Table 1 Summary of (potential and recognized) podocyte immune functions

CD80 (or B7-1)/CD86

Class I/II MHC

Cultured human podocytes can express antigen-presenting cell molecules

Activation of specific T-cell immune responses in renal diseases

[14, 15, 28,29,30, 33, 34]

Chemokine receptors (CCR and CXCR)

CCR4, CCR8, CCR9, CCR10, CXCR1, CXCR3, CXCR4, and CXCR5 are expressed in cultured human podocytes

CXCR1, CXCR3, and CXCR5 have been identified on podocytes from kidney biopsies of PMN patients

Possible pathogenic role in acute and chronic glomerular inflammation

NADPH-oxidases hyperactivation and ROS production — possible contribution to glomerular filtration barrier damage, and onset of proteinuria

[12, 35,36,37,38,39]

Complement system components

Cultured human podocytes can produce and express complement components, including regulators

Possible local activation of the complement cascade

[16, 17, 43]

FcRn

Both in vitro and in vivo podocytes express FcRn

IgG clearance from the glomerular basement membrane, albumin recycling

[31, 32]

Cytokines/growth factors/inflammasone components

Both in vitro and in vivo podocytes produce cytokines and growth factors (i.e., TNF-α, IL-1α and β, IL-6, IL-8, VEGF). They can also express inflammasome components (NOD-like receptor family proteins)

Possible role in the local inflammatory response in glomerular diseases

[40,41,42]

Toll-like receptors (TLRs)

Constitutive expression of cell surface TLRs has been identified on cultured human podocytes

De novo expression of intracellular TLRs has been detected in podocytes of patients with glomerular disease (upregulation of intracellular TLR9 with activation of NF-κB/p38 MAPK)

Possible role in the defense against microbial agents

Possible role in immune response and glomeruli inflammation

[12, 13, 24,25,26]