IgG hexamers initiate complement-dependent acute lung injury

Antibodies can initiate lung injury in a variety of disease states such as autoimmunity, transfusion reactions, or after organ transplantation, but the key factors determining in vivo pathogenicity of injury-inducing antibodies are unclear. Harmful antibodies often activate the complement cascade. A model for how IgG antibodies trigger complement activation involves interactions between IgG Fc domains driving assembly of IgG hexamer structures that activate C1 complexes. The importance of IgG hexamers in initiating injury responses was unclear, so we tested their relevance in a mouse model of alloantibody and complement-mediated acute lung injury. We used three approaches to block alloantibody hexamerization (antibody carbamylation, the K439E Fc mutation, or treatment with domain B from Staphylococcal protein A), all of which reduced acute lung injury. Conversely, Fc mutations promoting spontaneous hexamerization made a harmful alloantibody into a more potent inducer of acute lung injury and rendered an innocuous alloantibody pathogenic. Treatment with a recombinant Fc hexamer 'decoy' therapeutic protected mice from lung injury, including in a model with transgenic human FCGR2A expression that exacerbated pathology. These results indicate an in vivo role of IgG hexamerization in initiating acute lung injury and the potential for therapeutics that inhibit or mimic hexamerization to treat antibody-mediated diseases.

Decoding functional hematopoietic progenitor cells in the adult human lung

The bone marrow is the main site of blood cell production in adults, however, rare pools of hematopoietic stem and progenitor cells with self-renewal and differentiation potential have been found in extramedullary organs. The lung is primarily known for its role in gas exchange but has recently been described as a site of blood production in mice. Here, we show that functional hematopoietic precursors reside in the extravascular spaces of the human lung, at a frequency similar to the bone marrow, and are capable of proliferation and engraftment. The organ-specific gene signature of pulmonary and medullary CD34+ hematopoietic progenitors indicates greater baseline activation of immune, megakaryocyte/platelet and erythroid-related pathways in lung progenitors. Spatial transcriptomics mapped blood progenitors in the lung to a vascular-rich alveolar interstitium niche. These results identify the lung as a pool for uniquely programmed blood stem and progenitor cells with the potential to support hematopoiesis in humans.

IgG hexamers initiate acute lung injury

Antibodies can initiate lung injury in a variety of disease states such as autoimmunity, transfusion reactions, or after organ transplantation, but the key factors determining in vivo pathogenicity of injury-inducing antibodies are unclear. A previously overlooked step in complement activation by IgG antibodies has been elucidated involving interactions between IgG Fc domains that enable assembly of IgG hexamers, which can optimally activate the complement cascade. Here, we tested the in vivo relevance of IgG hexamers in a complement-dependent alloantibody model of acute lung injury. We used three approaches to block alloantibody hexamerization (antibody carbamylation, the K439E Fc mutation, or treatment with domain B from Staphylococcal protein A), all of which reduced acute lung injury. Conversely, Fc mutations promoting spontaneous hexamerization made a harmful alloantibody into a more potent inducer of acute lung injury and rendered an innocuous alloantibody pathogenic. Treatment with a recombinant Fc hexamer 'decoy' therapeutic protected mice from lung injury, including in a model with transgenic human FCGR2A expression that exacerbated pathology. These results indicate a direct in vivo role of IgG hexamerization in initiating acute lung injury and the potential for therapeutics that inhibit or mimic hexamerization to treat antibody-mediated diseases.

NKG2D receptor activation drives primary graft dysfunction severity and poor lung transplantation outcomes

Clinical outcomes after lung transplantation, a life-saving therapy for patients with end-stage lung diseases, are limited by primary graft dysfunction (PGD). PGD is an early form of acute lung injury with no specific pharmacologic therapies. Here, we present a large multicenter study of plasma and bronchoalveolar lavage (BAL) samples collected on the first posttransplant day, a critical time for investigations of immune pathways related to PGD. We demonstrated that ligands for NKG2D receptors were increased in the BAL from participants who developed severe PGD and were associated with increased time to extubation, prolonged intensive care unit length of stay, and poor peak lung function. Neutrophil extracellular traps (NETs) were increased in PGD and correlated with BAL TNF-α and IFN-γ cytokines. Mechanistically, we found that airway epithelial cell NKG2D ligands were increased following hypoxic challenge. NK cell killing of hypoxic airway epithelial cells was abrogated with NKG2D receptor blockade, and TNF-α and IFN-γ provoked neutrophils to release NETs in culture. These data support an aberrant NK cell/neutrophil axis in human PGD pathogenesis. Early measurement of stress ligands and blockade of the NKG2D receptor hold promise for risk stratification and management of PGD.

ADAM8 signaling drives neutrophil migration and ARDS severity

Acute respiratory distress syndrome (ARDS) results in catastrophic lung failure and has an urgent, unmet need for improved early recognition and therapeutic development. Neutrophil influx is a hallmark of ARDS and is associated with the release of tissue-destructive immune effectors, such as matrix metalloproteinases (MMPs) and membrane-anchored metalloproteinase disintegrins (ADAMs). Here, we observed using intravital microscopy that Adam8-/- mice had impaired neutrophil transmigration. In mouse pneumonia models, both genetic deletion and pharmacologic inhibition of ADAM8 attenuated neutrophil infiltration and lung injury while improving bacterial containment. Unexpectedly, the alterations of neutrophil function were not attributable to impaired proteolysis but resulted from reduced intracellular interactions of ADAM8 with the actin-based motor molecule Myosin1f that suppressed neutrophil motility. In 2 ARDS cohorts, we analyzed lung fluid proteolytic signatures and identified that ADAM8 activity was positively correlated with disease severity. We propose that in acute inflammatory lung diseases such as pneumonia and ARDS, ADAM8 inhibition might allow fine-tuning of neutrophil responses for therapeutic gain.

[Intein-Mediated Protein trans-Splicing of the Recombinant Streptavidin on Magnetosomes]

When expressing streptavidin recombinant polypeptide on magnetosomes (called bacterial magnetic nanoparticles, or BMPs), the presence of endogenous bacterial biotin might be detrimental. In the study, the streptavidin monomer fragment (S1-116) was fused with the intein N-terminal (termed precursor S1-116-IN), and S1-116-IN was expressed in E. coli (BL21). Meanwhile, the SA117-160 fragment was fused with the C-terminal intein, and then this chimeric polypeptide was expressed on magnetosomes by fusion with magnetosome membrance protein MamF. In the in vitro protein splicing system, the purified engineered magnetosomes (BMP-SA117-160-IC) and the S1-116-IN precursor were mixed. Intein-mediated trans-splicing reaction was induced to produce the functional magnetic beads BMP-SA. Our results indicate that intein-mediated protein trans-splicing may lead to efficient synthesis of the recombinant streptavidin on the magnetosomes, showing its promising potential to produce other functional magnetic nanoparticles.

Complement activation on endothelium initiates antibody-mediated acute lung injury

Antibodies targeting human leukocyte antigen (HLA)/major histocompatibility complex (MHC) proteins limit successful transplantation and transfusion, and their presence in blood products can cause lethal transfusion-related acute lung injury (TRALI). It is unclear which cell types are bound by these anti-leukocyte antibodies to initiate an immunologic cascade resulting in lung injury. We therefore conditionally removed MHC class I (MHC I) from likely cellular targets in antibody-mediated lung injury. Only the removal of endothelial MHC I reduced lung injury and mortality, related mechanistically to absent endothelial complement fixation and lung platelet retention. Restoration of endothelial MHC I rendered MHC I-deficient mice susceptible to lung injury. Neutrophil responses, including neutrophil extracellular trap (NET) release, were intact in endothelial MHC I-deficient mice, whereas complement depletion reduced both lung injury and NETs. Human pulmonary endothelial cells showed high HLA class I expression, and posttransfusion complement activation was increased in clinical TRALI. These results indicate that the critical source of antigen for anti-leukocyte antibodies is in fact the endothelium, which reframes our understanding of TRALI as a rapid-onset vasculitis. Inhibition of complement activation may have multiple beneficial effects of reducing endothelial injury, platelet retention, and NET release in conditions where antibodies trigger these pathogenic responses.

Cystic fibrosis transmembrane conductance regulator dysfunction in platelets drives lung hyperinflammation

Cystic fibrosis (CF) lung disease is characterized by an inflammatory response that can lead to terminal respiratory failure. The cystic fibrosis transmembrane conductance regulator (CFTR) is mutated in CF, and we hypothesized that dysfunctional CFTR in platelets, which are key participants in immune responses, is a central determinant of CF inflammation. We found that deletion of CFTR in platelets produced exaggerated acute lung inflammation and platelet activation after intratracheal LPS or Pseudomonas aeruginosa challenge. CFTR loss of function in mouse or human platelets resulted in agonist-induced hyperactivation and increased calcium entry into platelets. Inhibition of the transient receptor potential cation channel 6 (TRPC6) reduced platelet activation and calcium flux, and reduced lung injury in CF mice after intratracheal LPS or Pseudomonas aeruginosa challenge. CF subjects receiving CFTR modulator therapy showed partial restoration of CFTR function in platelets, which may be a convenient approach to monitoring biological responses to CFTR modulators. We conclude that CFTR dysfunction in platelets produces aberrant TRPC6-dependent platelet activation, which is a major driver of CF lung inflammation and impaired bacterial clearance. Platelets and TRPC6 are what we believe to be novel therapeutic targets in the treatment of CF lung disease.

Mitochondrial DNA Stimulates TLR9-Dependent Neutrophil Extracellular Trap Formation in Primary Graft Dysfunction

The immune system is designed to robustly respond to pathogenic stimuli but to be tolerant to endogenous ligands to not trigger autoimmunity. Here, we studied an endogenous damage-associated molecular pattern, mitochondrial DNA (mtDNA), during primary graft dysfunction (PGD) after lung transplantation. We hypothesized that cell-free mtDNA released during lung ischemia-reperfusion triggers neutrophil extracellular trap (NET) formation via TLR9 signaling. We found that mtDNA increases in the BAL fluid of experimental PGD (prolonged cold ischemia followed by orthotopic lung transplantation) and not in control transplants with minimal warm ischemia. The adoptive transfer of mtDNA into the minimal warm ischemia graft immediately before lung anastomosis induces NET formation and lung injury. TLR9 deficiency in neutrophils prevents mtDNA-induced NETs, and TLR9 deficiency in either the lung donor or recipient decreases NET formation and lung injury in the PGD model. Compared with human lung transplant recipients without PGD, severe PGD was associated with high levels of BAL mtDNA and NETs, with evidence of relative deficiency in DNaseI. We conclude that mtDNA released during lung ischemia-reperfusion triggers TLR9-dependent NET formation and drives lung injury. In PGD, DNaseI therapy has a potential dual benefit of neutralizing a major NET trigger (mtDNA) in addition to dismantling pathogenic NETs.

[The oncologic and functional outcomes of supracricoid partial laryngectomy for the treatment of laryngeal cancer]

Objective: To evaluate the oncologic and functional outcomes of laryngeal squamous cell carcinomas treated by supracricoid laryngectomy. Methods: The clinical data of 134 patients with laryngeal cancer who underwent supracricoid laryngectomy with cricohyoidoepiglottopexy (CHEP) or cricohyoidopexy (CHP) between July 2005 and April 2014 at Shandong Provincial ENT Hospital were retrospectively reviewed. Ninety-one patients including 31 cases of stage Ⅰ, 36 of stage Ⅱ, 18 of stage Ⅲ and 6 of stage Ⅳ underwent CHEP and 43 patients underwent CHP. Two patients received CHEP due to recurrence after open surgery and laser surgery. Three patients received CHP due to the recurrence of disease after open surgery and postradiotherapy persistence of disease. The Kaplan-Meier method was used to calculate the 3-year and 5-year survival rates. The Chi-square test was used to compare the survival rates between different surgical procedures. Results: All 91 patients who underwent CHEP had successful removals of PEG tubes, and 88 (96.7%) of them had tracheostomy tube decannulation. Among 43 patients with CHP, 42(97.6%) cases removal of PEG tubes(97.6%), including and 40(93.0%) cases with tracheostomy tube decannulation. There was one patient with local recurrence in all cases. In CHEP group, 3-year local control rate was 98.2%; 3-year and 5-year overall survival rate were 94.5% and 93.9%, respectively. In CHP group, 3-year local control rate was 97.6%; 3-year and 5-year overall survival rates were 86.0% and 83.3%, respectively. Pharyngeal fistula appeared in 2 cases of CHEP group and 4 cases of CHP group, and all of them were cured by conservative treatment. Conclusion: Supracricoid laryngectomy shows excellent oncologic and functional results for treatment of laryngeal cancer while maintaining laryngeal functions, especially in terms of local control rate and tracheostomy tube decannulation.

[Treatment and prognosis of 264 patients with hypopharyngeal carcinoma]

Objective: To investigate the key factors influencing the prognosis of hypopharyngeal carcinoma and the therapeutic methods improving the efficacy of treatments for hypopharyngeal carcinoma. Methods: Two hundred and sixty-four cases of hypopharyngeal squamous cell carcinoma treated from May 2010 to May 2015 were analyzed retrospectively. There were 211 cases of pyriform sinus carcinoma, 37 cases of posterior pharyngeal wall carcinoma, and 16 cases of postcricoid carcinoma. According to UICC 2002 criteria, 2 cases were for stage Ⅰ, 14 for stage Ⅱ, 32 for stage Ⅲ and 216 for stage Ⅳ. Postoperative circumferential defects existed in 112 (42.4%) cases, and 86 of them were reconstructed with free jejunum transplantation. Among all cases, 54 patients (20.5%) had the preservation of laryngeal functions after surgery and 210 patients (79.5%) with total laryngectomy; 238 cases (90.2%) underwent bilateral cervical lymph node dissection and 203 patients received posterior pharyngeal lymph node exploration and dissection, with positive metastases for posterior pharyngeal lymph nodes in 36 cases (17.7%). Eight cases with cervical lymph node metastasis extensively involving the soft tissue, prevertebral fascia or encases carotid artery received preoperative radiotherapy of 50 Gy. After surgery 13 patients received concurrent radiotherapy and chemotherapy, 337 underwent adjuvant radiotherapy with a dose of 50-60 Gy each, and 14 patients did not receive radiotherapy or did not completed their radiotherapy programs. SPSS 13.0 saftware was used to analyze the data. Results: All patients were followed up for more than 2 years. With Kaplan-Meier method, the 2-, 3- and 5-years survival rates were 69.6%, 62.8% and 51.3%, respectively. There were significant differences in 3-year survival rates between T1-2 group (75.5%) and T3-4 group (59.2%) (χ(2)=4.282 P=0.039), N0 group (81.6%) and N+ group (58.2%) (χ(2)=6.802 P=0.009), laryngeal functions preserved (81.8%) and unpreserved group (58.9%) (χ(2)=5.314 P=0.021). Multivariate Logistic regression analysis showed that cervical lymph node metastasis was an independent prognostic factor (P=0.027). The success rate of free jejunum transplantation was 98.8%. Local recurrence, cervical lymph node recurrence, second primary cancer, and distant metastasis accounted respectively for 11.2%, 18.8%, 12.5% and 45.0% of death cases. Conclusions: The prognosis-associated factors for hypopharyngeal carcinoma should be taken into account, including the evaluation of the carcinogenesis of the mucosal area, early screening of premalignant lesion or second primary cancer in the esophagus and dissection of the posterior pharyngeal lymph nodes, which will help to improve the local control rate and recent survival rate in patients with hypopharyngeal cancer.

[Significance of retropharyngeal node dissection in treatment of hypopharyngeal carcinoma]

Objective: investigate the incidence of retropharyngeal lymph node (RPLN) metastasis and the risk factors for RPLN metastasis in hypopharyngeal cancer, and the relationship of planned dissection of the RPLN with the survival and tumor control rates in patients with hypopharyngeal cancer. Methods: A total of 203 patients with hypopharyngeal squamous cell carcinoma who underwent radical surgery as initial treatment from February 2011 to July 2015 were analyzed retrospectively. There were 167 cases of pyriform sinus carcinoma, 23 cases of posterior pharyngeal wall carcinoma, and 13 cases of postcricoid carcinoma. Results: The incidence of RPLN metastasis in HPC was 17.7%, with a highest rate of 43.5% in pharyngeal wall carcinoma. The incidence of RPLN metastasis in T3-4 pyriform sinus carcinoma was 18.3%, which significantly higher than 2.8% in T1-2 cases(χ(2)=5.360, P=0.020). The rate of RPLN metastasis was 23.8% in N2b-3 and 8.6% in N0-2a, with a statistically significant difference(χ(2)=7.637, P=0.006). There was no statistically significant difference in overall survival rates between patients with and without RPLN metastasis(P>0.05). Data were analyzed by SPSS 13.0 software. Conclusions: RPLN metastasis is not rare in hypopharyngeal carcinoma. Planned dissection of the RPLN should be performed with the initial surgery in patients with advanced hypopharyngeal cancer, especially posterior pharyngeal wall carcinoma, T3-4 pyriform sinus carcinoma and staged N2b-3 disease, which can reduce the regional recurrence rate and provided with a better prognosis.

Arterial spin-labeling perfusion MRI stratifies progression-free survival and correlates with epidermal growth factor receptor status in glioblastoma

BACKGROUND AND PURPOSE

Glioblastoma is a common primary brain tumor with a poor but variable prognosis. Our aim was to investigate the feasibility of MR perfusion imaging by using arterial spin-labeling for determining the prognosis of patients with glioblastoma.

MATERIALS AND METHODS

Pseudocontinuous arterial spin-labeling with 3D background-suppressed gradient and spin-echo was acquired before surgery on 53 patients subsequently diagnosed with glioblastoma. The calculated CBF color maps were visually evaluated by 3 independent readers blinded to patient history. Pathologic and survival data were correlated with CBF map findings. Arterial spin-labeling values in tumor tissue were also quantified by using manual fixed-size ROIs.

RESULTS

Two perfusion patterns were characterized by visual evaluation of CBF maps on the basis of either the presence (pattern 1) or absence (pattern 2) of substantial hyperperfused tumor tissue. Evaluation of the perfusion patterns was highly concordant among the 3 readers (κ = 0.898, P < .001). Pattern 1 (versus pattern 2) was associated with significantly shorter progression-free survival by Kaplan-Meier analysis (median progression-free survival of 182 days versus 485 days, P < .01) and trended with shorter overall survival (P = .079). There was a significant association between pattern 1 and epidermal growth factor receptor variant III expression (P < .01).

CONCLUSIONS

Qualitative evaluation of arterial spin-labeling CBF maps can be used to stratify survival and predict epidermal growth factor receptor variant III expression in patients with glioblastoma.

Effects of shrimp consumption on plasma lipoproteins

Shrimp is very low in total fat, yet it has a high cholesterol content. Although shrimp is a popular food in the American diet, many people avoid it because of its high cholesterol content. The objective of this study was to test the effect of the addition of cholesterol from shrimp to a low-fat baseline diet as well as to compare the effect of an equal amount of dietary cholesterol derived from shrimp or egg on the plasma lipoprotein pattern of normolipidemic subjects. In a randomized crossover trial, a diet containing 300 g shrimp/d, which supplied 590 mg dietary cholesterol/d, significantly increased low-density-lipoprotein (LDL) cholesterol by 7.1% (P = 0.014) and high-density-lipoprotein (HDL) cholesterol by 12.1% (P = 0.0001) when compared with a baseline diet matched for fat content but containing only 107 mg cholesterol/d. However, because the percentage increase in LDL cholesterol was less than for HDL cholesterol, the shrimp diet did not worsen the ratio of total cholesterol to HDL cholesterol or the ratio of LDL to HDL cholesterol. Moreover, shrimp consumption decreased triacylglycerol (triglyceride) concentrations by 13% (P = 0.004). The diet containing two large eggs per day with 581 mg dietary cholesterol/d also raised LDL- and HDL-cholesterol concentrations compared with baseline, but the percentage increase in LDL cholesterol (10.2%, P = 0.0001) was more than for HDL cholesterol (7.6%, P = 0.004) and there was a trend toward worse lipoprotein ratios. In a comparison of the two high-cholesterol diets, the shrimp diet produced significantly lower ratios of total to HDL cholesterol and lower ratios of LDL to HDL cholesterol than the egg diet as well as lower triacylglycerol concentrations. We conclude that moderate shrimp consumption in normolipidemic subjects will not adversely affect the overall lipoprotein profile and can be included in "heart healthy" nutritional guidelines.

On prediction of future observation in growth curve model

Rao proposed and compared several approaches for predicting future observations in a growth curve model. The assessment of associated prediction efficiency for different prediction methods were evaluated by Cross-Validation Assessment Error (CVAE). He used three data sets, each with a limited number of subjects (13-27) and also with a limited number of repeated measurements (4-7) per subject, to illustrate the prediction methods. In the present paper, we applied four of the prediction methods discussed by Rao, on a data set with a relatively large number of subjects (174) and also with a larger number of measurements (21) per subject, using the polynomial function and log-linear function. We propose to use the restricted cubic spline function as an alternative growth curve model and compare its performance with the polynomial function and log-linear function. It turns out that, at least for larger data sets such as that used in this paper, the prediction methods perform somewhat better when the growth is described by restricted cubic spline function than when the growth is described by polynomial function and log-linear function.