Tau and TDP-43 accumulation of the basal nucleus of Meynert in individuals with cerebral lobar infarcts or hemorrhage

Abstract

A previous study reported that a massive cerebral infarct in the territory of the middle cerebral artery (MCA) may be associated with development of neurofibrillary tangles (NFTs) in the ipsilateral basal nucleus of Meynert (BNM). We analyzed 19 cases of an MCA territory infarct and 12 with a putaminal hemorrhage (mean age 82.5 years; female/male ratio 8/23; mean time from stroke onset to autopsy 4182 days). In both groups, 74-100% had a significantly higher rate of phosphorylated tau immunoreactive or Gallyas Braak silver stain-positive neurons on the BNM-affected side than on the BNM-unaffected side. These NFTs were immunoreactive for anti-RD3 and anti-RD4 antibodies, and a triple-band pattern was observed by immunoblot analysis with anti-tau antibody. Most NFTs might be formed within the 5-10 years after stroke onset. There were significantly more TAR DNA-binding protein 43 (TDP43) immunoreactive structures on the BNM-affected side than on the BNM-unaffected side. We showed that many NFTs with TDP43-immunoreactive structures were observed in the ipsilateral BNM associated with a massive cerebral infarct in the MCA territory or a putaminal hemorrhage.

Keywords: Basal nucleus of Meynert (BNM); Cerebral hemorrhage; Cerebral infarction; Cerebrovascular disease; Neurofibrillary tangles (NFTs); TAR DNA-binding protein 43 (TDP43); Tau.

Fig. 1

Gallyas Braak stain in the BNM (a). Immunocytochemistry by anti-tau antibodies AT8 (b), RD3 (c), RD4 (d) and anti-4R (e) in the BNM. Immunocytochemistry by anti-phosphorylated TDP-43 antibody in the BNM. (f) Granular neuronal cytoplasmic inclusion (NCI). (g) Granular glial cytoplasmic inclusion (GCI). (h) Cat’s-eye neuronal intranuclear inclusion (NII). (i) Thread-like structures (dystrophic neurites, DNs). Bar = 100 μm (a-e), 10 μm (f-i)

Fig. 2

Rate of neurofibrillary tangles (NFTs) in neurons of the basal nucleus of Meynert (BNM) of cardiovascular disease (CVD). (a, b) The 19 middle cerebral artery (MCA) territory infarct cases. (c, d) The 11 putaminal hemorrhage cases. (e, f) Other CVD cases. (a, c, e) Phosphorylated tau-immunoreactive (ptau+) neurons. (b, d, f) Gallyas Braak stain-positive (GB+) neurons. (a) In most cases (14/19, 74%), the ratio of ptau+ neurons in total neurons was higher on the BNM-affected side than on the unaffected side. The median rate was also significantly higher on the BNM-affected side than on the unaffected side (p < 0.01). (b) In most cases (16/19, 84%), the rate of GB+ neurons was higher on the BNM-affected side than on the unaffected side. The median rate was also significantly higher on the BNM-affected side than on the unaffected side (p < 0.01). (c) In most cases (11/12, 92%), the rate of ptau+ neurons was higher on the BNM-affected side than on the unaffected side. The median rate was significantly higher on the BNM-affected side than on the unaffected side (p < 0.01). (d) In all 11 cases (100%), the rate of GB+ neurons was higher on the BNM-affected side than on the unaffected side. The median the rate was significantly higher on the BNM-affected side than on the unaffected side (p < 0.01). (e, f) In the other CVD cases, there were no significant differences in ptau+ or GB+ BNM neurons on the affected and unaffected sides

Fig. 3

Rate of NFTs in neurons of the BNM cases of infarcts in the MCA territory and putaminal hemorrhages, by Braak NFT stage. (a, b) Braak NFT stages I and II cases. (c, d) Stages III and IV cases. (e, f) Stages V and VI cases. (a, c, e) Phosphorylated tau-immunoreactive (ptau+) neurons. (b, d, f) Gallyas Braak stain-positive (GB+) neurons. (a) In most cases (21/22, 95%), the rate of ptau+ neurons was higher on the BNM-affected side than on the unaffected side. The median rate was significantly higher on the BNM-affected side than on the unaffected side (p < 0.01). (b) In most Braak NFT stage I and II cases (21/22, 95%), the rate of GB+ neurons was higher on the BNM-affected side than on the unaffected side. The median rate was significantly higher on the BNM-affected side than on the unaffected side (p < 0.01). (c-f) No differences in ptau+ or GB+ BNM neurons on BNM-affected and unaffected sides

Fig. 4

RD3+ and RD4+ (a) or anti-4R+ (b) neurons of the BNM in cases of MCA territory infarcts and putaminal hemorrhages. There were more anti-RD3 antibody immunoreactive (RD3+) neurons when there were more anti-RD4 antibody immunoreactive (RD4+) neurons, regardless of Braak stage. Except for stage V or VI (r = 0.26, p = 0.83), the numbers of RD3+ and RD4+ neurons were strongly correlated (total: r = 0.78, p < 0.01; stage I or II: r = 0.83, p < 0.01; stage III or IV: r = 0.82, p = 0.046) (a). The total number of RD3+ and 4R+ neurons or in stage I or II were strongly correlated (total: r = 0.78, p < 0.01; stage I or II: r = 0.69, p < 0.01), whereas there was no correlation in stage III or IV (r = − 0.14, p = 0.78) or stage V or VI (r = − 1.00) (b)

Fig. 5

NFTs in the BNM and the time interval from stroke to death. (a) In the 22 Braak stage I and II cases, the rate of the differences in the number of phosphorylated tau-immunoreactive (ptau+) neurons between BNM-affected and BNM-unaffected sides and was correlated with the time interval from stroke to death (r = 0.48, p = 0.02). (b) The rates of the number of GB+ neurons and the stroke–death interval were correlated (r = 0.69, p < 0.01). According to the logarithmic curves, NFTs increased during the 5–10 years following stroke onset until death

Fig. 6

Grading the anti-phosphorylated TDP-43 (pTDP-43) structure in the BNM. pTDP-43 immunoreactive neuronal cytoplasmic inclusions (NCIs), glial cytoplasmic inclusions (GCIs), and neuronal intranuclear inclusions (NIIs) were semi-quantitatively scored as 0–3 depending on their total number: 0 = none; 1 = 1–3; 2 = 4–9; 3 = ≥10. pTDP-43 immunoreactive dystrophic neurites (DNs) were semi-quantitatively scored as 0 to 3: 0, absent; 1, sparse; 2, moderate; 3, severe. The grades of the pTDP immunoreactive NCIs/GCIs/NIIs and DNs were significantly higher on the BNM-affected side than on the BNM-unaffected side (p = 0.01, p < 0.01, respectively)

Fig. 7

Immunoblotting of sarkosyl-insoluble fractions with anti-tau antibodies T46, RD3, anti-4R, and RD4. Frozen BNM tissue from one case of an MCA territory infarct was subjected to immunoblotting. Three major abnormal tau bands of 60, 64, and 68 kDa were detected with T46. The lower 60- and 64-kDa bands were detected with RD3, and the upper 64- and 68-kDa bands were detected with anti-4R. RD4 failed to detect these bands. The pattern of these tau bands was indistinguishable from that seen in Alzheimer’s disease