Severe oxidative stress in an acute inflammatory demyelinating model in the rhesus monkey

Oxidative stress is increasingly implicated as a co-factor of tissue injury in inflammatory/demyelinating disorders of the central nervous system (CNS), such as multiple sclerosis (MS). While rodent experimental autoimmune encephalomyelitis (EAE) models diverge from human demyelinating disorders with respect to limited oxidative injury, we observed that in a non-human primate (NHP) model for MS, namely EAE in the common marmoset, key pathological features of the disease were recapitulated, including oxidative tissue injury. Here, we investigated the presence of oxidative injury in another NHP EAE model, i.e. in rhesus macaques, which yields an acute demyelinating disease, which may more closely resemble acute disseminated encephalomyelitis (ADEM) than MS. Rhesus monkey EAE diverges from marmoset EAE by abundant neutrophil recruitment into the CNS and destructive injury to white matter. This difference prompted us to investigate to which extent the oxidative pathway features elicited in MS and marmoset EAE are reflected in the acute rhesus monkey EAE model. The rhesus EAE brain was characterized by widespread demyelination and active lesions containing numerous phagocytic cells and to a lesser extent T cells. We observed induction of the oxidative stress pathway, including injury, with a predilection of p22phox expression in neutrophils and macrophages/microglia. In addition, changes in iron were observed. These results indicate that pathogenic mechanisms in the rhesus EAE model may differ from the marmoset EAE and MS brain due to the neutrophil involvement, but may in the end lead to similar induction of oxidative stress and injury.</p

NUAK1 and NUAK2 Fine-Tune TGF-β Signaling

Transforming growth factor-β (TGF-β) signaling plays a key role in governing various cellular processes, extending from cell proliferation and apoptosis to differentiation and migration. Due to this extensive involvement in the regulation of cellular function, aberrant TGF-β signaling is frequently implicated in the formation and progression of tumors. Therefore, a full understanding of the mechanisms of TGF-β signaling and its key components will provide valuable insights into how this intricate signaling cascade can shift towards a detrimental course. In this review, we discuss the interplay between TGF-β signaling and the AMP-activated protein kinase (AMPK)-related NUAK kinase family. We highlight the function and regulation of these kinases with focus on the pivotal role NUAK1 and NUAK2 play in regulating TGF-β signaling. Specifically, TGF-β induces the expression of NUAK1 and NUAK2 that regulates TGF-β signaling output in an opposite manner. Besides the focus on the TGF-β pathway, we also present a broader perspective on the expression and signaling interactions of the NUAK kinases to outline the broader functions of these protein kinases. Simple Summary TGF-β is a growth factor implicated in a plethora of processes and malignancies, which include cancer and fibrosis. Via binding to its receptor, TGF-β activates a complex intracellular signal transduction pathway, which is controlled by many forms of positive as well as negative feedback. The integrated sum of this feedback determines the outcome and cellular response to TGF-β. In this review, we discuss the role of NUAK1 and NUAK2, a subgroup of the 5′AMP-activated protein kinase family, in providing feedback on intracellular TGF-β signaling. In addition, we discuss how NUAKs mechanistically augment or attenuate the TGF-β response to steer the cell towards a specific output. Understanding the role of NUAKs may aid in developing specific therapeutic agents to combat TGF-β-dependent disease.Title in Web of Science: NUAK1 and NUAK2 Fine-Tune TGF-beta Signaling</p

Quantification of lesion cellularity.

<p>From 5 monkeys with clinically evident EAE, cell infiltrates in 15 NAWM and 15 active demyelinating areas were quantified with ImageJ and expressed as cells/mm². Shown is the quantification of microglia/macrophage (Iba-1), macrophage and neutrophils (MRP14), neutrophils (CD66) and T cells (CD3) as NAWM versus active lesion (A-D). Lesions of each individual animal are shown by similar symbols: closed circle, R06030; closed square, R06052; open circle, R06088; open square, R07035; closed triangle, R08043. Statistics was calculated with the mean per animal. Results were also combined and reported as cells/mm²(F). Statistical significance is indicated as: * when p<0.05.</p

Iron accumulates in rhesus brain.

<p>To determine tissue specific iron, Turnbull staining was performed on healthy control and EAE brain tissue from rhesus monkeys. Shown are overview images of PLP (A,D), MRP14 (B,E), and Turnbull (C,F) of a control brain (A-C) and an EAE brain (D-F). In the control brain, iron accumulation was strongest in the GM (A,C). In the EAE brain no distinct pattern of iron staining emerged. Image scale bars are 200 μm (open square).</p

Characterization of rhesus monkey EAE brain pathology.

<p>Tissue was stained for myelin (PLP; A-B), microglia/macrophages (Iba-1; C-D), macrophages & neutrophils (MRP14; E-F), neutrophils (CD66; G-H), and T cell markers (CD3; I-J). In the NAWM (left column), infiltrating immune cells were sparse or absent, yet markedly upregulated in the active lesions (right column). The dominant immune cell types of the active lesion were macrophage/microglia (D, F) and neutrophils (H). T cells, as determined by CD3 positivity, were readily detected in large numbers, yet visually less abundant than other cell types (J). The image scale bar is 100 μm.</p

Antibodies used for immunocytochemistry.

<p>Antibodies used for immunocytochemistry.</p