Akihiro Matsukawa

A novel, visible light-induced, rapidly cross-linkable gelatin scaffold for osteochondral tissue engineering

Osteochondral injuries remain difficult to repair. We developed a novel photo-cross-linkable furfurylamine-conjugated gelatin (gelatin-FA). Gelatin-FA was rapidly cross-linked by visible light with Rose Bengal, a light sensitizer, and was kept gelled for 3 weeks submerged in saline at 37°C. When bone marrow-derived stromal cells (BMSCs) were suspended in gelatin-FA with 0.05% Rose Bengal, approximately 87% of the cells were viable in the hydrogel at 24u2005h after photo-cross-linking, and the chondrogenic differentiation of BMSCs was maintained for up to 3 weeks. BMP4 fusion protein with a collagen binding domain (CBD) was retained in the hydrogels at higher levels than unmodified BMP4. Gelatin-FA was subsequently employed as a scaffold for BMSCs and CBD-BMP4 in a rabbit osteochondral defect model. In both cases, the defect was repaired with articular cartilage-like tissue and regenerated subchondral bone. This novel, photo-cross-linkable gelatin appears to be a promising scaffold for the treatment of osteochondral injury.

Elevated Levels of Monocyte Chemoattractant Protein-1 in the Aqueous Humor after Phacoemulsification

PURPOSEnTo elucidate the impact of phacoemulsification on aqueous monocyte chemoattractant protein-1 (MCP-1) levels, and identify its cell origin.nnnMETHODSnFor clinical study, aqueous humor samples were collected before and after surgery (17.0 ± 4.0 months postoperatively) from 21 cataract cases that underwent phacoemulsification and intraocular lens (IOL) implantation. Aqueous MCP-1 levels were determined using a multiplex immunoassay. For animal experiments, rabbits underwent phacoemulsification (± IOL). Aqueous humor samples were collected from nonoperated eyes and operated eyes, and immunoassays were performed. Eyes were analyzed by reverse transcription-polymerase chain reaction and immunohistochemical studies.nnnRESULTSnIn the clinical study, mean (± SD) aqueous MCP-1 levels were higher postoperatively (1773.5 ± 321.2 pg/mL) than preoperatively (796.9 ± 211.3 pg/mL; P < 0.0001). In animal experiments, mean aqueous MCP-1 levels (pg/mL) were higher in postoperative eyes on day 30 (207.1 ± 62.9) than in nonoperated eyes (31.2 ± 12.5; P = 0.018). IOL implantation did not affect the changes in MCP-1 levels. After phacoemulsification, MCP-1 mRNA expression was increased in the cornea, iris, ciliary body, and capsular bag. Expression of MCP-1 mRNA in the capsular bag, but not the other tissues, increased from day 30 to 90. Immunohistochemical studies showed positive immunoreactivity for MCP-1 in cells of the posterior capsule after phacoemulsification.nnnCONCLUSIONSnaqueous MCP-1 levels were elevated in both human and animal eyes after phacoemulsification. Proliferated Lens epithelial cells on the capsule might be the major cell origin for prolonged MCP-1 production after phacoemulsification. (http://www.umin.ac.jp/ number, UMIN000005788.).

Redox-Active Protein Thioredoxin-1 Administration Ameliorates Influenza A Virus (H1N1)-Induced Acute Lung Injury in Mice

Objectives:Influenza virus infections can cause severe acute lung injury leading to significant morbidity and mortality. Thioredoxin-1 is a redox-active defensive protein induced in response to stress conditions. Animal experiments have revealed that thioredoxin-1 has protective effects against various severe disorders. This study was undertaken to evaluate the protective effects of recombinant human thioredoxin-1 administration on influenza A virus (H1N1)-induced acute lung injury in mice. Design:Prospective animal trial. Setting:Research laboratory. Subjects:Nine-week-old male C57BL/6 mice inoculated with H1N1. Intervention:The mice were divided into a vehicle-treated group and recombinant human thioredoxin-1-treated group. For survival rate analysis, the vehicle or recombinant human thioredoxin-1 was administered intraperitoneally every second day from day –1 to day 13. For lung lavage and pathological analyses, vehicle or recombinant human thioredoxin-1 was administered intraperitoneally on days –1, 1, and 3. Measurements and Main Results:Lung lavage and pathological analyses were performed at 24, 72, and 120 hrs after inoculation. The recombinant human thioredoxin-1 treatment significantly improved the survival rate of H1N1-inoculated mice, although the treatment did not affect virus propagation in the lung. The treatment significantly attenuated the histological changes and neutrophil infiltration in the lung of H1N1-inoculated mice. The treatment significantly attenuated the production of tumor necrosis factor-&agr; and chemokine (C-X-C motif) ligand 1 in the lung and oxidative stress enhancement, which were observed in H1N1-inoculated mice. H1N1 induced expressions of tumor necrosis factor-&agr; and chemokine (C-X-C motif) ligand 1 in murine lung epithelial cells MLE-12, which were inhibited by the addition of recombinant human thioredoxin-1. The recombinant human thioredoxin-1 treatment started 30 mins after H1N1 inoculation also significantly improved the survival of the mice. Conclusions:Exogenous administration of recombinant human thioredoxin-1 significantly improved the survival rate and attenuated lung histological changes in the murine model of influenza pneumonia. The protective mechanism of thioredoxin-1 might be explained by its potent antioxidative and anti-inflammatory actions. Consequently, recombinant human thioredoxin-1 might be a possible pharmacological strategy for severe influenza virus infection in humans.

Notch system in the linkage of innate and adaptive immunity

The lung is one of the most immunologically challenged organs and can be affected by a number of pathogens, including bacteria, virus, fungi, and parasites. The development and chronicity of pulmonary infection are determined by the early innate response to the pathogenic stimuli and are regulated at multiple levels. Initial studies have indicated that the interaction of Notch and Notch ligands plays a critical role during development, and further, the Notch system is an important bridge between APCs and T cell communication circuits. APCs are essential regulators of the innate immune response. They can respond to PAMPs through PRRs, which function in the recognition of pathogenic components and play an important role in the innate and adaptive immune response. T cells are essential regulators of adaptive immune responses and infectious diseases. However, the role of the Notch system in the cross‐talk between APC and T cells during pulmonary infection is still poorly understood. In the present review, we discuss recent findings that explore the mechanisms underlying the role of Notch signaling in the linkage of innate and adaptive immunity, including pulmonary infection though PPRs and Notch activation.

Spred-2 Deficiency Exacerbates Lipopolysaccharide-Induced Acute Lung Inflammation in Mice

Background Acute respiratory distress syndrome (ARDS) is a severe and life-threatening acute lung injury (ALI) that is caused by noxious stimuli and pathogens. ALI is characterized by marked acute inflammation with elevated alveolar cytokine levels. Mitogen-activated protein kinase (MAPK) pathways are involved in cytokine production, but the mechanisms that regulate these pathways remain poorly characterized. Here, we focused on the role of Sprouty-related EVH1-domain-containing protein (Spred)-2, a negative regulator of the Ras-Raf-extracellular signal-regulated kinase (ERK)-MAPK pathway, in lipopolysaccharide (LPS)-induced acute lung inflammation. Methods Wild-type (WT) mice and Spred-2−/− mice were exposed to intratracheal LPS (50 µg in 50 µL PBS) to induce pulmonary inflammation. After LPS-injection, the lungs were harvested to assess leukocyte infiltration, cytokine and chemokine production, ERK-MAPK activation and immunopathology. For ex vivo experiments, alveolar macrophages were harvested from untreated WT and Spred-2−/− mice and stimulated with LPS. In in vitro experiments, specific knock down of Spred-2 by siRNA or overexpression of Spred-2 by transfection with a plasmid encoding the Spred-2 sense sequence was introduced into murine RAW264.7 macrophage cells or MLE-12 lung epithelial cells. Results LPS-induced acute lung inflammation was significantly exacerbated in Spred-2−/− mice compared with WT mice, as indicated by the numbers of infiltrating leukocytes, levels of alveolar TNF-α, CXCL2 and CCL2 in a later phase, and lung pathology. U0126, a selective MEK/ERK inhibitor, reduced the augmented LPS-induced inflammation in Spred-2−/− mice. Specific knock down of Spred-2 augmented LPS-induced cytokine and chemokine responses in RAW264.7 cells and MLE-12 cells, whereas Spred-2 overexpression decreased this response in RAW264.7 cells. Conclusions The ERK-MAPK pathway is involved in LPS-induced acute lung inflammation. Spred-2 controls the development of LPS-induced lung inflammation by negatively regulating the ERK-MAPK pathway. Thus, Spred-2 may represent a therapeutic target for the treatment of ALI.

Chemokine receptor CCR8 is required for lipopolysaccharide-triggered cytokine production in mouse peritoneal macrophages

Chemokine (C-C motif) receptor 8 (CCR8), the chemokine receptor for chemokine (C-C motif) ligand 1 (CCL1), is expressed in T-helper type-2 lymphocytes and peritoneal macrophages (PMφ) and is involved in various pathological conditions, including peritoneal adhesions. However, the role of CCR8 in inflammatory responses is not fully elucidated. To investigate the function of CCR8 in macrophages, we compared cytokine secretion from mouse PMφ or bone marrow-derived macrophages (BMMφ) stimulated with various Toll-like receptor (TLR) ligands in CCR8 deficient (CCR8- /-) and wild-type (WT) mice. We found that CCR8-/- PMφ demonstrated attenuated secretion of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 when stimulated with lipopolysaccharide (LPS). In particular, LPS-induced IL-10 production absolutely required CCR8. CCR8-dependent cytokine secretion was characteristic of PMφ but not BMMφ. To further investigate this result, we selected the small molecule compound R243 from a library of compounds with CCR8-antagonistic effects on CCL1-induced Ca2+ flux and CCL1-driven PMφ aggregation. Similar to CCR8-/- PMφ, R243 attenuated secretion of TNF-α, IL-6, and most strikingly IL-10 from WT PMφ, but not BMMφ. CCR8-/- PMφ and R243-treated WT PMφ both showed suppressed c-jun N-terminal kinase activity and nuclear factor-κB signaling after LPS treatment when compared with WT PMφ. A c-Jun signaling pathway inhibitor also produced an inhibitory effect on LPS-induced cytokine secretion that was similar to that of CCR8 deficiency or R243 treatment. As seen in CCR8-/- mice, administration of R243 attenuated peritoneal adhesions in vivo. R243 also prevented hapten-induced colitis. These results are indicative of cross talk between signaling pathways downstream of CCR8 and TLR-4 that induces cytokine production by PMφ. Through use of CCR8-/- mice and the new CCR8 inhibitor, R243, we identified a novel macrophage innate immune response pathway that involves a chemokine receptor.

Local effects of intra-articular injection of anti-rabbit tumor necrosis factor alpha monoclonal antibody in antigen-induced arthritis of the rabbit temporomandibular joint

BACKGROUNDnLocal effects of intra-articular (IA) injection of anti-rabbit tumor necrosis factor alpha monoclonal antibody (anti-TNFα mAb) for antigen-induced mono-arthritis (AIA) of the rabbit temporomandibular joint (TMJ) and its systemic influences were evaluated.nnnMETHODSnBiochemical analysis of synovial fluid (SF), clinical and histopathological analyses of TMJ, and serum analysis were performed after inducing AIA in bilateral TMJs of 40 New Zealand White rabbits. IA injection of anti-TNFα mAb in unilateral TMJ (TNF blockade side; n = 12) and IgG (n = 12) was performed while saline injected on the contralateral side. TNFα and IL-1β in SF was analyzed at Days 1, 3, 7, and 21. Joint swelling and head withdrawal reflex threshold (WRT) over TMJs were evaluated in TNF blockade side (n = 12) with histopathological analysis at Days 3, 7, and 21. In remaining four animals with TNF blockade, TNFα and anti-TNFα mAb in serum were analyzed.nnnRESULTSnTumor necrosis factor alpha in SF was significantly lower in TNF blockade side on all days but IL-1β was lower only on Day 3. WRT was significantly higher at all times in the blockade side. Less inflammatory reactions and degenerative changes of cartilage were observed on Days 7 and 21 in the blockade side. TNFα and anti-TNFα mAb were under detection level in serum at all times.nnnCONCLUSIONSnIntra-articular injection of anti-rabbit TNFα mAb in mono-arthritis model was effective to control local inflammation and degenerative joint changes. Further, low-dose IA injection of antibody may not have systemic side effects.

Spred-2 deficiency exacerbates acetaminophen-induced hepatotoxicity in mice.

MAPKs are involved in acetaminophen (APAP)-hepatotoxicity, but the regulatory mechanism remains unknown. Here, we explored the role of Spred-2 that negatively regulates Ras/ERK pathway in APAP-hepatotoxicity. Spred-2 knockout (KO) mice demonstrated exacerbated liver injury, an event that was associated with increased numbers of CD4(+) T, CD8(+) T and NK cells in the liver compared to the control. Levels of CXCL9/CXCL10 that attract and activate these cells were increased in Spred-2 KO-liver. Kupffer cells isolated from Spred-2 KO mice after APAP challenge expressed higher levels of CXCL9/CXCL10 than those from the control. Upon stimulation with APAP or IFNγ, naïve Kupffer cells from Spred-2 KO mice expressed higher levels of CXCL9/CXCL10. NK cell-depletion attenuated APAP-hepatotoxicity with lowered hepatic IFNγ and decreased numbers of not only NK cells but also CD4(+) T and CD8(+) T cells in the liver. These results suggest that Spred-2 negatively regulates APAP-hepatotoxicity under the control of Kupffer cells and NK cells.

Effects of pharyngeal cooling on brain temperature in primates and humans: a study for proof of principle.

Background: Pharyngeal cooling decreases brain temperature by cooling carotid arteries. This study was designed to evaluate the principle of pharyngeal cooling in monkeys and humans. Methods: Monkeys (n = 10) were resuscitated following 12 min of cardiac arrest. Pharyngeal cooling (n = 5), in which cold saline (5°C) was perfused into the cuff at the rate of 500 ml/min, was initiated simultaneously with the onset of resuscitation for 30 min. Patients (n = 3) who were in an intensive care unit were subjected to 30 min of pharyngeal cooling under propofol anesthesia. Results: In the animal study, core brain temperature was significantly decreased compared with that in the control group by 1.9°C (SD = 0.8, P < 0.001) and 3.1°C (SD = 1.0, P < 0.001) at 10 min and 30 min after the onset of cooling, respectively. The cooling effect was more evident in an animal with low postresuscitation blood pressure. Total dose of epinephrine, number of direct current shocks, and recovery of blood pressure were not different between the two groups. The pharyngeal epithelium was microscopically intact on day 5. In the clinical study, insertion of the cuff and start of perfusion did not affect heart rate or blood pressure. Tympanic temperature was decreased by 0.6 ± 0.1°C/30 min without affecting bladder temperature. The pharynx was macroscopically intact for 3 days. Conclusions: Pharyngeal cooling rapidly and selectively decreased brain temperature in primates and tympanic temperature in humans and did not have adverse effects on return of spontaneous circulation, even when initiated during cardiac arrest in primates.

Egr1: a novel target for ameliorating acute allograft rejection in an experimental lung transplant model †

OBJECTIVESnAcute allograft rejection is one of the significant complications occurring in lung transplant recipients. Early growth response-1 (Egr-1), zinc-finger-type transcription factor, is known as a master switch regulator of diverse chemical mediators. We used an orthotopic mouse model of left lung transplant to elucidate the function of Egr-1 in acute pulmonary rejection.nnnMETHODSnLeft lung grafts retrieved from C57BL/6 wild mice or C57BL/6 Egr-1-null mice were orthotopically transplanted into BALB/c mice; the lungs were harvested at day 1, 3, 5 or 7 after lung transplantation. The grade of acute rejection was histopathologically evaluated. The intragraft gene expression levels of Egr-1 and downstream target mediators were quantitatively measured by real-time polymerase chain reaction. Immunohistochemical analysis was used to determine the location and distribution of the Egr-1 protein in the pulmonary graft.nnnRESULTSnSevere acute rejection was observed in allografts from wild-type mice at 5 days after transplantation. Only minimal rejection was seen in the lung graft from Egr-1-null donor mice at 5 days after transplantation. Strong upregulation of Egr-1 mRNA transcripts was observed at day 1, which then decreased during the next 5 days. The mRNA of Egr-1 target mediators [interleukin-1-beta (IL-1β), monocyte chemotactic protein-1 (MCP-1) and plasminogen activator inhibitor-1] reached maximal levels at day 5. Egr-1-null allografts exhibited significantly lower expressions of IL-1β and MCP-1 mRNA (P < 0.05).nnnCONCLUSIONSnOur study showed that deletion of Egr-1 in lung allografts ameliorates severe acute rejection with the reduction of expression levels of chemical mediators, implying a new possible strategy for treating acute pulmonary allograft rejection.