Reactive microglia are the major source of tumor necrosis factor alpha and contribute to astrocyte dysfunction and acute seizures in experimental temporal lobe epilepsy.

in Glia (2023), 71(2), 168-186

Extensive microglia reactivity has been well described in human and experimental temporal lobe epilepsy (TLE). To date, however, it is not clear whether and based on which molecular mechanisms microglia ... [more ▼]

Extensive microglia reactivity has been well described in human and experimental temporal lobe epilepsy (TLE). To date, however, it is not clear whether and based on which molecular mechanisms microglia contribute to the development and progression of focal epilepsy. Astroglial gap junction coupled networks play an important role in regulating neuronal activity and loss of interastrocytic coupling causally contributes to TLE. Here, we show in the unilateral intracortical kainate (KA) mouse model of TLE that reactive microglia are primary producers of tumor necrosis factor (TNF)α and contribute to astrocyte dysfunction and severity of status epilepticus (SE). Immunohistochemical analyses revealed pronounced and persistent microglia reactivity, which already started 4 h after KA-induced SE. Partial depletion of microglia using a colony stimulating factor 1 receptor inhibitor prevented early astrocyte uncoupling and attenuated the severity of SE, but increased the mortality of epileptic mice following surgery. Using microglia-specific inducible TNFα knockout mice we identified microglia as the major source of TNFα during early epileptogenesis. Importantly, microglia-specific TNFα knockout prevented SE-induced gap junction uncoupling in astrocytes. Continuous telemetric EEG recordings revealed that during the first 4 weeks after SE induction, microglial TNFα did not significantly contribute to spontaneous generalized seizure activity. Moreover, the absence of microglial TNFα did not affect the development of hippocampal sclerosis but attenuated gliosis. Taken together, these data implicate reactive microglia in astrocyte dysfunction and network hyperexcitability after an epileptogenic insult. [less ▲]

Soluble TAM receptors sAXL and sTyro3 predict structural and functional protection in Alzheimer's disease.

in Neuron (2022), 110(6), 1009-10224

There is an urgent need to improve the understanding of neuroinflammation in Alzheimer's disease (AD). We analyzed cerebrospinal fluid inflammatory biomarker correlations to brain structural volume and ... [more ▼]

There is an urgent need to improve the understanding of neuroinflammation in Alzheimer's disease (AD). We analyzed cerebrospinal fluid inflammatory biomarker correlations to brain structural volume and longitudinal cognitive outcomes in the DELCODE study and in a validation cohort of the F.ACE Alzheimer Center Barcelona. We investigated whether respective biomarker changes are evident before onset of cognitive impairment. YKL-40; sTREM2; sAXL; sTyro3; MIF; complement factors C1q, C4, and H; ferritin; and ApoE protein were elevated in pre-dementia subjects with pathological levels of tau or other neurodegeneration markers, demonstrating tight interactions between inflammation and accumulating neurodegeneration even before onset of symptoms. Intriguingly, higher levels of ApoE and soluble TAM receptors sAXL and sTyro3 were related to larger brain structure and stable cognitive outcome at follow-up. Our findings indicate a protective mechanism relevant for intervention strategies aiming to regulate neuroinflammation in subjects with no or subjective symptoms but underlying AD pathology profile. [less ▲]

CNS Superficial Siderosis Mimicking a Motor Neuron Disease.

in Brain sciences (2022), 12(11),

Superficial siderosis of the central nervous system (SS-CNS) is a rare condition characterized by a hemosiderin accumulation along the subpial surfaces and arises from an intermittent chronic bleeding in ... [more ▼]

Superficial siderosis of the central nervous system (SS-CNS) is a rare condition characterized by a hemosiderin accumulation along the subpial surfaces and arises from an intermittent chronic bleeding in the subarachnoid space usually as a result of a chronic subarachnoid hemorrhage by trauma, vascular malformations, CNS tumors, or cerebral amyloid angiopathy (CAA). We present a 61-year-old male with a 12-year history of limb weakness, muscle wasting, cramps, clumsiness, progressive unsteady gait, and fine motor impairments. His medical history included the resection of a left parietal meningioma and a myxopapillary ependymoma near the conus terminalis (L3/4) at the age of 51 years. The clinical examination revealed a motor neuron syndrome with a clear bilateral wasting of the hand muscles, a diffuse atrophy of the shoulder and calf muscles, and a weakness of the arms, fingers, hips, and feet. Deep tendon reflexes were symmetrically briskly hyperactive. Standing and walking were only possible with a support. Magnetic resonance imaging of the entire neuroaxis showed progressive severe cerebral, brainstem, and spinal superficial siderosis in form of extensive hypointensities on T2-weighted gradient-echo images and susceptibility-weighted sequences. Despite a successful neurosurgical removal of the tumors and delaed medical treatment with an iron chelator for one year, we observed no clinical recovery or stability in our patient, making this case unique, and suggesting an irreversible neurodegenerative process. This case reinforces the need of including SS-CNS in the list of amyotrophic lateral sclerosis (ALS)-mimics and demonstrates the fundamental use of a complete neuraxial MRI investigation on evaluating possible ALS cases. [less ▲]