The TWIK2 Potassium Efflux Channel in Macrophages Mediates NLRP3 Inflammasome-Induced Inflammation.

Potassium (K+) efflux across the plasma membrane is thought to be an essential mechanism for ATP-induced NLRP3 inflammasome activation, yet the identity of the efflux channel has remained elusive. Here we identified the two-pore domain K+ channel (K2P) TWIK2 as the K+ efflux channel triggering NLRP3 inflammasome activation. Deletion of Kcnk6 (encoding TWIK2) prevented NLRP3 activation in macrophages and suppressed sepsis-induced lung inflammation. Adoptive transfer of Kcnk6-/- macrophages into mouse airways after macrophage depletion also prevented inflammatory lung injury. The K+ efflux channel TWIK2 in macrophages has a fundamental role in activating the NLRP3 inflammasome and consequently mediates inflammation, pointing to TWIK2 as a potential target for anti-inflammatory therapies.

Emergency and Prophylactic Extracorporeal Membrane Oxygenation for Patients Undergoing Valve-in-Valve Transcatheter Aortic Valve Implantation With Small Surgical Bioprosthesis: A Report of Four Cases.

Mechanical circulatory support (MCS) using veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is widely implemented as a rescue device in transcatheter aortic valve implantation (TAVI). Although prophylactic VA-ECMO (pECMO) in TAVI is preferable to emergency VA-ECMO (eECMO) in terms of overall survival, there is currently no consensus on the introduction criteria for pECMO. Here, we report four cases of eECMO and pECMO performed in valve-in-valve TAVI (ViV-TAVI) with a small surgical bioprosthesis to consider the validity of the current pECMO indications. In the two cases that were placed on eECMO, a 19 mm and 21 mm Carpentier-Edwards perimount bioprosthesis (CEP), a stented bioprosthetic valve, were sewn. After the transcatheter heart valve (THV) passed through the surgical aortic valve, acute aortic regurgitation developed, thus leading to hemodynamic instability requiring cardiopulmonary resuscitation, and therefore VA-ECMO was introduced. In the two cases using pECMO, 19 mm of CEP were sewn, and the THV was safely placed once MCS had been established. In all four cases, the patients were removed from VA-ECMO in the operating room following ViV-TAVI. The eECMO patients were discharged on postoperative days 12 and 20, while the pECMO patients were discharged on postoperative days 7 and 9, respectively. From our experience and based on the findings of some published reviews, ViV-TAVI with a small surgical bioprosthesis is considered to belong to a high-risk patient group demonstrating hemodynamic instability. The introduction of pECMO for such cases may therefore be an effective option for obtaining a better prognosis.

A Case Report of Inhaled Nitric Oxide for Transfusion-Related Acute Lung Injury.

Transfusion-related acute lung injury (TRALI) is an acute respiratory distress syndrome (ARDS) occurring during or within six hours after transfusion. On the other hand, while inhaled nitric oxide (iNO) temporarily improves arterial oxygenation with selective pulmonary vasodilation, there is no evidence of mortality reduction in ARDS. We herein report a case in which TRALI was diagnosed with severe hypoxemia during cardiovascular surgery, and extracorporeal membrane oxygenation (ECMO) was avoided by using iNO for respiratory management. Administering iNO to patients with acute respiratory failure may be useful as a bridging therapy to help patients recover. However, further evidence is needed before this treatment can become standard practise.

Evaluation of Platelet Function Using Thromboelastography for a Patient With Pseudothrombocytopenia Requiring Cardiac Reoperation.

Pseudothrombocytopenia (PTCP) is a phenomenon in which platelet aggregation occurs in vitro when an anticoagulant such as ethylenediaminetetraacetic acid (EDTA) is used in a blood sample, causing automated cell counters (ACC) to calculate a lower platelet count than the actual count. While a peripheral blood smear is required to assess platelet count in PTCP accurately, such a time-consuming test is not accessible during the perioperative period. In this study, we evaluated platelet function using thromboelastography (TEG) for a patient with PTCP requiring cardiac reoperation. The preoperative TEG value of the patient was within the normal range, suggesting that TEG for PTCP reflects platelet function more accurately than ACC. Since there is an insufficient number of case reports on the use of TEG for PTCP, it is necessary to consider its usefulness not only during the perioperative period but also for other critical care.

Chiral Silica with Preferred-Handed Helical Structure via Chiral Transfer.

A strategy to obtain chiral silica using an achiral stereoregular polymer with polyhedral oligomeric silsesquioxane (POSS) side chains is described herein. The preferred helical conformation of the POSS-containing polymer could be achieved by mixing isotactic polymethacrylate-functionalized POSS (it-PMAPOSS) and a chiral dopant. The array structure of POSS molecules, which are placed along the helical conformation, is memorized even after removing the chiral dopant at high temperatures, leading to a chiral silica compound with exclusive optical activity after calcination.

Ubiquitin-mediated proteasomal degradation of non-synonymous SNP variants of human ABC transporter ABCG2.

Clinical relevance is implicated between the genetic polymorphisms of the ABC (ATP-binding cassette) transporter ABCG2 (ABC subfamily G, member 2) and the individual differences in drug response. We expressed a total of seven non-synonymous SNP (single nucleotide polymorphism) variants in Flp-In-293 cells by using the Flp (flippase) recombinase system. Of these, ABCG2 F208S and S441N variants were found to be expressed at markedly low levels, whereas their mRNA levels were equal to those of the other SNP variants and ABCG2 WT (wild-type). Interestingly, protein expression levels of the ABCG2 F208S and S441N variants increased 6- to 12-fold when Flp-In-293 cells were treated with MG132, a proteasome inhibitor. Immunoprecipitation followed by immunoblot analysis showed that the ABCG2 F208S and S441N variant proteins were endogenously ubiquitinated in Flp-In-293 cells, and treatment with MG132 significantly enhanced the level of these ubiquitinated variants. Immunofluorescence microscopy demonstrated that MG132 greatly affected the ABCG2 F208S and S441N variants in terms of both protein levels and intracellular distribution. Immunoblot analysis revealed that those variants were N-glycosylated; however, their oligosaccharides were immature compared with those present on ABCG2 WT. The ABCG2 F208S and S441N variant proteins do not appear to be processed in the Golgi apparatus, but undergo ubiquitin-mediated protein degradation in proteasomes, whereas ABCG2 WT is sorted to the plasma membrane and then degraded via the lysosomal pathway. The present study provides the first evidence that certain genetic polymorphisms can affect the protein stability of ABCG2. Control of proteasomal degradation of ABCG2 would provide a novel approach in cancer chemotherapy to circumvent multidrug resistance of human cancers.

In vitro evaluation of photosensitivity risk related to genetic polymorphisms of human ABC transporter ABCG2 and inhibition by drugs.

Since porphyrins are regarded as endogenous substrates for the ATP-binding cassette (ABC) transporter ABCG2, it is hypothesized that functional impairment owing to genetic polymorphisms or inhibition of ABCG2 by drugs may result in a disruption of cellular porphyrin homeostasis. In the present study, we expressed ABCG2 genetic variants, i.e., V12M, Q141K, S441N, and F489L, as well as the wild type (WT) in Flp-In-293 cells to examine the hypothesis. Cells expressing S441N and F489L variants exhibited high levels of both cellularly accumulated pheophorbide a and photosensitivity, when those cells were incubated with pheophorbide a and irradiated with visible light. To further elucidate the significance of ABCG2 in cellular porphyrin homeostasis, we observed cellular accumulation and compartmentation of porphyrin and pheophorbide a by means of a new fluorescence microscopy technology, and found that accumulation of porphyrin and pheophorbide a in the cytoplasm compartment was maintained at low levels in Flp-In-293 cells expressing ABCG2 WT, V12M, or Q141K. When ABCG2 was inhibited by imatinib or novobiocin, however, those cells became sensitive to light. Based on these results, it is strongly suggested that certain genetic polymorphisms and/or inhibition of ABCG2 by drugs can enhance the potential risk of photosensitivity.