A phosphorylation‑independent monoclonal antibody improves detection of TDP‑43 pathology across frontotemporal lobar degeneration, amyotrophic lateral sclerosis, and limbic predominant age related TDP‑43 encephalopathy neuropathological change

07/08/2026

AI Summary

Phosphorylation-independent monoclonal antibody MAb No. 9 detects pathological TDP-43 across FTLD-TDP, ALS-TDP, and LATE-NC, enhancing neuritic and thread/dot-like pathology detection in types A/B and ALS-TDP.
MAb No. 9 matched pSer409/410 in FTLD-TDP type C and revealed greater limbic burden with both alpha and beta inclusions in stage 3 ADNC LATE-NC.
MAb No. 9 burden correlated with cortical neurodegeneration in FTLD-TDP type A, but correlations were weaker in severely atrophic cortex; filament architecture governs epitope accessibility.

AI Summary

We compared a phosphorylation-independent monoclonal antibody targeting a C-terminal epitope (MAb No. 9) with the phospho-specific pSer409/410 antibody to determine whether its signal relates to regional neurodegeneration in a multicenter autopsy cohort spanning FTLD-TDP types A-C, ALS-TDP, and Alzheimer disease neuropathologic change (ADNC) with or without LATE-NC.

Immunolabeling with MAb No. 9 detected pathological TDP-43 across all diagnostic groups with enhanced labeling of dystrophic neurites and thread/dot-like pathology in FTLD-TDP types A/B and in ALS-TDP.

Basic summary

J Neuropathol Exp Neurol. 2026 Aug 6:nlag085. doi: 10.1093/jnen/nlag085. Online ahead of print.

ABSTRACT

TDP-43 proteinopathies encompass frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP), amyotrophic lateral sclerosis (ALS-TDP), and limbic predominant age related TDP-43 encephalopathy neuropathological change (LATE-NC). These proteinopathies exhibit subtype-specific aggregate architectures that may constrain epitope accessibility in situ. We compared a phosphorylation-independent monoclonal antibody targeting a C-terminal epitope (MAb No. 9) with the phospho-specific pSer409/410 antibody to determine whether its signal relates to regional neurodegeneration in a multicenter autopsy cohort spanning FTLD-TDP types A-C, ALS-TDP, and Alzheimer disease neuropathologic change (ADNC) with or without LATE-NC. Immunolabeling with MAb No. 9 detected pathological TDP-43 across all diagnostic groups with enhanced labeling of dystrophic neurites and thread/dot-like pathology in FTLD-TDP types A/B and in ALS-TDP. MAb No. 9 performance was equivalent to p409/410 in FTLD-TDP type C. In ADNC with stage 3 LATE-NC, MAb No. 9 revealed a greater limbic burden and labeled both α type and β type inclusions. Dual label immunofluorescence demonstrated strong spatial overlap with p409/410 but additionally highlighted fine punctate pathology. MAb No. 9 burden in FTLD-TDP type A correlated strongly with cortical neurodegeneration but showed weaker and variable associations, particularly in severely atrophic cortex. These findings indicate that filament architecture governs C-terminal epitope accessibility and that MAb No. 9 may be a complementary tool for subtype refinement, clinicopathologic correlation and translational biomarker development in TDP-43 proteinopathies.

PMID:42562773 | DOI:10.1093/jnen/nlag085

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