In multiple sclerosis (MS) and other neuroinflammatory diseases, monocyte-derived cells (MoCs) traffic through distinct central nervous system (CNS) barriers and gain access to the organ parenchyma exerting detrimental or beneficial functions. How and where these MoCs acquire their different functional commitments during CNS invasion remains however unclear, thus hindering the design of MS treatments specifically blocking detrimental MoC actions. To clarify this issue, we investigated the distribution of iNOS+ pro-inflammatory and arginase-1+ anti-inflammatory MoCs at the distinct border regions of the CNS in a mouse model of MS. Interestingly, MoCs within perivascular parenchymal spaces displayed a predominant pro-inflammatory phenotype compared to MoCs accumulating at the leptomeninges and at the intraventricular choroid plexus (ChP). Furthermore, in an in vitro model, we could observe the general ability of functionally-polarized MoCs to migrate through the ChP epithelial barrier, together indicating the ChP as a potential CNS entry and polarization site for MoCs. Thus, pro- and anti-inflammatory MoCs differentially accumulate at distinct CNS barriers before reaching the parenchyma, but the mechanism for their phenotype acquisition remains undefined. Shedding light on this process, we observed that endothelial (BBB) and epithelial (ChP) CNS barrier cells can directly regulate transcription of Nos2 (coding for iNOS) and Arg1 (coding for arginase-1) in interacting MoCs. More specifically, while TNF-α+IFN-γ stimulated BBB cells induced Nos2 expression in MoCs, IL-1β driven activation of endothelial BBB cells led to a significant upregulation of Arg1 in MoCs. Supporting this latter finding, less pro-inflammatory MoCs could be found nearby IL1R1+ vessels in the mouse spinal cord upon neuroinflammation. Taken together, our data indicate differential distribution of pro- and anti-inflammatory MoCs at CNS borders and highlight how the interaction of MoCs with CNS barriers can significantly affect the functional activation of these CNS-invading MoCs during autoimmune inflammation.
Copyright © 2021 Ivan, Walthert and Locatelli.

CD62L (L-Selectin) dependent lymphocyte infiltration is known to induce inflammatory bowel disease (IBD), while its function in the liver, especially in non-alcoholic steatohepatitis (NASH), remains unclear. We here investigated the functional role of CD62L in NASH in humans as well as in two mouse models of steatohepatitis. Hepatic expression of a soluble form of CD62L (sCD62L) was measured in patients with steatosis and NASH. Furthermore, CD62L-/- mice were fed with a methionine and choline deficient (MCD) diet for 4 weeks or with a high fat diet (HFD) for 24 weeks. Patients with NASH displayed increased serum levels of sCD62L. Hepatic CD62L expression was higher in patients with steatosis and increased dramatically in NASH patients. Interestingly, compared to wild type (WT) mice, MCD and HFD-treated CD62L-/- mice were protected from diet-induced steatohepatitis. This was reflected by less fat accumulation in hepatocytes and a dampened manifestation of the metabolic syndrome with an improved insulin resistance and decreased cholesterol and triglyceride levels. Consistent with ameliorated disease, CD62L-/- animals exhibited an enhanced hepatic infiltration of Treg cells and a strong activation of an anti-oxidative stress response. Those changes finally resulted in less fibrosis in CD62L-/- mice. Additionally, this effect could be reproduced in a therapeutic setting by administrating an anti-CD62L blocking antibody. CD62L expression in humans and mice correlates with disease activity of steatohepatitis. CD62L knockout and anti-CD62L-treated mice are protected from diet-induced steatohepatitis suggesting that CD62L is a promising target for therapeutic interventions in NASH.

Necrotizing enterocolitis (NEC) triggers an intense inflammatory response in the neonatal gut associated with cytokine activation, altered nutrient status and intracellular O2-deprivation. Endothelial cell adhesion molecules (ECAMs) play critical roles in driving immune cell infiltration into inflamed gut. Currently, relationships between inflammation, metabolism and ECAM expression remain poorly understood in NEC. We studied the effects of metabolic depletion (aglycemia/ hypoxia) on TNF-α  mediated ECAM expression including ICAM-1, MAdCAM-1, VCAM-1 and E-selectin, in vitro in intestinal microvascular endothelial cells (IMEC).
To study the effects of TNF-α, aglycemia and hypoxia (alone or in combination) IMECs expression of adhesion molecules was studied using cell surface ELISA and immunoblotting.
Total VCAM-1 expression was induced TNF-α and by hypoxia + TNF-α, cell surface expression was induced by hypoxia, TNF-α, TNF- α+hypoxia, and TNF- α+hypoxia and aglycemia. Total ICAM-1 increased following TNF- α, TNF- α+hypoxia, hypoxia + aglycemia, and TNF- α+hypoxia + aglycemia. Total MAdCAM-1 protein expression was significantly induced by a combination of TNF-α+hypoxia + aglycemia and cell surface expression induced by TNF- α+hypoxia. Surface expression of E-selectin was induced by TNF- α+aglycemia and TNF- α+hypoxia + aglycemia.
Energy metabolism influences inflammation induced injury through mobilization of intestinal ECAMs, and may represent an important mechanism in NEC pathology.
Copyright © 2019 Elsevier B.V. All rights reserved.

Regulatory T cells (Tregs) are essential to suppress unwanted immunity or inflammation. After islet allo-transplant Tregs must migrate from blood to allograft, then via afferent lymphatics to draining LN to protect allografts. Here we show that Tregs but not non-Treg T cells use lymphotoxin (LT) during migration from allograft to draining LN, and that LT deficiency or blockade prevents normal migration and allograft protection. Treg LTαβ rapidly modulates cytoskeletal and membrane structure of lymphatic endothelial cells; dependent on VCAM-1 and non-canonical NFκB signalling via LTβR. These results demonstrate a form of T-cell migration used only by Treg in tissues that serves an important role in their suppressive function and is a unique therapeutic focus for modulating suppression.

Perineural invasion (PNI) is one of the important routes for local spread of gastric carcinoma associated with poor prognosis. However, the exact cellular characteristics and molecular mechanisms of PNI are still unclear.
To identify the interaction between gastric carcinoma cells and neural cells, and whether vascular cell adhesion molecule-1 (VCAM1) is involved in this process.
We adopted in vitro cell coculture assays to investigate the cellular and molecular interaction between gastric cancer cells and neural cells.
We find upregulation of VCAM1 in clinical gastric cancer tissue samples. In in vitro tumor-neural cell coculture system, gastric cancer cells with high level of VCAM1 promote proliferation of neural progenitor cells and induce the process outgrowth and branching of neural cells. Reciprocally, neural cells enhance neurotropic migration and mobility of tumor cells. Repressing VCAM1 function through VCAM1 blocking antibody can attenuate these effects.
Our study indicates that VCAM1 is significantly involved in tumor invasion via mediating nerve-tumor interaction, which is a mutually beneficial process. It is possible that interaction between neural cells and tumor cells might contribute to PNI of gastric carcinoma. Inhibiting the activity of VCAM1 could be a potential strategy targeting PNI in gastric carcinoma therapy.