Search

Background: Arteriovenous fistula (AVF) patency is important for patients undergoing hemodialysis. The association between early AVF failure and the prognosis, including all-cause mortality and major adverse cardiovascular events (MACE), has not been fully investigated. The present study was performed to investigate the association between early AVF failure and 3-year mortality, cardiovascular disease (CVD) mortality, and MACE., Methods: We analyzed 358 patients who started hemodialysis in our institution from October 2008 to February 2020. We defined early AVF failure as cases requiring percutaneous transluminal angioplasty or reoperation within 1 year after AVF surgery. The patients were divided into two groups according to the presence or absence of early AVF failure, and the prognosis of each group was examined. The association between early AVF failure and outcomes (3-year all-cause mortality, CVD mortality, and MACE) was determined using Cox proportional hazards regression analysis., Results: During the 3-year follow-up, 75 (20.9%) patients died (cardiovascular death: n  = 39) and 145 patients developed MACE. According to the multivariable analysis, the early AVF failure group had a significantly higher risk of 3-year all-cause mortality (hazard ratio [HR], 1.42; 95% confidence interval [CI], 1.09-1.83; p  = 0.009), CVD mortality (HR, 1.54; 95% CI, 1.29-2.08; p  < 0.001), and MACE (HR, 1.68; 95% CI, 1.25-2.26; p  < 0.001). When the patients were stratified by age, early AVF failure was associated with 3-year all-cause mortality in all groups except for the younger group (<65 years of age)., Conclusions: Early AVF failure was associated with an increased risk of 3-year all-cause mortality, CVD mortality, and MACE., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Aim: This study investigated the features of fatty livers using near-infrared (NIR) spectroscopy and validated the usefulness of NIR spectroscopy for the measurement of intrahepatic triglyceride (TG) contents and evaluation of viability in fatty livers., Methods: In vitro, we examined specific spectra for each purified TG fraction by NIR. In vivo, the differences between the spectra obtained from normal and fatty livers before warm ischemia and the differences between the spectra obtained from each rat liver before and after warm ischemia were subjected to multicomponent analysis., Results: In vitro experiments revealed a specific peak at 925 nm in major TG fractions, and NIR spectroscopy precisely detected changes in TG volume. In vivo experiments revealed that NIR spectroscopy detected TG content changes in rat fatty livers induced by a choline-deficient diet following the addition of purified TG spectrum for NIR spectroscopic analysis in least square curve fitting. The TG level in the fatty livers measured by NIR spectroscopy significantly correlated with the morphometric measurement of lipid content in the livers. NIR spectroscopy also revealed decreased levels of total hemoglobin (Hb) and oxidized Hb and maintenance of homeostasis in cytochrome redox states in fatty livers under normal condition. However, NIR spectroscopy showed irreversible deterioration of hepatic microcirculation, Hb oxygenation and homeostasis of the cytochrome redox states in fatty livers after 60-min warm ischemia reperfusion., Conclusion: These studies demonstrated that NIR spectroscopy can quantitatively measure the intrahepatic TG content in addition to simultaneously evaluating microcirculation and Hb oxygenation., (© 2014 The Japan Society of Hepatology.)

In a group of 209 colorectal cancer patients with unresectable tumors, 10 patients underwent curative resection after combination chemotherapy at our hospital between 2006 and 2012. Of these 10 patients, 5 presented with peritoneal dissemination at the start of chemotherapy. With the exception of 1 patient with peritoneal recurrence, peritoneal dissemination and liver metastasis were observed in all patients at the time of diagnosis of colorectal cancer. Computed tomography (CT) and/ or positron emission tomography-CT examination revealed disappearance of peritoneal dissemination in response to chemotherapy, except in 1 patient with peritoneal recurrence. After combination chemotherapy, surgical resection of liver metastases and peritoneal dissemination was performed. Pathological and intraoperative findings indicated disappearance of peritoneal dissemination in 3 patients and P2 grade peritoneal dissemination in 1 patient. In the patient with peritoneal recurrence, 1 tumor was completely resected. Interestingly, none of the 3 patients that exhibited complete disappearance of peritoneal dissemination showed peritoneal recurrence, although 1 patient exhibited metastases in the lung and non-regional lymph nodes. In contrast, the patient with P2 grade peritoneal dissemination showed peritoneal recurrence and lung metastasis. All 5 patients survived (duration from diagnosis of colorectal cancer, 31-83 months). Herein, we report the use of combination chemotherapy to achieve the disappearance of peritoneal dissemination, changing unresectable colorectal cancer with peritoneal dissemination into resectable cancer.

We report a case of a 64-year-old woman with Stage IV breast cancer who responded well to chemotherapy containing bevacizumab. She noticed a left breast tumor with acute progression and was diagnosed as having Stage IV, estrogen receptor( ER)(-), progesterone receptor(PgR)(-), human epidermal growth factor receptor 2(HER2)(-)breast cancer (T4cN3cM1[lymph nodes]). She received 5 courses of adriamycin(60mg/m / 2)plus cyclophosphamide(600mg/m2)(AC therapy)and 4 courses of weekly paclitaxel(PTX 90mg/m / 2)plus bevacizumab(AVA 10 mg/m2)as systemic therapy. Computed tomography(CT)and magnetic resonance imaging(MRI)revealed a complete response(CR). After local resection of the breast tumor and radiation to the breast and regional lymph nodes, capecitabine therapy was initiated. Currently, at 5 months after surgery, no new lesion has been detected.

We report the complete nucleotide sequence and analysis of pETBTY825, a Staphylococcus aureus TY825 plasmid encoding exfoliative toxin B (ETB). S. aureus TY825 is a clinical isolate obtained from an impetigo patient in 2002. The size of pETBTY825, 60.6 kbp, was unexpectedly larger than that of the archetype pETBTY4 (∼30 kbp). Genomic comparison of the plasmids shows that pETBTY825 has the archetype pETBTY4 as the backbone and has a single large extra DNA region of 22.4 kbp. The extra DNA region contains genes for resistance to aminoglycoside [aac(6')/aph(2″)], macrolide (msrA), and penicillin (blaZ). A plasmid deletion experiment indicated that these three resistance elements were functionally active. We retrospectively examined the resistance profile of the clinical ETB-producing S. aureus strains isolated in 1977 to 2007 using a MIC determination with gentamicin (GM), arbekacin (ABK), and erythromycin (EM) and by PCR analyses for aac(6')/aph(2″) and msrA using purified plasmid preparations. The ETB-producing S. aureus strains began to display high resistance to GM, which was parallel with the detection of aac(6')/aph(2″) and mecA, after 1990. Conversely, there was no significant change in the ABK MIC during the testing period, although it had a tendency to slightly increase. After 2001, isolates resistant to EM significantly increased; however, msrA was hardly detected in ETB-producing S. aureus strains, and only five isolates were positive for both aac(6')/aph(2″) and msrA. In this study, we report the emergence of a fusion plasmid carrying the toxin gene etb and drug resistance genes. Prevalence of the pETBTY825 carrier may further increase the clinical threat, since ETB-producing S. aureus is closely related to more severe impetigo or staphylococcal scalded-skin syndrome (SSSS), which requires a general antimicrobial treatment.

Background: Congestion in the right paramedian sector of a right liver graft without a middle hepatic vein (MHV) may lead to graft dysfunction. To solve this problem, we have developed a technique for reconstructing the MHV tributaries of the right liver grafts by using the preserved recipient's native MHV trunk., Methods: Between 2005 and 2007, among 34 right liver graft liver transplant patients with significant MHV tributaries (>5 mm in diameter), 21 patients underwent right liver graft living-donor liver transplantation: draining MHV tributaries with recipient's native MHV trunk. We evaluated the patency of the reconstructed MHV tributaries, graft regeneration, and graft survival., Results: The 3-month patency rates of the reconstructed V8 and V5 were 92% and 76%, respectively. The 1-year survival rate and the regeneration index of the right paramedian sector 6 months after transplantation were higher in patients with reconstructed MHV tributaries than that for patients without reconstructed MHV tributaries., Conclusion: The use of the recipient's MHV trunk for the reconstruction of the MHV tributaries of the right liver grafts is considered to be a valuable and a feasible strategy in right liver graft living-donor liver transplantation.

Porcine thymus grafts support robust murine and human thymopoiesis, generating a diverse T cell repertoire that is deleted of donor and host-reactive cells, achieving specific xenograft tolerance. Positive selection is mediated exclusively by the xenogeneic thymic MHC. Although thymectomized, T cell-depleted normal mice usually remain healthy following xenogeneic thymic transplantation, thymus-grafted congenitally athymic mice frequently develop multiorgan autoimmunity. We investigated the etiology of this syndrome by adoptively transferring lymphocyte populations from fetal pig thymus-grafted BALB/c nude mice to secondary BALB/c nude recipients. Fetal pig thymus-grafted nude mice generated normal numbers of CD25(+)Foxp3(+)CD4 T cells, but these cells lacked the capacity to block autoimmunity. Moreover, thymocytes and peripheral CD4(+)CD25(-) cells from fetal pig thymus-grafted nude mice, but not those from normal mice, induced autoimmunity in nude recipients. Injection of thymic epithelial cells from normal BALB/c mice into fetal pig thymus grafts reduced autoimmunity and enhanced regulatory function of splenocytes. Our data implicate abnormalities in postthymic maturation, expansion, and/or survival of T cells positively selected by a xenogeneic MHC, as well as incomplete intrathymic deletion of thymocytes recognizing host tissue-specific Ags, in autoimmune pathogenesis. Regulatory cell function is enhanced and negative selection of host-specific thymocytes may potentially also be improved by coimplantation of recipient thymic epithelial cells in the thymus xenograft.

Background/aims: Although antiviral prophylaxis with the combined high-dose hepatitis B immunoglobulin (HBIg) and lamivudine therapy has effectively reduced post-liver transplantation recurrence of hepatitis B virus infection, its use is limited by cost and availability., Methodology: Fourteen living-donor liver transplant patients were performed with the mean follow-up of the 23 months (range, 5 to 58 months). We examined the effectiveness of prophylaxis against recurrence of hepatitis B with much lower dose of HBIg. HBIg (10000 IU/day) was two or three times intra- and postoperatively administered and then the serum titers of HBIg was maintained at more than 100 IU/mL., Results: Although two patients were preoperatively HBV-DNA positive (DNA concentrations were 4.4 and 4.7 LGE, respectively) by a transcription-mediated amplification assay (TMA) method, all 14 patients postoperatively became HBV-DNA-negative and HBsAg-negative., Conclusions: Our protocol of the combination low-dose HBIg and lamivudine therapy prevents the recurrence of hepatitis B and is likely to be more cost-effective than high-dose HBIg regimens. Further study is needed to develop the combination therapy of the optimal dose of HBIg and lamivudine.

Background: Xenogeneic thymus transplantation is an effective approach to achieving T cell tolerance across highly disparate xenogeneic species barriers. We have previously demonstrated that phenotypically normal, specifically tolerant human T cells are generated in porcine thymic grafts. In this study, we assessed the diversity of the human T cell repertoire generated in porcine thymic xenografts. We also examined the ability of porcine thymus grafts to coexist with human thymus grafts., Methods: Fetal swine (SW) or human (HU) thymus with human fetal liver fragments were transplanted under the kidney capsule of 3Gy irradiated NOD/SCID mouse recipients. Thymus tissue was harvested approximately 16 weeks posttransplant for analysis of mixed lymphocyte reactions and spectratyping of human CD4 and CD8 single positive thymocytes., Results: T cell receptor beta genes of human CD4 and CD8 single positive cells developing in HU and SW thymus grafts showed similar, normal CDR3 length distributions. Human T cells developing in SW thymus grafts showed specific unresponsiveness to the major histocompatibility complex of the donor swine in mixed leukocyte reaction assays. In two of three animals receiving SW and HU thymus grafts under opposite kidney capsules, both grafts functioned. In animals with surviving SW grafts, thymocytes from the SW but not the HU grafts showed specific unresponsiveness to the SW donor., Conclusion: Swine thymus grafts support generation of human T cells with a diverse T cell receptor repertoire. Human thymocytes in human thymus grafts are not tolerized by the presence of an additional porcine thymus, but tolerance might be achieved by postthymic encounter with porcine antigens.

A right liver graft lacking the middle hepatic vein can result in congestion of the anterior segment. We describe a method of reconstructing the middle hepatic vein tributaries by using the recipient's own middle hepatic vein with vascular closure staples. During a living donor right liver transplantation, the middle hepatic vein tributaries draining segments V (V5) and VIII (V8) of the right lobe graft were reconstructed using the recipient's own middle hepatic vein and secured with vascular closure staples. Computed tomography showed good venous outflow from the middle hepatic vein and no congestion or atrophy of the anterior segment of the right liver grafts. Thus, using the recipient's own middle hepatic vein is a suitable option for reconstructing the middle hepatic vein tributaries (V8 and V5) in right-liver living donor transplantation and the application of vascular closure staples helps to accomplish this.

Background: In living-donor liver transplantation (LDLT), biliary complications are recognized as a significant cause of post-transplantation morbidity., Methods: Eighty patients who underwent LDLT with duct-to-duct biliary reconstruction at Hiroshima University Hospital were enrolled in this study. The mean follow-up was 24 months (range, 3-72 months). Eighteen patients underwent the basiliximab-based immunosuppressive therapy, and 62 patients underwent non-basiliximab-based immunosuppressive therapy. The development of biliary complications after LDLT was retrospectively analyzed. Biliary complications were initially treated by endoscopic or radiological modalities., Results: Biliary leakages and strictures occurred in 12 (15%) and 20 (25%) of the 80 patients, respectively. Stepwise multivariate analysis demonstrated bile leakage to be an independent risk factor for the development of biliary stricture (p = 0.001) and basiliximab-based immunosuppressive therapy to be an independent protective factor for postoperative biliary leakage (p = 0.005). The 1-week total doses of steroids were significantly lower in the basiliximab-based immunosuppressive regimes (mean dose: 573 mg) than in the non-basiliximab-based ones (mean dose: 1,121 mg) (p = 0.01). All patients with biliary leakage were successfully treated with endoscopic or radiological modalities, except one patient who was treated by surgical treatment. Endoscopic or radiological modalities were successful as primary treatment modalities in 12 (60%) of 20 patients with biliary strictures. Lastly, six patients were treated surgically with long-term success, except for one patient with chronic cholangitis who died after 16 months., Conclusions: Steroid-sparing basiliximab-based immunosuppressive therapy reduced the incidence of biliary leakage, and biliary leakage was the independent factor for biliary stricture. The non-surgical and surgical treatments for biliary complications were satisfactory.

Prostaglandin E2 (PGE2) acts in synergy with other inflammatory stimuli such as tumor necrosis factor (TNF) to induce the maturation of migratory-type monocyte-derived dendritic cells (MoDCs). However, PGE2 has been reported to inhibit IL-12p70 production by MoDCs and to promote the generation of Th2 T cell responses. We demonstrate here that the addition of PGE2 to TNF for the maturation of MoDCs enhanced CD4 and CD8 T cell proliferative responses to neoantigen and recall antigen, and enhanced Th1-type responses. The increased stimulatory capacity of MoDCs matured with PGE2 was associated with a fully mature, migratory-type MoDC phenotype and more rapid down-regulation of the expression of inflammatory chemokines, with up-regulated expression of the constitutive chemokines TARC and MDC. In addition, although MoDCs matured with TNF and PGE2 selectively produced the inhibitory IL-12p40 subunit at steady state, they were able to produce the bioactive IL-12p70 heterodimer after stimulation with CD40 ligand and/or IFN-gamma. Despite increased IL-6 mRNA expression, MoDCs matured with PGE2 did not overcome the suppressive effects of CD4+ CD25+ T cells in allogeneic mixed lymphocyte reactions. In conclusion, MoDCs matured in the presence of PGE2 display characteristics of more efficient antigen-presenting cells that might be optimal for use in cancer vaccine-based clinical trials.

Virulent strains of Staphylococcus hyicus can cause exudative epidermitis in pigs. The major symptom of this disease is exfoliation of the skin in the upper stratum spinosum. Exfoliation of the skin is strongly associated with exfoliative toxin including ExhA, ExhB, ExhC, ExhD, SHETA, and SHETB. Recently, genes for ExhA, ExhB, ExhC and ExhD were cloned. Exfoliative toxins produced by S. aureus have been shown to selectively cleave human or mouse desmoglein 1, a desmosomal adhesion molecule, that when inactivated results in blisters. In this study, we attempted to identify the molecular target of Exhs in porcine skin. Each of recombinant Exhs injected in the skin of pigs caused superficial epidermal blisters or crust formation. Cell surface staining of desmoglein 1, but not that of desmoglein 3, was abolished when cryosections of normal porcine skin were incubated with one of Exhs suggesting that Exh selectively degrade porcine desmoglein 1. In vitro incubation of the recombinant extracellular domains of desmoglein 1 and desmoglein 3 of human, mouse or canine origin demonstrated that only mouse desmogleins 1alpha and 1beta were cleaved by ExhA and ExhC at high concentration. Furthermore, injection of ExhA and ExhC at high concentration caused superficial blisters in neonatal mice. These findings strongly suggest that Exhs cause blister formation of porcine skin by digesting porcine desmoglein 1 in a similar fashion to exfoliative toxins from S. aureus.

Exudative epidermitis (EE) is an acute, often fatal skin disease of piglets caused by Staphylococcus hyicus. Clinical and histopathological manifestations of EE are similar to those of staphylococcal scalded skin syndrome (SSSS), a human blistering skin disease, in which exfoliative toxins produced by Staphylococcus aureus digest the extracellular domains of desmoglein (Dsg) 1 and cause loss of epidermal cell-cell adhesion. The aims of this study were to isolate and characterize cDNA for full length of swine Dsg1, and to determine whether the extracellular domains of swine Dsg1 produced by baculovirus (sDsg1-His) could be digested by four isoforms of exfoliative toxin produced by S. hyicus (ExhA, ExhB, ExhC and ExhD). Nucleotide sequencing revealed that swine Dsg1 cDNA consisted of an open reading frame of 3138 bp, encoding a precursor protein of 1045 amino acids. Deduced amino acid sequence of the swine Dsg1 precursor were highly homologous to corresponding bovine, canine, human and murine sequences. Immunoadsorption assay with a secreted form of sDsg1-His revealed that sDsg1-His specifically absorbs the immunoreactivity of 10 human pemphigus foliaceus sera against swine keratinocyte cell surfaces, suggesting its proper conformation. When sDsg1-His was incubated in vitro with Exhs, all four isoforms of Exh directly digested sDsg1-His into smaller peptides, whereas removal of calcium from sDsg1-His completely inhibited its proteolysis by these four Exhs. Recognition and digestion of calcium-stabilized structure on the extracellular domains of swine Dsg1 by Exhs indicated that EE shares similar molecular pathophysiological mechanisms of intra-epidermal splitting with SSSS in humans.

Bone marrow transplantation from diabetes-resistant strains with complete replacement of the recipient immune system by the allogeneic donor has led to tolerance to donor islets and cure of diabetes in a mouse model of type 1 diabetes. However, the ability to tolerize host T-cells of diabetic NOD mice is unknown. We demonstrate that nonmyeloablative conditioning achieves mixed hematopoietic chimerism across major histocompatibility complex (MHC) barriers in spontaneously diabetic NOD mice. This conditioning preserves alloreactive and autoreactive diabetogenic host NOD T-cells, but when mixed chimerism was established, diabetic NOD mice accepted donor-type allogeneic islet grafts and were cured of diabetes, despite a significant recipient T-cell contribution. Furthermore, induction of mixed chimerism permitted acceptance of NOD islet grafts, demonstrating reversal of autoimmunity. Allogeneic bone marrow transplantation was critical for tolerization of diabetogenic and alloreactive host T-cells. Thus, mixed hematopoietic chimerism induces tolerance to donor islets and reverses established autoimmunity in diabetic NOD mice.

Background: Hepatocyte growth factor (HGF) is a growth factor with multiple biologic properties, including mitogenic, morphogenic, anti-apoptotic, and antifibrogenic activities. Long-term administration of the deletion variant of HGF (dHGF) might contribute to the prevention of chronic liver allograft dysfunction, which is attributed to immunologic and nonimmunologic reactions., Methods: Low-dose tacrolimus was administered to rat-liver recipients after transplantation. Effects of dHGF on transplanted livers treated with low-dose tacrolimus were investigated., Results: Rats receiving liver transplants treated with only low-dose tacrolimus administration showed chronic allograft dysfunction. Treatment with dHGF prolonged the survival time of rats that received liver allografts and suppressed fibrosis of liver allograft. Treatment with dHGF also suppressed the expression levels of interleukin (IL)-1beta, caspase-1, and transforming growth factor (TGF)-beta mRNAs in liver allografts., Conclusions: The findings indicate that dHGF may prevent chronic liver-allograft dysfunction and thus may become a novel treatment for chronic liver-allograft dysfunction.

Background: We demonstrated that hepatic stellate cells (HSCs) isolated from rat livers exposed to warm ischemia are significantly contractile when compared with HSCs from intact rat livers. This suggests that ischemia-reperfusion (IR)-induced impairment of sinusoidal microcirculation results, at least in part, from contraction of HSCs., Methods: Rho-associated coiled-coil forming protein serine/threonine kinase (ROCK) is one of the key regulators of HSCs motility. Therefore we investigated whether Y-27632, a p160ROCK-specific inhibitor, has beneficial effects on warm IR injury in an in vivo rat partial liver IR model and a rat orthotopic liver transplantation model., Results: After reperfusion following 90 min of warm ischemia, livers in untreated control rats had persistent congestion and impaired mitochondrial respiration, as demonstrated by increasing deoxy-hemoglobin and reduced cytochrome oxidase contents in the hepatic tissues using in vivo near-infrared spectroscopy. Serum levels of transaminase and endothelin (ET)-1 in these rats were markedly increased 1 hr after reperfusion. In contrast, when Y-27632 (3-30 mg/kg) was administered orally, hepatic tissue contents of deoxy-hemoglobin and cytochrome oxidase rapidly normalized. In such animals, the elevation of serum transaminase levels, but not that of ET-1 levels, was significantly suppressed. This is consistent with in vitro data demonstrating that Y-27632 causes HSCs to undergo relaxation even in the presence of ET-1. Moreover, in a rat orthotopic liver transplantation model, Y-27632 pretreatment dramatically improved the survival of recipients with liver grafts subjected to 45 min of warm ischemia., Conclusions: Y-27632 attenuates IR-induced hepatic microcirculation disruption by inhibiting contraction of HSCs.

Hepatic stellate cells (HSCs) can easily be activated by ischemia/reperfusion, and this activation results in hepatic microcirculatory disturbance by cell contraction. ROCK is one of the key regulators of the motility of HSCs, and Y-27632 suppresses the activation of HSCs. We examined whether Y-27632 treatment prevents primary graft non-function caused by 45-min warm ischemia in orthotopic liver transplantation (OLT). Donor and recipient rats were administered Y-27632 (3-30 mg/kg). Y-27632 treatment at 30 mg/kg in both donor and recipient prevented congestion of the grafted livers, as demonstrated by analysis of hemoglobin (Hb) content in the grafted livers, using in-vivo near-infrared spectroscopy. Serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and hyaluronic acid at 4 h after OLT in the 30-mg/kg Y-27632-treated group were significantly lower than those in the control group. Specimens from the untreated control recipients showed sinusoidal congestion and massive fresh hepatocyte necrosis, whereas specimens from the Y-27632-treated recipients demonstrated minimal histological changes. Moreover, Y-27632 pre-treatment dramatically improved the survival of recipients. These results suggest that Y-27632 would be clinically useful for preventing liver failure associated with ischemia/reperfusion in liver transplantation.

We identified a novel pathogenicity island in Staphylococcus aureus which contains open reading frames (ORFs) similar to the exfoliative toxin (ET) gene, glutamyl endopeptidase gene, and edin-B gene in tandem and the phage resistance gene, flanked by hsdM, hsdS (restriction and modification system), and IS256. The protein encoded by the ET-like gene showed 40, 59, and 68% amino acid sequence identities with exfoliative toxin A (ETA), exfoliative toxin B (ETB), and Staphylococcus hyicus ETB (ShETB), respectively. When injected into neonatal mice, the recombinant protein derived from the ET-like gene induced exfoliation of the skin with loss of cell-to-cell adhesion in the upper part of the epidermis as observed in histological examinations, just as was found in neonatal mice injected with ETA or ETB. Western blot analysis indicated that the recombinant protein is serologically distinct from ETA and ETB. Therefore, the product encoded by this new ORF is a new ET member produced by S. aureus and is termed ETD. ETD did not induce blisters in 1-day-old chickens. In the skins of mice injected with ETD, cell surface staining of desmoglein 1 (Dsg1), a cadherin type cell-to-cell adhesion molecule in desmosomes, was abolished without affecting that of desmoglein 3 (Dsg3). Furthermore, in vitro incubation of the recombinant extracellular domains of Dsg1 and Dsg3 with the recombinant protein demonstrated that both mouse and human Dsg1, but not Dsg3, were directly cleaved in a dose-dependent manner. These results demonstrate that ETD and ETA induce blister formation by identical pathophysiological mechanisms. Clinical strains positive for edin-B were suggested to be clonally associated, and all edin-B-positive strains tested were positive for etd. Among 18 etd-positive strains, 12 produced ETD extracellularly. Interestingly, these strains are mainly isolated from other sources of infections and not from patients with bullous impetigo or staphylococcal scalded-skin syndrome. This strongly suggests that ETD might play a pathogenic role in a broader spectrum of bacterial infections than previously considered.

Bullous impetigo due to Staphylococcus aureus is one of the most common bacterial infections of man, and its generalized form, staphylococcal scalded skin syndrome (SSSS), is a frequent manifestation of staphylococcal epidemics in neonatal nurseries. Both diseases are mediated by exfoliative toxins (ETs), which show exquisite pathologic specificity in blistering only the superficial epidermis. We show that these toxins act as serine proteases with extremely focused molecular specificity to cleave mouse and human desmoglein 1 (Dsg1) once after glutamic acid residue 381 between extracellular domains 3 and 4. Mutation of the predicted catalytically active serine to alanine completely inhibits cleavage. The mutated ETs bind specifically to Dsg1 by immunofluorescence colocalization and by coimmunoprecipitation. Thus, ETs, through specific recognition and proteolytic cleavage of one structurally critical peptide bond in an adhesion molecule, cause its dysfunction and allow S. aureus to spread under the stratum corneum, the main barrier of the skin, explaining how, although they circulate through the entire body in SSSS, they cause pathology only in the superficial epidermis.