Amyloid deposits and amyloidosis. The beta-fibrilloses (first of two parts)

Single-domain antibodies recognize selectively small oligomeric forms of amyloid beta, prevent Abeta-induced neurotoxicity and inhibit fibril formation

Neurotoxic oligomers of amyloid beta (Abeta) peptide have been incriminated in the pathogenesis of Alzheimer's disease. Further exploration of this issue has been hampered to this date by the fact that all previously described anti-Abeta antibodies are unable to discriminate between the different conformations of the peptide (oligomers, protofibrils and fibrils). Here, we describe the generation of novel camelid single-chain binding domains (VHHs) that recognizes specifically low molecular-weight (MW) oligomers. Three VHH specific for Abeta were obtained from an immunized alpaca phage display library. Two were able to recognize selectively intraneuronal Abeta oligomers; furthermore, one of them, V31-1, prevented Abeta-induced neurotoxicity and inhibited fibril formation. This study confirms that VHHs may recognize non-conventional epitopes and illustrates their potential for the immunodiagnostic of diseases due to protein accumulation.

Electrochemical Assay of Human Islet Amyloid Polypeptide and Its Aggregation

Square wave voltammetry is used in this work to detect human islet amyloid polypeptide (hIAPP) by using the oxidized signal of the tyrosine residue in hIAPP. A detection limit of 1×10^-6 M for hIAPP has been obtained. A kinetic study of the aggregation process has been carried out according to the relationship between the anodic peak current in the square wave voltammograms of hIAPP and the incubation period. The results show that the nucleation starts in the first hour of incubation and then, during the next two hours, aggregation may occur rapidly. hIAPP can therefore be monitored with a label-free electrochemical method with low detection limit and high sensitivity. This electrochemical method can be also utilized to study the kinetics of hIAPP aggregation, and it may be also employed to study the conformational changes of the polypeptide.

Paraneoplastic glomerular diseases and malignancies

Paraneoplastic glomerulopathies are rare manifestations of neoplastic disease to be distinguished from iatrogenic renal damage. Solid tumors are preferentially associated with membranous nephropathy, whereas Hodgkin's lymphomas are associated with minimal change disease. The most common neoplasia associated with paraneoplastic glomerular disease are carcinomas of the lung and of the gastrointestinal tract. Nephrotic syndrome is the most frequent presentation of paraneoplastic glomerulopathy and the most critical glomerular disease regarding prognosis and patient care. Renal biopsy is recommended in patients with glomerular proteinuria or nephrotic syndrome and cancer, depending on life expectancy and therapeutic options. The primary treatment must be directed at the cancer in all cases. Symptomatic treatment of the nephrotic syndrome with diuretics and ACE inhibitors is justified. Prevention of nephrotic syndrome complications, i.e. thromboses and infections, should also be addressed and systematic regular renal follow-up is warranted. All treatments should be regularly reviewed to avoid toxicity, associated renal function loss or low albumin levels for patients receiving albumin-binding drugs. Epidemiologic studies have low evidence-based value. There is no widely accepted experimental model of the association of glomerulopathy and cancer. Thus, epidemiologic and mechanistic studies are needed to determine the true prevalence of paraneoplastic glomerulopathies and investigate new pathophysiologic approaches.

Inhibition of Amyloid Fibrillization of Hen Egg-White Lysozymes by Rifampicin and p-Benzoquinone

It has been reported that more than 20 different human proteins can fold abnormally, resulting in the formation of pathological deposits and several lethal degenerative diseases. Despite extensive investigations on amyloid fibril formation, the detailed molecular mechanism remained rather elusive. The current research, utilizing hen egg-white lysozymes as a model system, is aimed at exploring inhibitory activities of two potential molecules against lysozyme fibril formation. We first demonstrated that the formation of lysozyme amyloid fibrils at pH 2.0 was markedly enhanced by the presence of agitation in comparison with its quiescent counterpart. Next, via numerous spectroscopic techniques and transmission electron microscopy, our results revealed that the inhibition of lysozyme amyloid formation by either rifampicin or its analogue p-benzoquinone followed a concentration-dependent fashion. Furthermore, while both inhibitors were shown to acquire an anti-aggregating and a disaggregating activity, rifampicin, in comparison with p-benzoquinone, served as a more effective inhibitor against in vitro amyloid fibrillogenesis of lysozyme. It is our belief that the data reported in this work will not only reinforce the findings validated by others that rifampicin and p-benzoquinone serve as two promising preventive molecules against amyloid fibrillogenesis, but also shed light on a rational design of effective therapeutics for amyloidogenic diseases.

Real-time monitoring of apoptosis by caspase-3-like protease induced FRET reduction triggered by amyloid aggregation

Amyloid formation is cytotoxic and can activate the caspase cascade. Here, we monitor caspase-3-like activity as reduction of fluorescence resonance energy transfer (FRET) using the contstruct pFRET2-DEVD containing enhanced cyan fluorescent protin (EYFP) linked by the caspase-3 specific cleavage site residues DEVD. Beta-TC-6 cells were transfected, and the fluoorescence was measured at 440 nm excitation and 535 nm (EYFP) and 480 nm (ECFP) emission wavelength. Cells were incubated with recombinant pro lset Amyloid Polypeptide (rec prolAPP) or the processing metabolites of prolAPP; the N-terminal flanking peptide withIAPP (recN+IAPP); IAPP with the C-terminal flanking peptied (recIAPP+C) and lslet Amyloid Polypeptide (recIAPP) . Peptides were added in solubilized from (50 microM) or as performed amyloid-like fibrils, or as a combination of these. FRET was measured and incubation with a mixture of solubilized peptide and performed fibrils resulted in loss of FRET and apoptosis was determined to occure in cells incubated with recproIAPP (49%), recN+IAPP (46%), recIAPP (72%) and recIAPP+C (59%). These results show that proIAPP and the processing intermediates reside the same cell toxic capacity as IAPP, and they can all have a central role in the reduction of beta-cell number in type 2 diabetes.

Effect of methionine oxidation on the structural properties, conformational stability, and aggregation of immunoglobulin light chain LEN

Light chain amyloidoses arise from the overproduction and abnormal deposition of the immunoglobulin light chain in various organs. LEN is the variable domain of an immunoglobulin light chain originally isolated from the urine of a patient suffering from multiple myeloma, with no sign of renal dysfunction or amyloidosis. LEN was shown to form fibrils in vitro under mildly destabilizing conditions. In this work, we investigated the changes induced by methionine oxidation in the structural properties, conformational stability, and aggregation behavior of immunoglobulin light chain domain LEN. We established that LEN was well-protected from oxidation in its native state, but successful oxidation was achieved in the presence of 4 M GuHCl. Oxidation induced noticeable structural changes in LEN and destabilized this protein. The methionine-oxidized LEN preferred to form amorphous aggregates instead of fibrils. The results indicated that the LEN oxidation may play an important role in amorphous deposition of the protein, but not in its fibrillation.

Unfolding and aggregation of transthyretin by the truncation of 50 N-terminal amino acids

Senile systemic amyloidosis (SSA) is caused by amyloid deposits of wild-type transthyretin in various organs. Amyloid deposits from SSA contain large amounts of the C-terminal fragments starting near amino acid residue 50 as well as full-length transthyretin. Although a number of previous studies suggest the importance of the C-terminal fragments in the pathogenesis of SSA, little is known about the structure and aggregation properties of the C-terminal fragments of transthyretin. To understand the role of C-terminal fragments in SSA, we examined the effects of the truncation of the N-terminal portions on the structure and aggregation properties of wild-type transthyretin. The deletion mutant lacking 50 N-terminal residues was largely unfolded in terms of secondary and tertiary structure, leading to self-assembly into spherical aggregations under nearly physiological conditions. By contrast, the deletion mutant lacking 37 N-terminal residues did not have a strong tendency to aggregate, although it also adopted a largely unfolded conformation. These results suggest that global unfolding of transthyretin by proteolysis near amino acid residue 50 is an important step of self-assembly into aggregations in SSA.

Review article: gastrointestinal amyloidosis - clinical features, diagnosis and therapy

BACKGROUND

Amyloidosis is one of the unusual diseases about which a physician may not think when it is affecting the patient. During the last three decades, there has been an enormous progress in the understanding of the chemical nature, classification, pathogenesis, clinical features, diagnostic measures and therapy of this disorder.

AIM

To provide an updated review of amyloidosis affecting the gastrointestinal tract.

METHODS

Review of current medical literature.

RESULTS

Amyloid proteins (irrespective of the type) can deposit in various parts of the gastrointestinal tract and liver resulting in symptoms of abdominal pain, dysmotility, diarrhoea, gastrointestinal bleeding, hepatomegaly and even portal hypertension with its associated complications. Definitive diagnosis can only be made by histological examination of the affected organ. Disease modifying treatment with high-dose chemotherapy followed by autologous stem-cell transplantation has shown promise. Liver transplantation is an option for a select group of patients.

CONCLUSIONS

Suspicion of gastrointestinal amyloidosis in patients without known history of amyloidosis is difficult, but should be considered in those older than 30 years with unexplained diarrhoea, weight loss, autonomic dysfunction, malabsorption or proteinuria. While most gastrointestinal complications are managed symptomatically, causal therapy is reserved for a select few from various subtypes of this disorder.

A case of AA amyloidosis associated with rheumatoid arthritis effectively treated with Infliximab

We report the case of a 55-year-old Japanese woman with reactive AA amyloidosis associated with rheumatoid arthritis, in which inflammatory disease was completely suppressed with infliximab. Nephrotic syndrome was observed and renal biopsy specimens revealed amyloidosis deposits. Treatment with infliximab normalized the serum amyloid A (SAA) protein level, and subsequently nephritic syndrome disappeared and her creatinine clearance improved. Serial gastrointestinal biopsy specimens showed marked lasting regression of amyloid deposits. Thus treatment with infliximab represents an important therapeutic strategy for AA amyloidosis associated with RA.

Current and future uses of neuroimaging for cognitively impaired patients

Technological advances have led to greater use of both structural and functional brain imaging to assist with the diagnosis of dementia for the increasing numbers of people with cognitive decline as they age. In current clinical practice, structural imaging (CT or MRI) is used to identify space-occupying lesions and stroke. Functional methods, such as PET scanning of glucose metabolism, could be used to differentiate Alzheimer's disease from frontotemporal dementia, which helps to guide clinicians in symptomatic treatment strategies. New neuroimaging methods that are currently being developed can measure specific neurotransmitter systems, amyloid plaque and tau tangle concentrations, and neuronal integrity and connectivity. Successful co-development of neuroimaging surrogate markers and preventive treatments might eventually lead to so-called brain-check scans for determining risk of cognitive decline, so that physicians can administer disease-modifying medications, vaccines, or other interventions to avoid future cognitive losses and to delay onset of disease.

Lambda II immunoglobulin light chain protein in primary localized rectal amyloidosis

Rectal involvement is usually part of a systemic amyloidosis, whereas, localized rectal amyloidosis is a rare entity. We present a case of asymptomatic localized rectal amyloidoma. Amyloid fibrils were isolated from rectal biopsy tissue and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) which showed bands at 17 kDa, 21 kDa and 28 kDa, a broad doublet band at 7-8 kDa and weaker bands at 15 kDa and 24 kDa. Edman sequence analysis of the isolated protein and its tryptic peptides showed that the amyloid protein was derived from an immunoglobulin lambdaII-light chain. To our knowledge, this is the first reported case to isolate and chemically characterize amyloid fibrils from a localized rectal amyloidoma. The development of specific therapies for patients with amyloid-associated disorders emphasizes the need to characterize the biochemical nature of the amyloid fibril protein.

Refined fibril structures: the hydrophobic core in Alzheimer's amyloid beta-protein and prion as revealed by X-ray diffraction

From the wide-angle, equatorial X-ray data of a beta-amyloid analogue, we previously calculated the electron density of the constituent beta-crystallite, which assembles as multimers (four to six crystallites) in building the amyloid fibre. In the scattering region where the spacing d < approximately 10 A, the observed reflections were indexed by an orthogonal lattice with a unit cell having a = 9.44 A, b = 6.92 A and c = 10.76 A. The phases were initially derived from the atomic coordinates of the beta-keratin backbone and were optimized by including new peaks (as point atom or sphere) in the subsequent Fourier iteration. The R-factor between the observed and calculated amplitudes was refined to 35%. In further developing our analysis, we have now applied an alternative constraint to the optimization by eliminating the negative electron densities, and found that the R-factor decreased to 19% after three iterations. The refined electron density map fits phenylalanine, indicating that the amyloid core likely comes from the hydrophobic Leu-Val-Phe-Phe residues. We have applied the same type of optimization, using beta-silk as an initial phase model, to the hydrophobic H1 domain of the prion protein for which the monoclinic unit cell constants are a = 9.51 A, b = 7.06 A, c = 15.94 A and beta = 88.4 degrees. The R-factor decreased to 11% from 64% after two iterations. The electron density map shows a silk-like quarter-staggered arrangement of beta-sheets which, in the intersheet direction, have circular peaks in one beta-sheet and elongated peaks in the alternating beta-sheet. These peaks were interpreted as arising from the C-terminal alanine-rich domain and N-terminal hydrophobic residues. Skeletal atomic models for these core regions support this interpretation.

Metabolism of amyloid proteins

Metabolic processing of amyloid precursor proteins is an important factor in the genesis of practically all forms of amyloidosis. Of the three major forms of systemic amyloidosis, reactive amyloid (amyloid A protein; AA) formation shows the most consistent role of partial proteolysis of serum amyloid A (SAA) to AA proteins which form fibrils. Immunoglobulin amyloidosis is also usually associated with C-terminal degradation of the fibril precursor light chain protein. Although it is commonly thought that transthyretin amyloidosis is associated with fibril formation from the tetrameric circulating plasma transthyretin, chemical analyses of transthyretin fibril deposits show significant fragmentation of the fibril protein constituents. In addition, it has been documented that proteolytic fragments are the fibril subunit proteins in gelsolin, cystatin C. Alzheimer's beta-amyloid precursor protein and apolipoprotein AI (apoAI) amyloidoses. Notable exceptions to the role of proteolysis in amyloid fibril formation would appear to be the lysozyme and beta 2-microglobulin amyloidoses. Few studies have examined the metabolism of amyloid-forming proteins. Perhaps the best data are on apoAI, which show decreased plasma residence time for the amyloidogenic Gly26Arg apoAI (1.8 d vs. normal 4.5 d). Similarly, preliminary data show increased clearance of Val30Met transthyretin when compared with the wild-type protein (18 h vs. 26 h). Also, biosynthetically 35S-labelled SAA proteins reconstituted with HDL show increased plasma clearance of murine SAA2, the amyloid fibril subunit protein, when compared with murine SAA1. Few data are available on metabolism of amyloid immunoglobulin light chain proteins, but it has been shown that radiolabelled Bence-Jones proteins are cleared very rapidly from the circulation. A better understanding of the metabolism of precursor proteins in each of the amyloid deposition diseases will give insight into the mechanisms of fibril formation and pathogenesis of amyloidosis.

Pathogenesis of amyloid formation in Alzheimer's disease, Down's syndrome and scrapie

Paired helical filaments (PHF) are abnormal fibrous structures found in human nerve cells and their processes. Ultrastructural studies of the proto-filaments that make up the PHF revealed that the individual proto-filaments have a different substructure from normal neurofilaments or any other known fibrous profiles. Studies using immunological and biochemical methods suggested that abnormally phosphorylated tau, ubiquitin and neurofilament peptides are part of the PHF. Deposits of amyloid fibres in Alzheimer's disease and senile dementia of the Alzheimer type (AD/SDAT) are found in meningeal and brain vessels, choroid plexus and neuritic plaques. In 1984 Glenner and Wong reported the sequence of a beta-protein isolated from cerebrovascular amyloid. We used the amino acid sequence of the cerebrovascular amyloid protein to synthesize oligonucleotide probes specific for the gene encoding this amyloid protein. Screening of a human brain cDNA library allowed us to isolate a clone which encodes the amyloid peptide. In situ hybridization studies and Southern blot analysis of a DNA sample isolated from a human-mouse hybrid cell line indicated that the corresponding genomic sequences of this cDNA clone are located on human chromosome 21. Using immunochemical and histochemical methods, we have identified the cells associated with the formation of the amyloid fibres. With immunochemical and biochemical methods we and others also showed that the protein constituting amyloid in AD/SDAT is different from amyloid in unconventional slow virus diseases.

Ageing and amyloid fibrillogenesis: lessons from apolipoprotein AI, transthyretin and islet amyloid polypeptide

The age-associated (or senile) amyloidoses encompass a heterogeneous group of systemic or localized forms of amyloidosis. In this paper we present an overview of three age-associated amyloid forms derived from transthyretin, apolipoprotein AI and islet amyloid polypeptide. Mutations in the respective genes give rise to transthyretin and apolipoprotein AI forms of familial amyloidosis while senile forms of amyloid are associated with the wild-type proteins. Different mechanisms are probably of importance in the fibrillogenesis associated with these three amyloid types. It is also possible that different amyloidogenic pathways exist for a single amyloidogenic protein. Thus, limited proteolysis may be necessary in the fibrillogenesis in senile transthyretin amyloidosis but not in most familial transthyretin amyloidoses. Other factors in the pathogenesis of amyloidosis such as local concentration, nidus formation and glycation are also discussed.

Scrapie: a virus-induced amyloidosis of the brain

We have studied the pathogenesis of scrapie in hamsters, in particular the increase of infectivity and the formation of scrapie-associated fibrils in relation to clinical disease. The results of such studies after intraperitoneal or intracerebral infection are consistent with the idea that transmissible spongiform encephalopathies are a type of virus-induced, brain-specific amyloidosis. Therefore, an appropriate name for the class of viruses that cause these diseases might be amyloid-inducing viruses.

G Protein-Coupled Receptor Trafficking in Health and Disease: Lessons Learned to Prepare for Therapeutic Mutant Rescue in Vivo

G protein-coupled receptors (GPCR) comprise the largest family of drug targets. This is not surprising as many signaling systems rely on this class of receptor to convert external and internal stimuli to intracellular responses. As is the case with other membrane proteins, GPCRs are subjected to a stringent quality control mechanism at the endoplasmic reticulum, which ensures that only correctly folded proteins enter the secretory pathway. Because of this quality control system, point mutations resulting in protein sequence variations may result in the production of misfolded and disease-causing proteins that are unable to reach their functional destinations in the cell. There is now a wealth of information demonstrating the functional rescue of misfolded mutant receptors by small nonpeptide molecules originally designed to serve as receptor antagonists; these small molecules ("pharmacoperones") serve as molecular templates, promoting correct folding and allowing the mutants to pass the scrutiny of the cellular quality control system and be expressed at the cell surface membrane. Two of these systems are especially well characterized: the gonadotropin-releasing hormone and the vasopressin type 2 receptors, which play important roles in regulating reproduction and water homeostasis, respectively. Mutations in these receptors can lead to well defined diseases that are recognized as being caused by receptor misfolding that may potentially be amenable to treatment with pharmacoperones. This review is focused on protein misfolding and misrouting related to various disease states, with special emphasis on these two receptors, which have proved to be of value for development of drugs potentially useful in regulating GPCR trafficking in healthy and disease states.

AL Amyloidosis with Renal Involvement

Primary (AL amyloidosis) is a systemic disease characterized by an amyloid deposition process in many organs, with unsatisfactory survival of patients. The monoclonal light chains form the fibrils that deposit and accumulate in tissues. Renal involvement is very frequent in AL amyloidosis and could lead to development of nephrotic syndrome followed by the renal failure in many cases. Classic therapeutic combination melphalan and prednisone has been supplemented with drugs with different mechanisms of action in this group of patients: high-dose dexamethasone, high-dose dexamethasone with melphalan, combination of vincristine, doxorubicin, and dexamethasone or newly high-dose melphalan supported by peripheral blood stem cell transplantation. This progressive therapy leads to the better survival and prognosis in the majority of patients. Alternative therapeutic approaches include thalidomide (alone or in combination with cyclophosphamide), lenalidomide, iododoxorubicin, etanercept and rituximab. The development of immunotherapy is expected in the near future.

Elastic fibers and amyloid deposition in vascular tissue

Amyloid fibrils are associated with a large number of diseases, such as Alzheimer’s dementia and others. Evidence links Alzheimer’s dementia with vascular diseases and only few data connect amyloids and atherosclerosis and aging via deposits in the aortic intima. Recent results demonstrate that some elastin polypeptide sequences are also able to produce amyloid fibers. This finding could have useful implications in the study of amyloids in cardiovascular tissue whose main constituent is elastin. In this review, we have also outlined the main characterizing features regarding the structure of amyloid fibrils. Finally, we describe, as a future perspective, the design of proper inhibitors of amyloid deposition in vascular walls as potential therapeutic drugs.

Severe amyloid deposition in mammary glands of familial amyloid polyneuropathy patients

Clinical pictures of familial amyloid polyneuropathy (FAP) vary considerably, perhaps because of the many gene mutations of transthyretin (TTR), but even in patients having the most common mutation of TTR (the substitution of methionine for valine at position 30 (ATTRVal30Met)), the age of onset ranges from the late 20s to the early 60s. Although genetic anticipation has been considered to play a role in producing this wide range of ages of onset, the precise pathogenesis is incompletely understood. It has been experimentally shown that murine systemic AA and AApoAII amyloidoses can be transmitted by ingestion of amyloid fibrils themselves or amyloid-like pathological agents. In this study, we examined biopsied mammary glands obtained from three female ATTRVal30Met FAP patients who were of gestation age. Amyloid deposition was commonly seen in the glands and, in the two patients with apparent FAP symptoms, heavy deposits of amyloid surrounded many lactiferous alveoli and ducts, where some deposits of amyloid actually faced the central lumens. These findings raise the possibility that milk from FAP mothers contains ATTR-derived amyloid fibrils and/or fragments, which might be causally related to the development of genetic anticipation in this disease.

[Obstructive jaundice caused by duodenal amyloidosis succesfully treated with surgery]

We present a case of obstructive jaundice due to duodenal amyloidosis presenting as a bulbar pseudotumor (amyloidoma). The duodenal and biliary obstruction were treated by double bypass, hepatojejunostomy and gastroenterostomy. Our case suggests that surgical palliative treatment may be effective, and that anastomosis is probably safe, allowing the patient a good quality of life.

Simulation of two-dimensional infrared spectroscopy of amyloid fibrils

We propose to use infrared coherent two-dimensional correlation spectroscopy (2DCS) to characterize the fibril structure of Ab42, the dominant composition of Ab deposit, which is crucial for investigating its toxicity and aggregation mechanism. By optimizing the pulse polarization configurations with a genetic algorithm combined with sensitivity analysis, we obtained signals with well resolved cross-peak features attributed to the couplings within and between different structural motifs. These signals may provide new constraints for refining of the currently available NMR structure. Two-dimensional correlation spectroscopy also can differentiate the turn structure of Ab42 and other Ab derivatives.

Cyanine dye–protein interactions: Looking for fluorescent probes for amyloid structures

We ascertained the ability to detect fibrillar beta-lactoglobulin (BLG) of a series of mono-, tri-, penta-, and heptamethinecyanines based on benzothiazole and benzimidazole heterocycles, and of benzothiazole squaraine. Fluorescence properties of these cyanine dyes were measured in the unbound state and in the presence of monomeric and fibrillar BLG and compared with those for the commercially available benzothiazole dye Thioflavin T. The correlation between the chemical nature of the dye molecules and the ability of dyes to bind aggregated proteins was established. We found that meso-substituted cyanines with amino substituents in heterocycle in contrast to the corresponding unsubstituted dyes have a binding preference to fibrillar BLG and a noticeable fluorescence response in the presence of the aggregated protein. For the squaraines and benzimidazole penthamethinecyanines studied, fluorescence emission increased both in the presence of native and fibrillar protein. The trimethinecyanines T-49 and SH-516 exhibit specifically increased fluorescence in the presence of fibrillar BLG. These dyes demonstrated the same or higher emission intensity and selectivity to aggregated BLG as Thioflavin T, and are proposed for application in selective fluorescent detection of aggregated proteins.

Immunohistochemical and immunochemical study of amyloid in liver affected by systemic Alambda amyloidosis with antibodies against three different regions of immunoglobulin lambda light chain

The purpose of the present paper was to investigate the heterogeneous nature of amyloid deposits in the liver, by immunohistochemical and immunochemical examination of liver samples from cases of immunoglobulin lambda light chain amyloidosis (Alambda amyloidosis) with antibodies generated against the peptides corresponding to the three different regions of the lambda light chain. Amyloid deposits in the hepatic artery tended to react better with anti-lambda(118-134) than with anti-lambda(159-175). Amyloid deposits in the space of Disse tended to react weakly or partially with anti-lambda(118-134) but well with anti-lambda(159-175). Amyloid deposits in the portal vein reacted relatively well with both antibodies. By western blotting of water-extracted amyloid in which amyloid deposits were not stained with anti-lambda(118-134) immunohistochemically, the three antibodies detected 27 kDa bands consistent with the full-length Ig lambda chain and some smaller bands. These findings indicate that amyloid deposits may not be homogeneous in the liver of AL amyloidosis, and that molecular heterogeneity of amyloid fibril protein or a difference in the mode of deposition results in the histopathological heterogeneity of AL amyloid deposits even within a single patient.

Multiple amyloidomas in an HIV patient presented as inguinal and mediastinal masses: a case report diagnosed by fine-needle aspiration

Systemic amyloidosis can occur rarely as multiple masses with replacement of lymph nodes, causing lymphadenopathy and potentially mimicking neoplasms. We report a case of multiple amyloidomas in the inguinal lymph nodes and mediastinum in a 30-yr-old HIV positive woman with remote history of high grade dysplasia. Abundant amorphous material was obtained on fine-needle aspiration, making metastatic squamous cell carcinoma with abundant keratin a potential differential diagnosis. The prudent use of special stains such as Congo red, crystal violet, and immunohistochemical stains for keratin and kappa and beta light chains can be invaluable in helping to clarify the diagnosis. In patients with chronic inflammation, amyloidomas must be considered in the differential diagnosis of mass lesions so the appropriate work-up can be undertaken to minimize this potential pitfall.

Amyloidosis in transgenic mice expressing murine amyloidogenic apolipoprotein A-II (Apoa2c)

In mice, apolipoprotein A-II (apoA-II) self-associates to form amyloid fibrils (AApoAII) in an age-associated manner. We postulated that the two most important factors in apoA-II amyloidosis are the Apoa2(c) allele, which codes for the amyloidogenic protein APOA2C (Gln5, Ala38) and transmission of amyloid fibrils. To characterize further the contribution of the Apoa2(c) allele to amyloidogenesis and improve detection of amyloidogenic materials, we established transgenic mice that overexpress APOA2C protein under the cytomegalovirus (CMV) immediate early gene (CMV-IE) enhancer/chicken beta promoter. Compared to transgene negative (Tg(-/-)) mice that express apoA-II protein mainly in the liver, mice homozygous (Tg(+/+)) and heterozygous (Tg(+/-)) for the transgene express a high level of apoA-II protein in many tissues. They also have higher plasma concentrations of apoA-II, higher ratios of ApoA-II/apolipoprotein A-I (ApoA-I) and higher concentrations of high-density lipoprotein (HDL) cholesterol. Following injection of AApoAII fibrils into Tg(+/+) mice, amyloid deposition was observed in the testis, liver, kidney, heart, lungs, spleen, tongue, stomach and intestine but not in the brain. In Tg(+/+) mice, but not in Tg(-/-) mice, amyloid deposition was induced by injection of less than 10(-8) mug AApoAII fibrils. Furthermore, deposition in Tg(+/+) mice occurred more rapidly and to a greater extent than in Tg(-/-) mice. These studies indicate that increased levels of APOA2C protein lead to earlier and greater amyloid deposition and enhanced sensitivity to the transmission of amyloid fibrils in transgenic mice. This transgenic mouse model should prove valuable for studies of amyloidosis.

Fibrillary glomerulonephritis with small fibrils in a patient with the antiphospholipid antibody syndrome successfully treated with immunosuppressive therapy

BACKGROUND

Fibrillary glomerulonephritis is a rare cause of progressive renal dysfunction, often leading to the need for dialysis within a few years. The role of immunosuppressive treatment is still uncertain although this has been tried with variable success.

CASE PRESENTATION

A 56 year old woman with the antiphospholipid antibody syndrome (IgM anticardiolipin antibodies) was seen in the nephrology clinic with haematuria, proteinuria, and worsening renal function. A renal biopsy demonstrated a mesangial proliferative glomerulonephritis on light microscopy and smaller fibrils (10.6-13.8 nm in diameter) than is usual for fibrillary glomerulonephritis (typically 18-22 nm) on electron microscopy. Amyloidosis was excluded following detailed evaluation. On account of rapidly worsening renal failure she was started on cyclophosphamide and prednisolone which led to the partial recovery and stabilization of her renal function.

CONCLUSION

This case highlights the need for routine electron microscopy in native renal biopsies, where the differential diagnosis is wide and varied and the light and immunofluorescence microscopic findings may be non specific.

Unusual clinical presentation of amyloidosis: bilateral stenosis of the external auditory canal, hoarseness and a rapid course of cutaneous lesions

We report a patient with multiple myeloma associated with primary systemic amyloidosis who had a rapid evolution and a very unusual form of presentation. The association of amyloidosis in patients with multiple myeloma is 15%, and clinically evident mucocutaneous involvement occurs in up to 40% of patients.

Structural variation manipulates the differential oxidative susceptibility and conformational stability of apolipoprotein E isoforms

A growing amount of evidence implicates the involvement of apolipoprotein E (apoE) in the development of late-onset and sporadic forms of Alzheimer's disease (AD). It is now generally believed that the epsilon4 allele is associated with AD and the oxidative stress is more pronounced in AD. However, only limited data are available on apoE isoform-specificity and its relationship to both the oxidative susceptibility and conformational stability of apoE. In this article, we use site-directed mutagenesis to investigate the structural role of amino acid residue 112, which is the only differing residue between apoE3 and E4. We examine the structural variation manipulating the oxidative susceptibility and conformational stability of apolipoprotein E isoforms. Arg112 in apoE4 was changed to Ala and Glu. Previous research has reported that apoE4 is more susceptible to free radicals than apoE3. In protein oxidation experiments, apoE4-R112A becomes more resistant to free radicals to the same extent as apoE3. In contrast, apoE4-R112E becomes the most susceptible protein to free radicals among all the apoE proteins. We also examine the conformational stability and the quaternary structural change by fluorescence spectroscopy and analytical ultracentrifugation, respectively. ApoE3 and E4 show apparent three- and two-state unfolding patterns, respectively. ApoE4-R112A, similar to apoE3, demonstrates a biphasic denaturation with an intermediate that appears. The denaturation curve for apoE4-R112E, however, also displays a biphasic profile but with a slight shoulder at approximately 1.5M GdmCl, implying that an unstable intermediate existed in the denaturation equilibrium. The size distribution of apoE isoforms display similar patterns. ApoE4-R112E, however, has a greater tendency to dissociate from high-molecular-weight species to tetramers. These experimental data suggest that the amino acid residue 112 governs the differences in salt-bridges between these two isoforms and thus has a significant impact on the free radical susceptibility and structural variation of the apoE isoforms.

Destabilization of transthyretin by pathogenic mutations in the DE loop

Transthyretin single-amino-acid variants are responsible for familial amyloidotic polyneuropathy, in which transthyretin variants accumulate extracellularly in the form of fibrillar aggregates. We studied the structural stabilities of four transthyretin variants (L58H, L58R, T59K, and E61K), in which a positively charged amino acid is introduced in a loop region between the D- and E-strands. In addition to being located in the DE-loop, L58 and T59 are involved in the core of the transthyretin monomer. The L58H, L58R, and T59K substitutions destabilized transthyretin more than the E61K mutation did, indicating that transthyretin is substantially destabilized by the substitution of residues located in both the DE-loop and the monomer core. By utilizing hydrogen-deuterium exchange and nuclear magnetic resonance, we demonstrated that residues in the G-strand and the loop between the A- and B-strands were destabilized by these pathogenic mutations in the DE loop. At the quaternary structural level, the DE-loop mutations destabilized the dimer-dimer contact area, which may lead to transient dissociation into a dimer. Our results suggest that the destabilization of the dimer-dimer interface and the monomer core is important for the amyloidogenesis of transthyretin.

Outcome of patients with reactive amyloidosis associated with rheumatoid arthritis in dialysis treatment

The aim was to analyze the clinical outcome of a group of 51 patients diagnosed with systemic amyloidosis associated with rheumatoid arthritis who received hemodialysis (HD) as renal replacement therapy. We monitored the clinical course of the disease and factors that could influence survival. Determination of the onset of the underlying disorder was made retrospectively by reviewing the patient's chart when a diagnosis of amyloid was confirmed. During a 96.9 person-year follow-up, 42 patients died. Survival of these 51 patients from the initiation of HD at 251 days was 50%. Poor prognosis in amyloid patients was mainly due to a large number of sudden deaths immediately following HD therapy. Out of 51 patients 21 needed unplanned initiation of HD. The unplanned initiation was significantly associated with poor survival. Seventy-five percentile of creatinine clearance (Ccr) was 9.7 ml/min, and 75% of these patients who initiated HD had highly impaired renal functional states. These data indicated that amyloidotic patients with HD showed a high mortality rate; therefore, planned initiation of HD was highly recommended to improve the patient's survival. Particular attention was given to the Ccr levels, because the levels of serum creatinine may not be a useful marker for some patients with amyloidosis.

Systemic AA-amyloidosis related to MPO-ANCA microscopic polyangiitis: a case report

We report autopsy findings in an 83-year-old woman with myeloperoxidase-type anti-neutrophil cytoplasmic antibody (MPO-ANCA)-positive microscopic polyangiitis and systemic AA amyloidosis. With a diagnosis of MPO-ANCA-related microscopic polyangiitis, the patient was treated with corticosteroids, but she died of intractable enteritis. Autopsy showed inactive vasculitis affecting small arteries in kidney, lung, intestinal tract, and skeletal muscle. Gastrointestinal viscera were thickened, and AA-amyloid was demonstrated in arterioles and surrounding tissues. Amyloidosis also involved heart, kidney, gallbladder, pancreas, salivary gland, and subcutis. ANCA-positive microscopic polyangiitis appears to have been the likely cause of this patient's AA-amyloidosis.

[Lymphoma with initial renal involvement: four cases]

PURPOSE

To present a comprehensive description of the clinical features of patients with renal manifestations during lymphoma.

METHODS

Retrospective review of medical records from all patients diagnosed with lymphoma associated with kidney involvement in our hospital between 1996 to 2004. Four cases were identified and analysed.

RESULTS

Four patients presented a non-Hodgkin's lymphoma. One patient showed intravascular large B-cell lymphoma, revealed by proteinuria. Another patient had a nephrotic syndrome, and two had a renal mass. Renal histology allowed diagnosis of lymphoma in 3 cases.

CONCLUSION

The diagnosis of lymphoma associated with renal involvement is rather difficult, and more specifically in case of intravascular large B-cell lymphoma, or even primary renal lymphoma. We present here a comprehensive review of the literature and we discuss pathogenesis of these conditions.

The genetics of the amyloidoses: interactions with immunity and inflammation

Historically, the amyloidoses have been associated with inflammation and the immune response. From Virchow's original description in human pathologic inflammatory states through their identification in horses used to produce antitoxin to their frequent occurrence in the course of multiple myeloma and a somewhat abortive designation as 'gammaloid', the disorders were felt to have an inflammatory origin. These presumptive associations antedated the availability of a reliable method for tissue extraction that would allow chemical analysis of the major deposited molecules. With the identification of the multiple precursors and the realization that most were not intrinsic elements of immune/inflammatory pathways, the investigative emphasis shifted to the analysis of the biophysical events involved in aggregation and fibril formation. As more in vivo models and better tools for examination of tissues have become available, it appears as if inflammation may participate as both a response to, and an amplifier of, the effects of the fibrillar aggregates. Hence, while only a limited number of amyloid protein precursors are involved in immunity and inflammation per se, host defense, in its broadest sense, is likely to be involved in the clinically relevant amyloidoses. Further it now appears that harnessing the immune response in an appropriate fashion may be able to play a role in treatment.

Occurrence and co-localization of amyloid beta-protein and apolipoprotein E in perivascular drainage channels of wild-type and APP-transgenic mice

The deposition of the amyloid beta-protein (Abeta) is a hallmark of Alzheimer's disease (AD). One reason for Abeta-accumulation and deposition in the brain may be an altered drainage along perivascular channels. Extracellular fluid is drained from the brain towards the cervical lymph nodes via perivascular channels. The perivascular space around cerebral arteries is the morphological correlative of these drainage channels. Here, we show that Abeta is immunohistochemically detectable within the perivascular space of 25 months old wild-type and amyloid precursor protein (APP)-transgenic mice harboring the Swedish double mutation driven by a neuron specific promoter. Only small amounts of Abeta can be detected immunohistochemically in the perivascular space of wild-type mice. Cerebrovascular and parenchymal Abeta-deposits were absent. In APP-transgenic mice, large amounts of Abeta were found in the perivascular drainage channels accompanied with cerebrovascular and parenchymal Abeta-deposition. The apolipoprotein E (apoE) immunostaining within the perivascular channels did not vary between wild-type and APP-transgenic mice. Almost 100% of the area that represents the perivascular space was stained with an antibody directed against apoE. Here, Abeta co-localized with apoE indicating an involvement of apoE in the perivascular clearance of Abeta. Fibrillar congophilic amyloid was not seen in wild-type mice. In APP-transgenic animals, congophilic fibrillar amyloid material was seen in the wall of cerebral blood vessels but not in the perivascular space. In conclusion, our results suggest that non-fibrillar forms of Abeta are drained along perivascular channels and that apoE is presumably involved in this clearance mechanism. Overloading such a clearance mechanism in APP-transgenic mice appears to result in insufficient Abeta-clearance, increased Abeta-levels in the brain and the perivascular drainage channels, and finally in Abeta-deposition. In so doing, our results strengthen the hypothesis that an alteration of perivascular drainage supports Abeta-deposition and the development of AD.

Classification of amyloidosis: misdiagnosing by way of incomplete immunohistochemistry and how to prevent it

Classification of every individual case of amyloid disease is necessary in order to recognize its origin and its possible pathogenesis for therapeutic consideration. Classification of the amyloids can be performed in different ways. One method primarily exploits serum proteins-but these are risk factors only, and therefore render only ancillary information. In principle, one cannot establish the diagnosis alone through their use. Another approach analyzes the origin of the deposited amyloids, either by extracting the amyloid proteins followed by immunochemical or chemical analysis, or by using immunohistochemistry. Based on chemical analysis of prototypes of amyloid fibril proteins, we have developed a profile of antibodies over the years that specifically identify amyloid in tissue sections. These antibodies have been used for years as a routine service for clinicians and pathologists in immunohistochemically classifying amyloid found in formalin-fixed tissue sections. The typing is always controlled by established amyloid classes. In several cases, we have been asked for a second opinion on a diagnosed amyloid class. Our own immunohistochemical data were then compared with those submitted. These submitted immunohistochemical results represented misdiagnoses of amyloid classes in most patients, since the technique performed was usually incomplete. It is the purpose of this report to analyze such cases and to document some of the typical mistakes. Here, we show how to avoid common pitfalls and how one can arrive at a correct diagnosis using immunohistochemistry appropriately.

Localized amyloidosis of the urinary tract: Case series of nine patients

OBJECTIVES

To report 9 cases of primary localized amyloidosis of the urinary tract and correlate the pathologic findings with clinical and cystoscopic information.

METHODS

Patients diagnosed with amyloidosis of the ureters, urinary bladder, or urethra from 1976 to 2003 were identified. Their medical records were reviewed, and histochemical and immunoperoxidase stains were performed on the tissue.

RESULTS

Eight cases of amyloidosis of the urinary bladder and one of the renal pelvis/ureter were identified. None of our cases showed evidence of systemic amyloidosis. Of the 8 patients with amyloidosis of the urinary bladder, 5 presented with gross hematuria and 1 with irritative bladder symptoms and 2 had amyloidosis detected during cystoscopic follow-up for urothelial carcinoma. The patient with amyloidosis of the renal pelvis/ureter presented with flank pain and gross hematuria. The clinical impression was malignancy in 75% of the bladder cases. Most patients with bladder involvement were treated with localized bladder resection; however, 1 patient required total cystectomy for symptom control. Of 5 patients with follow-up information, 2 developed recurrence. The pathologic assessment diagnosed amyloid deposits consistent with primary or AL type amyloid in all cases. Immunoperoxidase stains revealed lymphoid cells in the vicinity of the amyloid deposits to be lambda-restricted in 78% of cases.

CONCLUSIONS

Primary amyloidosis of the urinary tract is a rare condition that mimics malignancy in its clinical presentation and cystoscopic appearance and on diagnostic imaging. In our study, all cases of urinary amyloid deposits represented localized amyloidosis rather than manifestations of systemic amyloidosis. Monoclonal lymphoid populations evolving from chronic inflammation in the urinary tract may be the source of the amyloid AL proteins.