Light chain deposition disease: novel biological insights and treatment advances

Skeletal Myopathy as the Initial Manifestation of Light Chain Multiple Myeloma

Monoclonal gammopathies due to plasma cell dyscrasias can cause various rare neuromuscular disorders. The peripheral nervous system is most commonly affected, while muscle diseases associated with monoclonal gammopathies are rare. Skeletal myopathy, as a manifestation in the context of multiple myeloma, is extremely uncommon and is usually the result of immunoglobulin light chain (AL) amyloidosis deposits in the muscles. Here we present an atypical case of a patient with generalized myopathy as the presenting manifestation of light chain multiple myeloma. Interestingly, muscle involvement in our case was not the consequence of AL amyloidosis deposits but rather due to non-amyloid light chain deposition disease associated with light chain multiple myeloma.

LEARNING POINTS

Light chain multiple myeloma can present as myopathy.Creatine kinase and muscle biopsy specimens only examined using routine stains can be normal in this condition.

An Unusual Case of Cholestatic Hepatitis due to Light-Chain Deposition Disease

Light-chain deposition disease (LCDD) is a rare paraproteinaemia characterized by the deposition of monoclonal immunoglobulins with a non-fibrillar structure and hence Congo red negative deposits. Kidney disease is the more frequent manifestation, but other organs may also be involved. A 70-year-old man with hypertension and mild chronic renal failure showed a hepatomegaly without splenomegaly. His renal and liver test rapidly got worse. A serum electrophoresis and immunofixation isolated monoclonal kappa light-chain gammopathy, with serum free kappa light chain excess. The bone marrow biopsy showed the presence of interstitial infiltration of plasma cells like multiple myeloma type at initial phase. Periumbilical fat biopsy was negative. Echocardiography demonstrated an infiltrative cardiac disease. The biopsies of the duodenum small intestine mucosa showed flaps with eosinophil material (Masson's staining) with atrophic crypts and chronic inflammation at chorion level. Amyloid substance was negative. There was a strong positivity for light chains kappa compatible with LCDD. A liver biopsy confirmed this finding. Therapy with dexamethasone and bortezomib improved clinical state and hepatic and renal laboratory tests. Chemotherapy based on novel anti-myeloma agents should be rapidly considered in LCDD patients with severe organ involvement.

Understanding Mesangial Pathobiology in AL-Amyloidosis and Monoclonal Ig Light Chain Deposition Disease

Patients with plasma cell dyscrasias produce free abnormal monoclonal Ig light chains that circulate in the blood stream. Some of them, termed glomerulopathic light chains, interact with the mesangial cells and trigger, in a manner dependent of their structural and physicochemical properties, a sequence of pathological events that results in either light chain–derived (AL) amyloidosis (AL-Am) or light chain deposition disease (LCDD). The mesangial cells play a key role in the pathogenesis of both diseases. The interaction with the pathogenic light chain elicits specific cellular processes, which include apoptosis, phenotype transformation, and secretion of extracellular matrix components and metalloproteinases. Monoclonal light chains associated with AL-Am but not those producing LCDD are avidly endocytosed by mesangial cells and delivered to the mature lysosomal compartment where amyloid fibrils are formed. Light chains from patients with LCDD exert their pathogenic signaling effect at the cell surface of mesangial cells. These events are generic mesangial responses to a variety of adverse stimuli, and they are similar to those characterizing other more frequent glomerulopathies responsible for many cases of end-stage renal disease. The pathophysiologic events that have been elucidated allow to propose future therapeutic approaches aimed at preventing, stopping, ameliorating, or reversing the adverse effects resulting from the interactions between glomerulopathic light chains and mesangium.

The pathogenesis of renal injury and treatment in light chain deposition disease

Light chain deposition disease (LCDD) is a rare clinical disorder. The deposition of light chain immunoglobulins mainly affects the kidneys, which have different characteristics than other tissues. To date, the therapeutic approach for the treatment of LCDD has no evidence-based consensus, and clinical experience of reported cases guides current disease management strategies. The present systematic review investigates and summarizes the pathological mechanisms of renal injury and the subsequent treatments for LCDD.

Bortezomib-Based Chemotherapy with Autologous Stem Cell Transplantation for Monoclonal Gammopathy of Renal Significance: A Case Report and Literature Review

BACKGROUND/AIMS

The term monoclonal gammopathy of renal significance (MGRS) was introduced in 2012 to emphasize kidney lesions in monoclonal gammopathy patients. Bortezomib-based chemotherapy has become the first-line treatment for MGRS.

OBJECTIVES

The objective of this study was to investigate whether the strategy of combining chemotherapy with autologous stem cell transplantation (ASCT) could improve prognosis and decrease functional kidney impairment in patients with MGRS.

METHODS

We reported the case of a 44-year-old Asian patient who was diagnosed with MGRS and received 5 cycles of Velcade® (a trade name for bortezomib), thalidomide, and dexamethasone therapy (VTD therapy), and subsequently underwent ASCT. In addition, we performed a literature review and summarized the latest advances in the characterization, treatment, and prognosis of MGRS.

RESULTS

The patient was diagnosed with light chain deposition disease by renal biopsy. After 5 cycles of VTD therapy, the patient had a very good partial response characterized by the resolution of M-protein (20.2% before treatment vs. 2.5% after treatment), remission of the level of serum free lambda (FLAM; over 80% decline), and normalization of the serum free light chain (sFLC) ratio (κ to λ). He also had a renal response characterized by a decreased serum creatinine level (1.61 vs.1.34 mg/dL) and less severe proteinuria (6.77 g/24 h vs.1.264 g/24 h) after chemotherapy. Importantly, after ASCT, the patient achieved a complete response (CR) characterized by a negative serum immunofixation electrophoresis (IFE) result and a dramatic decrement in FLAM (over 90%). Furthermore, 6 months after ASCT, the patient still remained in stable condition with a negative IFE result, normal sFLC ratio, and low level of serum creatinine (1.31 mg/dL) and proteinuria (0.339 g/24 h). In our retrospective literature analysis, we found that MGRS patient survival time and renal outcome had been markedly improved by current therapies due to the popularization of bortezomib-based chemotherapy and ASCT.

CONCLUSIONS

The patient successfully achieved CR after VTD therapy followed by ASCT. However, this treatment is controversial, and a standard therapy recommendation for MGRS has not been established. Bortezomib-based chemotherapy combined with ASCT may have prospects for the treatment of MGRS, but the exact effects of ASCT remain unclear and should be thoroughly investigated.

Free immunoglobulin light chain (FLC) promotes murine colitis and colitis-associated colon carcinogenesis by activating the inflammasome

Numerous studies have demonstrated that free Ig light chain (FLC), a novel inflammation mediator, participates in many inflammatory diseases by activating mast cells and extending the survival of neutrophils. However, it remains unclear whether FLC is involved in colitis and colitis-associated colon carcinogenesis (CAC). In this study, we found a significant increase in FLC in murine models of DSS (Dextran Sulfate Sodium Salt)-induced colitis and CAC compared to controls. Peptide F991, a functional blocker of FLC, significantly attenuated colitis progression, which included abrogating the development of diarrhea and tumor burden, elevating survival rate, greatly reducing the infiltration of inflammatory cells (such as ROS⁺ active neutrophils), especially reducing tumorigenesis in CAC. Furthermore, we demonstrated that F991 inhibited the activation of the inflammasome by reducing the expression of cleaved caspase-1 and the maturation of IL-1β and IL-18. Altogether, our findings demonstrate that FLC can promote the pathogenesis of colitis and CAC and may be used as novel biomarker for the diagnosis of inflammatory bowel disease. Additionally, F991 may become a potential therapeutic option for colitis or colorectal cancer.

Protein Misfolding, Amyloid Formation, and Human Disease: A Summary of Progress Over the Last Decade

Peptides and proteins have been found to possess an inherent tendency to convert from their native functional states into intractable amyloid aggregates. This phenomenon is associated with a range of increasingly common human disorders, including Alzheimer and Parkinson diseases, type II diabetes, and a number of systemic amyloidoses. In this review, we describe this field of science with particular reference to the advances that have been made over the last decade in our understanding of its fundamental nature and consequences. We list the proteins that are known to be deposited as amyloid or other types of aggregates in human tissues and the disorders with which they are associated, as well as the proteins that exploit the amyloid motif to play specific functional roles in humans. In addition, we summarize the genetic factors that have provided insight into the mechanisms of disease onset. We describe recent advances in our knowledge of the structures of amyloid fibrils and their oligomeric precursors and of the mechanisms by which they are formed and proliferate to generate cellular dysfunction. We show evidence that a complex proteostasis network actively combats protein aggregation and that such an efficient system can fail in some circumstances and give rise to disease. Finally, we anticipate the development of novel therapeutic strategies with which to prevent or treat these highly debilitating and currently incurable conditions.

Light chain Fanconi syndrome in a patient with acute myeloid leukemia and monoclonal gammopathy of undetermined significance

Proximal tubules are a target for paraproteinemic diseases. Cast nephropathy, light chain deposition diseases, and amyloidosis are frequently encountered in patients with multiple myeloma. Rarely, a subset of patients develop light chain Fanconi syndrome (LCFS). LCFS has been reported with multiple myeloma, monoclonal gammopathy of renal significance (MGRS), chronic lymphocytic leukemia, Waldenstrom's macroglobulinemia and diffuse large B-cell lymphoma. No cases have been described with other hematologic malignancies. We report the first case of lambda LCFS in a patient with both acute myeloid leukemia (AML) and monoclonal gammopathy of undetermined significance (MGUS).

Association between left ventricular function and paraprotein type in patients with multiple myeloma

BACKGROUND/AIMS

Multiple myeloma (MM)-associated cardiac damage, particularly according to the type of monoclonal (M) protein has not been elucidated. We sought to investigate relationship between elevated serum M protein levels and echocardiographic indices of cardiac structure and function in patients with MM.

METHODS

We evaluated a total of 184 consecutive MM patients who underwent echocardiography for bone marrow pre-transplant screening. Serum levels of intact immunoglobulin M protein and free light chain kappa/lambda (FLC-κ/-λ) were measured.

RESULTS

One hundred thirty-nine patients were non-light chain MM (non-LCMM) and 45 patients belonged to LCMM. In patients with non-LCMM, significant correlations were found between serum M protein and left atrial volume index (LAVi; r = 0.720, p < 0.0001), E/e' (r = 0.511, p < 0.0001), and systolic pulmonary arterial pressure (r = 0.485, p < 0.0001). In patients with LCMM, log-transformed FLC-λ (log-λ) was correlated with left ventricular ejection fraction (LVEF, r = -0.536, p = 0.010), left ventricular (LV) end-systolic dimension (r = 0.500, p = 0.018), and LV end-systolic volume (r = 0.444, p = 0.038). On multivariate analyses, hematocrit and serum M protein were independent predictors of LAVi in patients with non-LCMM. In patient with LCMM, FLC-λ isotype was only found to be an independent determinant of LVEF.

CONCLUSIONS

An increase in serum M protein was associated with LV diastolic dysfunction, whereas an increase in serum FLC-λ concentration showed a negative correlation with the echocardiographic parameters of LV systolic function. These findings also suggest that serum M protein has different effects on LV function according to the type of paraproteins in patients with MM.

Light Chain Deposition Disease Diagnosed with Laser Micro-dissection, Liquid Chromatography, and Tandem Mass Spectrometry of Nodular Glomerular Lesions

A 42-year-old man developed nephrotic syndrome and rapidly progressive renal failure. Kidney biopsy demonstrated nodular glomerulosclerosis, negative Congo red staining, and no deposition of light or heavy chains. Laser micro-dissection and liquid chromatography with tandem mass spectrometry of nodular lesions revealed the presence of a kappa chain constant region and kappa III variable region, which signified light chain deposition disease. Dexamethasone and thalidomide were effective in decreasing the serum levels of free kappa light chain from 147.0 to 38.0 mg/L, eliminating proteinuria, and halting the worsening of the kidney dysfunction, with serum creatinine levels stable around 4.0 mg/dL for 3 years.

Light Chain Deposition Disease in an Older Adult Patient Successfully Treated with Long-term Administration of Bortezomib, Melphalan and Prednisone

A 70-year-old woman was admitted to our hospital because of fatigue and renal dysfunction and was diagnosed with light chain deposition disease (LCDD) with multiple organ involvement (kidney, thyroid gland, heart and eyes). After chemotherapy with bortezomib, cyclophosphamide and dexamethasone, hepatobiliary enzyme levels increased abruptly. A liver biopsy showed light chain deposition in Disse spaces. After two years of treatment with bortezomib, melphalan and prednisone (VMP) administered at shorter intervals relative to regular cycles, the patient showed a hematological and organ response. This case indicates that a relatively low dose intensity VMP regimen is preferable for elderly patients with LCDD with multiple organ involvement.

Five Sequential Evaluations of Renal Histology in a Patient with Light Chain Deposition Disease

A 58-year-old man was referred to our institution for an evaluation of nephrotic range proteinuria. Renal biopsy showed a marked expansion of the mesangial matrix and thickening of glomerular basement membrane (GBM) in periodic acid-silver methenamine (PAM). Immunofluorescence (IF) revealed strong staining for the monoclonal kappa light chain. EM demonstrated massive subendothelial and mesangial dense deposits. As a result, light chain deposition disease (LCDD) was diagnosed. Melphalan and prednisolone (MP) therapy was started, which was continued for 10 years with minimal complications. Serial evaluations of renal histology revealed the resolution of nodular lesions and the glomeruli became nearly normal. MP therapy can therefore be an effective therapeutic option for LCDD if it is continued over the long term.

Nonamyloid tumoral light-chain-deposition disease (aggregoma) of the paraspinal region

Aggregomas are rare localized masses of monoclonal nonamyloid immunoglobulin light-chain deposits. To date, there have been only a few reports of isolated aggregomas, with the majority detailing renal, lymph node and brain deposition. We present a rare case of paraspinal aggregoma in a 67-year-old female who presented with a complaint of cough and chest pain. Imaging demonstrated a left-sided paravertebral mass extending from T7-T10. Pathological analysis showed lamellar deposition of extracellular eosinophilic material with an associated lymphoplasmacytic nonamyloid infiltrate. To our knowledge, this is the first report of a paraspinal aggregoma. While exceedingly rare, this tumor can be included in the radiologic differential diagnosis of paravertebral soft tissue tumors in adults. The observation of our case adds to the limited understanding of the etiology, pathogenesis, natural history, and treatment of nonamyloid light-chain depositions.

Light-Chain Deposition Disease Successfully Treated with Bortezomib in an Elderly Patient: A Case Report and Review of the Literature

We herein report the case of an elderly patient with light-chain deposition disease (LCDD) successfully treated with bortezomib. An 83-year-old woman was admitted because of nephrotic syndrome. She was diagnosed to have monoclonal gammopathy of undetermined significance (IgG-κ type) and LCDD, on the basis of serum and urinary immunoelectrophoresis and renal biopsy. She responded to a modified regimen of bortezomib-based chemotherapy with disappearance of proteinuria without any adverse effects. According to a literature review of 16 cases, including the present case, bortezomib-based chemotherapy appears to be a convincing strategy for the treatment of LCDD even in elderly patients.

Isolated intracerebral light chain deposition disease: novel imaging and pathologic findings

Light chain deposition disease (LCDD) is a rare clinicopathologic entity first described in 1976 and is characterized by a monoclonal gammopathy resulting in nonamyloid immunoglobulin light chain tissue deposition. Only four cases of intracerebral LCDD have been previously reported, all in the setting of a known plasma cell dyscrasia or in the presence of local mature plasma cells. We present the first case of intracranial LCDD in the absence of a known plasma cell dyscrasia or local mature plasma cells.

Thermal stability threshold for amyloid formation in light chain amyloidosis

Light chain (AL) amyloidosis is a devastating disease characterized by amyloid deposits formed by immunoglobulin light chains. Current available treatments involve conventional chemotherapy and autologous stem cell transplant. We have recently concluded a phase III trial comparing these two treatments. AL amyloidosis patients who achieve hematological complete response (CR) do not necessarily achieve organ response regardless of the treatment they received. In order to investigate the possible correlation between amyloid formation kinetics and organ response, we selected AL amyloidosis patients from the trial with kidney involvement and CR after treatment. Six patients were selected and their monoclonal immunoglobulin light chains were characterized. The proteins showed differences in their stability and their kinetics of amyloid formation. A correlation was detected at pH 7.4, showing that less stable proteins are more likely to form amyloid fibrils. AL-T03 is too unstable to form amyloid fibrils at pH 7.4. This protein was found in the only patient in the study that had organ response, suggesting that partially folded species are required for amyloid formation to occur in AL amyloidosis.

Modern approaches to the treatment of amyloidosis: the critical importance of early detection in surgical pathology

The amyloidoses comprise a group of disorders of diverse etiology, in which different proteins undergo abnormal folding, leading to their deposition in tissues and concomitant tissue toxicity. This process ultimately leads to tissue destruction, with organ failure and progressive disease. Recent progress in the treatment of the systemic amyloidoses has dramatically changed the outlook for affected patients and their families. From a relatively rare and esoteric disorder that was typically diagnosed only at autopsy, or was invariably fatal if diagnosed during life, it has now become a disease for which, with modern therapies, durable responses and long-term survival can be achieved. The clinical symptoms are largely nonspecific, and therefore misdiagnosis, or late diagnosis, have been major detriments in achieving better treatment outcomes. Despite advances in laboratory medicine, amyloidoses are still diagnosed on the basis of the pathologic detection of deposits in tissues. Thus, effective primary screening for these diseases requires the active engagement of the pathology community at large, while specialized laboratories and treatment centers can offer secondary consultation and assistance with further steps. This review provides an update on pathogenesis, the clinical and pathologic features, and treatments of various amyloidoses, as well as the current terminology, classification, and practical considerations that are relevant to the diagnosis.

Differential diagnosis of monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is an asymptomatic plasma cell disorder occurring in 4.2% of adults > 50 years of age, which can progress into symptomatic diseases either through proliferation of the plasma cell clone, giving rise to multiple myeloma and other lymphoplasmacellular neoplasms, or through organ damage caused by the monoclonal protein, as seen in light-chain amyloidosis and related conditions. Differential diagnosis of asymptomatic and symptomatic monoclonal gammopathies is the determinant for starting therapy. The criteria for determining end-organ damage should include markers of organ injury caused by the monoclonal protein. Patient assessment and optimal follow-up are now performed using risk stratification models that should also take into account the risk of developing AL amyloidosis. Patients with low-risk MGUS (approximately 40% of all MGUS patients) need limited assessment and very infrequent follow-up. The ongoing development of novel molecular biomarkers and advanced imaging techniques will improve the identification of high-risk patients who may benefit from early therapeutic intervention through innovative clinical trials.