CCL4 induces inflammatory signalling and barrier disruption in the neurovascular endothelium

Abstract

Background During neuroinflammation many chemokines alter the function of the blood-brain barrier (BBB) that regulates the entry of macromolecules and immune cells into the brain. As the milieu of the brain is altered, biochemical and structural changes contribute to the pathogenesis of neuroinflammation and may impact on neurogenesis. The chemokine CCL4, previously known as MIP-1β, is upregulated in a wide variety of central nervous system disorders, including multiple sclerosis, where it is thought to play a key role in the neuroinflammatory process. However, the effect of CCL4 on BBB endothelial cells (ECs) is unknown. Materials and methods Expression and distribution of CCR5, phosphorylated p38, F-actin, zonula occludens-1 (ZO-1) and vascular endothelial cadherin (VE-cadherin) were analysed in the human BBB EC line hCMEC/D3 by Western blot and/or immunofluorescence in the presence and absence of CCL4. Barrier modulation in response to CCL4 using hCMEC/D3 monolayers was assessed by measuring molecular flux of 70 ​kDa RITC-dextran and transendothelial lymphocyte migration. Permeability changes in response to CCL4 in vivo were measured by an occlusion technique in pial microvessels of Wistar rats and by fluorescein angiography in mouse retinae. Results CCR5, the receptor for CCL4, was expressed in hCMEC/D3 cells. CCL4 stimulation led to phosphorylation of p38 and the formation of actin stress fibres, both indicative of intracellular chemokine signalling. The distribution of junctional proteins was also altered in response to CCL4: junctional ZO-1 was reduced by circa 60% within 60 ​min. In addition, surface VE-cadherin was redistributed through internalisation. Consistent with these changes, CCL4 induced hyperpermeability in vitro and in vivo and increased transmigration of lymphocytes across monolayers of hCMEC/D3 cells . Conclusion These results show that CCL4 can modify BBB function and may contribute to disease pathogenesis.

C5aR1 antagonism alters microglial polarization and mitigates disease progression in a mouse model of Alzheimer’s disease

“…Ccl4 signaling sent from microglia 16 is enriched in PMX205 treated mice. Ccl4 stimulation has led to brain barrier disruption in vivo and in vitro [ 53 ], which can lead to increased PVM macrophage infiltration. Interestingly, in the PMX205 treated mice, both microglia 13 and 16 are sources of App signaling, which ligates to Cd74 receptors in PVM macrophages (Fig.…”

Small immunological clocks identified by Deep Learning and Gradient Boosting

“…This step of the study is shown schematically as a part of the general flowchart in Figure 3(b). The following biomarkers from the Top-10 IL6 97,98 , CSF1 99 , CXCL10 100 , PDGFA 101 , CCL2 102 are associated with aging, while the rest CXCL9 31 , CCL22 103 , PDGFB 104 , CCL4 105 , IL1RA 106 are associated with different age-related and inflammatory pathological conditions.…”

“…This step of the study is shown schematically as part of the general flowchart in Figure 3(b). Such Top-10 biomarkers as IL6 96,97 , CSF1 98 , CXCL10 99 , PDGFA 100 , CCL2 101 are associated with aging, and the other CXCL9 31 , CCL22 102 , PDGFB 103 , CCL4 104 , IL1RA 105 are associated with different age-associated and inflammatory pathological conditions. Figure 4(b) shows the relative distribution of the 10 selected immunological biomarker values and chronological age.…”

C5aR1 antagonism alters microglial polarization and mitigates disease progression in a mouse model of Alzheimer’s disease

“…Ccl4 signaling sent from microglia 16 is enriched in PMX205 treated mice. Ccl4 stimulation has led to brain barrier disruption in vivo and in vitro ( 43 ), which can lead to increased PVM macrophage infiltration. Interestingly, in the PMX205 treated mice, both microglia 13 and 16 are sources of App signaling, which ligates to Cd74 receptors in PVM macrophages ( Fig.…”