Background: We identified a spliced isoform of FKBP51 (FKBP51s) as a factor associated to PDL-1. FKBP51s stains TILs and is measurable in PBMC of melanoma patients. We also provided evidence that FKBP51s is a tumor edited and tolerance associated signature. Methods: qPCR served to measure FKBP51s in RNA extracted from PBMC of 102 melanoma patients (stages III, IV) undergoing immunotherapy (IT) with ipilimumab and 125 age matched healthy donors. Flow cytometry served to analyze protein expression in PBMC subsets of 61 patients and 56 controls. Fourty patients were analyzed also at the end of IT. Results: Compared with control value, FKBP51s transcript increased in patients (p < 0.01). In non responders, such transcript further increased after IT (p = 0.02). CD8 lymphocytes resulted increased in patients (32%+10) vs controls (27%+10) (p < 0.01). CD8 double staining with FKBP51s revealed that 20%+8 and 13%+7 were CD8+FKBP51s+, in patients and controls respectively (p < 0.01). The ratio CD8tot/CD8+FKBP51s+ was 1.9+0.7 and 2.7+1.4 for patients and controls (p < 0.01). In responders, IT produced a decrease of CD8+FKBP51s+ subset to 11%+6 (p = 0.01). Accordingly, in responders, the ratio CD8tot/CD8+FKBP51s+ increased to 2.8+1.0 (p = 0.03). In non responders, no variation of CD8+FKBP51s+ count or CD8tot/CD8+FKBP51s+ ratio was registered. Total CD4 lymphocytes did not differ between patients and controls, even if the FKBP51s+ component resulted increased and FKBP51s- decreased. No significant variation of such subsets was registered before and after IT. Interestingly, FKBP51s stained 55%+25 and 36%+27 of CD25 lymphocytes, in patients and controls respectively (p < 0.01). In responders, FKBP51s stained 68%+22 and 41%+16 of CD25 lymphocytes, before and after IT respectively (p < 0.01). In non responders, FKBP51s expression in CD25 lymphocytes was 53%+26 and remained unchanged after IT. Conclusions: FKBP51s transcript level may provide a guidance for assessing IT response. CD8+/FKBP51s+ subset is very sensitive to IT efficacy and the ratio CD8tot/CD8 FKBP51s+ is a promising tool to monitor IT. FKBP51s might also be a marker of a Treg subset which decreases in response to IT. Ongoing studies will address this issue.

Expansion of a lymphocyte subset expressing a spliced FKBP51 isoform in melanoma patients.

ROMANO, MARIA FIAMMETTA;D'ANGELILLO, ANNA;STAIBANO, STEFANIA;BISOGNI, RITA;ROMANO, SIMONA
2015

Abstract

Background: We identified a spliced isoform of FKBP51 (FKBP51s) as a factor associated to PDL-1. FKBP51s stains TILs and is measurable in PBMC of melanoma patients. We also provided evidence that FKBP51s is a tumor edited and tolerance associated signature. Methods: qPCR served to measure FKBP51s in RNA extracted from PBMC of 102 melanoma patients (stages III, IV) undergoing immunotherapy (IT) with ipilimumab and 125 age matched healthy donors. Flow cytometry served to analyze protein expression in PBMC subsets of 61 patients and 56 controls. Fourty patients were analyzed also at the end of IT. Results: Compared with control value, FKBP51s transcript increased in patients (p < 0.01). In non responders, such transcript further increased after IT (p = 0.02). CD8 lymphocytes resulted increased in patients (32%+10) vs controls (27%+10) (p < 0.01). CD8 double staining with FKBP51s revealed that 20%+8 and 13%+7 were CD8+FKBP51s+, in patients and controls respectively (p < 0.01). The ratio CD8tot/CD8+FKBP51s+ was 1.9+0.7 and 2.7+1.4 for patients and controls (p < 0.01). In responders, IT produced a decrease of CD8+FKBP51s+ subset to 11%+6 (p = 0.01). Accordingly, in responders, the ratio CD8tot/CD8+FKBP51s+ increased to 2.8+1.0 (p = 0.03). In non responders, no variation of CD8+FKBP51s+ count or CD8tot/CD8+FKBP51s+ ratio was registered. Total CD4 lymphocytes did not differ between patients and controls, even if the FKBP51s+ component resulted increased and FKBP51s- decreased. No significant variation of such subsets was registered before and after IT. Interestingly, FKBP51s stained 55%+25 and 36%+27 of CD25 lymphocytes, in patients and controls respectively (p < 0.01). In responders, FKBP51s stained 68%+22 and 41%+16 of CD25 lymphocytes, before and after IT respectively (p < 0.01). In non responders, FKBP51s expression in CD25 lymphocytes was 53%+26 and remained unchanged after IT. Conclusions: FKBP51s transcript level may provide a guidance for assessing IT response. CD8+/FKBP51s+ subset is very sensitive to IT efficacy and the ratio CD8tot/CD8 FKBP51s+ is a promising tool to monitor IT. FKBP51s might also be a marker of a Treg subset which decreases in response to IT. Ongoing studies will address this issue.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11588/612640
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