Clonal hematopoiesis of indeterminate potential is associated with acute kidney injury

Age is a predominant risk factor for acute kidney injury (AKI), yet the biological mechanisms underlying this risk are largely unknown. Clonal hematopoiesis of indeterminate potential (CHIP) confers increased risk for several chronic diseases associated with aging. Here we sought to test whether CHIP increases the risk of AKI. In three population-based epidemiology cohorts, we found that CHIP was associated with a greater risk of incident AKI, which was more pronounced in patients with AKI requiring dialysis and in individuals with somatic mutations in genes other than DNMT3A, including mutations in TET2 and JAK2. Mendelian randomization analyses supported a causal role for CHIP in promoting AKI. Non-DNMT3A-CHIP was also associated with a nonresolving pattern of injury in patients with AKI. To gain mechanistic insight, we evaluated the role of Tet2-CHIP and Jak2V617F-CHIP in two mouse models of AKI. In both models, CHIP was associated with more severe AKI, greater renal proinflammatory macrophage infiltration and greater post-AKI kidney fibrosis. In summary, this work establishes CHIP as a genetic mechanism conferring impaired kidney function recovery after AKI via an aberrant inflammatory response mediated by renal macrophages.

Epidermal growth factor receptor activation is essential for kidney fibrosis development

Fibrosis is the progressive accumulation of excess extracellular matrix and can cause organ failure. Fibrosis can affect nearly every organ including kidney and there is no specific treatment currently. Although Epidermal Growth Factor Receptor (EGFR) signaling pathway has been implicated in development of kidney fibrosis, underlying mechanisms by which EGFR itself mediates kidney fibrosis have not been elucidated. We find that EGFR expression increases in interstitial myofibroblasts in human and mouse fibrotic kidneys. Selective EGFR deletion in the fibroblast/pericyte population inhibits interstitial fibrosis in response to unilateral ureteral obstruction, ischemia or nephrotoxins. In vivo and in vitro studies and single-nucleus RNA sequencing analysis demonstrate that EGFR activation does not induce myofibroblast transformation but is necessary for the initial pericyte/fibroblast migration and proliferation prior to subsequent myofibroblast transformation by TGF-ß or other profibrotic factors. These findings may also provide insight into development of fibrosis in other organs and in other conditions.

Clonal Hematopoiesis of Indeterminate Potential is Associated with Acute Kidney Injury

Age is a predominant risk factor for acute kidney injury (AKI), yet the biological mechanisms underlying this risk are largely unknown and to date no genetic mechanisms for AKI have been established. Clonal hematopoiesis of indeterminate potential (CHIP) is a recently recognized biological mechanism conferring risk of several chronic aging diseases including cardiovascular disease, pulmonary disease and liver disease. In CHIP, blood stem cells acquire mutations in myeloid cancer driver genes such as DNMT3A, TET2, ASXL1 and JAK2 and the myeloid progeny of these mutated cells contribute to end-organ damage through inflammatory dysregulation. We sought to establish whether CHIP causes acute kidney injury (AKI). To address this question, we first evaluated associations with incident AKI events in three population-based epidemiology cohorts (N = 442,153). We found that CHIP was associated with a greater risk of AKI (adjusted HR 1.26, 95% CI: 1.19-1.34, p<0.0001), which was more pronounced in patients with AKI requiring dialysis (adjusted HR 1.65, 95% CI: 1.24-2.20, p=0.001). The risk was particularly high in the subset of individuals where CHIP was driven by mutations in genes other than DNMT3A (HR: 1.49, 95% CI: 1.37-1.61, p<0.0001). We then examined the association between CHIP and recovery from AKI in the ASSESS-AKI cohort and identified that non-DNMT3A CHIP was more common among those with a non-resolving pattern of injury (HR 2.3, 95% CI: 1.14-4.64, p = 0.03). To gain mechanistic insight, we evaluated the role of Tet2-CHIP to AKI in ischemia-reperfusion injury (IRI) and unilateral ureteral obstruction (UUO) mouse models. In both models, we observed more severe AKI and greater post-AKI kidney fibrosis in Tet2-CHIP mice. Kidney macrophage infiltration was markedly increased in Tet2-CHIP mice and Tet2-CHIP mutant renal macrophages displayed greater proinflammatory responses. In summary, this work establishes CHIP as a genetic mechanism conferring risk of AKI and impaired kidney function recovery following AKI via an aberrant inflammatory response in CHIP derived renal macrophages.

Ambulatory sagittal split ramus osteotomy: strategy for enhanced recovery after surgery

The sagittal split ramus osteotomy (SSRO) has been performed mainly on an inpatient basis because of the duration of anaesthesia and the potential risk of postoperative complications, such as bleeding, pain, nausea, and vomiting. However, advances in both surgical and anaesthetic management have enabled the reduction of these risks and shortened the length of hospital stay. Thus, the SSRO may be feasible even in the ambulatory setting in elective cases. The clinical records of all patients who underwent an outpatient SSRO between August 2011 and September 2020 at Lilla Craniofacial Clinic were reviewed retrospectively. Data on age, sex, duration of surgery, operative procedures, intraoperative bleeding, and admission status were investigated. In total, 143 patients underwent a bilateral SSRO. The SSRO was performed as an isolated procedure in 73 patients and concomitantly with other surgical procedures in the remaining 70 patients. Overall, 142 of the 143 patients were discharged on the day of surgery (99.3%); only one (0.7%) required an overnight stay because of a submental haemorrhage after genioplasty. No emergency hospitalizations or readmissions occurred after discharge. Multimodal perioperative management, both surgical and anaesthetic, facilitated enhanced patient recovery after surgery, and SSRO was performed successfully and safely as an ambulatory procedure.

EGFR-mediated activation of adipose tissue macrophages promotes obesity and insulin resistance

Obesity and obesity-related health complications are increasing in prevalence. Adipose tissue from obese subjects has low-grade, chronic inflammation, leading to insulin resistance. Adipose tissue macrophages (ATMs) are a source of proinflammatory cytokines that further aggravate adipocyte dysfunction. In response to a high fat diet (HFD), ATM numbers initially increase by proliferation of resident macrophages, but subsequent increases also result from infiltration in response to chemotactic signals from inflamed adipose tissue. To elucidate the underlying mechanisms regulating the increases in ATMs and their proinflammatory phenotype, we investigated the role of activation of ATM epidermal growth factor receptor (EGFR). A high fat diet increased expression of EGFR and its ligand amphiregulin in ATMs. Selective deletion of EGFR in ATMs inhibited both resident ATM proliferation and monocyte infiltration into adipose tissue and decreased obesity and development of insulin resistance. Therefore, ATM EGFR activation plays an important role in adipose tissue dysfunction.

Macrophage interferon regulatory factor 4 deletion ameliorates aristolochic acid nephropathy via reduced migration and increased apoptosis

Aristolochic acid (AA) is the causative nephrotoxic alkaloid in aristolochic acid nephropathy, which results in a tubulointerstitial fibrosis. AA causes direct proximal tubule damage. There is also an influx of macrophages, although their role in the pathogenesis is poorly understood. Here we demonstrate that AA directly stimulates migration, inflammation, and reactive oxygen species (ROS) production in macrophages ex vivo. Cells lacking interferon regulatory factor 4 (IRF4), a known regulator of macrophage migration and phenotype, had a reduced migratory response, though effects on ROS production and inflammation were preserved or increased relative to wild-type cells. Macrophage-specific IRF4 knockout mice were protected from both acute and chronic kidney effects of AA administration based on functional and histological analysis. Renal macrophages from kidneys of AA-treated macrophage-specific IRF4 knockout mice demonstrated increased apoptosis and ROS production compared with wildtype controls, indicating that AA directly polarizes macrophages to a promigratory and proinflammatory phenotype. However, knockout mice had reduced renal macrophage abundance following AA administration. While macrophages lacking IRF4 can adopt a proinflammatory phenotype upon AA exposure, their inability to migrate to the kidney and increased rates of apoptosis upon infiltration provide protection from AA in vivo. These results provide evidence of direct AA effects on macrophages in AAN and add to the growing body of evidence that supports a key role of IRF4 in modulating macrophage function in kidney injury.

Myeloid cyclooxygenase-2/prostaglandin E2/E-type prostanoid receptor 4 promotes transcription factor MafB-dependent inflammatory resolution in acute kidney injury

Following acute injury to the kidney, macrophages play an important role in recovery of functional and structural integrity, but organ fibrosis and progressive functional decline occur with incomplete recovery. Pro-resolving macrophages are characterized by increased cyclooxygenase 2 (COX-2) expression and this expression was selectively increased in kidney macrophages following injury and myeloid-specific COX-2 deletion inhibited recovery. Deletion of the myeloid prostaglandin E2 (PGE2) receptor, E-type prostanoid receptor 4 (EP4), mimicked effects seen with myeloid COX-2-/- deletion. PGE2-mediated EP4 activation induced expression of the transcription factor MafB in kidney macrophages, which upregulated anti-inflammatory genes and suppressed pro-inflammatory genes. Myeloid Mafb deletion recapitulated the effects seen with either myeloid COX-2 or EP4 deletion following acute kidney injury, with delayed recovery, persistent presence of pro-inflammatory kidney macrophages, and increased kidney fibrosis. Thus, our studies identified a previously unknown mechanism by which prostaglandins modulate macrophage phenotype following acute organ injury and provide new insight into mechanisms underlying detrimental kidney effects of non-steroidal anti-inflammatory drugs that inhibit cyclooxygenase activity.

Profile of Podocyte Translatome During Development of Type 2 and Type 1 Diabetic Nephropathy Using Podocyte-Specific TRAP mRNA RNA-seq

Podocyte injury is important in development of diabetic nephropathy (DN). Although several studies have reported single-cell-based RNA sequencing (RNA-seq) of podocytes in type 1 DN (T1DN), the podocyte translating mRNA profile in type 2 DN (T2DN) has not previously been compared with that of T1DN. We analyzed the podocyte translatome in T2DN in podocin-Cre; Rosa26^fsTRAP; eNOS^-/-; db/db mice and compared it with that of streptozotocin-induced T1DN in podocin-Cre; Rosa26^fsTRAP; eNOS^-/- mice using translating ribosome affinity purification (TRAP) and RNA-seq. More than 125 genes were highly enriched in the podocyte ribosome. More podocyte TRAP genes were differentially expressed in T2DN than in T1DN. TGF-β signaling pathway genes were upregulated, while MAPK pathway genes were downregulated only in T2DN, while ATP binding and cAMP-mediated signaling genes were downregulated only in T1DN. Genes regulating actin filament organization and apoptosis increased, while genes regulating VEGFR signaling and glomerular basement membrane components decreased in both type 1 and type 2 diabetic podocytes. A number of diabetes-induced genes not previously linked to podocyte injury were confirmed in both mouse and human DN. On the basis of differences and similarities in the podocyte translatome in T2DN and T1DN, investigators can identify factors underlying the pathophysiology of DN and novel therapeutic targets to treat diabetes-induced podocyte injury.

Deletion of Myeloid Interferon Regulatory Factor 4 (Irf4) in Mouse Model Protects against Kidney Fibrosis after Ischemic Injury by Decreased Macrophage Recruitment and Activation

BACKGROUND

AKI is characterized by abrupt and reversible kidney dysfunction, and incomplete recovery leads to chronic kidney injury. Previous studies by us and others have indicated that macrophage infiltration and polarization play key roles in recovery from AKI. The role in AKI recovery played by IFN regulatory factor 4 (IRF4), a mediator of polarization of macrophages to the M2 phenotype, is unclear.

METHODS

We used mice with myeloid or macrophage cell-specific deletion of Irf4 (MΦ Irf4^-/- ) to evaluate Irf4's role in renal macrophage polarization and development of fibrosis after severe AKI.

RESULTS

Surprisingly, although macrophage Irf4 deletion had a minimal effect on early renal functional recovery from AKI, it resulted in decreased renal fibrosis 4 weeks after severe AKI, in association with less-activated macrophages. Macrophage Irf4 deletion also protected against renal fibrosis in unilateral ureteral obstruction. Bone marrow-derived monocytes (BMDMs) from MΦ Irf4^-/- mice had diminished chemotactic responses to macrophage chemoattractants, with decreased activation of AKT and PI3 kinase and increased PTEN expression. PI3K and AKT inhibitors markedly decreased chemotaxis in wild-type BMDMs, and in a cultured macrophage cell line. There was significant inhibition of homing of labeled Irf4^-/- BMDMs to postischemic kidneys. Renal macrophage infiltration in response to AKI was markedly decreased in MΦ Irf4^-/- mice or in wild-type mice with inhibition of AKT activity.

CONCLUSIONS

Deletion of Irf4 from myeloid cells protected against development of tubulointerstitial fibrosis after severe ischemic renal injury in mice, due primarily to inhibition of AKT-mediated monocyte recruitment to the injured kidney and reduced activation and subsequent polarization into a profibrotic M2 phenotype.

Podocyte EGFR Inhibits Autophagy Through Upregulation of Rubicon in Type 2 Diabetic Nephropathy

Renal epidermal growth factor receptor (EGFR) signaling is activated in models of diabetic nephropathy (DN), and inhibition of the EGFR signaling pathway protects against the development of DN. We have now determined that in cultured podocytes, high glucose led to increases in activation of EGFR signaling but decreases in autophagy activity as indicated by decreased beclin-1 and inhibition of LC3B autophagosome formation as well as increased rubicon (an autophagy inhibitor) and SQSTM1 (autophagy substrate). Either genetic (small interfering [si]EGFR) or pharmacologic (AG1478) inhibition of EGFR signaling attenuated the decreased autophagy activity. In addition, rubicon siRNA knockdown prevented high glucose-induced inhibition of autophagy in podocytes. We further examined whether selective EGFR deletion in podocytes affected the progression of DN in type 2 diabetes. Selective podocyte EGFR deletion had no effect on body weight or fasting blood sugars in either db/db mice or nos3 ^-/-; db/db mice, a model of accelerated type 2 DN. However selective podocyte EGFR deletion led to relative podocyte preservation and marked reduction in albuminuria and glomerulosclerosis, renal proinflammatory cytokine/chemokine expression, and decreased profibrotic and fibrotic components in nos3 ^-/-; db/db mice. Podocyte EGFR deletion led to decreased podocyte expression of rubicon, in association with increased podocyte autophagy activity. Therefore, activation of EGFR signaling in podocytes contributes to progression of DN at least in part by increasing rubicon expression, leading to subsequent autophagy inhibition and podocyte injury.

Activation of hypoxia-sensing pathways promotes renal ischemic preconditioning following myocardial infarction

Ischemic heart disease is the leading cause of death worldwide and is frequently comorbid with chronic kidney disease. Physiological communication is known to occur between the heart and the kidney. Although primary dysfunction in either organ can induce dysfunction in the other, a clinical entity known as cardiorenal syndrome, mechanistic details are lacking. Here, we used a model of experimental myocardial infarction (MI) to test effects of chronic cardiac ischemia on acute and chronic kidney injury. Surprisingly, chronic cardiac damage protected animals from subsequent acute ischemic renal injury, an effect that was accompanied by evidence of chronic kidney hypoxia. The protection observed post-MI was similar to protection observed in a separate group of healthy animals housed in ambient hypoxic conditions prior to kidney injury, suggesting a common mechanism. There was evidence that chronic cardiac injury activates renal hypoxia-sensing pathways. Increased renal abundance of several glycolytic enzymes following MI suggested that a shift toward glycolysis may confer renal ischemic preconditioning. In contrast, effects on chronic renal injury followed a different pattern, with post-MI animals displaying worsened chronic renal injury and fibrosis. These data show that although chronic cardiac injury following MI protected against acute kidney injury via activation of hypoxia-sensing pathways, it worsened chronic kidney injury. The results further our understanding of cardiorenal signaling mechanisms and have implications for the treatment of heart failure patients with associated renal disease.NEW & NOTEWORTHY Experimental myocardial infarction (MI) protects from subsequent ischemic acute kidney injury but worsens chronic kidney injury. Observed protection from ischemic acute kidney injury after MI was accompanied by chronic kidney hypoxia and increased renal abundance of hypoxia-inducible transcripts. These data support the idea that MI confers protection from renal ischemic injury via chronic renal hypoxia and activation of downstream hypoxia-inducible signaling pathways.

The Role of the EGF Receptor in Sex Differences in Kidney Injury

BACKGROUND

Sex differences mediating predisposition to kidney injury are well known, with evidence indicating lower CKD incidence rates and slower decline in renal function in nondiabetic CKD for premenopausal women compared with men. However, signaling pathways involved have not been elucidated to date. The EGF receptor (EGFR) is widely expressed in the kidney in glomeruli and tubules, and persistent and dysregulated EGFR activation mediates progressive renal injury.

METHODS

To investigate the sex differences in response to renal injury, we examined EGFR expression in mice, in human kidney tissue, and in cultured cell lines.

RESULTS

In wild type mice, renal mRNA and protein EGFR levels were comparable in males and females at postnatal day 7 but were significantly lower in age-matched adult females than in adult males. Similar gender differences in renal EGFR expression were detected in normal adult human kidneys. In Dsk5 mutant mice with a gain-of-function allele that increases basal EGFR kinase activity, males had progressive glomerulopathy, albuminuria, loss of podocytes, and tubulointerstitial fibrosis, but female Dsk5 mice had minimal kidney injury. Oophorectomy had no effect on renal EGFR levels in female Dsk5 mice, while castration protected against the kidney injury in male Dsk5 mice, in association with a reduction in EGFR expression to levels seen in females. Conversely, testosterone increased EGFR expression and renal injury in female Dsk5 mice. Testosterone directly stimulated EGFR expression in cultured kidney cells.

CONCLUSIONS

These studies indicate that differential renal EGFR expression plays a role in the sex differences in susceptibility to progressive kidney injury that may be mediated at least in part by testosterone.

TGF-β promotes fibrosis after severe acute kidney injury by enhancing renal macrophage infiltration

TGF-β signals through a receptor complex composed of 2 type I and 2 type II (TGF-βRII) subunits. We investigated the role of macrophage TGF-β signaling in fibrosis after AKI in mice with selective monocyte/macrophage TGF-βRII deletion (macrophage TGF-βRII-/- mice). Four weeks after injury, renal TGF-β1 expression and fibrosis were higher in WT mice than macrophage TGF-βRII-/- mice, which had decreased renal macrophages. The in vitro chemotactic response to f-Met-Leu-Phe was comparable between bone marrow-derived monocytes (BMMs) from WT and macrophage TGF-βRII-/- mice, but TGF-βRII-/- BMMs did not respond to TGF-β. We then implanted Matrigel plugs suffused with either f-Met-Leu-Phe or TGF-β1 into WT or macrophage TGF-βRII-/- mice. After 6 days, f-Met-Leu-Phe induced similar macrophage infiltration into the Matrigel plugs of WT and macrophage TGF-βRII-/- mice, but TGF-β induced infiltration only in WT mice. We further determined the number of labeled WT or TGF-βRII-/- BMMs infiltrating into WT kidneys 20 days after ischemic injury. There were more labeled WT BMMs than TGF-βRII-/- BMMs. Therefore, macrophage TGF-βRII deletion protects against the development of tubulointerstitial fibrosis following severe ischemic renal injury. Chemoattraction of macrophages to the injured kidney through a TGF-β/TGF-βRII axis is a heretofore undescribed mechanism by which TGF-β can mediate renal fibrosis during progressive renal injury.

Inhibition of Epidermal Growth Factor Receptor Activation Is Associated With Improved Diabetic Nephropathy and Insulin Resistance in Type 2 Diabetes

Previous studies by us and others have indicated that renal epidermal growth factor receptors (EGFR) are activated in models of diabetic nephropathy (DN) and that inhibition of EGFR activity protects against progressive DN in type 1 diabetes. In this study we examined whether inhibition of EGFR activation would affect the development of DN in a mouse model of accelerated type 2 diabetes (BKS db/db with endothelial nitric oxide knockout [eNOS^-/-db/db]). eNOS^-/-db/db mice received vehicle or erlotinib, an inhibitor of EGFR tyrosine kinase activity, beginning at 8 weeks of age and were sacrificed at 20 weeks of age. In addition, genetic models inhibiting EGFR activity (waved 2) and transforming growth factor-α (waved 1) were studied in this model of DN in type 2 diabetes. Compared with vehicle-treated mice, erlotinib-treated animals had less albuminuria and glomerulosclerosis, less podocyte loss, and smaller amounts of renal profibrotic and fibrotic components. Erlotinib treatment decreased renal oxidative stress, macrophage and T-lymphocyte infiltration, and the production of proinflammatory cytokines. Erlotinib treatment also preserved pancreas function, and these mice had higher blood insulin levels at 20 weeks, decreased basal blood glucose levels, increased glucose tolerance and insulin sensitivity, and increased blood levels of adiponectin compared with vehicle-treated mice. Similar to the aforementioned results, both waved 1 and waved 2 diabetic mice also had attenuated DN, preserved pancreas function, and decreased basal blood glucose levels. In this mouse model of accelerated DN, inhibition of EGFR signaling led to increased longevity.

Selective activation of epidermal growth factor receptor in renal proximal tubule induces tubulointerstitial fibrosis

Epidermal growth factor receptor (EGFR) has been implicated in the pathogenesis of diabetic nephropathy and renal fibrosis; however, the causative role of sustained EGFR activation is unclear. Here, we generated a novel kidney fibrotic mouse model of persistent EGFR activation by selectively expressing the EGFR ligand, human heparin-binding EGF-like growth factor (hHB-EGF), in renal proximal tubule epithelium. hHB-EGF expression increased tyrosine kinase phosphorylation of EGFR and the subsequent activation of downstream signaling pathways, including ERK and AKT, as well as the profibrotic TGF-β1/SMAD pathway. Epithelial-specific activation of EGFR was sufficient to promote spontaneous and progressive renal tubulointerstitial fibrosis, as characterized by increased collagen deposition, immune cell infiltration, and α-smooth muscle actin (α-SMA)-positive myofibroblasts. Tubule-specific EGFR activation promoted epithelial dedifferentiation and cell-cycle arrest. Furthermore, EGFR activation in epithelial cells promoted the proliferation of α-SMA⁺ myofibroblasts in a paracrine manner. Genetic or pharmacologic inhibition of EGFR tyrosine kinase activity or downstream MEK activity attenuated the fibrotic phenotype. This study provides definitive evidence that sustained activation of EGFR in proximal epithelia is sufficient to cause spontaneous, progressive renal tubulointerstitial fibrosis, evident by epithelial dedifferentiation, increased myofibroblasts, immune cell infiltration, and increased matrix deposition.-Overstreet, J. M., Wang, Y., Wang, X., Niu, A., Gewin, L. S., Yao, B., Harris, R. C., Zhang, M.-Z. Selective activation of epidermal growth factor receptor in renal proximal tubule induces tubulointerstitial fibrosis.

Macrophage Cyclooxygenase-2 Protects Against Development of Diabetic Nephropathy

Diabetic nephropathy (DN) is characterized by increased macrophage infiltration, and proinflammatory M1 macrophages contribute to development of DN. Previous studies by us and others have reported that macrophage cyclooxygenase-2 (COX-2) plays a role in polarization and maintenance of a macrophage tissue-reparative M2 phenotype. We examined the effects of macrophage COX-2 on development of DN in type 1 diabetes. Cultured macrophages with COX-2 deletion exhibited an M1 phenotype, as demonstrated by higher inducible nitric oxide synthase and nuclear factor-κB levels but lower interleukin-4 receptor-α levels. Compared with corresponding wild-type diabetic mice, mice with COX-2 deletion in hematopoietic cells (COX-2 knockout bone marrow transplantation) or macrophages (CD11b-Cre COX2f/f) developed severe DN, as indicated by increased albuminuria, fibrosis, and renal infiltration of T cells, neutrophils, and macrophages. Although diabetic kidneys with macrophage COX-2 deletion had more macrophage infiltration, they had fewer renal M2 macrophages. Diabetic kidneys with macrophage COX-2 deletion also had increased endoplasmic reticulum stress and decreased number of podocytes. Similar results were found in diabetic mice with macrophage PGE2 receptor subtype 4 deletion. In summary, these studies have demonstrated an important but unexpected role for macrophage COX-2/prostaglandin E2/PGE2 receptor subtype 4 signaling to lessen progression of diabetic kidney disease, unlike the pathogenic effects of increased COX-2 expression in intrinsic renal cells.

IL-4/IL-13-mediated polarization of renal macrophages/dendritic cells to an M2a phenotype is essential for recovery from acute kidney injury

Cytokines IL-4 and IL-13 play important roles in polarization of macrophages/dendritic cells to an M2 phenotype, which is important for recovery from acute kidney injury. Both IL-4 and IL-13 activate JAK3/STAT6 signaling. In mice with diphtheria toxin receptor expression in proximal tubules (selective injury model), a relatively selective JAK3 inhibitor, tofacitinib, led to more severe kidney injury, delayed recovery from acute kidney injury, increased inflammatory M1 phenotype markers and decreased reparative M2 phenotype markers of macrophages/dendritic cells, and development of more severe renal fibrosis after diphtheria toxin administration. Similarly, there was delayed recovery and increased tubulointerstitial fibrosis in these diphtheria toxin-treated mice following tamoxifen-induced deletion of both IL-4 and IL-13, with increased levels of M1 and decreased levels of M2 markers in the macrophages/dendritic cells. Furthermore, deletion of IL-4 and IL-13 led to a decrease of tissue reparative M2a phenotype markers but had no effect on anti-inflammatory M2c phenotype markers. Deletion of IL-4 and IL-13 also inhibited recovery from ischemia-reperfusion injury in association with increased M1 and decreased M2 markers and promoted subsequent tubulointerstitial fibrosis. Thus, IL-4 and IL-13 are required to effectively polarize macrophages/dendritic cells to an M2a phenotype and to promote recovery from acute kidney injury.

Formation of novel polymeric nanoparticles

We have found that not only block copolymers but also ionomers can self-assemble in a selective solvent to form surfactant-free nanoparticles. The self-assembly can be induced by chemical reaction, polymer-polymer complexation, and microphase inversion in addition to the temperature. A recently developed microwave method for the preparation of uniform surfactant-free polymeric nanoparticles is also reviewed. Our results have revealed that for a given dispersion, the particle surface area occupied per stabilizer (surfactant, polymer chains, and ionic groups) is close to a constant.

Beta-alanine-based dendritic beta-peptides: dendrimers possessing unusually strong binding ability towards protic solvents and their self-assembly into nanoscale aggregates through hydrogen-bond interactions

A series of poly(beta-alanine) dendrimers 1-4 with Boc-carbamate as the surface functionality, beta-alanine as the dendritic branch, 3,5-diaminobenzoic acid as the branching agent, and 1,2diaminoethane as the interior core has been synthesized by a solution-phase peptide-coupling method. The structural identities and purities of the products have been fully characterized by spectroscopic and chromatographic methods. 1H NMR studies on the dendrimers indicated that the Boc-carbamate surface groups exist as a mixture of syn and anti rotamers in solution, and that the dendrimers adopt an open structure in polar solvents; this allows the free interaction of the interior core functionality with solvent molecules. Due to the cooperative effect of a large number of carbamate and amide groups, the dendrimers exhibit an unusually strong binding ability towards protic solvents and behave as H-bond sponges. As a result, the H/D exchange rates of the N-H protons are significantly enhanced in such dendritic structures, as compared to those of nondendritic carbamates and amides. These dendritic peptide dendrimers also exhibit a strong tendency to form nanoscopic aggregates in nonpolar or polar aprotic solvents through intermolecular H-bond interactions.

New eyebrow lift technique using a semiautomatic suturing device (maniceps) for patients with facial paralysis

Direct browlift and the traditional fascial suspension technique sometimes leave a prominent scar above the eyebrow. Coronal browlift, mid-forehead browlift, and endoscopic browlift leave no prominent scar, but they are sometimes not suitable for patients with facial paralysis because they have been developed for rejuvenative surgery. The authors present a new browlift fascial suspension technique for patients with facial paralysis. This method uses a semiautomatic suturing device (Maniceps), which they have used to graft three fascial strips to the forehead from the fascia lata, and to suspend and lift the eyebrow with only two small incisions posterior to the hairline. The authors treated 13 facial paralysis patients, with follow-up periods of more than 6 months. The lifted eyebrows adapted to stabilized positions within 3 months. The results in all 13 patients were satisfactory, with no severe complications. This new technique is very useful because it has wide applicability, including facial paralysis patients who experience severe ptosis.

Congenital choledochal cyst with pancreatitis

OBJECTIVE

To understand the relationship among congenital choledochal cyst, anomalous junction of pancreaticobiliary duct (AJPBD) and pancreatitis.

METHODS

25 children with choledochal cyst treated in our hospital were included in this study. Their ages ranged from 2 months to 14 years. Intraoperative cholangiography was performed in 24 children. Pancreatic samples obtained from the head and body of the pancreas at operation were observed under light and electron microscope. Serum amylase was analyzed one week before and after operation respectively. Bile amylase in the cyst and gallbladder was measured at operation.

RESULTS

The incidence of AJPBD was 70%. Inflammatory cell infiltration and fibrous hyperplasia were seen in the pancreatic specimens of 5 children, of whom 4 had AJPBD. No ultrastructural changes were found in 2 children without AJPBD, while different changes were seen in 6 with AJPBD, including those showing no pathological changes under light microscope. All the changes became more severe as the age of the patient increased. The bile and serum amylase levels were higher in children with AJPBD than those without AJPBD (P < 0.05).

CONCLUSION

Congenital choledochal cyst has a close relationship with AJPBD and pancreatitis. Pancreatic pathological changes have a long and chronic course from ultrastructural changes to macroscopic changes for the developing of pancreatitis.

[The detection of Toxoplasma gondii in abortion tissues of sheep using the polymerase chain reaction]

A polymerase chain reaction was applied to detect Toxoplasma gondii DNA in placental and fetal tissue samples of 47 unselected ovine abortions of the lambing season 1990/91 (Baden-Württemberg, Rhineland, Hesse). For the amplification a 190 bp or 223 bp sequence of the B1-gene of T. gondii was selected as the target sequence. Both sequences were detected in five abortions. All positive results were immunohistochemically confirmed using the peroxidase antiperoxidase technique (PAP-staining). Thus, in Germany, too, T. gondii infection in sheep during pregnancy should be considered as a possible cause of abortions, particularly in case of abortions of unknown genesis.

A new three-dimensional reconstruction method using algebraic reconstruction techniques

Three-dimensional image reconstruction plays a very important role in noninvasive diagnosis of biological systems and nondestructive evaluation of manufactured work-pieces. A new direct three-dimensional reconstruction algorithm, called TART (Three-dimensional ART), is presented in this paper. Oblique projection data are used and an ART-based algorithm is introduced to compensate for the limiting constraints of incomplete projection and/or limited angular coverage. The fact that oblique projection gives useful information to the reconstruction algorithm is shown mathematically. The algorithm can be used to solve the reconstruction problem under the conditions of both complete data and incomplete data. The algorithm first maps geometric information and projection data from an oblique plane into a horizontal plane, then calculates the weighting factors for the voxels based on this horizontal plane, and finally performs a 3-D ART reconstruction. Two experimental results illustrate the superiority of the algorithm over the previous reconstruction methods.