Table 1.

Activity of different bacterial exopolysaccharides on immune response.

Exopolysaccharide	Species	Activity on Immune Response	Proinfl. ↑ Anti-Infl. ↓	Ref.
PIA (Poly-β-(1,6)-N-acetylglucosamine)	S. aureus	Prevents antibody-independent opsonic killing by PMNs and complement	↓	[50]
	S. epidermidis	Protects bacteria from phagocytosis and bacterial killing by PMNs	↓	[48]
		Protects from AMPs (e.g., β-defensin 3, LL-37, and anionic dermcidin)	↓	[48]
		Resistance to opsonic PMN killing for diminished immunoglobulin and complement (C3b) deposition	↓	[53]
		Less PMNs activation and cytokine release	↓	[52]
		Strong complement activation	↑ ↑	[52]
Psl (Neutral mannose-rich polysaccharide)	P. aeruginosa	Reduce neutrophil phagocytosis Reduce ROS response (by limiting complement-mediated opsonization)	↓	[56]
		Purified Psl does not stimulate ROS production by the PMNs	↓	[61]
Alginate (Acetylated copolymer of 1–4 linked β-d-mannuronic acid and α-l-guluronic acid)	P. aeruginosa	Reduced phagocytosis by MØs and PMNs Scavenges ROS Inhibits chemotaxis	↓	[62,63,64,65]
Pel	P. aeruginosa	Possibly protecting bacteria from MØs phagocytosis	↓	[66]
		Purified Pel does not stimulate ROS production by the PMNs	↓	[61]
Alginate/Psl-rich biofilms	P. aeruginosa	Increased activation of the PMNs (ROS and degranulation)	↑ ↑	[55]
Alginate/Pel-rich biofilms	P. aeruginosa	Lower activation of the PMNs with respect to the Alginate/Psl combination	↑	[55]
Polysaccharide capsule	K. kingae	Protection from complement-mediated lysis Prevents neutrophil ROS production Interferes with neutrophil K. kingae binding	↓	[60]
Exopolysaccharide (Galactan, a galactofuranose homopolymer with formula [→5)-β-Galf-(1→]n homopolymer [F3])	K. kingae	Protects against complement-mediated lysis Evasion of neutrophil-mediated killing Blocks neutrophil phagocytosis	↓	[59,60]
Exopolysaccharide (Strain-dependent mixture of different polysaccharides)	Burkholderia cepacia	Inhibits PMNs chemotaxis Inhibits PMNs ROS production	↓	[67,68]