Table 1 Table summarizing CP changes in inflammatory diseases

Inflammation and infection

Systemic inflammation

↑ COX-2 and IκBα expression

[113, 115]

↓ Occludin mRNA expression

[116]

↑ CCL2 expression

[122]

↑ TLR1, TLR3, TLR4, CD14 expression

↓ Occludin expression

[110,111,112, 114, 116]

↑ Expression of ICAM-1, GlyCAM-1, MAdCAM-1, Jam2, Selpl, chemokines CXCL1, CCL7, CCL2, IL-16

[123]

↑ TNFα expression

[119, 120]

Collagen I cleavage

[118]

↑ Il-1β, TNFα, LPTGDS expression

[102]

↑ mRNA expression of TNFRI, TNFRII, IL1β, IL1 receptor type I, type II, Il6 and its signal transducing component – Il6 signal transducer

[121]

↑ LCN2 expression

[103, 104]

↑ Expression of Hamp, Cp, Fth1, Stat3, Smad4, Tfr2, Il6 genes

[107]

↑ MMP-8 expression

[118]

↑ EVs secretion

[125]

Bacterial infections

(Streptococcus suis)

fibrinous exudate, disruption of epithelial “brush border”

[134]

(Streptococcus suis)

Disruption of normal pattern of the TJ—Occludin, ZO-1, claudin-1

[128]

↓ (Streptococcus suis)

Number of epiplexus cells

[134]

(Haemophilus influenzae)

Paracellular invasion into CSF

[145]

↑ (Streptococcus pneumoniae)

NF-κB, PAF, laminin receptor expression in CP endothelial cells

[136]

↓ (Streptococcus pneumoniae)

TNFα -mRNA expression

[138]

↓ (Streptococcus suis)

Claudin-2 expression

[131]

(Listeria monocytogenes)

Using the “Trojan horse” mechanism by occupying mononuclear cells in the CP

[139]

(Streptococcus suis)

Apoptosis and necrosis of CP epithelial cells

[132]

(Streptococcus suis)

Transcellular migration in endocytic vacuoles

[133]

(Listeria monocytogenes)

Interaction of internalin A and B with E-cadherin on CP epithelial cells

[140]

(Streptococcus suis)

Transepithelial migration of polymorphonuclear leukocytes

[135]

↑ (Streptococcus suis)

ICAM-1, VCAM-1, MMP-3, NFκB, MAPK, TNFα, Il-1β, IL-6, IL-8, LIF, ARG1, ARG2, NOS2, indoleamine 2,3-dioxygenase expression

[129,130,131]

(Neisseria meningitidis)

Migration through CP epithelial cells

[148]

(Streptococcus pneumoniae)

Antibacterial effect of TLR2

[136]

(Escherichia coli)

Invasion through CP epithelial cells

[144]

↑ (Neisseria meningitidis)

IL6, CCL20, CXCL1-3, Nfkbiz, GM-CSF expression

[150]

(Haemophilus influenzae)

Transcellular migration from the basolateral side of CP epithelial cells

[146]

(Listeria monocytogenes)

Activation of MAPKs, Erk1/2 and p38

[142]

Viral infections

(Echovirus 30)

Invasion and replication in CP epithelial cells

[161]

(HIV)

MHC II + dendritic cells in the CP as reservoir of HIV

[160]

(Zika virus)

Entry to the brain through CP epithelial cells

[152]

(HIV)

Endothelial cells in the CP as a reservoir of HIV

[159]

↑ (Echovirus 30)

CXCL3, CXCL10, CXCL11, CCL20, IL8, IL7, M-CSF expression

[162]

(HIV)

Monocytes-like cells in the CP as a reservoir of HIV

[156]

(Polyomavirus JC)

CP cells as a reservoir

[153]

(Coxsackievirus B3)

Diapedesis of infected myeloid cells expressing high level of Ki67 and pERK1/2 through the TJ of the CP

[163]

Fungal infections

(Cryptococcuis neoformans)

CP plexitis in HIV patients

[170, 172]

Parasitic infections

(Trypanosoma brucei)

Present in perivascular region of CP and in CP epithelial cells

[174]

(Leishmania chagasi)

Infiltration of inflammatory cells with lymphoplasmatic morphology around the blood vessels and diffusely in CP stroma

[176]

(Leishmania chagasi)

Deposits of perivascular hyaline substances

[176]

(Trypanosoma evansi)

Edema and rupture of the CP epithelial cell layer

[175]

(Trypanosoma evansi)

Infiltration of CP by inflammatory cells

[175]

↑ (Leishmania infantum)

TLR2 and TLR9 expression,

no changes in TLR4 expression

[177]

(Leishmania infantum)

Inflammatory infiltration via CD3+ T lymphocytes

[176]

(Leishmania infantum)

Accumulation of perivascular hyaline substances consistent with IgG and parasite DNA

[176]