Objective To investigate the characteristics of immune exhaustion in sepsis and analyze its association with gut microbiota translocation.Methods A total of 130 mice were randomly divided into a cecal ligation and puncture(CLP)group(n=100)and a Sham group(n=30)Mouse model of sepsis was established with CLP procedure.Flow cytometry was used to analyze the proportions of peripheral blood CD4+T and CD8+T cells and programmed cell death protein 1(PD-1)positive T cell subsets in mice.Bacterial colonization in organs such as the heart,liver and kidneys was quantified by plating homogenates of the organs.Pathological changes in immune organs were observed with HE staining.The expression and localization of CD4?,CD8?,and PD-1?cells in immune organs were detected with immunohistochemical staining,and Image J software was employed for subsequent quantification of the number of the positive cells.Results HE staining demonstrated that immune organs exhibited varying degrees of pathological damages with disease progression.Compared with the Sham mice,the CLP mice exhibited significantly increased bacterial colonization in parenchymal organs and peripheral blood(P<0.05),notably in the liver,which showed the most severe infection.In the CLP group,the proportion of CD4+T lymphocytes in peripheral blood at days 1,3,and 5 postoperatively was decreased by 56%,70.57%,and 87.42%,respectively,when compared with the Sham group(P<0.001).The proportion of CD8+T lymphocytes was decreased by 48.33%relative to the Sham group only at day 5(P<0.001).In contrast,the proportion of CD4+T cell subsets expressing PD-1 was increased to 673.08,423.08,and 600 times that of the Sham group,respectively,at the same postoperative time points(P<0.001).Immunohistochemical results showed that,in the CLP group,the proportion of CD4+T cells in the thymus,spleen,and mesenteric lymph nodes was increased to 7.65,2.66,and 3.7 times that of the Sham group,respectively,at the early-stage peak(P<0.001),and then these proportions were decreased by 82.8%(P<0.001),41.9%(P<0.01),and 60.15%(P<0.001),respectively,at the late-stage trough when compared with the early-stage peak in the corresponding organs.The proportion of CD8+positive cells was increased in the early stage and then decreased insignificantly,while the proportion of PD-1+positive cells was increased continuously,and reached 6.24,13.9,and 20.96 times that of the Sham group at the peak in the thymus,spleen,and mesenteric lymph nodes respectively(P<0.001),with their expression regions showing a rough overlap with those of CD4+cells.Conclusion During sepsis,the inflammatory response can cause severe damage to immune organs and persistent exhaustion of CD4?T lymphocytes,leading to declined defenses against infection,which may be the main causes for exacerbated gut microbiota translocation and then systemic infection.

The World Health Organization redefined the type 2 vaccine-derived poliovirus (VDPV) in 2010. To study the genetic characteristics and evolution of type 2 VDPV under this new definition, we conducted genome sequencing and analyses of type 2 VDPVs isolated from one patient with acute flaccid paralysis in Shanxi province (China) in 2014. Nucleotide sequencing revealed that the full-length of type 2 VDPV is 7439 bases encoding 2207 amino acids with no insertion or deletion of nucleotides compared with Sabin2. One nucleotide substitution identified as a key determinant of the attenuated phenotype of the Sabin 2 strain (A-G reversion at nucleotide nt 481 in the 5-end of the untranslated region) had reverted in the Shanxi type 2 VDPV. The other known key determinant of the attenuated phenotype of the Sabin 2 strain (U-->C reversion at nt2909 in the VP1 coding region that caused a Ile143Thr substitution in VP1) had not reverted in the Shanxi VDPV. The Shanxi type 2 VDPV was S2/S1 recombinant, the crossover site of which mapped to the 3-end of the 3D region (between nt 6247 and nt 6281). A phylogentic tree based on the VP1 coding region showed that evolution of the Shanxi type 2 VDPV was independent of other type 2 VDPVs detected worldwide. We estimated that the strain circulated for approximately = 11 months in the population according to the known evolution rate. The present study confirmed that the Chinese Polio Laboratory Network could discover the VDPV promptly and that it played an important part in maintenance of a polio-free China.
Amino Acid Sequence ; Base Sequence ; Capsid Proteins ; chemistry ; genetics ; China ; Humans ; Infant ; Male ; Molecular Sequence Data ; Phylogeny ; Poliomyelitis ; virology ; Poliovirus ; chemistry ; genetics ; metabolism ; Poliovirus Vaccines ; adverse effects ; chemistry ; genetics ; metabolism ; Sequence Alignment