Title Analiza diferencijacije T folikularnih pomoćničkih limfocita uslijed virusnih infekcija Title (english) Analysis of T follicular helper cell development in the context of viral infections Author Vendi Šinkovec Mentor Mirela Kuka (mentor) Committee member Ivana Ratkaj (predsjednik povjerenstva)Committee member Felix Martinus Wensveen (član povjerenstva)Committee member Ivana Munitić (član povjerenstva)Granter University of Rijeka Defense date and country 2018-09-26, Croatia Scientific / art field, BIOTECHNICAL SCIENCES Abstract T folikularne pomoćničke stanice (TFH) su podskupina CD4 T limfocita.
Specijalizirane su za pružanje pomoći folikularnim B stanicama – stanicama
zaduženim za proizvodnju neutralizirajućih protutijela visokog afiniteta. Virusi koji
nemaju izražen citopatološki učinak, kao što je virus limfocitnog koriomeningitisa,
izbjegavaju neutralizaciju protutijelima kako bi produljili svoje trajanje u domaćinu.
Stoga je infekcija virusom limfocitnog koriomeningitisa karakterizirana niskim titrom
protutijela specifičnih za virus, koji se može detektirati tek 50-80 dana nakon
početka infekcije. Virus pritom sprječava rano stvaranje neutralizirajućih protutijela
tako što inhibira preživljenje i diferencijaciju B stanica te uzrokuje imunopatološke
promjene u strukturi sekundarnih limfnih organa. S obzirom da su TFH stanice
ključne za stvaranje germinalnih centara i proizvodnju protutijela, u ovom radu se
analizirala rana TFH diferencijacija nakon potkožnih virusnih infekcija. Fenotip CD4 T
pomoćničkih stanica tijekom infekcije virusom limfocitnog koriomeningitisa je
uspoređen s fenotipom stanica diferenciranih tijekom infekcije virusom vezikularnog
stomatitisa. Virus vezikularnog stomatitisa je virus s citopatološkim učinkom koji
potiče stvaranje velike količine neutralizirajućih protutijela. Analiza CD4 T stanica
specifičnih za virus u različitim trenutcima nakon infekcije pokazala je da tijekom
infekcije virusom limfocitnog koriomeningitisa dolazi do smanjene diferencijacije TFH
stanica u uspredbi s infekcijom virusom vezikularnog stomatitisa. Većina CD4 T
stanica se diferencirala u TH1 stanice tijekom infekcije virusom limfocitnog
koriomeningitisa, dok one gotovo uopće nisu uočene tijekom infekcije virusom
vezikularnog stomatitisa. Kako bi istražili moguće razloge smanjene diferencijacije
TFH stanica, provedeni su eksperimenti na miševima s delecijom receptora za tip I
interferona (IFNAR-/-) u kojima, suprotno miševima divljeg soja, aktivacija B
limfocita nije smanjena tijekom infekcije virusom limfocitnog koriomeningitisa.
Transfer B i T stanica specifičnih za virus omogućio je bolju aktivaciju B stanica u
IFNAR-/- miševima te je doveo do diferencijacije većeg broja TFH stanica. Ali, nije
objasnio izraženu TH1 diferencijaciju prethodno uočenu rano nakon početka infekcije.
Analiza TFH stanica tijekom imunizacije miševa s GP-1 glikoproteinom virusa
limfocitnog koriomeningitisa, pokazala je da afinitet T stanica specifičnih za virus
(Smarta stanica) nije odgovoran za mali broj TFH stanica 3 i 5 dana nakon infekcije.
Na temelju rezultata vezanih uz ranu TFH diferencijaciju i rezultata na IFNAR-/-
miševima, može se zaključiti da tijekom infekcije virusom limfocitnog
koriomeningitisa postoje nedostaci i u inicijaciji TFH razvoja i u održavanju TFH
programa.
Abstract (english) T follicular helper (TFH) cells are a subset of CD4 T lymphocytes specialized in
providing help to antibody-producing follicular B cells. Follicular B cell responses are
extremely important for the generation of high-affinity neutralizing antibodies.
Poorly cytopathic or non-cytopathic viruses such as lymphocytic choriomeningitis
virus (LCMV) avoid neutralizing antibody response to prolong their persistence in
the host. Indeed, LCMV infection is characterized by low neutralizing antibody titers,
which are undetectable until 50-80 days post infection. LCMV impairs early
neutralizing antibody production by interfering with B cell survival and
differentiation, as well as by inducing immunopathology leading to the destruction
of the secondary lymphoid organ structure. Because TFH play a key role in the
generation of germinal centers and antibody responses, a research plan was
designed to analyze early TFH differentiation during subcutaneous LCMV infection.
The phenotype of CD4 T helper cells generated upon LCMV infection was compared
to that induced by subcutaneous infection with vesicular stomatitis virus (VSV), a
cytopathic virus that induces high levels of neutralizing antibodies. Analysis of virusspecific
CD4 T cell activation at different time-points showed that LCMV infection
leads to a diminished TFH differentiation when compared to VSV-infected mice. On
the contrary, the majority of CD4 T cells in LCMV-infected mice differentiated into
TH1, whereas virtually no TH1 were detected in VSV-infected mice. To investigate the
possible reasons for the diminished TFH response during LCMV infection, we
performed experiments in IFNAR-/- mice, where B cell activation during LCMV
infection is not diminished as in WT mice. Co-transfer of virus-specific B and T cells
improved B cell activation in IFNAR-/- mice and led to a slight increase in TFH
numbers, but did not explain entirely the striking TH1 differentiation observed
already at the early time-points. By analyzing TFH differentiation upon LCMV GP-1
immunization, we eliminated the possibility that low TFH differentiation observed at
day 5 and day 3 post infection, was a consequence of low TCR affinity of virusspecific
(Smarta) T cells for LCMV. Based on the results obtained from early TFH
differentiation, and the results from IFNAR-/- mice, it can be concluded that defects
in both TFH priming and TFH maintenance stage are present during LCMV infection.
Keywords
T folikularne pomoćničke (TFH) stanice
virus limfocitnog koriomeningitisa
virus vezikularnog stomatitisa
potkožna infekcija
Keywords (english)
T follicular helper cells (TFH)
lymphocytic choriomeningitis virus (LCMV)
vesicular stomatitis virus (VSV)
subcutaneous infection
Language croatian URN:NBN urn:nbn:hr:193:263873 Study programme Title: Biotechnology in medicine Type of resource Text File origin Born digital Access conditions Closed access Terms of use Created on 2018-10-31 08:55:58
