Editing Sepsis (section)

=== Microbial factors ===
Bacterial [[virulence factor]]s, such as [[glycocalyx]] and various [[adhesins]], allow colonization, immune evasion, and establishment of disease in the host.<ref name=Critical2005/> Sepsis caused by [[gram-negative]] bacteria is thought to be largely due to a response by the host to the [[lipid A]] component of [[lipopolysaccharide]], also called [[endotoxin]].<ref name="Park2013"/><ref name="Cross2014"/> Sepsis caused by [[gram-positive]] bacteria may result from an immunological response to cell wall [[lipoteichoic acid]].<ref name=Fournier2005/> Bacterial [[exotoxin]]s that act as [[superantigens]] also may cause sepsis.<ref name=Critical2005 /> Superantigens simultaneously bind [[major histocompatibility complex]] and [[T-cell receptor]]s in the absence of [[antigen presentation]]. This forced receptor interaction induces the production of pro-inflammatory chemical signals ([[cytokines]]) by T-cells.<ref name=Critical2005 />

There are a number of microbial factors that may cause the typical septic [[Inflammation|inflammatory cascade]]. An invading pathogen is recognized by its [[pathogen-associated molecular pattern]]s (PAMPs). Examples of PAMPs include lipopolysaccharides and [[flagellin]] in gram-negative bacteria, [[muramyl dipeptide]] in the [[peptidoglycan]] of the gram-positive bacterial cell wall, and [[CpG dinucleotide|CpG bacterial DNA]]. These PAMPs are recognized by the [[pattern recognition receptors]] (PRRs) of the innate immune system, which may be membrane-bound or cytosolic.<ref name=Leentjens2013/> There are four families of PRRs: the [[toll-like receptors]], the [[C-type lectin]] receptors, the [[NOD-like receptor]]s, and the [[RIG-I-like receptor]]s. Invariably, the association of a PAMP and a PRR will cause a series of intracellular signalling cascades. Consequentially, transcription factors such as [[nuclear factor-kappa B]] and [[AP-1 transcription factor|activator protein-1]], will up-regulate the expression of pro-inflammatory and anti-inflammatory cytokines.<ref name=Antonopoulou2011/>

Other immunological responses related to microbial infections, such as [[Neutrophil extracellular traps|NETs]], can also play a role or be observed in sepsis. NET formation only occurs via neutrophil cell death, which occurs during microbial infections. Neutrophil extracellular traps called NETs eliminate bacteria from blood flow. These compounds are part of the innate immune system, which is activated initially during infections.<ref>{{Cite journal |last1=Denning |first1=Naomi-Liza |last2=Aziz |first2=Monowar |last3=Gurien |first3=Steven D. |last4=Wang |first4=Ping |date=2019-10-30 |title=DAMPs and NETs in Sepsis |journal=Frontiers in Immunology |language=English |volume=10 |page=2536 |doi=10.3389/fimmu.2019.02536 |doi-access=free |pmid=31736963 |pmc=6831555 |issn=1664-3224}}</ref>