Loss of interleukin-21 receptor activation in hypoxic endothelial cells impairs perfusion recovery after hindlimb ischemia.

OBJECTIVE: Surgical hindlimb ischemia (HLI) in mice has become a valuable preclinical model to study peripheral arterial disease. We previously identified that the different phenotypic outcomes after HLI across inbred mouse strains is related to a region on the short arm of mouse chromosome 7. The gene coding the interleukin-21 receptor (IL-21R) lies at the peak of association in this region. APPROACH AND RESULTS: With quantitative real-time polymerase chain reaction, we found that a mouse strain with a greater ability to upregulate IL-21R after HLI had better perfusion recovery than a strain with no upregulation after HLI. Immunofluorescent staining of ischemic hindlimb tissue showed IL-21R expression on endothelial cells (ECs) from C57BL/6 mice. An EC-enriched fraction isolated from ischemic hindlimb muscle showed higher Il-21R levels than an EC-enriched fraction from nonischemic limbs. In vitro, human umbilical vein ECs showed elevated IL-21R expression after hypoxia and serum starvation. Under these conditions, IL-21 treatment increased cell viability, decreased cell apoptosis, and augmented tube formation. In vivo, either knockout Il21r or blocking IL-21 signaling by treating with IL-21R-Fc (fusion protein that blocks IL-21 binding to its receptor) in C57BL/6 mice resulted in less perfusion recovery after HLI. Both in vitro and in vivo modulation of the IL-21/IL-21R axis under hypoxic conditions resulted in increased signal transducer and activator of transcription 3 phosphorylation and a subsequent increase in the B-cell lymphoma leukemia-2/BCL-2-associated X protein ratio. CONCLUSION: Our data indicate that IL-21R upregulation and ligand activation in hypoxic ECs may help perfusion recovery by limiting/preventing apoptosis and favoring cell survival and angiogenesis through the signal transducer and activator of transcription 3 pathway.

Relationship between HBV genotypes B, C and follicular helper T cells in patients with chronic hepatitis B and its significance.

BACKGROUND: Clinical observations have shown that patients infected with chronic hepatitis B virus (HBV) genotype C versus genotype B had a higher load of the virus, more serious illness, and poorer responses to antiviral therapy and prognosis. However, the disparity between the two has not been clarified. OBJECTIVES: To explore possible relationship between HBV genotypes B and C and peripheral blood follicular helper T cells (Tfh) and its significance in treating chronic hepatitis B (CHB) patients. PATIENTS AND METHODS: One hundred and fifty CHB patients were enrolled into this study, including 70 cases infected with HBV genotype C and 79 cases with genotype B. One patient had suffered from both genotypes B and C. The levels of Tfh, also known as interleukin-21 (IL-21), HBV specific cytotoxic T lymphocytes (CTL), HBV DNA and alanine transaminase (ALT) were evaluated and compared in patients infected with genotype B and C. RESULTS: Levels of Tfh, IL-21 and HBV specific CTL of patients infected with HBV genotype C were significantly lower than those of patients infected with HBV genotype B, P < 0.01. Levels of HBV DNA and ALT of patients infected with genotype C were significantly higher than those of the patients infected with HBV genotype B, P < 0.01. CONCLUSIONS: Compared with chronic hepatitis B (CHB) patients infected with genotype B, higher levels of serum HBV DNA, ALT and TBil of patients infected with HBV genotype C may be related to their lower level of peripheral blood Tfh, which may result in lower IL-21, and it may result in lower HBV specific CTL.

Effects of infliximab induced clinical remission of active Crohn's disease on the level of interleukin-21 and interleukin-21 receptor / 中华消化杂志

Objective To investigate the changes of interleukin-21 (IL 21) and interleukin-21 receptor (IL 21R) expression level in Crohn's disease (CD) patients before and after accepted infliximab (IFX) treatment.Methods From June 2009 to July 2011,twenty-two CD patients met the research criteria were recruited at Tenth People's Hospital of Tongji University.Patients were treated with infliximab at weeks 0,2,6,and 16 healthy individuals were set as healthy control group at same time.Peripheral blood of healthy control group was taken at regular physical examination and blood of CD patients was taken before treatment and 10 weeks after treatment,intestinal mucosa biopsy samples were taken under colon endoscopy examination.The changes of Crohn's disease activity index (CDAI),erythrocyte sedimentation rate (ESR),C-reactive protein (CRP) in CD patients were observed.The change of IL-21R in peripheral blood CD4+ T lymphocytes was detected by flow cytometry.The change of IL-21 expression at mRNA level in intestinal mucosa was determined by realtime quantitative polymerase chain reaction (PCR).The data were analyzed by t test.Results Before treatment,the level of IL21R in peripheral blood CD4+ T lymphocytes of CD patients (12.25％±3.25％) and the expression of IL-21 at mRNA level in inflamed intestinal mucosa (1.38±0.32) were both significantly higher than those of healthy controls (4.25 ％ ± 1.41％,0.44±0.18),the differences were statistically significant (F=15.88,6.75 ; both P＜0.05).At 10th week,the level of IL-21R in peripheral blood CD4+ T lymphocytes of CD patients (8.12％ ± 2.05％) and the expression of IL-21 at mRNA level in intestinal mucosa (0.77 ± 0.24) were both significantly lower than those before treatment,the differences were statistically significant ( t=4.880,8.019; both P＜0.01).Before treatment,ESR,CRP and CDAI of CD patients was (46.8±11.4) mm/1 h,(52.4±11.5) mg/L and 319±74,which was (23.5±9.0) mm/1 h,(11.6±4.6) mg/L and 113±42 after treatment,the differences were statistically significant (t=9.485,16.458,11.100; all P＜0.05).Conclusion The IL-21 expression of active CD patients decreases after IFX treatment,which indicates that IL-21 may involve in IFX induced clinical remission of active CD.