Human anti-laminin 5 autoantibodies induce subepidermal blisters in an experimental human skin graft model

Patients with one form of cicatricial pemphigoid have IgG antibasement membrane autoantibodies against laminin 5 (alpha3beta3gamma2). Although passive transfer of rabbit anti-laminin 5 IgG to neonatal mice has been shown to induce subepidermal blisters that mimic those in patients, it has not been possible to directly assess the pathogenic activity of human autoantibodies in this animal model because the latter do not bind murine skin. To address this question, a disease model in adult mice as well as SCID mice bearing human skin grafts was developed. Adult BALB/C mice challenged with rabbit anti-laminin 5 IgG developed, in a concentration-related fashion, erythema, erosions, and crusts surrounding injection sites, histologic evidence of noninflammatory, subepidermal blisters, and deposits of rabbit IgG and murine C3 in epidermal basement membranes. Anti-laminin 5 IgG also induced subepidermal blisters in: adult complement-, mast cell-, and immuno-deficient mice; adult BALB/C mice pretreated with dexamethasone; and human skin grafts on SCID mice. Alterations did not develop in matching controls challenged with identical amounts of purified normal rabbit IgG or bovine serum albumin. Using this adult mouse model, human skin grafts on SCID mice were challenged with purified IgG from patients with alpha subunit-specific, anti-laminin 5 autoantibodies, or normal controls. Patient (but not control) IgG induced epidermal fragility as well as noninflammatory, subepidermal blisters in grafted human (but not adjacent murine) skin. Moreover, whereas all mice that received patient autoantibodies had anti-laminin 5 IgG in their circulation, deposits of human IgG were present only in the epidermal basement membranes of grafts. Interestingly, these in situ and circulating autoantibodies were predominately of the IgG4 subclass. These studies demonstrate that human anti-laminin 5 autoantibodies are pathogenic in vivo and describe an animal model that can be used to define disease pathomechanisms and biologically important domains within this autoantigen.

Endoscopy-based triage significantly reduces hospitalization rates and costs of treating upper GI bleeding: a randomized controlled trial

BACKGROUND

Many patients with upper gastrointestinal (GI) bleeding have a benign outcome and could receive less intensive and costly care if accurately identified. We sought to determine whether early endoscopy performed shortly after admission in the emergency department could significantly reduce the health care use and costs of caring for patients with nonvariceal upper GI bleeding without adversely affecting the clinical outcome.

METHODS

All eligible patients with upper GI bleeding and stable vital signs were randomized after admission to undergo endoscopy in 1 to 2 days (control) or early endoscopy in the emergency department. Patients with low-risk findings on early endoscopy were discharged directly from the emergency department. Clinical outcomes and costs were prospectively assessed for 30 days.

RESULTS

We randomized 110 consecutive stable patients with nonvariceal upper GI bleeding during the 12-month study period. The baseline demographic features, endoscopic findings, and the clinical outcomes were no different between the two groups. However the findings of the early endoscopy allowed us to immediately discharge 26 of 56 (46%) patients randomized to that group. No patient discharged from the emergency department suffered an adverse outcome. The hospital stay (median of 1 day [interquartile range of 0 to 3 days] vs. 2 days [interquartile range of 2 to 3 days], p = 0.0001) and the cost of care ($2068 [interquartile range of $928 to $3960] versus $3662 [interquartile range of $2473 to $7280], p = 0.00006) were significantly less for the early endoscopy group.

CONCLUSIONS

Early endoscopy performed shortly after admission in the emergency department safely triaged 46% of patients with nonvariceal upper GI bleeding to outpatient care, which significantly reduced hospital stay and costs.

Mucosal morbidity in patients with epidermolysis bullosa acquisita

BACKGROUND

Epidermolysis bullosa acquisita is an acquired inflammatory and/or dermolytic subepidermal blistering disease characterized by IgG autoantibodies to type VII collagen. Four patients with documented epidermolysis bullosa acquisita were evaluated by a multidisciplinary team of care providers (4 dermatologists, an ophthalmologist, a radiologist, a voice and speech specialist, and an otolaryngologist) for 1 to 5 years to characterize mucosal involvement and its complications and response to treatment. Patients were evaluated clinically and by slitlamp examinations, endoscopies, computed tomographic scans, and videofluorographic swallowing studies. Spiral computed tomographic scans for virtual endoscopy were used for the nontraumatic evaluation of airways in 2 patients with respiratory tract compromise.

OBSERVATIONS

Involvement of 5 or more mucosal sites--mouth, nose, conjunctiva, pharynx, and larynx--was documented in all patients. Complications included ankyloglossia, periodontal disease, scarring and crusting of nasal mucosa, symblepharon formation, obstruction of nasolacrimal ducts, deformation of the epiglottis, impaired phonation, dysphagia, esophageal strictures, and supraglottic stenosis requiring emergency tracheostomy.

CONCLUSIONS

Epidermolysis bullosa acquisita may extensively (or predominantly) affect mucosal epithelia in a manner resembling cicatricial pemphigoid. Mucosal disease in these patients is often subclinical, can lead to serious complications, and is best managed using a multidisciplinary approach.

Anti-epiligrin cicatricial pemphigoid with antibodies against the gamma2 subunit of laminin 5

BACKGROUND

Cicatricial pemphigoid (CP) is a scarring subepithelial mucocutaneous blistering disease characterized by anti-basement membrane zone autoantibodies. Anti-epiligrin CP is an uncommon variant that has been recently characterized. Severe laryngeal involvement is infrequently observed in all forms of CP and has been documented in only 2 patients with anti-epiligrin CP.

OBSERVATIONS

We report a case of CP exhibiting extensive laryngeal and ocular involvement. Histological, immunofluorescence, and immunoprecipitation studies confirmed the diagnosis of anti-epiligrin CP. Immunoblotting studies demonstrated the presence of antibodies against the alpha3 and the gamma2 subunit of laminin 5.

CONCLUSION

This article expands the diversity of the clinical and immunopathologic features of this newly characterized variant of CP.

Antiepiligrin cicatricial pemphigoid represents an autoimmune response to subunits present in laminin 5 (alpha3beta3gamma2)

Sera from 20 patients with antiepiligrin cicatricial pemphigoid were studied to define the specific reactivity of their IgG autoantibodies. IgG from all patients bound exclusively to the dermal side of 1 mol/L NaCl split skin and immunoprecipitated laminin 5 (alpha3beta3gamma2) from extracts of human keratinocytes (HKs). Immunoblot studies on purified laminin 5 subunits demonstrated that patient IgG bound alpha3 alone in 16 patients. In two patients, IgG autoantibodies were directed predominantly to the gamma2 subunit, yet showed trace reactivity to alpha3 as well. Sera from two patients did not immunoblot any laminin 5 subunits, their IgG presumably immunoprecipitating laminin 5 via a conformational epitope. Sera from patients with alpha3 subunit-specific IgG immunoprecipitated all subunits of laminin 5 as well as polypeptides of 190 and 200 kDa from the conditioned media of HKs. Preclearance studies and experiments utilizing affinity-purified patient IgG demonstrated that the latter signified laminin 6 (alpha3beta1gamma1) that was bound by cross-reactive alpha3 subunit-specific patient IgG. Sera from patients with gamma2 subunit-specific IgG showed no reactivity to laminin 6, except for faint reactivity provided by low levels of their alpha3 subunit-specific IgG. Taken together, these findings indicate that antiepiligrin cicatricial pemphigoid signifies an autoimmune response to subunits present in laminin 5.

Anti-epiligrin cicatricial pemphigoid: a case associated with gastric carcinoma and features resembling epidermolysis bullosa acquisita

A 48-year-old woman with anti-epiligrin cicatricial pemphigoid (CP) who showed clinical features resembling epidermolysis bullosa acquisita was found to have adenocarcinoma of the stomach. Histological examination of lesional skin demonstrated a subepidermal blister. Direct immunofluorescence microscopy of perilesional skin revealed linear deposits of IgG and C3 at the basement membrane zone. The patient's serum contained IgG autoantibodies that bound to the dermal side of 1 mol/L NaCl-split normal human skin as determined by indirect immunofluorescence microscopy, and the lamina lucida as determined by indirect immunoelectron microscopy. The patient's serum immunoprecipitated laminin-5 from extracts and media of biosynthetically radiolabelled human keratinocytes. Immunoblot studies showed that the patient's autoantibodies specifically bound the alpha3 subunit of this laminin isoform. Fragility of the skin and bullous lesions disappeared after total gastrectomy, but soon reappeared possibly in association with metastatic disease in a lymph node. The possibility that anti-epiligrin CP may develop paraneoplastically in some patients is discussed.

Protein kinase C-mediated down-regulation of beta1-adrenergic receptor gene expression in rat C6 glioma cells

In the current study, we investigated the mechanism by which protein kinase C (PKC) regulates the expression of beta1-adrenergic receptor (beta1AR) mRNA in rat C6 glioma cells. Exposure of the cells to 4beta-phorbol-12-myristate-13-acetate (PMA), an activator PKC, resulted in a down-regulation of both beta1AR binding sites and mRNA levels in a time- and concentration-dependent manner. This effect was not observed with phorbol esters that do not activate PKC and was blocked by bisindolylmaleimide, a specific PKC inhibitor. Activation of PKC did not reduce the half-life of beta1AR mRNA but significantly decreased the activity of the beta1AR promoter, as determined by reporter analysis. A putative response element, with partial homology to a consensus cAMP response element, was identified by mutation analysis of the promoter at positions -343 to -336, relative to the translational start site. Mutation of this putative regulatory element, referred to as a beta1AR-PKC response element, completely blocked the PKC-mediated down-regulation of beta1AR promoter activity. Gel mobility shift analysis detected two specific bands when C6 cell extracts were incubated with a labeled DNA probe containing the beta1AR-PKC response element sequence. Formation of one of these bands was inhibited by an oligonucleotide probe containing a consensus CRE and disrupted by an antibody for cAMP response element binding protein. Based on these studies, we propose that the PKC-induced down-regulation of beta1AR gene transcription in C6 cells is mediated in part by a cAMP response element binding protein-dependent mechanism acting on a novel response element.

A model for red blood cell motion in glycocalyx-lined capillaries

The interior surfaces of capillaries are lined with a layer (glycocalyx) of macromolecules bound or absorbed to the endothelium. Here, a theoretical model is used to analyze the effects of the glycocalyx on hematocrit and resistance to blood flow in capillaries. The glycocalyx is represented as a porous layer that resists penetration by red blood cells. Axisymmetric red blood cell shapes are assumed, and effects of cell membrane shear elasticity are included. Lubrication theory is used to compute the flow of plasma around the cell and within the glycocalyx. The effects of the glycocalyx on tube hematocrit (Fahraeus effect) and on flow resistance are predicted as functions of the width and hydraulic resistivity of the layer. A layer of width 1 micron and resistivity 10(8) dyn.s/cm4 leads to a relative apparent viscosity of approximately 10 in a 6-micron capillary at discharge hematocrit 45% and flow velocity of approximately 1 mm/s. This is consistent with experimental observations of increased flow resistance in microvessels in vivo, relative to glass tubes with the same diameters.

[Cicatricial pemphigoid with autoantibodies to laminin 5 (epiligrin) in a patient with metastatic endometrial carcinoma]

A 71-year-old female patient presented with erosions of the oral, genital and ocular mucosa, but without skin lesions. One year prior to the onset of lesions, a metastatic adenocarcinoma of the endometrium had been diagnosed. In perilesional skin, direct immunofluorescence showed linear deposits of C3 and IgG along the basement membrane zone. Indirect immunofluorescence demonstrated anti-basement membrane zone antibodies which bound exclusively to the dermal side of 1M NaCl-split skin. In immunoprecipitation studies, the autoantibodies bound a set of proteins characteristic of epiligrin/laminin-5, and they specifically immunoblotted the alpha-subunit of this protein. These results confirmed our presumed diagnosis of anti-epiligrin cicatricial pemphigoid. Combined treatment with methylprednisolone and dapsone resulted in prompt remission, despite progression of her malignancy. So far, only eight patients with anti-epiligrin cicatricial pemphigoid have been reported worldwide. Our patient represents the first case from Austria and is clinically and immunopathologically similar to previously reported cases.

Resistance to blood flow in nonuniform capillaries

OBJECTIVE

Microvessels in living tissues an not uniform cylinders, and red blood cells (RBCs) are continually deformed when traversing them. This may contribute to higher resistance to blood flow observed in microvessels compared with that in corresponding uniform glass tubes. Here, a theoretical model was used to estimate flow resistance in nonuniform capillaries and its dependence on hematocrit, flow rate, and mechanical properties of RBCs.

METHODS

Single-file motion of RBCs through capillaries with sinusoidally varying cross-sections was simulated, assuming axisymmetrical geometry. Effects of cell membrane shear viscosity and elasticity were included. Lubrication theory was used to describe the plasma flow.

RESULTS

Predicted resistance to blood flow in capillaries with variable cross-sections was substantially higher than in uniform vessels with the same mean diameters. Resistance depended on vessel geometry, flow rate, and hematocrit. At tube hematocrit 30%, the increase in resistance was 40%-58% when diameter varied between 4.5 and 6 microns with wavelength 20 microns and 58%-77% for variations between 4 and 5 microns with wavelength 10 microns. Larger relative increases in resistance were predicted for RBCs with increased membrane shear viscosity.

CONCLUSIONS

Effects of transient RBC deformations in irregular capillaries contribute significantly to blood flow resistance in capillaries. However, this effect is not sufficient to account for the flow resistance observed in living tissues.

Noncomplement fixing, IgG4 autoantibodies predominate in patients with anti-epiligrin cicatricial pemphigoid

This study characterized the specific reactivity, IgG subclass, and complement fixing ability of anti-laminin-5 IgG from 12 patients with anti-epiligrin cicatricial pemphigoid. Circulating IgG from all patients bound the dermal side of 1 M NaCl split skin, immunoprecipitated laminin-5 produced by biosynthetically radiolabeled human keratinocytes, and (in 10 of 12 cases) immunoblotted the laminin-alpha3 subunit. Analysis of the distribution of IgG subclasses in these patients' circulating anti-laminin-5 autoantibodies by semiquantitative indirect immunofluorescence microscopy using the HP series of subclass-specific monoclonal antibodies revealed: (i) IgG4 predominant autoantibodies in seven of 11 sera; (ii) IgG1 and IgG2 at substantially lower levels in a smaller number of sera; and (iii) no specific IgG3 anti-laminin-5 autoantibodies in any patients. The same IgG4-dominant profile of anti-laminin-5 autoantibodies was found in enzyme-linked immunosorbent assay studies of purified human laminin 5. Direct immunofluorescence microscopy of six skin biopsies from three patients found that IgG4 was also the predominant subclass of IgG in epidermal basement membranes in situ. Consistent with these findings, sera from 11 of 11 patients with anti-laminin-5 IgG autoantibodies did not fix C3 to epidermal basement membranes in vitro. These immunochemical studies suggest that complement activation does not play a major role in the pathophysiology of this disease and that subepidermal blisters in these patients may develop via a direct effect of anti-laminin-5 IgG itself.

Synchrotron X-ray Studies of LiNbO3 and LiTaO3

The structural geometry, vibrations and deformation density Δρ for lithium niobate, LiNbO3, and lithium tantalate, LiTaO3, are derived from synchrotron radiation diffraction measurements. Electron density is transferred from the Nb (Ta) atom towards the large O3 triangle near the Li atom. Spontaneous polarizations of 0.43 (LiNbO3) and 0.33 cm−2 (LiTaO3), calculated with Hirshfeld charges, agree qualitatively with experimental values of 0.71 and 0.50 −2, respectively. Both strong Li...Nb (Ta) interactions in the structure are markedly shorter than all Li...Li, Nb...Nb or Ta...Ta vectors, as expected if the Li and Nb (Ta) cations carry charges of opposite sign. The Li atom's negative charge plays a pivotal role in the polarization responsible for ferroelectricity. LiNbO3, space group R3c, rhombohedral, M r = 147.8, a = 5.493 (2) Å, α = 55.89 (3)°, V = 106.02 (4) Å3, Z = 2, D x = 4.629 Mg m−3, F(000) = 136, μ(0.7 Å) = 5.01 mm−l, y min = 0.27, T = 293 K, R = 0.015, wR = 0.015, S = 3.276 (84) for 773 unique reflections. LiTaO3, R3c, rhombohedral, M r = 235.9, a = 5.471 (2) Å, α = 56.16 (3)°, V = 105.51 (4) Å3, Z = 2, D x = 7.412 Mg m−3, F(000) = 200, μ(0.7 Å) = 50.03 mm−1, y min = 0.32, T = 293 K, R = 0.016, wR = 0.022, S = 1.372(35) for 773 unique reflections.

Fluctuations in red cell flux in tumor microvessels can lead to transient hypoxia and reoxygenation in tumor parenchyma

Hypoxia occurs in two forms in tumors. Chronic or diffusion-limited hypoxia is relatively well characterized. In contrast, intermittent or perfusion-limited hypoxia is not well characterized, and it is not known how common it is in tumors. The purpose of this study was to determine whether spontaneous fluctuations in tumor microvessel flow rate can modify vessel oxygen tension (pO2) sufficiently to cause intermittent hypoxia (IH; tissue pO2 < 3 mmHg) in the tumor parenchyma supplied by such vessels. Microvessel red cell flux (RCF) and perivascular pO2 were measured simultaneously and continuously in dorsal flap window chambers of Fischer-344 rats with implanted R3230Ac tumors. In all vessels, RCF was unstable, with apex/nadir ratios ranging from 1.5 to 10. RCF and pO2 were temporally coordinated, and there were linear relationships between the two parameters. Vascular pO2 was less sensitive to changes in RCF in well-vascularized tumor regions compared with poorly vascularized regions. Simulations of oxygen transport in a well-vascularized region of a tumor demonstrated that two-fold variations in RCF can produce IH in 30% of the tissue in that region. In poorly vascularized regions, such fluctuations would lead to an even greater percentage of tissue involved in transient hypoxia. These results suggest that IH is a relatively common phenomenon. It could affect binding of hypoxic cytotoxins to tumor cells, in addition to being an important source of treatment resistance. Intermittent hypoxia also could contribute to tumor progression by providing repeated exposure of tumor cells to hypoxia-reoxygenation injury.

Motion of red blood cells in capillaries with variable cross-sections

Red blood cells undergo continual deformation when traversing microvessels in living tissues. This may contribute to higher resistance to blood flow observed in living microvessels, compared with that in corresponding uniform glass tubes. We use a theoretical model to simulate single-file motion of red cells though capillaries with variable cross-sections, assuming axisymmetric geometry. Effects of cell membrane shear viscosity and elasticity are included, but bending resistance is neglected. Lubrication theory is used to describe the flow of surrounding plasma. When a red cell encounters a region of capillary narrowing, additional energy is dissipated, due to membrane viscosity, and due to narrowing of the lubrication layer, increasing the flow resistance. Predicted resistance to cell motion in a vessel with periodic constrictions (diameter varying between 5 microns and 4 microns) is roughly twice that in a uniform vessel with diameter 4.5 microns. Effects of transient red cell deformations may contribute significantly to blood flow resistance in living microvessels.

A synchrotron X-ray study of the electron density in Y2BaCuO5

The deformation density (Δρ) for Y2BaCuO5, barium diyttrium cuprate, determined by single-crystal X-ray diffraction with synchrotron radiation, is affected to only a limited degree by the bonding interactions involving the O anions. Electron density is strongly depleted along the cation–cation contacts within the mirror plane in the structure and is transferred to regions between mirror planes that do not lie along short cation–cation vectors. The structural geometry for the CuO5 moiety, with the Cu atom in the +2 state, closely resembles that of the Cu2O5 group in YBa2Cu3O7−δ , for which the +3 state involvement for Cu has been suggested. Space group Pnma, orthorhombic, Mr = 458.68, a = 12.1793 (7), b = 5.6591 (5), c = 7.1323 (4) Å, V = 491.6 Å3, Z = 4, Dx = 6.197 Mg m−3, λ = 0.9 Å, μ 0.9 = 28.893 mm−1, F(000) = 812, T = 293 K, R = 0.020, wR = 0.020, S = 3.09 (5) for 2225 unique reflections.

Analysis of red blood cell motion through cylindrical micropores: effects of cell properties

Filtration through micropores is frequently used to assess red blood cell deformability, but the dependence of pore transit time on cell properties is not well understood. A theoretical model is used to simulate red cell motion through cylindrical micropores with diameters of 3.6, 5, and 6.3 microns, and 11-microns length, at driving pressures of 100-1000 dyn/cm2. Cells are assumed to have axial symmetry and to conserve surface area during deformation. Effects of membrane shear viscosity and elasticity are included, but bending resistance is neglected. A time-dependent lubrication equation describing the motion of the suspending fluid is solved, together with the equations for membrane equilibrium, using a finite difference method. Predicted transit times are consistent with previous experimental observations. Time taken for cells to enter pores represents more than one-half of the transit time. Predicted transit time increases with increasing membrane viscosity and with increasing cell volume. It is relatively insensitive to changes in internal viscosity and to changes in membrane elasticity except in the narrowest pores at low driving pressures. Elevating suspending medium viscosity does not increase sensitivity of transit time to membrane properties. Thus filterability of red cells is sensitively dependent on their resistance to transient deformations, which may be a key determinant of resistance to blood flow in the microcirculation.

Red blood cell mechanics and functional capillary density

The relationship between red blood cell mechanics and functional capillary density is examined. Experimental observations of capillary recruitment in skeletal muscle have shown sequential recruitment and derecruitment of capillaries fed by a single arteriole, implying that flow may cease in individual capillaries at small nonzero driving pressures. Such behavior is not expected in uniform blood-perfused tubes, but could occur when moving red cells encounter geometrical irregularities in capillaries. From known elastic properties of the red cell membrane, a lower bound is computed for the pressure required to sustain red cell motion in irregular capillaries. This may be an underestimate of the pressure required, because it neglects the viscous resistance of the red cell membrane when it undergoes transient deformations. Simulations including membrane viscosity show that viscous effects can substantially increase flow resistance. It is concluded that the mechanical properties of red blood cells can play a significant role in the modulation of functional capillary density.

The association of the amoebic colitis and chronic ulcerative colitis

Three patients with idiopathic ulcerative colitis and infection of Entamoeba histolytica were reviewed. They represented three different relationships between the two conditions, vis asymptomatic carrier, coexisting infection and superinfection causing exacerbation of colitis. A two-way relationship between amoebic colitis and ulcerative colitis has been discussed and the possible mechanisms in the literature have been reviewed. In patients with a short history of diarrhoea and in tropical countries where amoebic infection is endemic, it is important to role out amoebic colitis before commencing steroid therapy for inflammatory disease.

Analysis of the effects of oxygen supply and demand on hypoxic fraction in tumors

The extent of hypoxic regions in a tumor tissue depends on the arrangement, blood flow rate and blood oxygen content of microvessels, and on the tissue's oxygen consumption rate. Here, the effects of blood flow rate, blood oxygen content and oxygen consumption on hypoxic fraction are simulated theoretically, for a region whose microvascular geometry was derived from observations of a transplanted mammary andenocarcinoma (R3230AC) in a rat dorsal skin flap preparation. In the control state, arterial PO2 is 100 mmHg, consumption rate is 2.4 cm3 O2/100 g/min, and hypoxic fraction (tissue with PO2 < 3 mmHg) is 30%. Hypoxia is abolished by a reduction in consumption rate of at least 30%, relative to control, or an increase in flow rate by a factor of 4 or more, or an increase in arterial PO2 by a factor of 11 or more. These results suggest that reducing oxygen consumption rate may be more effective than elevating blood flow or oxygen content as a method to reduce tumor hypoxia.

Simulation of O2 transport in skeletal muscle: diffusive exchange between arterioles and capillaries

Theoretical simulations of oxygen transport in skeletal muscle are used to study the role of arterioles in oxygen delivery. A three-dimensional configuration of capillaries and arterioles in a cuboidal tissue region is simulated, based on observations of hamster cheek pouch retractor muscle. Equations describing convective and diffusive oxygen transport are solved using a Green's function method. In resting muscle, predicted oxygen saturation of capillary blood increases as it flows toward arterioles, and adjacent capillaries flowing in opposite directions show very similar variations in saturation. Diffusive oxygen loss from arterioles equals about 85% of consumption. Capillaries absorb much of this oxygen (equal to approximately 45% of consumption) and deliver it at downstream locations. Thus diffusive exchange between arterioles and capillaries plays an important part in distributing oxygen throughout the tissue. At higher flow and consumption rates, the relative amounts of oxygen diffusing out of arterioles and into capillaries decrease. The results are consistent with the hypothesis that oxygen content of arteriolar blood participates in metabolic regulation of blood flow.