Quantitative Assessment of Neuroinflammation, Myelinogenesis, Demyelination, and Nerve Fiber Regeneration in Immunostained Sciatic Nerves From Twitcher Mice With a Tissue Image Analysis Platform.

Scoring demyelination and regeneration in hematoxylin and eosin-stained nerves poses a challenge even for the trained pathologist. This article demonstrates how combinatorial multiplex immunohistochemistry (IHC) and quantitative digital pathology bring new insights into the peripheral neuropathogenesis of the Twitcher mouse, a model of Krabbe disease. The goal of this investigational study was to integrate modern pathology tools to traditional anatomic pathology microscopy workflows, in order to generate quantitative data in a large number of samples, and aid the understanding of complex disease pathomechanisms. We developed a novel IHC toolkit using a combination of CD68, periaxin-1, phosphorylated neurofilaments and SOX-10 to interrogate inflammation, myelination, axonal size, and Schwann cell counts in sciatic nerves from 17-, 21-, 25-, and 35-day-old wild-type and Twitcher mice using self-customized digital image algorithms. Our quantitative analyses highlight that nerve macrophage infiltration and interstitial expansion are the earliest detectable changes in Twitcher nerves. By 17 days of age, while the diameter of axons is small, the number of myelinated axons is still normal. However, from 21 days onward Twitcher nerves contain 75% of wild-type myelinated nerve fiber numbers despite containing 3 times more Schwann cells. In 35-day-old Twitcher mice when demyelination is detectable, nerve myelination drops to 50%.