Systemic AL (light-chain) amyloidosis and the gastrointestinal tract

Liver and Gastrointestinal Involvement: Update

The organs affected most commonly by AL amyloidosis are the kidneys and heart, however, liver and gastrointestinal (GI) tract are also commonly affected. Symptoms of GI amyloidosis often mimic those of other GI disorders; having a keen awareness of the need to evaluate for amyloidosis is critical in avoiding delay in diagnosis and intervention. GI and liver involvement is associated with significant complications, and challenges in symptomatic management. As with all AL-related organ disease, early systemic treatment can prevent progression of tissue damage and improve outcomes.

Liver and Gastrointestinal Involvement

Early diagnosis of AL amyloidosis and appreciation of the nutritional and coagulation abnormalities associated with liver and gastrointestinal involvement are critically important in the treatment and management. In cases of severe malabsorption total parenteral nutrition can be extremely helpful as a bridge to organ improvement. Rarely the use of antifibrinolytic agents such as oral aminocaproic acid with transfusion support may control severe bleeding in patients with coagulation abnormalities. It is important to keep in mind that organ improvement should follow in lag phase after the reduction in the pathologic free light chain with treatment. Closely following light chain levels may permit brief holidays from treatment and enable periods of recovery before resuming therapy in patients with prompt early and deep hematologic responses.

Primary gastrointestinal amyloidosis with gastrointestinal hemorrhage and intestinal pseudo-obstruction: a report of a rare case

Amyloidosis is a syndrome involving amyloid protein deposition in various organs, resulting in organ dysfunction. Symptoms of gastrointestinal amyloidosis are usually nonspecific, such as diarrhea and body weight loss. We, here, report a patient who presented to the hospital with simultaneous hematemesis, melena, and intestinal pseudo-obstruction, leading to a diagnosis of primary gastrointestinal amyloidosis based on computed tomography (CT) and endoscopic findings. CT showed diffuse wall thickening from the duodenum to the jejunum, jejunal dilation, and fluid accumulation throughout the gastrointestinal tract. Upper gastrointestinal endoscopy revealed duodenal mucosal edema, jejunal dilation, and small hemorrhages from jejunal mucosal erosion. The definite diagnosis was done based on biopsy results. This report describes the early diagnosis of gastrointestinal amyloidosis based on CT and endoscopy findings.

Incomplete ileus and hemafecia as the presenting features of multi-organ involved primary systemic AL amyloidosis: a rare case report

Background

AL Amyloidosis is known to be a systemic disease affecting multiple organs and tissue while it’s rare that patients present with gastrointestinal symptoms at first and later develop multiple-organ dysfuction. Clinical signs are not specific and the diagnosis is rarely given before performing immunofixation and endoscopy with multiple biopsies. We would like to emphasize the value of precise diagnostic process of AL amyloidosis.

Case presentation

In this case report, we describe a 56-year-old man who presented with recurrent periumbilical pain for 4 months and gradually worsened over a month. After a series of tests, he was finally diagnosed with primary systemic AL amyloidosis. He was treated with a chemotherapy regimen (Melphalan, dexamethasone and thalidomide) achieving a good clinical response.

Conclusion

On account of the high misdiagnosis rate, establishing the most precise diagnosis in first time with typing amyloidogenic protein becomes increasingly vital. Although the presenting feature is usually nonspecific, AL amyloidosis ought to be considered when multiple organs are involved in a short period.

Structural and mutational analysis of a monomeric and dimeric form of a single domain antibody with implications for protein misfolding

Camelid single domain antibodies (sdAb) are known for their thermal stability and reversible refolding. We have characterized an unusually stable sdAb recognizing Staphylococcal enterotoxin B with one of the highest reported melting temperatures (T(m) = 85°C). Unexpectedly, ∼10-20% of the protein formed a dimer in solution. Three other cases where <20% of the sdAb dimerized have been reported; however, this is the first report of both the monomeric and dimeric X-ray crystal structures. Concentration of the monomer did not lead to the formation of new dimer suggesting a stable conformationally distinct species in a fraction of the cytoplasmically expressed protein. Comparison of periplasmic and cytoplasmic expression showed that the dimer was associated with cytoplasmic expression. The disulfide bond was partially reduced in the WT protein purified from the cytoplasm and the protein irreversibly unfolded. Periplasmic expression produced monomeric protein with a fully formed disulfide bond and mostly reversible refolding. Crystallization of a disulfide-bond free variant, C22A/C99V, purified from the periplasm yielded a structure of a monomeric form, while crystallization of C22A/C99V from the cytoplasm produced an asymmetric dimer. In the dimer, a significant conformational asymmetry was found in the loop residues of the edge β-strands (S50-Y60) containing the highly variable complementarity determining region, CDR2. Two dimeric assemblies were predicted from the crystal packing. Mutation of a residue at one of the interfaces, Y98A, disrupted the dimer in solution. The pleomorphic homodimer may yield insight into the stability of misfolded states and the importance of the conserved disulfide bond in preventing their formation.