Amyloid and the GI tract

An unusual phenotype of hereditary AApoAI amyloidosis caused by a novel Asp20Tyr substitution is linked to pH-dependent aggregation of apolipoprotein A-I

Apolipoprotein A-I (apoA-I) plays beneficial roles as the major structural and functional protein on plasma high-density lipoproteins (HDL). However, APOA1 gene mutations can cause protein misfolding and pathologic amyloid deposition in various organs in human hereditary AApoAI amyloidosis, a potentially lethal systemic disease. We report esophageal and duodenal AApoAI amyloidosis in a 56-year-old patient with Barrett's esophagus, a condition involving chronic acid reflux. Amyloid deposits contained full-length apoA-I featuring a novel D20Y mutation identified by gene sequencing and protein mass spectrometry. Genetic analysis of asymptomatic family members revealed autosomal dominant inheritance. Fibril formation by the full-length variant apoA-I rather than its fragments and the location of the mutation in a conserved amyloid-prone N-terminal segment were highly unusual for hereditary AApoA-I amyloidosis. Structural and stability studies of the recombinant D20Y and wild-type apoA-I showed small but significant mutation-induced structural perturbations in the native lipid-free protein at pH 7.4. Major destabilization and aggregation of the variant protein were observed at pH 4.0. We propose that acidic conditions in Barrett's esophagus promoted protein misfolding and amyloid formation by the D20Y variant. These findings expand our understanding of the clinical features and molecular basis of AApoAI amyloidosis and suggest clinical strategies.

Digestive Amyloidosis Trends: Clinical, Pathological, and Imaging Characteristics

Amyloidosis is a group of diseases characterized by the extracellular deposition of abnormally folded, insoluble proteins that lead to organ dysfunction. While it commonly affects the cardiovascular system, gastrointestinal (GI) tract involvement is undetermined. Recent research has focused on understanding the pathophysiology, diagnostic challenges, and therapeutic approaches to GI amyloidosis, particularly in systemic amyloid light-chain (AL) and amyloid A (AA) forms. GI manifestations can include motility disorders, bleeding, and, in severe cases, bowel obstruction. This review highlights the importance of the early recognition of digestive symptoms and associated imagistic findings in GI amyloidosis by analyzing the research that included clinical, pathological, and endoscopic approaches to amyloidosis. A systematic search of the PubMed and Scopus databases identified 19 relevant studies. Our findings showed that amyloid deposits commonly affect the entire GI tract, with AL amyloidosis being the most predominant form. Endoscopic evaluations and biopsy remain key diagnostic tools, with Congo Red staining and mass spectrometry being used to confirm amyloid type. Although progress has been made in diagnosis, the absence of targeted therapies and the indistinct nature of GI symptoms continue to be challenging.

Gastroduodenal Involvement in AL Amyloidosis: Case Report and Literature Review

Gastrointestinal amyloidosis is a rare condition commonly found in the setting of systemic AL amyloidosis. Amyloid can deposit throughout the gastrointestinal tract and the resulting symptoms vary depending on the site of deposition. Gastrointestinal (GI) manifestations can range from weight loss or abdominal pain, to more serious complications like gastrointestinal bleeding, malabsorption, dysmotility, and obstruction. This case describes a patient with known history of IgG lambda AL amyloidosis, presenting with epigastric pain and unintentional weight loss found to have gastroduodenal amyloidosis. The definitive diagnosis of GI amyloidosis requires endoscopic biopsy with Congo red staining and visualization under polarized light microscopy. There are currently no specific guidelines for the management of GI amyloidosis. Generally, the goal is to treat the underlying cause of the amyloidosis along with symptom management. Our patient is being treated with cyclophosphamide, bortezomib, and dexamethasone (CyBorD) and started on hemodialysis due to progression of renal disease.

Gastrointestinal amyloidosis: an often unexpected finding with systemic implications

The gastrointestinal (GI) tract is a common site of amyloidosis, but the incidence, clinicopathologic features, and systemic implications of different types of GI amyloidosis are not well understood. GI amyloid specimens (N = 2511) typed using a proteomics-based method between 2008 and 2021 were identified. Clinical and morphologic features were reviewed in a subset of cases. Twelve amyloid types were identified, including AL (77.9%), ATTR (11.3%), AA (6.6%), AH (1.1%), AApoAIV (1.1%), AEFEMP1 (0.7%), ALys (0.4%), AApoAI (0.4%), ALECT2 (0.2%), Aβ2M (0.1%), AGel (0.1%), and AFib (<0.1%). Amino acid abnormalities indicative of known amyloidogenic mutations were detected in 24.4% ATTR cases. AL, ATTR, and AA types all commonly involved submucosal vessels. They also showed some characteristic patterns of involvement of more superficial anatomic compartments, although there was significant overlap. Common indications for biopsy were diarrhea, GI bleed, abdominal pain, or weight loss. Amyloidosis was usually an unexpected finding, but most AL and ATTR patients were ultimately found to have cardiac involvement (83.5% of AL; 100% of ATTR). Although most GI amyloid is of AL type, over 10% are ATTR, over 5% are AA, and twelve different types were identified in total. GI amyloid is often unexpected but usually signals systemic amyloidosis, thus there should be a low threshold to perform biopsy with Congo red stain in patients with unexplained GI symptoms. Clinical and histologic features are nonspecific, and typing should be performed via a robust method such as proteomics as treatment hinges on correctly identifying the amyloid type.

Primary gastric amyloidosis associated with linitis plastica and delayed progression to systemic amyloidosis and multiple myeloma

We report the case of a woman in her 50s who underwent, 5 years prior, a total gastrectomy after neoadjuvant chemotherapy for diffuse-type gastric cancer diagnosed during a workup for isolated gastric primary light chain (AL) amyloidosis. At the time of diagnosis, immunoglobulins light chain measurements and bone marrow biopsy were performed to rule out multiple myeloma and came back normal. Three years later, the patient developed systemic amyloidosis involving the heart and the lungs, after which she developed multiple myeloma. Isolated amyloid deposits in the stomach are a rare finding. While AL amyloidosis is frequently found in concomitance with multiple myeloma, late progression of primary AL amyloidosis to systemic amyloidosis and multiple myeloma is uncommon.

Factors Associated with Dose Modification of Lenalidomide Plus Dexamethasone Therapy in Multiple Myeloma

Long-term combination treatment with lenalidomide and low-dose dexamethasone is important to achieve a curative effect in patients with multiple myeloma (MM). In this study, the plasma concentration of lenalidomide was measured at 3 h after oral administration, when the drug is in the elimination phase and can be easily measured in outpatients, to identify factors that may lead to the discontinuation of this combination therapy. Patients were assigned to continuation or discontinuation of therapy groups, and the baseline characteristics of patients, lenalidomide concentration, and concentration/dose (C/D) ratios reflecting oral clearance were compared between the two groups. The efficacy and severity of adverse events were also compared. The results showed that patients who discontinued or modified treatment had low plasma concentrations of lenalidomide and C/D ratios, indicating high oral clearance of lenalidomide. The estimated creatinine clearance rate was negatively correlated with the C/D ratio. The plasma concentrations of lenalidomide were independent from kidney function and differed significantly among patients. Taken together, the results indicate that low plasma concentrations of lenalidomide and low C/D ratios may lead to discontinuation of combination therapy in patients with MM. This suggests that early measurement of lenalidomide plasma continuation would help to prevent discontinuation of therapy or a delay in modifying the dose of lenalidomide.

Comparing Clinical, Imaging, and Physiological Correlates of Intestinal Pseudo-Obstruction: Systemic Sclerosis vs Amyloidosis and Paraneoplastic Syndrome

INTRODUCTION

Intestinal pseudo-obstruction is characterized by impaired transit and luminal dilation in the absence of mechanical obstruction. Our study aims to describe the clinical, radiographic, and physiological findings in pseudo-obstruction associated with systemic sclerosis (SSc), amyloidosis, and paraneoplastic syndrome.

METHODS

A retrospective cohort of patients evaluated at our institution between January 1, 2008, and August 1, 2018, was assembled. Clinical, imaging, and physiological characteristics were abstracted from electronic medical records.

RESULTS

We identified 100 cases of pseudo-obstruction (55 SSc, 27 amyloidosis, and 18 paraneoplastic). Female population predominance was seen in SSc (71%) vs male population in amyloidosis (74%). Most common symptom was abdominal bloating in all 3 groups. Vomiting was more common in SSc than amyloidosis (73% vs 46%, P = 0.02). Diarrhea was more common in amyloidosis and SSc compared with paraneoplastic (81% and 67% vs 28%, P < 0.01). Weight loss (>5%) was more common in SSc compared with amyloidosis and paraneoplastic (78% vs 31% and 17%, P < 0.0001). Only small bowel dilation was seen in 79%, 40%, and 44% and only large bowel dilation in 2%, 44%, and 44% of patients in SSc, amyloidosis, and paraneoplastic, respectively. Five of 8 SSc patients had myopathic and 3 of 5 paraneoplastic had neuropathic involvement on gastroduodenal manometry.

DISCUSSION

SSc-associated pseudo-obstruction demonstrates female population predominance and presents with vomiting, diarrhea, and weight loss. Amyloidosis-associated pseudo-obstruction shows male population predominance. Small bowel is more commonly involved than large bowel on both imaging and transit studies in SSc. Myopathic involvement was more common in SSc, contrary to neuropathic in paraneoplastic syndrome.

Malabsorption Secondary to Gout-Induced Amyloidosis

Many chronic inflammatory conditions can lead to systemic amyloidosis. However, secondary amyloidosis has rarely been associated with gout, and the literature reports only a handful of cases, all presenting with renal disease. We report a patient with a history of poorly controlled gout who presented with malabsorption. Endoscopic biopsies confirmed a diagnosis of small intestinal amyloidosis. This was believed to be a consequence of gout. Interestingly, renal involvement was subclinical. Our case raises awareness of this rare association and highlights the importance of considering a diagnosis of amyloidosis in patients who present with the combination of gout and gastrointestinal symptoms.

Acute liver failure due to primary amyloidosis in a nephrotic syndrome: a swiftly progressive course

AL amyloidosis is a clonal plasma cell proliferative disorder characterised by extracellular tissue deposits of insoluble fibrils derived from κ or λ immunoglobulin light chains. The most common organs affected by AL amyloidosis are the kidney, presenting with nephrotic syndrome and/or progressive renal dysfunction, and the heart, with restrictive cardiomyopathy. Hepatic deposition of fibrils occurs in half the cases but the liver is rarely the predominantly affected organ. The most common presentation of hepatic amyloidosis is hepatomegaly with elevated alkaline phosphatase. Acute liver failure with cholestasis and jaundice is a rare complication, with a prevalence of approximately 5%, and is usually associated with a worse prognosis. We report a case of a 39-year-old man admitted to our nephrology department with an unusual presentation of primary amyloidosis with nephrotic syndrome and acute liver failure, complicated by obstructive cholestasis resulting in death 2 months after diagnosis.

Gastric outlet obstruction due to gastric amyloidosis mimicking malignancy in a patient with ankylosing spondylitis

Amyloidosis is a group of disorders characterized by the extracellular accumulation of insoluble, fibrillar proteins in various organs and tissues. It is classified, on the basis of the identity of the precursor protein, as primary, secondary, or familial amyloidosis. Gastrointestinal amyloidosis usually presents as bleeding, ulceration, malabsorption, protein loss, and diarrhea. However, gastric amyloidosis with gastric outlet obstruction mimicking linitis plastica is rare. We report a case of gastrointestinal amyloidosis with gastric outlet obstruction in a patient with ankylosing spondylitis. The patient was indicated for subtotal gastrectomy because of the aggravation of obstructive symptoms, but refused the operation and was transferred to another hospital. Three months later, the patient died of aspiration pneumonia during medical treatment.

Successful use of tocilizumab in a patient with nephrotic syndrome due to a rapidly progressing AA amyloidosis secondary to latent tuberculosis

AA (secondary) amyloidosis is one of the most severe and uncommon complications of several rheumatic disorders and chronic infections such as tuberculosis (TB). Successful treatment depends on the control of the underlying inflammatory process, what can lead to an improvement or a regression in organ dysfunction. If the disorder persists, it has been reported in some cases of AA amyloidosis secondary to rheumatic diseases, that the use of biologic therapy is so far the only opportunity to reduce the development of AA amyloidosis and to reverse established deposits. We report herein a case of a latent TB infection complicated by a life-threatening AA amyloidosis presented as nephrotic syndrome. After an adequate antituberculostatic treatment, AA amyloidosis remained active and Tocilizumab (TCZ) was started with a dramatic resolution of the proteinuria, stabilization of the amyloid deposits and improvement in general condition.

Renal amyloidosis in children

Renal amyloidosis is a detrimental disease caused by the deposition of amyloid fibrils. A child with renal amyloidosis may present with proteinuria or nephrotic syndrome. Chronic renal failure may follow. Amyloid fibrils may deposit in other organs as well. The diagnosis is through the typical appearance on histopathology. Although chronic infections and chronic inflammatory diseases used to be the causes of secondary amyloidosis in children, the most frequent cause is now autoinflammatory diseases. Among this group of diseases, the most frequent one throughout the world is familial Mediterranean fever (FMF). FMF is typically characterized by attacks of clinical inflammation in the form of fever and serositis and high acute-phase reactants. Persisting inflammation in inadequately treated disease is associated with the development of secondary amyloidosis. The main treatment is colchicine. A number of other monogenic autoinflammatory diseases have also been identified. Among them cryopyrin-associated periodic syndrome (CAPS) is outstanding with its clinical features and the predilection to develop secondary amyloidosis in untreated cases. The treatment of secondary amyloidosis mainly depends on the treatment of the disease. However, a number of new treatments for amyloid per se are in the pipeline.