Table 2.
Immune evasion strategies of K. pneumoniae.
| Immune evasion strategies | Mechanism | Bacterial factor | References |
|---|---|---|---|
| (i) Stealth pathogen | |||
| Preventing the antimicrobial action of soluble innate immune effectors | |||
| Preventing complement bactericidal effect, and opsonisation | Limiting C3b deposition | CPS, LPS O-polysaccharide | Merino et al.1992; Alvarez et al.2000; de Astorza et al.2004 |
| Limiting antimicrobial activity of collectins | Blunting interaction with SP-A and SP-D | CPS | Kabha et al.1997; Ofek et al.2001; Kostina et al.2005 |
| Counteracting bactericidal action CAMPs and polymyxins | Limiting the interaction with the bacterial surface. Efllux of CAMPs. | CPS, LPS lipid A decorations, AcrAB | Campos et al.2004; Llobet et al.2011; Kidd et al.2017; Mills et al.2017; Padilla et al.2010 |
| Attenuating the interaction with immune cells | |||
| Attenuating engulfment by epithelial cells | CPS | Cortes et al.2002; Regueiro et al.2006 | |
| Avoiding phagocytosis by neutrophils | CPS, OmpK36 | Regueiro et al.2006; Pan et al.2011 | |
| Avoiding phagocytosis by macrophages | CPS, LPS lipid A decorations, OmpA, OmpK36 | March et al.2013 | |
| Limiting the activation of PPRs | Limiting the recognition of LPS by TLR4 | LPS lipid A 2-hydroxylation | Llobet et al.2015 |
| (ii) Subversion host defences | |||
| Attenuating cell-intrinsic immunity | |||
| Controlling maturation dendritic cells | CPS, LPS O-polysaccharide | Evrard et al.2010 | |
| Manipulation phagosome maturation | Activation PI3K-AKT-Rab14 axis | Unknown | Cano et al.2015 |
| Controlling cell death | Cytotoxicity in epithelial cells. Triggering apoptosis in macrophages. | CPS Unknown | Cano et al.2009; Leone et al.2016 |
| Abrogating TLR-controlled inflammatory responses: | |||
| Abolishing TLR signalling | CPS, LPS O-polysaccharide, OmpA, T2SS | March et al.2011; Frank et al.2013; Tomas et al.2015 | |
| Blunting NF-κB signalling | Upregulation deubiquitinase CYLD by targeting NOD1 and EGFR. | CPS, and other unknown factor(s) | Regueiro et al.2011; Frank et al.2013 |
| Blunting MAPKs | Upregulation MAPKs phosphatase MKP-1 via NOD1 activation. | Unknown | Regueiro et al.2011 |
| Manipulating mucosal immunity | Induction of IL10. | Unknown | Greenberger et al.1995; Yoshida et al.2001 |
| Counteracting nutritional immunity | Secretion of several siderophores | Yersiniabactin, salmochelin, aerobactin | Lawlor, O’connor and Miller 2007; Bachman et al.2011; Russo et al.2011 |