Anti-Neurofascin-Associated Nephrotic-Range Proteinuria in Chronic Inflammatory Demyelinating Polyneuropathy

Effectiveness and safety of rituximab in autoimmune nodopathy: a single-center cohort study

Autoimmune nodopathy is a peripheral neuropathy characterized by acquired motor and sensory deficit with autoantibodies against the node of Ranvier or paranodal region in the peripheral nervous system. The clinical and pathological characteristics of the disease are distinct from that of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and the standard treatment for CIDP is partially effective. Rituximab is a chimeric monoclonal antibody which binds and depletes B cells in peripheral blood. This prospective observational study included 19 patients with autoimmune nodopathy. Participants received intravenous rituximab treatment 100 mg the first day and 500 mg the next day and given every 6 months. The Inflammatory Neuropathy Cause and Treatment (INCAT) disability score, Inflammatory Rasch-Built Overall Disability Scale (I-RODS), Medical Research Council (MRC) sum score, and Neuropathy Impairment Score (NIS) were collected at entry and before the rituximab infusion every 6 months. At the last visit, 94.7% (18/19) of the patients showed clinical improvement on either the INCAT, I-RODS, MRC, or NIS scale. After the first infusion, 9 patients (47.7%) showed improvement on the INCAT score, and 11 patients (57.9%) on cI-RODS. In patients who received more than one rituximab infusion, the improvement of INCAT score and cI-RODS at the last assessment was higher than that after the first infusion. We also observed tapered or withdrawn concomitant oral medications in these patients.

CIDP-like autoimmune nodopathy complicated with focal segmental glomerulosclerosis: a case study and literature review

BACKGROUND

This study aimed to investigate the role of neurofascin186 (NF186) in the pathogenesis of the concurrent focal segmental glomerulosclerosis (FSGS) in CIDP-like autoimmune nodopathy patients.

METHODS

We presented a case of CIDP-like autoimmune nodopathy complicated with FSGS. We measured NF186 antibodies by cell-binding assay (CBA) method. We performed immunofluorescence analysis in the renal cryosection samples from a patient with minimal nephropathy with rabbit anti-NF186 antibody or NF186 antibody positive human serum. Then we performed western blotting of recombinant NF186 protein and component of NF186 including Ig and FNIII domains incubating with human serum and corresponding rabbit polyclonal antibody. Cases of CIDP complicated with FSGS were searched form PubMed and reviewed.

RESULTS

We reported a 66-year-old Chinese woman with CIDP-like autoimmune nodopathy and concurrent FSGS. Her NF186 antibody was positive. The fluorescent signal for NF186 was detected in the renal tissue sections of the patient with minimal nephropathy. The staining for NF186 matched the podocyte spatially. In western blotting analysis, patients had antibodies in their serum recognizing the NF186 protein and their antibodies recognized the Ig domain of NF186. 3 cases of CIDP-like autoimmune nodopathy with positive NF186 antibody and FSGS have been reported. All these patients were responsive to corticosteroids rather than the intravenous immunoglobulin, in terms of both the neuropathy and renal disease.

CONCLUSIONS

NF186 was probably a targeted antigen in the pathogenesis of concurrent FSGS in CIDP-like autoimmune nodopathy with positive NF186 antibody. CIDP-like autoimmune nodopathy with positive NF186 antibody and FSGS is a rare entity, which may be responsive to corticosteroids combined with immunosuppressant.

Neuronal Proteins as Antigenic Targets in Membranous Nephropathy

CONTEXT

The discovery of new target antigens in membranous nephropathy (MN) has revealed new disease phenotypes and, in some cases, has suggested mechanisms of disease shared by two concurrent autoimmune diseases. Subject of Review: Several recent reports and an accompanying editorial describe the association of anti-contactin-1 (CNTN1) autoantibodies of the IgG4 subclass with a novel subtype of MN that co-occurs with a form of chronic inflammatory demyelinating polyradiculoneuropathy caused by anti-CNTN1 antibodies. CNTN1, the cellular source of which is still undetermined, is identified as the target antigen in the kidney since it is present within glomerular subepithelial deposits and anti-CNTN1 IgG4 antibodies can be eluted from the corresponding kidney biopsy tissue. Second Opinion: These new reports reinforce recent findings that many proteins targeted in several other types of primary and secondary MN are proteins whose expression is shared by podocytes and neurons. While complement-mediated podocyte damage represents a well-established paradigm in the pathogenesis of MN, interference with the normal functions of these shared proteins by autoantibodies should be considered as another potential mechanism of glomerular injury to be explored in future research.

Anti-Neuronal IgG4 Autoimmune Diseases and IgG4-Related Diseases May Not Be Part of the Same Spectrum: A Comparative Study

Background

IgG4 is associated with two emerging groups of rare diseases: 1) IgG4 autoimmune diseases (IgG4-AID) and 2) IgG4-related diseases (IgG4-RLD). Anti-neuronal IgG4-AID include MuSK myasthenia gravis, LGI1- and Caspr2-encephalitis and autoimmune nodo-/paranodopathies (CNTN1/Caspr1 or NF155 antibodies). IgG4-RLD is a multiorgan disease hallmarked by tissue-destructive fibrotic lesions with lymphocyte and IgG4 plasma cell infiltrates and increased serum IgG4 concentrations. It is unclear whether IgG4-AID and IgG4-RLD share relevant clinical and immunopathological features.

Methods

We collected and analyzed clinical, serological, and histopathological data in 50 patients with anti-neuronal IgG4-AID and 19 patients with IgG4-RLD.

Results

A significantly higher proportion of IgG4-RLD patients had serum IgG4 elevation when compared to IgG4-AID patients (52.63% vs. 16%, p = .004). Moreover, those IgG4-AID patients with elevated IgG4 did not meet the diagnostic criteria of IgG4-RLD, and their autoantibody titers did not correlate with their serum IgG4 concentrations. In addition, patients with IgG4-RLD were negative for anti-neuronal/neuromuscular autoantibodies and among these patients, men showed a significantly higher propensity for IgG4 elevation, when compared to women (p = .005). Last, a kidney biopsy from a patient with autoimmune paranodopathy due to CNTN1/Caspr1-complex IgG4 autoantibodies and concomitant nephrotic syndrome did not show fibrosis or IgG4+ plasma cells, which are diagnostic hallmarks of IgG4-RLD.

Conclusion

Our observations suggest that anti-neuronal IgG4-AID and IgG4-RLD are most likely distinct disease entities.

Tacrolimus Combined with Corticosteroids Improved the Outcome of CIDP Patients with Autoantibodies Against Paranodal Proteins

PURPOSE

To investigate the response of tacrolimus to chronic inflammatory demyelinating polyneuropathy (CIDP) with autoantibodies against paranodal proteins, including neurofascin-155 (NF155), contactin-1 (CNTN1) and contactin-associated protein 1 (Caspr1).

METHODS

We retrospectively reviewed all CIDP patients who carried anti-NF155, CNTN1 and Caspr1 antibodies and were treated with tacrolimus at Tongji hospital from Jan 2018 to Apr 2021.

RESULTS

There were 58 patients with CIDP and only 9 patients had autoantibodies against paranodal proteins (17.2%). Five of the 9 patients received tacrolimus treatment with an initial dose of 2-3 mg once daily. One patient with anti-CNTN1 antibody started tacrolimus and corticosteroid treatment, at the first episode and eventually achieved full clinical remission without relapse. Four patients with anti-NF155 or -Caspr1 antibodies experienced relapse during corticosteroids tapering. Then, they were given oral tacrolimus and presented with clinical improvement. During follow-up, only one patient developed worsening weakness due to unreasonable tacrolimus discontinuation. Moreover, 3 patients were successfully withdrawn from corticosteroids and 2 patients took corticosteroids at low maintenance dose (10mg/d) after tacrolimus treatment. No severe adverse events were observed in all the patients.

CONCLUSION

Patients with autoantibodies against paranodal proteins had a better long-term outcome after adding tacrolimus. Combination therapy with corticosteroids and tacrolimus may be an effective therapeutic regimen.

Efficacy of rituximab treatment in chronic inflammatory demyelinating polyradiculoneuropathy: a systematic review and meta-analysis

BACKGROUND

Current standard treatment in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) has been proved effective, but it is poorly effective in refractory patients and unclear for anti-IgG4 antibody-associated CIDP. Rituximab is a B cell-depleting monoclonal antibody. It has been applied as one of the management strategies in CIDP, but its efficacy is unknown.

OBJECTIVE

To perform a systematic review and a meta-analysis of the efficacy of rituximab treatment in CIDP patients.

METHODS

Through searches in MEDLINE, PubMed, EMBASE, BIOSOS, Web of Science, and Cochrane library on March 31st, 2021, 15 studies were identified. Patients' characteristics, treatment regime and outcome measure were extracted.

RESULTS

Ninety-six patients in 15 studies were included. The pooled estimate of responsiveness was 75% (95% CI 72-78%). The standard mean difference (SMD) of Inflammatory Neuropathy Cause and Treatment (INCAT) disability score improvement was 1.7 (95% CI 1.0-2.3, p value < 0.0001) and the Medical Research Council (MRC) score for muscle power is 1.3 (95% CI - 2.6 to - 0.1, p value 0.04). All of the anti-IgG4 antibody-positive patients showed excellent responses to rituximab treatment.

CONCLUSION

Rituximab was effective in the treatment in CIDP patients, especially in anti-IgG4 antibody-positive patients. Randomized clinical trials are needed to determine the effectiveness and safety of rituximab in CIDP patients.