THESIS
2012
xvii, 104 p. : ill. (some col.) ; 30 cm
Abstract
Inflammatory response has been implicated in the host defense, wound healing, and
pathogenesis of many diseases. According to the types of different stimuli, it can be further
divided into infection (microbe etc.) and sterile stimuli (non-microbe) induced response.
Compared to the relatively well-defined infectious inflammation, the area of sterile
inflammation remains largely unknown. By generating a double fluorescent reporter zebrafish,
which can distinguish macrophages and neutrophils, a platform has been established to study
the sterile inflammation related innate immune response in embryonic zebrafish. The reverse
and forward genetic methods were utilized to uncover the underlying mechanism of these
immediate and important cellular responses.
By using reverse genetic meth...[
Read more ]
Inflammatory response has been implicated in the host defense, wound healing, and
pathogenesis of many diseases. According to the types of different stimuli, it can be further
divided into infection (microbe etc.) and sterile stimuli (non-microbe) induced response.
Compared to the relatively well-defined infectious inflammation, the area of sterile
inflammation remains largely unknown. By generating a double fluorescent reporter zebrafish,
which can distinguish macrophages and neutrophils, a platform has been established to study
the sterile inflammation related innate immune response in embryonic zebrafish. The reverse
and forward genetic methods were utilized to uncover the underlying mechanism of these
immediate and important cellular responses.
By using reverse genetic method, interleukin 1 beta (il1β) was successfully identified as a key
player, which was involved in the directional migration of neutrophils during wound induced
sterile inflammation in vivo. Normally, during sterile inflammation induced by tissue injury,
both macrophages and neutrophils will rapidly flux into the site of inflammation. However, in
il1β morphant, compared with the normal macrophage influx, neutrophils can not migrate to
the wound site due to the defect of directional migration. What‘s more, we demonstrated that the Il1β signaling pathway and H
2O
2 signaling pathway were two independent pathways both
of which regulate the recruitment of neutrophils during sterile inflammation but not the
infection induced inflammation.
The ethylnitrosourea (ENU) mutagenesis based forward genetic screening was performed to
identify mutants which had inherited defects in the proper myeloid cell behaviors and
functions during normal development and sterile inflammation. The temperature sensitive
nlrp10-like
HKZ329 mutant which lacked NR staining positive microglia in the brain was
successfully identified. What‘s more, this mutant showed abnormal SB positive neutrophils
accumulation within the wound region for more than 6 hours at restrictive temperature. A
point mutation within the gene nlrp10-like on chromosome 15 that was responsible for the
defect of nlrp10-like
HKZ329 mutant was identified by positional cloning. In addition, it was
observed that although a quite decent number of SB positive neutrophils were trapped in the
wound region for longer than 6hpa in the nlrp10-like
HKZ329 mutant, the monocytes or dendritic
cells (DCs) could not flux into the wound site. Interestingly, the early myeloid development
and the capability of circulating macrophages to engulf bacteria appeared normal. To our big
surprise, the temperature shift experiment, from restrictive temperature to permissive
temperature, could rescue the microglia in the mutant brain to a decent number within a
relatively short time, 12~24 hours. More detailed observation by live imaging showed that
some peripheral macrophages can migrate into the brain during temperature shift experiment
in the mutant, which might partially contribute to the recovery of microglia. Collectively,
based on the above data and the nature of the mutated gene reported in mouse model recently,
the underlying mechanism for the failure of recruitment of tissue resident macrophages to
clean apoptotic cell bodies in the brain during normal development and wound induced dead
cells might be partially due to the migration defects of monocytes, macrophages or DCs.
Post a Comment