Leukocyte Cell-Derived Chemotaxin-2 Amyloidosis - An Overview

Introduction

An uncommon disorder called amyloidosis occurs when proteins misfold and create insoluble fibrils that accumulate outside cells. When exposed to polarized light, a unique stain known as Congo red, which exhibits an apple-green birefringence (the optical characteristic of a substance whose refractive index is dependent upon the direction and polarization of light), can be used to identify these amyloid plaques. These amyloid deposits are known to be formed by 31 different proteins.

Amyloidosis can have a localized or systemic effect, affecting multiple bodily parts. The most prevalent kind in the US (United States) and Europe is AL amyloidosis, caused by Ig light chains. The prevalence of AA (secondary) amyloidosis is higher in developing nations. The kidneys are frequently impacted by rare inherited forms of amyloidosis and AA and AL (primary or light chain) forms.

In 2008, a novel form of amyloidosis known as ALECT2 (amyloidosis associated with leukocyte cell-derived chemotaxin 2) was identified. Leukocyte cell-derived chemotaxin 2 (LECT2) is the protein that is involved. Research has demonstrated that the liver and kidneys are typically impacted by ALECT2 amyloidosis. It usually manifests as chronic kidney problems and is more prevalent in specific ethnic groups. Compared to patients with AL or AA amyloidosis, those with ALECT2 amyloidosis typically have higher survival rates. The current knowledge about ALECT2 amyloidosis is reviewed in this paper, including its incidence, effects on various organs, symptoms, etiology, appearance under a microscope, survival rates, poor prognostic indicators, and recurrence following kidney transplants.

What Organs Are Primarily Affected by ALECT2 Amyloidosis?

The liver and kidneys are the primary organs affected by ALECT2 amyloidosis, while others may also be affected. Between 2007 and 2012, 120 individuals in a study had an ALECT2 amyloidosis diagnosis. 36 of them had liver involvement, 72 had kidney involvement, and a handful had amyloid deposits in the parathyroid gland, pancreas, gallbladder, spleen, and small bowel.

For patients without symptoms in other organs, kidney or liver biopsies were used to make the majority of ALECT2 amyloidosis diagnoses. Despite reports of the lung condition, no verified examples of ALECT2 amyloidosis in the heart have been found. One patient exhibited amyloidosis in both the liver and the heart, but only the liver amyloid was identified as ALECT2.

In certain instances, amyloid deposits have been observed in patients with kidney ALECT2 amyloidosis bone marrow. To learn more about the systemic nature and prevalence of ALECT2 amyloidosis, ongoing autopsy studies are being conducted in the southwestern United States.

What Are the Typical Age of Diagnosis and Clinical Presentations of ALECT2 Amyloidosis?

The liver and kidneys are the most frequently affected organs in older persons with ALECT2 amyloidosis. Patients with kidney involvement are usually diagnosed at a median age of 69, whereas patients with liver involvement are normally diagnosed at 61. The youngest patient to receive a diagnosis before turning 50 is 33.

Chronic renal insufficiency is the typical presentation of kidney ALECT2 amyloidosis, with serum creatinine levels averaging approximately three mg/dl (milligrams per deciliter) at diagnosis. In contrast to other forms of renal amyloidosis, complete nephrotic syndrome (a kidney condition that results in excessive protein excretion in the urine) is uncommon, and proteinuria (high protein levels in the urine) varies from 33 percent to 79 percent of cases. Occasionally, ALECT2 amyloidosis is unintentionally found when performing kidney surgery to treat other diseases, like renal cell carcinoma (a type of kidney cancer).

Diabetes and chronic hypertension (high blood pressure) are prevalent in these people. Some people also have carcinoma (cancer). One patient had lung and kidney ALECT2 amyloidosis, but another illness probably caused their lung problems.

Liver biopsies for different reasons frequently result in the unintentional discovery of liver ALECT2 amyloidosis. Increased levels of alkaline phosphatase are the most typical symptom. Seldom does ALECT2 result in serious side effects such as portal hypertension (elevated pressure in the portal venous network) and variceal hemorrhage (a common and fatal side effect of portal hypertension), in contrast to liver AL amyloidosis, which typically manifests as liver enlargement and abnormal liver function tests.

What Role Does Leukocyte Cell–Derived Chemotaxin 2 (LECT2) Play in ALECT2 Amyloidosis?

First discovered in 1996, leukocyte cell-derived chemotaxin 2 (LECT2) is a tiny protein in humans and animals. It is mostly made by liver cells and resembles a protein found in bovine cartilage. LECT2 is involved in immunological response, cell proliferation, and tissue healing, among other bodily functions. It is also connected to certain malignancies and liver disorders.

The blood level of LECT2 can vary depending on one's health. For instance, it is reduced in severe infections but higher in obesity and liver illnesses. LECT2 may play a role in diseases like metabolic problems and arthritis.

Amyloid fibrils, abnormal clumps of LECT2 protein that can harm organs like the liver and kidneys, are a symptom of ALECT2 amyloidosis. Although the precise cause of this is unknown, it may be related to genetics or issues with the body's handling of LECT2.

According to research, ALECT2 amyloidosis may be caused by the overproduction of LECT2 by liver cells, which may be brought on by genetics or liver injury—organ damage results from the unstable LECT2 protein forming amyloid fibrils.

Improved prevention and therapy approaches for ALECT2 amyloidosis may result from a deeper comprehension of LECT2 and its function in the disease.

What Is the Recommended Diagnostic Approach for ALECT2 Amyloidosis?

The most effective method for diagnosing ALECT2 amyloidosis and other forms of amyloidosis is to use LC-MS (Liquid Chromatography Mass Spectrometry)-based proteomics, a single, extremely sensitive, and accurate test. Identifying the LECT2 protein, which plays a role in ALECT2 amyloidosis, is simple with this technique. Differentiating ALECT2 amyloidosis from other forms, such as AL amyloidosis, which necessitates multiple antibody stainings, is crucial. Even though LECT2 detection antibodies are available, they may produce false-positive results. Hence, LC-MS confirmation is advised, particularly in situations with faint staining or other anomalies. Using a panel of antibodies against various forms of amyloidosis and adhering to a meticulously tested testing protocol is essential for ensuring a precise diagnosis.

What Are the Prognosis and Treatments for ALECT2 Amyloidosis?

Because ALECT2 amyloidosis typically doesn't harm the heart, survivors with ALECT2 amyloidosis typically have better survival rates than those with AL or AA amyloidosis. Just six percent of the 72 individuals in the research with renal ALECT2 amyloidosis passed away following a follow-up of roughly 22 months. Nevertheless, renal function might deteriorate, and approximately 39 percent of patients may require kidney replacement therapy in the long run.

There is not a specific treatment for ALECT2 amyloidosis at the moment. The ALECT2 amyloidosis protein is normal, which means that liver transplantation, which is occasionally used to treat other forms of amyloidosis, may not be effective. On the other hand, certain patients with advanced kidney failure may benefit from renal transplantation. In one study, out of five kidney transplant recipients, one had the condition again; nevertheless, most patients recovered well in the short run.

Drugs that help the body eliminate the aberrant protein or lessen the development of the protein implicated in ALECT2 amyloidosis may be used as future treatments. It is crucial to distinguish ALECT2 amyloidosis from AL amyloidosis as the two conditions require distinct therapies, and administering the incorrect one could have negative effects. Chemotherapy intended for AL amyloidosis was sometimes administered to patients in error, which proved ineffective for ALECT2 amyloidosis.

Conclusion

Amyloidosis associated with leukocyte cell-derived chemotaxin 2 (ALECT2 amyloidosis) is an uncommon kind of amyloidosis primarily affecting the liver and kidneys. It is more common among Hispanics and several other ethnic groups and has unique clinical and pathologic features, including a strong ethnic bias. Because of its excellent sensitivity and specificity, proteomics based on LC-MS is often used in diagnosis. Even though patient survival is typically higher than in cases of other forms of amyloidosis, no particular medication is now available, which emphasizes the need for more research into efficacious treatment approaches.