb/c鼠。第二次免疫后1周及3个月取血,检测血清抗HPV6b、HPV11和BVP1 VLP和BPV1 VLP IgG滴度;血凝集抑制试验检测HPV6bVLP免疫产生的抗血清是否能阻止HPV11 VLP和BPV1 VLP与鼠红细胞凝集。结果：免疫后1周,应用ELISA方法检测抗HPV6b VLP、HPV11 VLP和BVP1 VLP血清IgG滴度分别为1：6400、1：600和1：600。3个月后,抗HPV6bVLP、HPV11 VLP 和BVP 1VLP血清IgG滴度分别为1：800、1：400和1：100。血凝集抑制试验显示HPV6bVLP产生的抗血清能够阻止高度同源性的HPV6b VLP和HPV11 VLP与鼠红细胞结合。结论：HPV6b VLP具有很强的免疫原性,免疫后产生的抗血清具有阻止HPV6b VLP和HPV11 VLP与细胞结合的能力。HPV6b和11型间确实存在交叉反应的中和表位,HPV6b VLP有可能用于防治HPV6b及HPV11感染的疫苗。