Chronic inflammatory demyelinating polyneuropathy associated with primary biliary cirrhosis

Autoantibodies Against Dihydrolipoamide S-Acetyltransferase in Immune-Mediated Neuropathies

BACKGROUND AND OBJECTIVES

This study aimed to identify disease-related autoantibodies in the serum of patients with immune-mediated neuropathies including chronic inflammatory demyelinating polyneuropathy (CIDP) and to investigate the clinical characteristics of patients with these antibodies.

METHODS

Proteins extracted from mouse brain tissue were used to react with sera from patients with CIDP by western blotting (WB) to determine the presence of common bands. Positive bands were then identified by mass spectrometry and confirmed for reactivity with patient sera using enzyme-linked immunosorbent assay (ELISA) and WB. Reactivity was further confirmed by cell-based and tissue-based indirect immunofluorescence assays. The clinical characteristics of patients with candidate autoantibody-positive CIDP were analyzed, and their association with other neurologic diseases was also investigated.

RESULTS

Screening of 78 CIDP patient sera by WB revealed a positive band around 60-70 kDa identified as dihydrolipoamide S-acetyltransferase (DLAT) by immunoprecipitation and mass spectrometry. Serum immunoglobulin G (IgG) and IgM antibodies' reactivity to recombinant DLAT was confirmed using ELISA and WB. A relatively high reactivity was observed in 29 of 160 (18%) patients with CIDP, followed by patients with sensory neuropathy (6/58, 10%) and patients with MS (2/47, 4%), but not in patients with Guillain-Barré syndrome (0/27), patients with hereditary neuropathy (0/40), and healthy controls (0/26). Both the cell-based and tissue-based assays confirmed reactivity in 26 of 33 patients with CIDP. Comparing the clinical characteristics of patients with CIDP with anti-DLAT antibodies (n = 29) with those of negative cases (n = 131), a higher percentage of patients had comorbid sensory ataxia (69% vs 37%), cranial nerve disorders (24% vs 9%), and malignancy (20% vs 5%). A high DLAT expression was observed in human autopsy dorsal root ganglia, confirming the reactivity of patient serum with mouse dorsal root ganglion cells.

DISCUSSION

Reactivity to DLAT was confirmed in patient sera, mainly in patients with CIDP. DLAT is highly expressed in the dorsal root ganglion cells, and anti-DLAT antibody may serve as a biomarker for sensory-dominant neuropathies.

Combined Hepatocholangiocarcinoma Associated with Humoral Hypercalcemia of Malignancy and Chronic Inflammatory Demyelinating Polyneuropathy

Paraneoplastic syndromes are often a diagnostic challenge to doctors and may have a heterogeneous presentation, including humoral hypercalcemia of malignancy (HHM), most commonly caused by squamous cell cancer and renal, ovarian, endometrial, and breast cancer. Chronic inflammatory demyelinating polyneuropathy (CIDP) has been described in patients affected by several types of cancer, especially hematologic malignancies, and a possible paraneoplastic pathogenesis of this neurological disease has been suggested. This report describes a 56-year-old man with a history of CIDP diagnosed 3 months earlier and persistently elevated aminotransferases for 18 months who was admitted to our internal medicine unit with abdominal pain, fatigue, and severe hypercalcemia with low serum intact parathyroid hormone. Parathyroid hormone-related protein (PTH-rP) was markedly high. Liver imaging showed a large hepatic mass in the right lobe, and percutaneous ultrasound-guided biopsy revealed histopathological findings consistent with a combined hepatocholangiocarcinoma (CHCC). We supposed that both HHM and CIDP could represent a paraneoplastic manifestation of CHCC.