muramidase and Amyloidosis--Familial

Lysozyme amyloidosis is a rare hereditary systemic amyloidosis with amyloid deposits in various tissues leading to progressive organ failure. It has been mainly reported in developed countries since 1993. Here we report a lysozyme amyloidosis family with variant lysozyme p.Trp82Arg in a Chinese family.. The main clinical manifestation of this case was dominant kidney involvement presenting with proteinuria and decreased renal function. Biopsy of the kidney showed massive amyloid deposits in the glomerular mesangium and subendothelium. Immunohistochemistry and mass spectrometry of renal tissue confirmed the lysozyme nature of the amyloid. DNA sequencing of the peripheral blood leukocytes revealed a single base-pair transition from T to C (TGG/ CGG) of codon 82, leading to the replacement of tryptophan by arginine in the mature protein (p.Trp82Arg). The affected patients in this family also presented with dominant kidney involvement, one of them has been confirmed by IHC and mass spectrometry on his renal biopsy and gene testing as well. As there is no radical therapy for lysozyme amyloidosis, patients were given symptomatic treatment such as antihypertensive drugs and antibiotics. To our knowledge, this is the first report of lysozyme amyloidosis in a Chinese family.. Hereditary amyloidosis with a variant lysozyme of p.Trp82Arg presented with dominant kidney involvement was firstly reported in a Chinese family.

Topics: Adult; Amino Acid Substitution; Amyloid; Amyloidosis, Familial; Biopsy; China; Exons; Humans; Kidney; Kidney Diseases; Male; Muramidase; Mutation; Pedigree; Proteinuria; Sequence Analysis, Protein

Mutations in a number of plasma proteins, including transthyretin, apolipoprotein AI, fibrinogen Aalpha-chain, lysozyme, and apolipoprotein AII, are associated with hereditary systemic amyloidosis. Transthyretin amyloidosis is the most common and is usually associated with peripheral neuropathy. Mutations in the other proteins usually have no neuropathic consequences and, instead, cause principally renal and cardiac amyloidosis. Only the apolipoprotein AI glycine 26 arginine mutation may cause peripheral neuropathy and then in only some of the kindreds with this disease. This review is concerned with the non-neuropathic hereditary systemic amyloidoses. It strives to present a synopsis of the present day knowledge of these diseases including each feature of each precursor protein and its mutations; the clinical phenotype of the disease; and suggestions for treatment when feasible. The main objective is to increase awareness of these autosomal dominant diseases, enhance the chances of early diagnosis, enhance the physician's and subsequently the patient's knowledge of each disease, and finally emphasize the need for more research to find ways to treat or prevent these diseases.

Topics: Amyloidosis, Familial; Apolipoprotein A-I; Apolipoprotein A-II; Diagnosis, Differential; Fibrinogen; Humans; Muramidase; Mutation; Peripheral Nervous System Diseases

Lysozyme-derived (ALys) amyloidosis is a rare type of hereditary amyloidosis. Nine amyloidogenic variants and ∼30 affected families have been described worldwide. The most common manifestations are renal dysfunction, gastrointestinal tract symptoms, and sicca syndrome. We report on the clinical course of ten patients from six families representing one of the largest cohorts published so far. Seven patients carried the W64R variant showing the whole spectrum of ALys-associated symptoms. Two patients-a mother-son pair-carried a novel lysozyme variant, which was associated with nephropathy and peripheral polyneuropathy. In accordance with previous findings, the phenotype resembled within these families but did not correlate with the genotype. To gain insights into the effect of the variants at the molecular level, we analysed the structure of lysozyme and performed comparative computational predictions on aggregation propensity and conformational stability. Our study supports that decreased conformational stability is a key factor for lysozyme variants to be prone to aggregation. In summary, ALys amyloidosis is a very rare, but still heterogeneous disease that can manifest at an early age. Our newly identified lysozyme variant is associated with nephropathy and peripheral polyneuropathy. Further research is needed to understand its pathogenesis and to enable the development of new treatments.

Topics: Amyloidosis; Amyloidosis, Familial; Gastrointestinal Diseases; Humans; Kidney Diseases; Muramidase; Polyneuropathies

Topics: Adult; Amyloidosis, Familial; Biopsy; Electrocardiography; Humans; Male; Muramidase; Mutation

Lysozyme amyloidosis (ALys) is a rare form of hereditary amyloidosis that typically manifests with renal impairment, gastrointestinal (GI) symptoms, and sicca syndrome, whereas cardiac involvement is exceedingly rare and neuropathy has not been reported. Here, we describe a 40-year-old man with renal impairment, cardiac and GI symptoms, and peripheral neuropathy. Renal biopsy specimen analysis revealed amyloidosis with extensive involvement of glomeruli, vessels, and medulla. Amyloid was also detected in the GI tract. Echocardiographic and electrocardiographic findings were consistent with cardiac involvement. Proteomic analysis of Congo red-positive renal and GI amyloid deposits detected abundant lysozyme C protein. DNA sequencing of the lysozyme gene in the patient and his mother detected a heterozygous c.305T>C alteration in exon 3, which causes a leucine to serine substitution at codon 102 (Human Genome Variation Society nomenclature: p.Leu102Ser; legacy designation: L84S). We also detected the mutant peptide in the proband's renal and GI amyloid deposits. PolyPhen analysis predicted that the mutation damages the encoded protein. Molecular dynamics simulations suggested that the pathogenesis of ALys p.Leu102Ser is mediated by shifting the position of the central β-hairpin coordinated with an antiparallel motion of the C-terminal helix, which may alter the native-state structural ensemble of the molecule, leading to aggregation-prone intermediates.

Topics: Adult; Amyloidosis, Familial; Humans; Male; Muramidase; Pedigree; Phenotype

Naturally occurring single mutants, I56T, F57I, W64R and D67H of lysozyme in human, have been known to form abnormal protein aggregates (amyloid fibrils) and to accumulate in several organs, including the liver, spleen and kidney, resulting in familial systemic amyloidosis. These human pathogenic lysozyme variants are considered to raise subtle conformational changes compared to the wild type.. Here we examined the effects of the aberrant mutant lysozymes I56T, F57I, W64R and D67H, each of which possesses a point mutation in its molecule, on a cultured human cell line, HEK293, in which the genes were individually integrated and overexpressed.. Western blot analyses showed lesser amounts of these variant proteins in the medium compared to the wild type, but they were abundant in the cell pellets, indicating that the modified lysozyme proteins were scarcely secreted into the medium but were retained in the cells. Immunocytochemistry revealed that these proteins resided in restricted regions which were stained by an endoplasmic reticulum (ER) marker. Moreover, the overexpression of the mutant lysozymes were accompanied by marked increases in XBP-1s and GRP78/BiP, which are downstream agents of the IRE1α signaling pathway responding to the unfolded protein response (UPR) upon ER stress. RNAi for the mutant lysozymes' expression greatly suppressed the increases of these agents.. Our results suggest that the accumulation of pathogenic lysozymes in the ER caused ER stress and the UPR response mainly via the IRE1α pathway.

Topics: Amyloidosis, Familial; DNA-Binding Proteins; Endoplasmic Reticulum; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Endoribonucleases; Gene Expression Regulation, Enzymologic; Genotype; Heat-Shock Proteins; HEK293 Cells; Humans; Models, Molecular; Muramidase; Mutation; Phenotype; Protein Conformation; Protein Serine-Threonine Kinases; Regulatory Factor X Transcription Factors; RNA Interference; RNA, Messenger; Signal Transduction; Structure-Activity Relationship; Transcription Factors; Transfection; Unfolded Protein Response; X-Box Binding Protein 1

Topics: Aged; Amyloidosis, Familial; DNA Mutational Analysis; Female; Hematoma; Humans; Liver Diseases; Molecular Diagnostic Techniques; Muramidase; Mutation, Missense; Recurrence

Systemic amyloidoses is a heterogeneous group of diseases either acquired or hereditary. Amyloidoses can involve the gastrointestinal tract and the nature of the precursor protein that forms the fibrils deposits should be identified to adjust the treatment and evaluate the prognosis. Lysozyme amyloidosis (ALys) is a rare, systemic non neuropathic hereditary amyloidosis with a heterogenous phenotype including gastrointestinal, renal and hepatic symptoms.. We report and describe symptoms and gastrointestinal tract involvement in a new family with hereditary lysozyme amyloidosis. Clinical manifestations and organ involvement of nine affected members of a new family with the p.Trp82Arg ALys variant were recorded. All affected individuals suffered with prevailing gastrointestinal symptoms leading to the diagnosis of ALys. 8/9 had non specific upper gastrointestinal symptoms and 3/9 had rectocolic inflammation evoking inflammatory bowel disease. No other organ involvement by amyloidosis was found. Histological examination revealed amyloid deposits in all cases and all carried the p.Trp82Arg ALys variant at a heterozygous state.. Hereditary amyloidosis associated with the p.Trp82Arg lysozyme variant in this new family is predominantly associated with mild upper gastrointestinal tract involvement and in some cases with inflammatory bowel disease. Amyloidosis should be considered in atypical or treatment resistant, upper or lower chronic gastrointestinal symptoms. When associated with a familial history a lysozyme gene mutation must be searched.

Topics: Adult; Aged; Amyloidosis, Familial; Female; Gastritis; Humans; Inflammatory Bowel Diseases; Male; Middle Aged; Muramidase; Mutation; Pedigree; Phenotype; Young Adult

Sarcoidosis is a multisystem inflammatory disorder of unknown cause which can affect any organ system. Autosomal dominant lysozyme amyloidosis is a very rare form of hereditary amyloidosis. The Arg64 variant is extraordinarily rare with each family showing a particular pattern of organ involvement, however while Sicca syndrome, gastrointestinal involvement and renal failure are common, lymph node involvement is very rare. In this case report we describe the first reported case of sarcoidosis in association with hereditary lysozyme amyloidosis.

Topics: Amyloidosis; Amyloidosis, Familial; Humans; Muramidase; Sarcoidosis; Sarcoidosis, Pulmonary

Lysozyme amyloidosis (ALys) is a form of hereditary systemic non-neuropathic amyloidosis, which is inherited in an autosomal dominant fashion. Lysozyme, which is the amyloidogenic precursor protein in ALys, is a ubiquitous bacteriolytic enzyme synthesized by hepatocytes, polymorphs and macrophages. The aim of this study is to describe the phenotype and outcome of patients with ALys including the role of solid organ transplantation.. Retrospective evaluation of patients with ALys.. UK National Amyloidosis Centre.. All 16 patients with ALys followed at the centre.. A family history of amyloidosis was present in every affected individual. Although the phenotype was broadly similar amongst those from the same kindred, there were marked phenotypic differences between kindreds who possessed the same amyloidogenic mutation. Symptomatic gastrointestinal (GI) amyloid was prevalent, and macroscopically visible amyloidotic lesions were present in nine of 10 patients who underwent GI endoscopy. All symptomatic ALys individuals had hepatic amyloid. Four patients received orthotopic liver transplants (OLT), three for spontaneous hepatic rupture and one case, who had extensive hepatic amyloid and a strong family history of hepatic rupture, pre-emptively. All of the liver grafts were functioning at censor 1.7, 5.8, 9.0 and 11.0 years after OLT. Five patients had progressive amyloidotic renal dysfunction culminating in end-stage renal failure, three of whom underwent renal transplantation (RTx). There was no evidence of renal allograft dysfunction at censor 6.6, 1.8 and 0.8 years after RTx.. Lysozyme amyloidosis is a disease of the GI tract, liver and kidneys, which has a slow natural history. There was a clear family history in all cases within this cohort, demonstrating a high clinical penetrance in the presence of an amyloidogenic lysozyme mutation. There is currently no amyloid-specific therapy for the condition which is managed symptomatically. OLT and RTx appear to be successful treatments for patients with liver rupture or end-stage renal disease, respectively, with excellent outcomes in terms of medium-term graft function and patient survival.

Topics: Adult; Aged; Amyloidosis, Familial; Child; Female; Gastrointestinal Diseases; Humans; Kidney Failure, Chronic; Kidney Transplantation; Liver Diseases; Liver Transplantation; Lymphatic Diseases; Male; Middle Aged; Muramidase; Mutation; Peptic Ulcer Hemorrhage; Phenotype; Purpura; Radionuclide Imaging; Retrospective Studies; Rupture, Spontaneous; Serum Amyloid P-Component; Sjogren's Syndrome; Survival Analysis; United Kingdom

Familial amyloidoses are a group of inherited disorders that cause deposition of misfolded amyloidogenic proteins in various tissues, resulting in organ dysfunction. Point mutations in the coding region of seven different genes are known to cause clinically significant systemic amyloid disease. We describe a new mutation in exon 2 of the lysozyme gene associated with amyloidosis (ALys) in a 61-year-old woman with a 7-year history of non-bloody, watery diarrhea, and weight loss. Biopsies of the duodenum and stomach were positive for amyloid deposits in the lamina propria and blood vessels. Direct DNA sequencing of the lysozyme gene revealed a single base nucleotide transversion from T to A at the first position of codon 54, resulting in replacement of Tyr by Asn in the mature lysozyme protein (pTyr54Asn). Immunoblot analysis of amyloid fibrils extracted from a fat tissue sample confirmed lysozyme as the amyloid protein. Clinically, the phenotype associated with this lysozyme mutation featured chronic abdominal pain, diarrhea, weight loss, malabsorption, and sicca syndrome. There was no associated nephropathy as has been reported for other ALys mutations. We describe a new mutant lysozyme that presents with abdominal discomfort, diarrhea, weight loss, and sicca syndrome.

Topics: Amyloid; Amyloidosis, Familial; Biopsy; Diarrhea; Duodenum; Exons; Female; Gastric Mucosa; Humans; Middle Aged; Muramidase; Pedigree; Point Mutation; Sequence Analysis, DNA; Stomach; Weight Loss

Fibril formation by mutational variants of human lysozyme is associated with a fatal form of hereditary non-neuropathic systemic amyloidosis. Defining the mechanistic details of lysozyme aggregation is of crucial importance for understanding the origin and progression of this disease and related misfolding conditions. In this study, we show that a biotin moiety can be introduced site-specifically at Lys33 of human lysozyme. We demonstrate, using biophysical techniques, that the structure and stability of the native-state of the protein are not detectably altered by this modification, and that the ability to form amyloid fibrils is unchanged. By taking advantage of biotin-avidin interactions, we show that super-resolution fluorescence microscopy can generate detailed images of the mature fibrils. This methodology can readily enable the introduction of additional probes into the protein, thereby providing the means through which to understand, in detail, the nature of the aggregation process of lysozyme and its variants under a variety of conditions.

Topics: Amyloid; Amyloidosis, Familial; Avidin; Biophysics; Biotinylation; Circular Dichroism; Genetic Engineering; Humans; Immunoblotting; Magnetic Resonance Spectroscopy; Mass Spectrometry; Microscopy, Electron, Transmission; Microscopy, Fluorescence; Muramidase

We report here the detailed characterisation of a non-naturally occurring variant of human lysozyme, I59T, which possesses a destabilising point mutation at the interface of the alpha- and beta-domains. Although more stable in its native structure than the naturally occurring variants that give rise to a familial form of systemic amyloidosis, I59T possesses many attributes that are similar to these disease-associated species. In particular, under physiologically relevant conditions, I59T populates transiently an intermediate in which a region of the structure unfolds cooperatively; this loss of global cooperativity has been suggested to be a critical feature underlying the amyloidogenic nature of the disease-associated lysozyme variants. In the present study, we have utilised this variant to provide direct evidence for the generic nature of the conformational transition that precedes the ready formation of the fibrils responsible for lysozyme-associated amyloid disease. This non-natural variant can be expressed at higher levels than the natural amyloidogenic variants, enabling, for example, singly isotopically labelled protein to be generated much more easily for detailed structural studies by multidimensional NMR spectroscopy. Moreover, we demonstrate that the I59T variant can readily form fibrils in vitro, similar in nature to those of the amyloidogenic I56T variant, under significantly milder conditions than are needed for the wild-type protein.

Topics: Amyloid; Amyloidosis, Familial; Deuterium Exchange Measurement; Humans; Models, Molecular; Muramidase; Nuclear Magnetic Resonance, Biomolecular; Point Mutation; Thermodynamics

Hepatic rupture is a rare condition, and treatment options are very limited. We report a case of hepatic rupture secondary to hereditary lysozyme amyloidosis that was successfully treated by liver transplantation. The mother of this patient had presented in an identical fashion 15 years earlier in the pretransplant era and died very rapidly.

Topics: Adult; Amyloidosis, Familial; Emergency Medical Services; Female; Humans; Liver Transplantation; Middle Aged; Mothers; Muramidase; Nuclear Family; Rupture, Spontaneous; Time Factors; Treatment Outcome

Topics: Adolescent; Adult; Amyloidosis, Familial; Female; Humans; Liver; Liver Transplantation; Male; Muramidase; Rupture; Treatment Outcome

One of the 20 or so human amyloid diseases is associated with the deposition in vital organs of full-length mutational variants of the antibacterial protein lysozyme. Here, we report experimental data that permit a detailed comparison to be made of the behaviour of two of these amyloidogenic variants, I56T and D67H, under identical conditions. Hydrogen/deuterium exchange experiments monitored by NMR and mass spectrometry reveal that, despite their different locations and the different effects of the two mutations on the structure of the native state of lysozyme, both mutations cause a cooperative destabilisation of a remarkably similar segment of the structure, comprising in both cases the beta-domain and the adjacent C-helix. As a result, both variant proteins populate transiently a closely similar, partially unstructured intermediate in which the beta-domain and the adjacent C-helix are substantially and simultaneously unfolded, whereas the three remaining alpha-helices that form the core of the alpha-domain still have their native-like structure. We show, in addition, that the binding of a camel antibody fragment, cAb-HuL6, which was raised against wild-type lysozyme, restores to both variant proteins the stability and cooperativity characteristic of the wild-type protein; as a consequence, it inhibits the formation of amyloid fibrils by both variants. These results indicate that the reduction in global cooperativity, and the associated ability to populate transiently a specific, partly unfolded intermediate state under physiologically relevant conditions, is a common feature underlying the behaviour of these two pathogenic mutations. The formation of intermolecular interactions between lysozyme molecules that are in this partially unfolded state is therefore likely to be the fundamental trigger of the aggregation process that ultimately leads to the formation and deposition in tissue of amyloid fibrils.

Topics: Amino Acid Substitution; Amyloidosis, Familial; Animals; Antibodies; Camelus; Enzyme Stability; Humans; In Vitro Techniques; Kinetics; Microscopy, Electron; Models, Molecular; Muramidase; Mutation; Nuclear Magnetic Resonance, Biomolecular; Protein Denaturation; Protein Structure, Secondary; Protein Structure, Tertiary; Recombinant Proteins; Spectrometry, Mass, Electrospray Ionization

Formation of amyloid deposits from the Ile56Thr or Asp67His variants of human lysozyme is a hallmark of autosomal hereditary systemic amyloidosis. It has recently been shown that amyloid fibrils can be formed in vitro from wild-type (WT), I56T, or D67H lysozyme variants upon prolonged incubation at acidic pH and elevated temperatures (1). Here, we have used hydrostatic pressure as a tool to generate amyloidogenic states of WT and variant lysozymes at physiological pH. WT or variant lysozyme samples were initially compressed to 3.5 kbar (at 57 degrees C, pH 7.4). Decompression led to the formation of amyloid fibrils, protofibrils, or globular aggregates, as indicated by light scattering, thioflavin T fluorescence, and transmission electron microscopy analysis. Increased 1-anilinonaphthalene-8-sulfonate binding to the proteins was also observed, indicating exposure of hydrophobic surface area. Thus, pressure appears to induce a conformational state of lysozyme that aggregates readily upon decompression. These results support the notion that amyloid aggregation results from the formation of partially unfolded protein conformations and suggest that pressure may be a useful tool for the generation of the amyloidogenic conformations of lysozyme and other proteins.

Topics: Amino Acid Substitution; Amyloid; Amyloidosis, Familial; Humans; Hydrogen-Ion Concentration; Hydrophobic and Hydrophilic Interactions; Hydrostatic Pressure; Microscopy, Electron; Muramidase; Nephelometry and Turbidimetry; Protein Conformation; Protein Folding; Recombinant Fusion Proteins; Spectrometry, Fluorescence; Temperature

A natural mutant of human lysozyme, D67H, causes hereditary systemic nonneuropathic amyloidosis, which can be fatal. In this disease, insoluble beta-stranded fibrils (amyloids) are found in tissues stemming from the aggregation of partially folded intermediates of the mutant. In this study, we specifically compare the conformation and properties of the structures adopted from the induced unfolding, at elevated temperature, using molecular dynamics. To increase the sampling of the unfolding conformational landscape, three 5 ns trajectories are performed for each of the wild-type and mutant D67H proteins resulting in a total of 30 ns simulation. Our results show that the mutant unfolds slightly faster than the wild-type with both wild-type and mutant proteins losing most of their native secondary structure within the first 2 ns. They both develop random transient beta-strands across the whole polypeptide chain. Clustering analysis of all the conformations shows that a high population of the mutant protein conformations have a distorted beta-domain. This is consistent with experimental results suggesting that this region is pivotal in the formation of conformations prone to act as "seeds" for amyloid fiber formation.

Topics: Amyloidosis, Familial; Computer Simulation; Crystallography; Enzyme Activation; Enzyme Stability; Hot Temperature; Humans; Models, Molecular; Motion; Muramidase; Protein Conformation; Protein Denaturation; Protein Folding; Protein Structure, Tertiary; Recombinant Proteins; Structure-Activity Relationship

Hereditary, autosomal dominant amyloidosis, caused by mutations in the genes encoding transthyretin, fibrinogen A alpha-chain, lysozyme, or apolipoprotein A-I, is thought to be extremely rare and is not routinely included in the differential diagnosis of systemic amyloidosis unless there is a family history.. We studied 350 patients with systemic amyloidosis, in whom a diagnosis of the light-chain (AL) type of the disorder had been suggested by clinical and laboratory findings and by the absence of a family history, to assess whether they had amyloidogenic mutations.. Amyloidogenic mutations were present in 34 of the 350 patients (9.7 percent), most often in the genes encoding fibrinogen A alpha-chain (18 patients) and transthyretin (13 patients). In all 34 of these patients, the diagnosis of hereditary amyloidosis was confirmed by additional investigations. A low-grade monoclonal gammopathy was detected in 8 of the 34 patients (24 percent).. A genetic cause should be sought in all patients with amyloidosis that is not the reactive systemic amyloid A type and in whom confirmation of the AL type cannot be obtained.

Topics: Adult; Aged; Amyloidosis; Amyloidosis, Familial; Apolipoprotein A-I; Diagnostic Errors; DNA Mutational Analysis; Female; Fibrinogen; Genotype; Heterozygote; Humans; Kidney; Middle Aged; Muramidase; Paraproteinemias; Point Mutation; Prealbumin; Radionuclide Imaging