Localized light chain amyloidosis involving the lacrimal sac: A case report

Amyloidosis involving the lacrimal sac is extremely rare. In this study, we demonstrated a rare case of localized light chain amyloidosis in the lacrimal sac region. The lacrimal sac lesion presented as infiltrative with bony erosion. Given the slow growth of the lesion and the absence of a blood flow signal inside, we concluded that the lesion was less likely to be malignant. Complete removal of the lacrimal sac lesion combined with simultaneous lacrimal passage reconstruction was performed. The diagnosis of light chain amyloidosis was confirmed by histology. The surgical results were favorable, and no recurrence was observed over one-year follow-up. Our case report enriches the understanding of amyloid deposition in the ocular adnexa.

A sensitive high-resolution mass spectrometry method for quantifying intact M-protein light chains in patients with multiple myeloma

To determine the disease status and the response to treatment for patients with multiple myeloma, measuring serum M-protein levels is a widely used alternative to invasive punctures to count malignant plasma cells in the bone marrow. However, the quantification of this monoclonal antibody, which varies from patient to patient, poses significant analytical challenges. This paper describes a sensitive and specific mass spectrometry assay that addresses two objectives: to overcome the potential interference of biotherapeutics in the measurement of M-proteins, and to determine the depth of response to treatment by assessing minimal residual disease. After immunocapture of immunoglobulins and free light chains in serum, heavy and light chains were dissociated by chemical reduction and separated by liquid chromatography. M-proteins were analyzed by high-resolution mass spectrometry using a method combining a full MS scan for isotyping and identification and a targeted single ion monitoring scan for quantification. This method was able to discriminate M-protein from the therapeutic antibody in all patient samples analyzed and allowed quantification of M-protein with a LLOQ of 2.0 to 3.5 µg/ml in 5 out of 6 patients. This methodology appears to be promising for assessing minimal residual disease with sufficient sensitivity, specificity, and throughput.

Prognosis prediction in cardiac amyloidosis by cardiac magnetic resonance imaging: a systematic review with meta-analysis

Cardiac involvement is the foremost determinant of the clinical progression of amyloidosis. The diagnostic role of cardiac magnetic resonance (CMR) imaging in cardiac amyloidosis has been established, but the prognostic role of various right and left CMR tissue characterization and functional parameters, including global longitudinal strain (GLS), late gadolinium enhancement (LGE), and parametric mapping, is yet to be delineated. We searched EMBASE, PubMed, and MEDLINE for studies analysing the prognostic use of CMR imaging in patients with light chain amyloidosis or transthyretin amyloidosis cardiac amyloidosis. The primary endpoint was all-cause mortality. A random effects model was used to calculate a pooled odds ratio using inverse-variance weighting. Nineteen studies with 2199 patients [66% males, median age 59.7 years, interquartile range (IQR) 58-67] were included. Median follow-up was 24 months (IQR 20-32), during which 40.8% of patients died. Both tissue characterization left heart parameters such as elevated extracellular volume [hazard ratio (HR) 3.95, 95% confidence interval (CI) 3.01-5.17], extension of left ventricular (LV) LGE (HR 2.69, 95% CI 2.07-3.49) elevated native T1 (HR 2.19, 95% CI 1.12-4.28), and functional parameters such as reduced LV GLS (HR 1.91, 95% CI 1.52-2.41) and reduced LV ejection fraction (EF; HR 1.20, 95% CI 1.17-1.23) were associated with increased all-cause mortality. Unlike the presence of right ventricular (RV) LGE (HR 3.40, 95% CI 0.51-22.54), parameters such as RV GLS (HR 2.08, 95% CI 1.6-2.69), RVEF (HR 1.13, 95% CI 1.05-1.22), and tricuspid annular systolic excursion (TAPSE) (HR 1.11, 95% CI 1.02-1.21) were also associated with mortality. In this large meta-analysis of patients with cardiac amyloidosis, CMR parameters assessing RV and LV function and tissue characterization were associated with an increased risk of mortality.

Discordance of light chain isotypes between serum and glomerular deposits in proliferative glomerulonephritis with monoclonal IgG deposits: a case report and review of the literature

BACKGROUND

Proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits (PGNMID) is a disease entity with nonorganized granular glomerular deposition with monoclonal proteins of both heavy and light chains. Dysproteinemia was observed in only 30% of the patients with PGNMID. We herein report a case of PGNMID with discrepancy between serum and glomerular deposits.

CASE PRESENTATION

The patient was a 50-year-old man who had been followed at a local clinic due to hypertension, type 2 diabetes, hyperlipidemia, hyperuricemia, fatty liver, and obesity. Proteinuria had been noted five years previously, and he had been referred to a hematology department due to hyperproteinemia, high gamma globulin, and κ Bence-Jones protein (BJP) positivity one year previously. Bone marrow aspiration showed 5% plasma cells, and he was referred to the nephrology department to evaluate persistent proteinuria. He was hypertensive, and his estimated glomerular filtration rate was 54.2 ml/min/1.73 m2. His urinary protein level was 0.84 g/g⋅Cr. Urine and serum immunofixation showed BJP-κ type and IgG-κ type, respectively. Kidney biopsy showed an increase in mesangial cells and matrix without nodular lesions under a light microscope. Immunofluorescence microscopy showed granular deposits of IgG and C3 on the capillary wall and weak positivity for C1q. IgG3 was predominant among the IgG subclasses, and intraglomerular κ and λ staining was negative for κ and positive for λ. Direct fast scarlet staining was negative. Electron microscopy showed lumpy deposits without a fibrillar structure in the subepithelial area. Based on the above findings, a diagnosis of membranous nephropathy-type PGNMID was made. Since proteinuria increased gradually after three years of treatment with valsartan (40 mg, daily), oral prednisolone (30 mg, daily) was initiated, which led to decreased proteinuria. The dose of oral prednisolone was gradually tapered to 10 mg per day. At that time, proteinuria was 0.88 g/g⋅Cr. We found 204 cases in 81 articles in the PubMed database, among which 8 showed discrepancy in the heavy and/or light chains between serum and kidney.

CONCLUSIONS

We experienced a case of membranous nephropathy-type PGNMID with discrepancy in light chains between serum and kidney that was successfully treated with oral prednisolone.

Amyloidosis: a case series and review of the literature

BACKGROUND

Systemic amyloidosis is group of disorders characterized by the accumulation of insoluble proteins in tissues. The most common form of systemic amyloidosis is light chain amyloidosis, which results from the accumulation of misfolded immunoglobulins. The disease is progressive, with treatment targeted at the underlying plasma cell dyscrasia. Since essentially any organ system can be affected, the presentation is variable and delays in diagnosis are common. Given this diagnostic difficulty, we discuss four different manifestations of light chain amyloidosis.

CASE PRESENTATIONS

In this case series, we discuss four cases of light chain amyloidosis. These include cardiac, hepatic, and gastrointestinal as well as autonomic and peripheral nerve involvement with amyloidosis. The patients in our series are of Caucasian background and include a  69-year-old female, a 29-year-old female, a 68-year-old male, and a 70-year-old male, respectively. The case discussions highlight variability in presentation and diagnostic challenges.

CONCLUSIONS

Amyloidosis is a rare but serious disease that is often complicated by long delays in diagnosis. Morbidity and mortality can sometimes be limited if diagnosed earlier. We hope our real life cases will contribute to understanding and to early suspicion that can lead to early diagnosis and management.

Widespread amyloidogenicity potential of multiple myeloma patient-derived immunoglobulin light chains

BACKGROUND

In a range of human disorders such as multiple myeloma (MM), immunoglobulin light chains (IgLCs) can be produced at very high concentrations. This can lead to pathological aggregation and deposition of IgLCs in different tissues, which in turn leads to severe and potentially fatal organ damage. However, IgLCs can also be highly soluble and non-toxic. It is generally thought that the cause for this differential solubility behaviour is solely found within the IgLC amino acid sequences, and a variety of individual sequence-related biophysical properties (e.g. thermal stability, dimerisation) have been proposed in different studies as major determinants of the aggregation in vivo. Here, we investigate biophysical properties underlying IgLC amyloidogenicity.

RESULTS

We introduce a novel and systematic workflow, Thermodynamic and Aggregation Fingerprinting (ThAgg-Fip), for detailed biophysical characterisation, and apply it to nine different MM patient-derived IgLCs. Our set of pathogenic IgLCs spans the entire range of values in those parameters previously proposed to define in vivo amyloidogenicity; however, none actually forms amyloid in patients. Even more surprisingly, we were able to show that all our IgLCs are able to form amyloid fibrils readily in vitro under the influence of proteolytic cleavage by co-purified cathepsins.

CONCLUSIONS

We show that (I) in vivo aggregation behaviour is unlikely to be mechanistically linked to any single biophysical or biochemical parameter and (II) amyloidogenic potential is widespread in IgLC sequences and is not confined to those sequences that form amyloid fibrils in patients. Our findings suggest that protein sequence, environmental conditions and presence and action of proteases all determine the ability of light chains to form amyloid fibrils in patients.

Multidisciplinary supportive care in systemic light chain amyloidosis

The immunoglobulin light-chain amyloidosis is a multisystemic disease which manifests by damage to the vital organs by light chain-derived amyloid fibril. Traditionally, the treatment has been directed to the underlying plasma cell clone with or without high dose chemotherapy followed by autologous stem cell transplantation using melphalan based conditioning. Now with the approval of highly tolerable anti-CD38 monoclonal antibody daratumumab based anti-plasma cell therapy in 2021, high rates of hematologic complete responses are possible even in patients who are otherwise deemed not a candidate for autologous stem cell transplantation. However, despite the progress, there remains a limitation in the strategies to improve symptoms particularly in patients with advanced cardiac involvement, those with nephrotic syndrome and autonomic dysfunction due to underlying systemic AL amyloidosis. The symptoms can be an ordeal for the patients and their caregivers and effective strategies are urgently needed to address them. The supportive care is aimed to counteract the symptoms of the disease and the effects of the treatment on involved organs’ function and preserve patients’ quality of life. Here we discuss multidisciplinary approach in a system-based fashion to address the symptom management in this dreadful disease. In addition to achieving excellent anti-plasma cell disease control, using treatment directed to remove amyloid from the vital organs can theoretically hasten recovery of the involved organs thereby improving symptoms at a faster pace. Ongoing phase III clinical trials of CAEL-101 and Birtamimab will address this question.

Amyloidogenic immunoglobulin light chain kinetic stabilizers comprising a simple urea linker module reveal a novel binding sub-site

In immunoglobulin light chain (LC) amyloidosis, the misfolding, or misfolding and misassembly of LC a protein or fragments thereof resulting from aberrant endoproteolysis, causes organ damage to patients. A small molecule "kinetic stabilizer" drug could slow or stop these processes and improve prognosis. We previously identified coumarin-based kinetic stabilizers of LCs that can be divided into four components, including a "linker module" and "distal substructure". Our prior studies focused on characterizing carbamate, hydantoin, and spirocyclic urea linker modules, which bind in a solvent-exposed site at the V_L-V_L domain interface of the LC dimer. Here, we report structure-activity relationship data on 7-diethylamino coumarin-based kinetic stabilizers. This substructure occupies the previously characterized "anchor cavity" and the "aromatic slit". The potencies of amide and urea linker modules terminating in a variety of distal substructures attached at the 3-position of this coumarin ring were assessed. Surprisingly, crystallographic data on a 7-diethylamino coumarin-based kinetic stabilizer reveals that the urea linker module and distal substructure attached at the 3-position bind a solvent-exposed region of the full-length LC dimer distinct from previously characterized sites. Our results further elaborate the small-molecule binding surface of LCs that could be occupied by potent and selective LC kinetic stabilizers.

Cardiac amyloidosis: Description of a series of 143 cases

INTRODUCTION AND OBJECTIVES

Recently, there have been important advances in the diagnosis and treatment of cardiac amyloidosis (CA). Our aim was to provide an updated description of its 2 most frequent types: the transthyretin CA (ATTR-CA) and the light chain CA (AL-CA).

METHODS

Prospective registry of patients with CA diagnosed in 7 institutions in Galicia (Spain) between January 1, 2018 and June 30, 2020. Variables related to clinical characteristics, complementary tests, survival and causes of death were collected.

RESULTS

One hundred and forty-three patients with CA were consecutively included, 128 ATTR-CA (89.5%) and 15 AL-CA (10.5%). Mean age was 79.6±7.7 years and 23.8% were women. Most patients with ATTR-CA were diagnosed non-invasively (87.5%). On physical examination, 35.7, 35 and 7% had Popeye's sign, Dupuytren's contracture and macroglossia, respectively. Twelve-month and 24-month survival was 92.1 and 76.2% in the ATTR-CA group, and 78.6 and 61.1% in the AL-CA group (P=.152). The cause of death was cardiovascular in 80.8% of the cohort.

CONCLUSIONS

ATTR-CA can be diagnosed non-invasively in most cases and it is the most common type of CA in routine clinical practice. Furthermore, an increase in the short-term survival of CA appears to be observed, which could be due to advances related to its diagnosis and treatment.

Primary oral mucosa-associated lymphoid tissue (MALT) lymphoma in patient with monoclonale gammopathy: a rare case report

Background

Monoclonal gammopathy is a biological reality encountered in approximately 1% of the general population. In the absence of clinical and biological signs, it is considered of undetermined significance; however, it can be a biological signature of a monoclonal lymphocytic or plasma-cell proliferation. Their localisation to the oral mucosa remains rare and difficult to diagnose, particularly in indolent forms that escape imaging techniques.

Case presentation

Here, we report the case of a 73-year-old woman with a history of IgM kappa gammopathy followed for 13 years. The patient did not have a chronic infection or an autoimmune disease, and all the biological investigations and radiological explorations were unremarkable during this period. The discovery of a submucosal nodule in the cheek led to the diagnosis of MALT lymphoma and regression of half of the IgM kappa level after resection. The review of the literature shows the dominance of clinical signs (i.e., a mass or swelling) in the diagnosis of primary MALT lymphomas of the oral cavity after surgical resection.

Conclusions

Our case illustrates the role of examination of the oral cavity in the context of a monoclonal gammopathy. The absence of clinical and radiological evidence in favor of lymphoplasmacytic proliferation, does not exclude a primary indolent MALT lymphoma of the oral mucosa.

Targeted treatments of AL and ATTR amyloidosis

The therapeutic landscape for cardiac amyloidosis is rapidly evolving. In the last decade, our focus has shifted from dealing with the inevitable complications of continued extracellular infiltration of amyloid fibrils to earlier identification of these patients with prompt initiation of targeted therapy to prevent further deposition. Although much of the focus on novel targeted therapies is within the realm of transthyretin amyloidosis, light chain amyloidosis has benefited due to an overlap particularly in the final common pathway of fibrillogenesis and extraction of amyloid fibrils from the heart. Here, we review the targeted therapeutics for transthyretin and light chain amyloidosis. For transthyretin amyloidosis, the list of current and future therapeutics continues to evolve; and therefore, it is crucial to become familiar with the underlying mechanistic pathways of the disease. Although targeted therapeutic choices in AL amyloidosis are largely driven by the hematology team, the cardiac adverse effect profiles of these therapies, particularly in those with advanced amyloidosis, provide an opportunity for early recognition to prevent decompensation and can help inform recommendations regarding therapy changes when required.

A real-world study on diagnosis and prognosis of light-chain cardiac amyloidosis in Southern China

Background

Light-chain cardiac amyloidosis (AL-CA) has been highly valued in developed countries, but in developing countries, the recognition and diagnosis of this condition is still limited. There are currently few reports on a large number of Chinese patients with AL-CA. The present study aimed to report real-world clinical characteristics and prognosis of AL-CA in China.

Methods and results

Consecutive patients with AL-CA diagnosed at the Second Xiangya Hospital of Central South University between June 2012 and September 2020 were reviewed. A total of 170 patients with AL-CA have been recruited, whose mean ages were 60.81 ± 10.46. 70.59% of the patients were male. They were from eight provinces in southern China, 55.7% were referred patients, and 37.3% had been misdiagnosed previously. 64 (37.6%) patients received chemotherapy. The median survival time for patients with AL-CA was 8.00 months, and survival time for patients who received chemotherapy was 13.00 months, which was significantly longer than that of patients with palliative treatment (13.00 vs 6.00, p = 0.004).

Conclusions

Although clinicians have improved their understanding of AL-CA in recent years, the prognosis of AL-CA is still poor, and the misdiagnosis rate and missed diagnosis rate are still very high in China. It is imperative to improve the recognition and early diagnosis of this condition, which may require multidisciplinary collaboration among cardiologists, hematologists and nephrologists.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02256-3.

Comprehensive approach to cardiac amyloidosis care: considerations in starting an amyloidosis program

Amyloidosis is a multisystem disease which continues to present in later stages due to delayed diagnosis. Once the disease is identified, the coordination of ongoing care and treatment becomes complex and often involves multiple specialists. As knowledge of the disease grows, healthcare providers within institutions have organized to create comprehensive amyloidosis programs to better serve patients in the region. In this review, we present considerations in starting a cardiac amyloidosis program from two institutions that have recently started such programs. Identification of multidisciplinary stakeholders, development of overarching program goals, creation of institutional buy-in, and emphasis on program growth and development are tenets of a successful program. The creation and growth of an amyloidosis program has the potential to raise awareness for the disease and benefit patients and institutions alike.

Progress and challenges in the treatment of cardiac amyloidosis: a review of the literature

Cardiac amyloidosis is a restrictive cardiomyopathy determined by the accumulation of amyloid, which is represented by misfolded protein fragments in the cardiac extracellular space. The main classification of systemic amyloidosis is determined by the amyloid precursor proteins causing a very heterogeneous disease spectrum, but the main types of amyloidosis involving the heart are light chain (AL) and transthyretin amyloidosis (ATTR). AL, in which the amyloid precursor is represented by misfolded immunoglobulin light chains, can involve almost any system carrying the worst prognosis among amyloidosis patients. This has however dramatically improved in the last few years with the increased usage of the novel therapies such as proteasome inhibitors and haematopoietic cell transplantation, in the case of timely diagnosis and initiation of treatment. The treatment for AL is directed by the haematologist working closely with the cardiologist when there is a significant cardiac involvement. Transthyretin (TTR) is a protein that is produced by the liver and is involved in the transportation of thyroid hormones, especially thyroxine and retinol binding protein. ATTR results from the accumulation of transthyretin amyloid in the extracellular space of different organs and systems, especially the heart and the nervous system. Specific therapies for ATTR act at various levels of TTR, from synthesis to deposition: TTR tetramer stabilization, oligomer aggregation inhibition, genetic therapy, amyloid fibre degradation, antiserum amyloid P antibodies, and antiserum TTR antibodies. Treatment of systemic amyloidosis has dramatically evolved over the last few years in both AL and ATTR, improving disease prognosis. Moreover, recent studies revealed that timely treatment can lead to an improvement in clinical status and in a regression of amyloid myocardial infiltration showed by imaging, especially by cardiac magnetic resonance, in both AL and ATTR. However, treating cardiac amyloidosis is a complex task due to the frequent association between systemic congestion and low blood pressure, thrombo-embolic and haemorrhagic risk balance, patient frailty, and generally poor prognosis. The aim of this review is to describe the current state of knowledge regarding cardiac amyloidosis therapy in this constantly evolving field, classified as treatment of the cardiac complications of amyloidosis (heart failure, rhythm and conduction disturbances, and thrombo-embolic risk) and the disease-modifying therapy.

Light chain subunit of a poorly soluble human IgG2λ crystallizes in physiological pH environment both in cellulo and in vitro

Prominent inclusion bodies can develop in the endoplasmic reticulum (ER) when overexpressed antibodies possess intrinsically high condensation propensities. These observations suggest that antibodies deemed to show notable solubility problems may reveal such characteristics preemptively in the form of ER-associated inclusion bodies during antibody overexpression. To define the relationships between solubility problems and inclusion body phenotypes, we investigated the biosynthesis of a model human IgG2λ that shows severe opalescence in an acidic formulation buffer yet retains high solubility at physiological pH. Consistent with the pH-dependent solubility characteristics, the model antibody did not induce notable inclusion body in the physiological pH environment of the ER lumen. However, when individual subunit chains of the antibody were expressed separately, the light chain (LC) spontaneously induced notable crystal-like inclusion bodies in the ER. The LC crystallization event was readily reproducible in vitro by simply concentrating the purified LC protein at physiological pH. Two independent structural determinants for the LC crystallization were identified through rational mutagenesis approach by monitoring the effect of amino acid substitutions on intracellular LC crystallogenesis. The effect of mutations on crystallization was also recapitulated in vitro using purified LC proteins. Importantly, when introduced directly into the model antibody, a mutation that prevents the LC crystallization remediated the antibody's solubility problem without compromising the secretory output or antigen binding. These results illustrate that the ER can serve as a "physiological test tube" that not only reports secretory cargo's high condensation propensity at physiological pH, but also provides an orthogonal method that guides antibody engineering strategy.

Amyloidosis with Cardiac Involvement: Identification, Characterization, and Management

PURPOSE OF REVIEW

Amyloidosis is a protein deposition disease whereby a variety of precursor proteins form insoluble fibrils that deposit in tissues, causing organ dysfunction and, many times, death. Accurate characterization of the disease based on the nature of the precursor protein, organ involvement, and extent of disease is paramount to guide management. Cardiac amyloidosis is critical to understand because of its impact on prognosis and new treatment options available.

RECENT FINDINGS

New imaging methods have proven to be considerably valuable in the identification of cardiac amyloid infiltration. For treating clinicians, a diagnostic algorithm for patients with suspected amyloidosis with or without cardiomyopathy is shown to help classify disease and to direct appropriate genetic testing and management. For patients with light chain disease, recently introduced treatments adopted from multiple myeloma therapies have significantly extended progression-free and overall survival as well as organ response. In addition, new medical interventions are now available for those with transthyretin amyloidosis. Although cardiac amyloidosis contributes significantly to the morbidity and mortality associated with systemic disease, new tools are available to assist with diagnosis, prognosis, and management.

Proliferative Glomerulonephritis With Fibrils, Monoclonal κ Light Chain, and C3 Deposits

There is increasing recognition of monoclonal gammopathy as a cause of proliferative glomerulonephritis (GN), including cases in which glomerular deposition of monoclonal immunoglobulin is demonstrated. Recently, proliferative GN with monoclonal immunoglobulin deposits (PGNMID) has incorporated a light chain variant of the disease (termed PGNMID-LC). Intriguingly, glomerular co-deposition of C3 is found in addition to monotypic light chain, implying complement activation via the alternative pathway (AP). We present a unique case of proliferative GN in a 42-year-old man who presented with nephrotic syndrome and was found to have κ light chain multiple myeloma. Immune staining of the glomerulus was positive only for κ light chain and C3, with the striking appearance of nonamyloid fibrils on electron microscopy. Following clonally targeted therapy for myeloma, the renal clinical abnormalities resolved completely. We present detailed molecular studies for light chain and complement and consider local mechanisms whereby monoclonal κ light chain fibrils may have triggered AP activation within the glomerulus.

Clinicopathological significance of light chain deposition in IgA nephropathy

BACKGROUND

Clinicopathological significance of light chain deposition in IgA nephropathy and the relation of monotypic IgA deposition to bone marrow abnormalities are important issues to be clarified.

METHODS

We retrospectively investigated light chain deposition in 526 patients with IgA nephropathy. We divided the patients into 5 groups according to the balance of intensity of both light chain deposition: lambda monotypic, lambda dominant, polytypic, kappa dominant and kappa monotypic. Clinicopathological parameters were compared among the groups. The relation of monotypic IgA deposition to hematological malignancy was also evaluated.

RESULTS

The prevalence of monotypic IgA deposition was 6.3%, 33 patients (21 lambda and 12 kappa). Thirty-two (4.0%) and 10 patients (1.9%) were classified into lambda and kappa dominant groups, respectively. Polytypic IgA deposition was observed in 455 patients (85.7%). Age of onset, age at biopsy, urinary protein creatinine ratio, the percentage of global glomerulosclerosis, and the degree of IgA and C3 deposition were different among the groups. However, there was no gradual difference according to the groups. No patient with monotypic IgA deposition showed hematological abnormality at biopsy and during follow-up.

CONCLUSIONS

The prevalence of IgA monotypic deposition was extremely low. Clinicopathologically, we could not differentiate patients with monotypic IgA deposition from those with polytypic one and no hematological disorder was documented in patients with monotypic IgA deposition. Whether IgA nephropathy with monotypic IgA deposition and that with polytypic one is the same entity or not, and relation between monotypic IgA deposition and hematological malignancy should be clarified by further investigations.

Two kinds of rare light chain cast nephropathy caused by multiple myeloma: case reports and literature review

BACKGROUND

Light chain cast nephropathy (LCCN) is the most common renal disease caused by multiple myeloma (MM). In addition to ordinary light chain protein casts, there are a few rare casts with unique shapes, including light chain amyloid casts (LCAC) and light chain crystal casts (LCCC).

CASE PRESENTATIONS

Here, we report two patients. Patient 1 is a 72-year-old man who was clinically diagnosed with MM and acute kidney injury (AKI). Pathological examination of a renal biopsy revealed that there were many amyloid casts in the distal tubules that had a lightly-stained central area and a deeply-stained burr-like edge. The marginal zone of the cast was positive for Congo red staining and contained numerous amyloid fibers, as observed by electron microscopy. No systemic amyloidosis was found. The patient received 4 courses of bortezomib-based chemotherapy, and then, his MM achieved partial remission. Patient 2 is a 57-year-old man who was also clinically diagnosed with MM and AKI. Pathological examination of a renal biopsy showed that there were many crystalline casts in the distal tubules that were fully or partially composed of crystals with different shapes, including rhomboid, needle, triangle, rectangle and other geometric shapes. Congo red staining was negative. Crystals were also detected in the urine of this patient. After 9 courses of treatment with a bortezomib-based regimen, his MM obtained complete remission and his renal function returned to normal.

CONCLUSIONS

LCAC and LCCC nephropathy caused by MM are two rare types of LCCN, and both have their own unique morphological manifestations. LCAC nephropathy may not be accompanied by systemic amyloidosis. The diagnosis of these two unique LCCNs must rely on renal biopsy pathology, and the discovery of urine crystals is of great significance for indicating LCCC nephropathy.

Light chain and transthyretin cardiac amyloidosis: Clinical characteristics, natural history and prognostic factors

INTRODUCTION AND OBJECTIVES

Light-chain amyloidosis (AL-CA) and transthyretin amyloidosis (ATTR-CA) are the most common types of cardiac amyloidosis (CA). We sought to study the clinical characteristics and prognosis of both diseases.

METHODS

We conducted a single-centre, retrospective review of all patients diagnosed with CA between 1998 and 2018. Clinical characteristics, complementary tests, survival and other adverse clinical events were studied.

RESULTS

We identified 105 patients with CA, 65 ATTR-CA and 40 AL-CA. Mean age was 74.4 years; 24.8% were women. In both groups, heart failure was the most frequent clinical presentation (55.2%). The most prevalent electrocardiographic findings were the pseudoinfarct pattern (68.5%) and a Sokolow-Lyon index < 1.5 mV (67.7%), with no differences between the two subtypes of CA. One-year, 3-year, and 5-year survival was 43.3%, 40.4% and 35.4%, respectively, in AC-AL patients, and 85.1%, 57.3% and 31.4% in AC-ATTR patients (p = 0.004). AL-CA subtype (HR 3.41; 95% CI 1.45-8.06; p = 0.005), previous admission for heart failure (HR 4.25; 95% CI 1.63-11.09; p = 0.003) and a NYHA class III-IV (HR 2.76; 95% CI; 1.09-7.03; p = 0.033) were independent predictors of mortality, while beta-blocker therapy was associated with longer survival (HR 0.23; 95% CI 0.09-0.59; p = 0.002).

CONCLUSIONS

Differences exist between the clinical presentation of AL-CA and ATTR-CA patients. Both diseases, particularly AL-CA, are associated with poor life prognosis.

Advances in the Treatment of Cardiac Amyloidosis

OPINION STATEMENT

Cardiac amyloidosis is associated with a high mortality rate, a long delay between the first signs and the diagnosis but a short interval between diagnosis and death. This scenario has changed recently due to improved disease awareness among doctors and significant progress in diagnosis thanks to multimodal imaging and a multidisciplinary approach. Therefore, during the last few years, we have had access to specific therapies for those patients. Those therapies are quite different depending on the type of amyloidosis, but there has been real progress. Systemic light chain amyloidosis (AL) with cardiac involvement is the most common form of cardiac amyloidosis. The severity of heart disease dictates the prognosis in AL amyloidosis. Advances in chemotherapy and immunotherapy that suppress light chain production have improved the outcomes. These recent improvements in survival rates have enabled therapies such as implanted cardiac defibrillators and heart transplantation that were usually not indicated for patients with advanced light chain amyloid cardiomyopathy to now be applied in selected patients. For transthyretin amyloidosis (ATTR), the second most common form of amyloidosis with cardiac involvement, there is also significant progress in treatment. Until recently, we had no specific therapy for ATTR cardiomyopathy (ATTR-CM), though now disease-modifying therapies are available. Therapies that stabilize transthyretin, such as tafamidis, have been shown to improve outcomes for patients with ATTR-CM. Modern treatments that stop the synthesis of TTR through gene silencing, such as patisiran and inotersen, have shown positive results for patients with TTR amyloidosis. Significant progress has been made in the treatment of amyloid cardiomyopathy, and hopefully, we will see even more progress with the spread of those treatments. We now can be optimistic about patients with this disease.

Complement activation is associated with crescent formation in IgA nephropathy

IgA nephropathy (IgAN) is common chronic glomerulonephritis with variable prognosis, ranging from minor urinary abnormalities to end-stage renal disease. The revised Oxford classification of IgAN explains that cellular/fibrocellular crescents are associated with poor renal prognosis, proposing an extension to the MEST-C score. C3 immunofluorescent staining follows a distribution similar to IgA staining. Therefore, complement activation was reported to play a pivotal role in IgAN pathogenesis. This study included 132 IgAN patients diagnosed by renal biopsies. The clinical parameters at the time of the biopsies were obtained from patient data records. We classified the patients into C ≥ 1 and C0 groups, and compared clinical, light microscopic, and immunofluorescent features. In the C ≥ 1 group, 2 (1.5%) and 31 (23.5%) patients were assigned to C2 and C1, respectively. The remaining 99 patients (75%) were classified as C0. The C ≥ 1 group had lower average age and rate of hypertension, and higher score of urinary occult blood and E score. The C ≥ 1 group had significantly higher average immunofluorescence scores for IgA, C5b-9, mannose-associated serine protease (MASP) 1/3, MASP2, properdin, factor B, and kappa. The steroid use rate was significantly higher in the C ≥ 1 group. During the follow-up period of 2.90 years on average, the rate of renal dysfunction was not significantly different between groups. Crescent formation in IgAN was associated with activation of the lectin and alternative pathways. The C ≥ 1 group had significantly increased use of steroids, which probably caused comparable renal function during the follow-up period.

Newer Therapies for Amyloid Cardiomyopathy

The heart and the kidneys are the most commonly involved organs in systemic amyloidosis. Cardiac involvement is associated with an increased morbidity, treatment intolerance, and poorer overall survival. The most common types of amyloidosis that are associated with cardiac involvement include light chain (AL) amyloidosis and transthyretin (TTR) amyloidosis (both mutant and wild type). The traditional first-line treatment for AL amyloidosis includes alkylator-based chemotherapy or high-dose melphalan followed by autologous stem cell transplantation (ASCT). Novel agents, including proteasome inhibitors, immunomodulators, and monoclonal antibodies, have shown promising activity in both frontline and relapsed settings. Orthotopic heart transplantation (OHT) followed by ASCT has led to superior outcomes compared to OHT alone. Orthotopic liver transplantation (OLT) is the first-line treatment for TTR amyloidosis. However, progression of cardiac amyloidosis after OLT is often noted due to deposition of wild TTR. Combined OLT and OHT also has a role in treatment and leads to superior outcomes in carefully selected candidates. Pharmacologic agents, including diflunisal, tafamidis, small interfering ribonucleic acid, and doxycycline, have shown promising activity in stabilizing TTR from misfolding into fibrils and are being actively investigated. Best supportive care and management of heart failure symptoms with diuretics are a mainstay of treatment in all cardiac amyloidosis subtypes. Robust data on the benefit of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or beta blockers in amyloid cardiomyopathy is lacking.

Rational design of botulinum neurotoxin A1 mutants with improved oxidative stability

Botulinum neurotoxins (BoNTs) are the most potent toxic proteins to mankind known but applied in low doses trigger a localized muscle paralysis that is beneficial for the therapy of several neurological disorders and aesthetic treatment. The paralytic effect is generated by the enzymatic activity of the light chain (LC) that cleaves specifically one of the SNARE proteins responsible for neurotransmitter exocytosis. The activity of the LC in a BoNT-containing therapeutic can be compromised by denaturing agents present during manufacturing and/or in the cell. Stabilization of the LC by reducing vulnerability towards denaturants would thus be advantageous for the development of BoNT-based therapeutics. In this work, we focused on increasing the stability of LC of BoNT/A1 (LC/A1) towards oxidative stress. We tackled this task by rational design of mutations at cysteine and methionine LC/A1 sites. Designed mutants showed improved oxidative stability in vitro and equipotency to wildtype toxin in vivo. Our results suggest that suitable modification of the catalytic domain can lead to more stable BoNTs without impairing their therapeutic efficacy.

Design of modified botulinum neurotoxin A1 variants with a shorter persistence of paralysis and duration of action

Botulinum neurotoxins (BoNTs) are classified by their antigenic properties into seven serotypes (A-G) and in addition by their corresponding subtypes. They are further characterized by divergent onset and duration of effect. Injections of low doses of botulinum neurotoxins cause localized muscle paralysis that is beneficial for the treatment of several medical disorders and aesthetic indications. Optimizing the therapeutic properties could offer new treatment opportunities. This report describes a rational design approach to modify the pharmacological properties by mutations in the C-terminus of BoNT/A1 light chain (LC). Toxins with C-terminal modified LC's displayed an altered onset and duration of the paralytic effect in vivo. The level of effect was dependent on the kind of the mutation in the sequence of the C-terminus. A mutant with three mutations (T420E F423M Y426F) revealed a faster onset and a shorter duration than BoNT/A1 wild type (WT). It could be shown that the C-terminus of BoNT/A1-Lc controls both onset and duration of effect. Thus, it is possible to create a mutated BoNT/A1 with different pharmacological properties which might be useful in the therapy of new indications. This strategy opens the way to design BoNT variants with novel and useful properties.

Rationale and design of DUAL study: Doxycycline to Upgrade response in light chain (AL) amyloidosis (DUAL): A phase 2 pilot study of a two-pronged approach of prolonged doxycycline with plasma cell-directed therapy in the treatment of AL amyloidosis

Light chain (AL) amyloidosis is a plasma cell neoplasm associated with insoluble fibril deposition from clonal immunoglobulin chains systemically. The disease is associated with high early mortality and morbidity owing to advanced organ deposition as well as lack of proven de-fibrillogenic therapies. Pre-clinical and retrospective clinical data suggests that doxycycline has benefit in AL amyloidosis. The ongoing DUAL study is a single center, open label, phase 2 study in which patients with AL amyloidosis who are undergoing clone-directed therapy for the underlying neoplasm with oral doxycycline given for 1 year to test the hypothesis that prolonged doxycycline use will be safe, feasible, and lead to reduced early mortality in systemic AL amyloidosis and hasten organ amyloid response. Clinical follow up visits will occur at monthly intervals for systemic AL patients and at 3 monthly intervals for localized AL patients. Blood tests will be collected during these time points for hematologic response assessment. Organ testing will be conducted at 3 monthly intervals and radiologic testing will be conducted at 6 monthly intervals. Research blood samples will be collected at baseline, 6 and 12 months. Other correlative studies include matrix metalloproteinases (MMP), tissue inhibitor of metalloproteinases (TIMP) testing and patient-reported outcomes.

Novel pharmacotherapies for cardiac amyloidosis

Amyloidosis refers to a range of protein misfolding disorders that can cause organ dysfunction through progressive fibril deposition. Cardiac involvement often leads to significant morbidity and mortality and increasingly has been recognized as an important cause of heart failure. The two main forms of cardiac amyloidosis, light chain (AL) and transthyretin (ATTR) amyloidosis, have distinct mechanisms of pathogenesis. Recent insights have led to the development of novel pharmacotherapies with the potential to significantly impact each disease. This review will summarize the preclinical and clinical data for these emerging treatments for AL and ATTR amyloidosis.

Emerging Advances in the Management of Cardiac Amyloidosis

Amyloidosis is a disease in which proteins misfold, aggregate into fibrils, and deposit extracellularly disrupting organ architecture and function. There are two main types which affect the heart: light chain (AL) amyloidosis and transthyretin cardiac amyloidosis (ATTR). There is a misconception that cardiac amyloidosis has no effective treatment options. However, over the past decade, there has been extensive research and drug development. Outcomes are improving in AL amyloidosis with evolving chemotherapeutic regimens and novel monoclonal antibodies. In ATTR, therapies that decrease protein production, prevent dissociation, and promote clearance have the potential to slow or even halt a disease which is uniformly fatal. Selected patients may be candidates for heart and/or stem cell transplant and should be promptly referred to an experienced amyloid program. Herein, we discuss the emerging advances for the treatment of cardiac amyloidosis.

Clinicopathological significance of monoclonal IgA deposition in patients with IgA nephropathy

BACKGROUND

Clinicopathological significance of monoclonal IgA deposition and its relation to bone marrow abnormalities in IgA nephropathy (IgAN) remains unclear.

METHODS

We retrospectively investigated the prevalence and clinicopathological significance of monoclonal IgA deposition in 65 patients with IgAN. Serum-free light chain ratio, and urinary Bence Jones protein were also measured.

RESULTS

Thirty-nine percent of patients were men, median age was 40 and median observation period was 31 months. Five patients (Group M) showed monoclonal IgA lambda deposition and one showed monoclonal IgA kappa deposition. Fifty-nine patients (Group P) showed polyclonal IgA deposition. There were no significant differences in the degree of proteinuria, hematuria and renal function between Group M and Group P. Total protein and albumin were significantly lower in Group M than in Group P. According to the Oxford classification, the percentage of patients with M1 was significantly higher in Group M than in Group P. One patient in Group P showed serum monoclonal IgG lambda. No patient showed abnormal serum-free light chain ratio. Seventy-five percent in Group M and 42 % in Group P were treated with steroid. Three patients in Group P progressed to end-stage renal disease (ESRD). The frequency of disappearance of proteinuria or hematuria and progression to ESRD was not different between the groups.

CONCLUSIONS

The prevalence of monoclonal IgA deposition was 9.2 %. Although some parameters differed between the groups, renal outcome were similar. Thus, IgAN with monoclonal IgA deposition seems not to be different entity from those with polyclonal IgA deposition.

Genomic variation in the porcine immunoglobulin lambda variable region

Production of a vast antibody repertoire is essential for the protection against pathogens. Variable region germline complexity contributes to repertoire diversity and is a standard feature of mammalian immunoglobulin loci, but functional V region genes are limited in swine. For example, the porcine lambda light chain locus is composed of 23 variable (V) genes and 4 joining (J) genes, but only 10 or 11 V and 2 J genes are functional. Allelic variation in V and J may increase overall diversity within a population, yet lead to repertoire holes in individuals lacking key alleles. Previous studies focused on heavy chain genetic variation, thus light chain allelic diversity is not known. We characterized allelic variation of the porcine immunoglobulin lambda variable (IGLV) region genes. All intact IGLV genes in 81 pigs were amplified, sequenced, and analyzed to determine their allelic variation and functionality. We observed mutational variation across the entire length of the IGLV genes, in both framework and complementarity determining regions (CDRs). Three recombination hotspot motifs were also identified suggesting that non-allelic homologous recombination is an evolutionarily alternative mechanism for generating germline antibody diversity. Functional alleles were greatest in the most highly expressed families, IGLV3 and IGLV8. At the population level, allelic variation appears to help maintain the potential for broad antibody repertoire diversity in spite of reduced gene segment choices and limited germline sequence modification. The trade-off may be a reduction in repertoire diversity within individuals that could result in an increased variation in immunity to infectious disease and response to vaccination.

Involvement of oral tissues by AL amyloidosis: a literature review and report of eight new cases

OBJECTIVE

Amyloidosis is a term used to describe a group of diseases in which there is an extracellular deposition of amorphous fibrillar proteins known as amyloid. The aim of this study was to present clinicopathological data from eight oral amyloidosis-affected patients and a deep review of the literature about the disease.

MATERIALS AND METHODS

A retrospective study was conducted based on the records of oral amyloidosis-affected patients diagnosed in our institution between 1978 and 2012. The clinicopathological features and immunohistochemical (IHC) staining with anti-kappa and anti-lambda light chain antibodies were carried out and analyzed.

RESULTS

Eight patients were diagnosed with the disease; the tongue and women in their sixth decade of life were mostly affected. All lesions demonstrated apple-green birefringence and immunoreactivity for kappa-light chain, and four cases also showed lambda positivity. According to our series, four cases were diagnosed with localized amyloidosis and four with systemic amyloidosis. Prognosis for the systemic ones was gloomy, but good for the localized ones, which was characterized by a slow pattern of deposition without evolution to systemic involvement.

CONCLUSIONS

This study reinforces our knowledge about predilections, outcomes, and the importance of making a correct and quick diagnosis of oral amyloidosis and shows the necessity of more studies detailing oral amyloidosis predilection on a global scale. The importance and utility of IHC in the typing of the biochemical nature of amyloid deposits are becoming increasingly necessary for proper management of the patient. Correct classification of the type of amyloid is important for treatment consequences.

CLINICAL RELEVANCE

This article highlights the clinicopathological data of patients with amyloidosis affecting oral tissues and compare these new findings with other worldwide descriptions. Because of its rarity, such data are often unfamiliar to most clinicians and pathologists.

Combined IgG4κ and IgG1λ deposition in the glomerular and tubular basement membrane accompanied by autoimmune neutropenia (AIN) and immune thrombocytopenia (ITP)

A 48-year-old male was admitted to our hospital with nephrotic syndrome. Light-microscopic examination of a renal biopsy specimen showed almost normal glomerular appearance, however, immunofluorescence examination revealed linear and granular IgG deposits on the glomerular basement membrane (GBM), accompanied by slight IgG deposition in the tubular basement membrane (TBM). Further investigation of the IgG subclass and light chain staining revealed that the glomerular deposits were composed of IgG1 and IgG4, with both κ and λ light chains, while the tubular deposits were composed of only IgG4 and κ light chains. The electron-microscopic findings of small granular deposits in the GBM and TBM closely resembled those of light and heavy chain deposition disease (LHCDD). Immunoelectron microscopy confirmed the presence of κ and λ chains in the GBM and TBM, however, only significant κ chain deposition was found in the TBM. There was no evidence of monoclonal gammopathy. Clinically, the patient subsequently developed neutropenia and thrombocytopenia associated with the presence of anti-neutrophil antibody and anti-GPIIb/IIIa antibody-producing B cells in the blood. Oral steroid administration was initiated, which led to amelioration of the neutropenia, thrombocytopenia and proteinuria. This may be a very rare case of combined IgG4κ and IgG1λ deposition disease accompanied by autoimmune neutropenia (AIN) and immune thrombocytopenia (ITP) suggestive of biclonal immunoglobulin deposition disease (BIDD). Investigation of the IgG subclass and of the light chains was useful for recognizing the clonality of the immunoglobulin deposits in the kidney.

Interactions of a potent cyclic peptide inhibitor with the light chain of botulinum neurotoxin A: Insights from X-ray crystallography

The seven antigenically distinct serotypes (A-G) of botulinum neurotoxin (BoNT) are responsible for the deadly disease botulism. BoNT serotype A (BoNT/A) exerts its lethal action by cleaving the SNARE protein SNAP-25, leading to inhibition of neurotransmitter release, flaccid paralysis and autonomic dysfunction. BoNTs are dichain proteins consisting of a ∼ 100 kDa heavy chain and a ∼ 50 kDa light chain; the former is responsible for neurospecific binding, internalization and translocation, and the latter for cleavage of neuronal SNARE proteins. Because of their extreme toxicity and history of weaponization, the BoNTs are regarded as potential biowarfare/bioterrorism agents. No post-symptomatic therapeutic interventions are available for BoNT intoxication other than intensive care; therefore it is imperative to develop specific antidotes against this neurotoxin. To this end, a cyclic peptide inhibitor (CPI-1) was evaluated in a FRET assay for its ability to inhibit BoNT/A light chain (Balc). CPI was found to be highly potent, exhibiting a Ki of 12.3 nM with full-length Balc448 and 39.2 nM using a truncated crystallizable form of the light chain (Balc424). Cocrystallization studies revealed that in the Balc424-CPI-1 complex, the inhibitor adopts a helical conformation, occupies a high percentage of the active site cavity and interacts in an amphipathic manner with critical active site residues. The data suggest that CPI-1 prevents SNAP-25 from accessing the Balc active site by blocking both the substrate binding path at the surface and the Zn(2+) binding region involved in catalysis. This differs from linear peptide inhibitors described to date which block only the latter.

Immunoglobulin light chain allelic inclusion in systemic lupus erythematosus

The principles of allelic exclusion state that each B cell expresses a single light and heavy chain pair. Here, we show that B cells with both kappa and lambda light chains (Igκ and Igλ) are enriched in some patients with the systemic autoimmune disease systemic lupus erythematosus (SLE), but not in the systemic autoimmune disease control granulomatosis with polyangiitis. Detection of dual Igκ and Igλ expression by flow cytometry could not be abolished by acid washing or by DNAse treatment to remove any bound polyclonal antibody or complexes, and was retained after two days in culture. Both surface and intracytoplasmic dual light chain expression was evident by flow cytometry and confocal microscopy. We observed reduced frequency of rearrangements of the kappa-deleting element (KDE) in SLE and an inverse correlation between the frequency of KDE rearrangement and the frequency of dual light chain expressing B cells. We propose that dual expression of Igκ and Igλ by a single B cell may occur in some patients with SLE when this may be a consequence of reduced activity of the KDE.

Structural and functional analysis of botulinum neurotoxin subunits for pH-dependent membrane channel formation and translocation

The structure-function relationship of Botulinum Neurotoxin (BoNT) proteins is greatly influenced by pH. While the low pH of endosome favors membrane interaction of the heavy chain (HC) for the formation of a membrane channel and translocation of the light chain (LC), the catalytic activity of the LC requires a neutral pH for cleavage of the soluble NSF attachment protein receptor (SNARE) complex in the cytosol. In this study, we monitored secondary structural characteristics of LC, HC and holotoxin at individual pHs 4.5 and 7.2 and at the transition pH4.5 to 7.2 to identify the structural signatures underlying their function. The HC showed higher thermal stability at pH4.5 with a melting temperature (Tm) of 60.4°C. The structural analysis of HC in the presence of liposomes showed no difference in ellipticity with that of HC at pH7.2 at 208 and 222 nm but a 25.2% decrease in ellipticity at 208 nm at acidic pH, indicating low pH-induced structural changes that might facilitate interaction with the membrane. Further, HC showed 18% release of K+ ions from liposomes at pH4.5 as against 6% at neutral pH, reinforcing its role in membrane channel formation. LC on the other hand, showed maximum ellipticity at pH7.2, a condition that is relevant to its endopeptidase activity in the cytosol of the neurons. Also, the similarity in the structures at pH7.2 and transition pH4.5 to 7.2 suggested that the flexibility acquired by the protein at low pH was reversible upon exposure to neutral pH for cleavage of SNARE proteins.

A Case of IgG2 Heavy Chain Deposition Disease in a Patient with Kappa Positive Plasma Cell Dyscrasia

IgG2 heavy chain deposition disease (HCDD) is extremely rare. To date, only 4 cases have been reported in medical literature. To our knowledge, we report the first case of IgG2 HCDD accompanied by kappa plasma cell dyscrasia.

Diversity of immunoglobulin lambda light chain gene usage over developmental stages in the horse

To further studies of neonatal immune responses to pathogens and vaccination, we investigated the dynamics of B lymphocyte development and immunoglobulin (Ig) gene diversity. Previously we demonstrated that equine fetal Ig VDJ sequences exhibit combinatorial and junctional diversity levels comparable to those of adult Ig VDJ sequences. Herein, RACE clones from fetal, neonatal, foal, and adult lymphoid tissue were assessed for Ig lambda light chain combinatorial, junctional, and sequence diversity. Remarkably, more lambda variable genes (IGLV) were used during fetal life than later stages and IGLV gene usage differed significantly with time, in contrast to the Ig heavy chain. Junctional diversity measured by CDR3L length was constant over time. Comparison of Ig lambda transcripts to germline revealed significant increases in nucleotide diversity over time, even during fetal life. These results suggest that the Ig lambda light chain provides an additional dimension of diversity to the equine Ig repertoire.

The N-terminal strand modulates immunoglobulin light chain fibrillogenesis

It has been suggested that the N-terminal strand of the light chain variable domain (V(L)) protects the molecule from aggregation by hindering spurious intermolecular contacts. We evaluated the impact of mutations in the N-terminal strand on the thermodynamic stability and kinetic of fibrillogenesis of the V(L) protein 6aJL2. Mutations in this strand destabilized the protein in a position-dependent manner, accelerating the fibrillogenesis by shortening the lag time; an effect that correlated with the extent of destabilization. In contrast, the effect on the kinetics of fibril elongation, as assessed in seeding experiments was of different nature, as it was not directly dependant on the degree of destabilization. This finding suggests different factors drive the nucleation-dependent and elongation phases of light chain fibrillogenesis. Finally, taking advantage of the dependence of the Trp fluorescence upon environment, four single Trp substitutions were made in the N-terminal strand, and changes in solvent exposure during aggregation were evaluated by acrylamide-quenching. The results suggest that the N-terminal strand is buried in the fibrillar state of 6aJL2 protein. This finding suggest a possible explanation for the modulating effect exerted by the mutations in this strand on the aggregation behavior of 6aJL2 protein.

Small molecule inhibitors of anthrax lethal factor toxin

This manuscript describes the preparation of new small molecule inhibitors of Bacillus anthracis lethal factor. Our starting point was the symmetrical, bis-quinolinyl compound 1 (NSC 12155). Optimization of one half of this molecule led to new LF inhibitors that were desymmetrized to afford more drug-like compounds.

A case of fatal intrahepatic cholestasis with primary AL amyloidosis: is early diagnosis possible?

Immunoglobulin light chain-associated (AL) amyloidosis is a multisystemic disorder characterized by extracellular deposition of immunoglobulin light chain produced by a proliferative plasma cell clone. Although the liver is the major organ involved in AL amyloidosis, hepatic involvement is often clinically asymptomatic and severe intrahepatic cholestasis as the primary manifestation of the disease is rare. A 60-year-old man with severe jaundice, massive ascites and highly elevated alkaline phosphatase was diagnosed with AL amyloidosis by a transjugular liver biopsy. He had undergone a yearly medical check that showed no abnormalities except for mild elevation of serum γ-glutamyltransferase at 1 year before admission. Owing to his poor condition and rapidly progressive liver and renal dysfunction, neither stem cell transplantation nor a combination of chemotherapeutic agents could be applied, and he died 1.5 months after admission. An autopsy revealed amyloid deposition in the systemic organs, and there was no evidence of multiple myeloma. Continuous elevation of γ-glutamyltransferase may be a useful marker for early diagnosis of fatal hepatic amyloidosis.

Engineering Clostridia Neurotoxins with elevated catalytic activity

BoNT/B and TeNT cleave substrate VAMP2 at the same scissile bond, yet these two toxins showed different efficiency on substrate hydrolysis and had different requirements for the recognition of P2' site of VAMP2, E(78). These differences may be due to their different composition of their substrate recognition pockets in the active site. Swapping of LC/T S1' pocket residue, L(230), with the corresponding isoleucine in LC/B increased LC/T activity by ∼25 fold, while swapping of LC/B S1' pocket residue, S(201), with the corresponding proline in LC/T increased LC/B activity by ∼10 fold. Optimization of both S1 and S1' pocket residues of LC/T, LC/T (K(168)E, L(230)I) elevated LC/T activity by more than 100-fold. The highly active LC/T derivative engineered in this study has the potential to be used as a more effective tool to study mechanisms of exocytosis in central neuron. The LC/B derivative with elevated activity has the potential to be developed into novel therapy to minimize the impact of immunoresistance during BoNT/B therapy.

Judging disease activity in rheumatoid arthritis by serum free kappa and lambda light chain levels

The study aimed to evaluate the levels of serum free kappa (κ) and lambda (λ) light chains in patients with rheumatoid arthritis (RA) as well as exploring the association between serum free κ and λ light chains and activity of RA. For this purpose, healthy individuals and patients with active RA and RA in remission were enrolled, and their serum levels of free κ and λ light chains were measured using rate nephelometry. The diagnostic accuracy of serum free κ and λ light chains was evaluated by receiver operating characteristic curves and 95% confidence intervals for areas under the curve (AUC). The results obtained indicated that the levels of serum free κ and λ light chains in patients with active RA were significantly higher than those of patients in remission and of healthy controls (p < 0.05). Further, the AUC values in patients with active RA were 0.871 for free κ light chain and 0.781 for free λ light chain. When the optimal cut-off point for serum κ light chain was 8.02 g/L, the maximum sensitivity and specificity were 82.5% and 82.5%, respectively, and when the optimal cut-off point for serum λ light chain was 3.57 g/L, the maximum sensitivity and specificity were 80% and 82.5%, respectively. It was thus found that serum levels of free κ and λ light chains were positively correlated with disease activity in RA, the Disease Activity Score 28 (DAS28), and values for C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), platelet count (PLT), rheumatoid factor (RF), and anticitrullinated protein antibody (ACPA) (p < 0.05). In conclusion, high serum levels of free κ and λ light chains in patients with active RA are closely correlated with disease activity parameters including DAS28, CRP, ESR, PLT, RF, and ACPA. Thus, the above-mentioned levels of serum free κ and λ light chains may be used as important indicators of activity of RA.

A closer look to botulinum neurotoxin type A-induced analgesia

Chronic pain indicates a type of pain that lasts over time and is accompanied by diagnostic and therapeutic difficulties. It follows that treatment failures are common and patients roam from doctor to doctor in search of an effective care program. So there is an urgent need for long-acting and effective therapeutics to alleviate symptoms of the varied forms of chronic pain. During the past few years, a good success has been achieved with a derivative of a neurotoxin. It has been shown that administration of this toxin can block the release of neurotransmitters and pain mediators. Botulinum neurotoxin type A (BoNT/A) is well known as a treatment for neuromuscular conditions such as dystonia and spasticity. However, the clinical application for BoNT/A has continued to expand. Its analgesic effect has been used in clinical practice with satisfactory results. This review provides an introduction of a hypothesis for the mechanism by which BoNT/A eases chronic pain. It also summarizes the clinical therapeutic effects of BoNT/A in different types of chronic pain and its potential prospects.

Production and characterization of recombinant light chain and carboxyterminal heavy chain fragments of tetanus toxin

BACKGROUND

Light chain (LC) and heavy chain carboxyterminal subdomain (HCC) fragments are the most important parts of tetanus neurotoxin (TeNT) which play key roles in toxicity and binding of TeNT, respectively. In the present study, these two fragments were cloned and expressed in a prokaryotic system and their identity was confirmed using anti-TeNT specific polyclonal and monoclonal antibodies.

METHODS

LC and HCC gene segments were amplified from Clostridium tetani genomic DNA by PCR, cloned into pET28b(+) cloning vector and transformed in Escherichia coli (E. coli) BL21(DE3) expression host. Recombinant proteins were then purified through His-tag using Nickel-based chromatography and characterized by SDS-PAGE, Western blotting and ELISA techniques.

RESULTS

Recombinant light chain and HCC fragments were successfully cloned and expressed in (E. coli) BL21 (DE3). Optimization of the induction protocol resulted in production of high levels of HCC (~35% of total bacterial protein) and to lesser extends of LC (~5%). Reactivity of the His-tag purified proteins with specific polyclonal and monoclonal antibodies confirmed their renatured structure and identity.

CONCLUSION

Our results indicate successful cloning and production of recombinant LC and HCC fragments of TeNT. These two recombinant proteins are potentially useful tools for screening and monitoring of anti-TeNT antibody response and vaccine production.

Generation and Characterization of Mouse Hybridomas Secreting Monoclonal Antibodies Specific for Human IgG3

Mammalians express several subclasses of the IgG molecule. In human being there are four homologous IgG subclasses, each of which is structurally unique and has different functions. Quantification of IgG subclasses is fundamental to clinical assessment and diagnosis of many diseases as such assessments depends on the availability of subclassspecific antibodies (Abs), particularly monoclonal antibodies (MAbs). In the present study, we produced and characterized two murine MAbs specific for human IgG3 molecule. These MAbs were obtained by the fusion of myeloma cells with splenocytes from Balb/c mice immunized with heavy chain of a human IgG3 myeloma protein. Fused cells were selected in hypoxanthine, aminopterine and thymidine (HAT) medium and cloned by limiting dilution assay. Ab-secreting cells were screened by enzyme-linked immunosorbent assay (ELISA) and the specificity of secreted MAbs was further analyzed, using a panel of purified myeloma proteins by ELISA and immunoblotting. Two stable hybridomas designated 1F18G7 and 1F18A11 were obtained secreting MAbs specific for Fc fragment of human IgG3. None of these MAbs showed cross-reactivity with other immunoglobulin isotypes derived from human and nine other animals, except 1F18A11 which displayed a weak cross-reactivity with only dog serum. Immunoblotting results indicate that these MAbs react with linear epitope(s) located in the heavy chain of human IgG3 molecules. The affinity constant of 1F18G7 and 1F18A11 MAbs was found to be 0.81×10(9) Mol (-1) and 0.71×10(9) Mol (-1), respectively, as measured by ELISA. These two MAbs with relatively high affinity can be useful tools for quantification of IgG3 subclass levels in human serum.