BackgroundAcute pancreatitis (AP) is a life-threatening disease that requires early identification of patients at risk of developing infectious complications. Immunosuppression is an initial event that is key to AP pathogenesis. The programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) system is reported to mediate evasion of host immune surveillance in many diseases; however, the relationship between PD-1/PD-L1 expression and these parameters or infectious complications in AP has not been elucidated. This study was conducted to determine whether PD-1 and PD-L1 are upregulated and to reveal the relationship between PD-1/PD-L1 expression and the development of infectious complications in AP.MethodsSixty-three patients with AP and 32 sex- and age-matched healthy control subjects were prospectively enrolled. On days 1 and 3 after the onset of AP, we measured PD-1 expression in peripheral CD4+ T cells and PD-L1 and human leukocyte antigen-DR (HLA-DR) expression in CD14+ monocytes using flow cytometry. Plasma interleukin (IL)-10 levels were measured by enzyme-linked immunosorbent assay.ResultsCompared with healthy volunteers, the percentages of PD-1-expressing CD4+ lymphocytes and PD-L1-expressing CD14+ monocytes were increased in patients with AP on days 1 and 3 after onset, especially those with infectious complications. Moreover, increased PD-1/PD-L1 expression was associated with increased occurrence of infectious complications, decreased circulating lymphocytes, and increased plasma IL-10 concentration. Multivariate regression analysis indicated that the increased percentage of PD-L1-expressing CD14+ monocytes was an independent risk factor for infectious complications in AP. Area under the ROC curve analysis showed the combination of Acute Physiology and Chronic Health Evaluation II score and PD-L1 and HLA-DR expression in CD14+ monocytes had high accuracy in predicting infectious complications in patients with AP.ConclusionsThe PD-1/PD-L1 system plays an essential role in the early immunosuppression of AP. PD-L1 expression in CD14+ monocytes may be a new marker for predicting risk of infectious complications in patients with AP.

Acute pancreatitis (AP) with infectious complications has high mortality because of early-stage immunosuppression. The programmed cell death-1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway is an important host immunosuppression mechanism. Soluble PD-L1 (sPD-L1) expression regulates co-inhibitory signals in malignancies or autoimmune disorders; however, its effects in AP are unknown. Here, we evaluated whether serum sPD-L1 is involved in immune dysfunction and assessed its relationship with infectious complications in early AP. Blood samples were obtained from 56 patients with acute pancreatitis and 21 healthy individuals in this prospective study. Serum sPD-L1 levels within 48 h after AP onset were tested by enzyme-linked immunosorbent assays. Relevant immune parameters (human leucocyte antigen-DR, lymphocyte count) and inflammatory markers (C-reactive protein, white blood cell count) were analysed. sPD-L1 was significantly upregulated in patients with early AP, especially those with infectious complications, compared to healthy controls. Significant negative correlations were observed among monocyte HLA-DR expression, lymphocyte count and sPD-L1 levels in AP. Multivariate regression indicated that sPD-L1 was an independent risk factor for infectious complications in AP. The findings suggest that increased sPD-L1 expression appears to be involved in the development of immunosuppression in the early stage of AP and that sPD-L1 might be an early parameter for prediction of infectious complications in patients with AP.

Programmed cell death 1 (PD-1) plays an important pathologic role in sepsis-induced immunosuppression. However, whether PD-1 overexpression occurs early during septic shock is unknown and its regulation mechanism is also unknown. Our study investigated the expressions of PD-1/programmed death-ligand 1 (PD-L1) on immune cells in peripheral blood from the early-stage septic shock patients. We found that both PD-1 and PD-L1 showed increased expressions on the CD4+ T cells and monocytes. It indicated that PD-1 expression might be an early biomarker to assess illness severity and predict the prognosis of septic shock. Then, we further investigated the mechanism underlying the regulation of PD-1 expression. Our data showed that Notch signaling pathway was activated in both septic shock patients and lipopolysaccharide- (LPS-) tolerant THP1 cells and both interleukin-10 (IL-10) and PD-1 were increased in the THP1 cells. Inhibition of Notch signaling by N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenyl glycinet-butyl ester (DAPT) induced significantly decreased expressions of PD-1 and IL-10 in the LPS-tolerant cell model. Our work suggested that Notch signaling pathway was involved in the regulation of PD-1 expression.

BackgroundNicotinamide adenine dinucleotide (NAD+) is a coenzyme and plays a crucial role in several metabolic processes. This study explored the association of nicotinamide adenine dinucleotide (NAD+) levels with metabolic disease (MD) in adults.MethodsIn this cross-sectional study, all data were collected from the Jidong community. MD was defined as the presence of one or more of the following disease components: hypertension, dyslipidemia, diabetes, hyperuricemia, obesity, and non-alcoholic fatty liver disease (NAFLD). The MD components were categorized into three groups: those with one component, those with two components, and those with three to six components. The whole blood NAD+ level was measured using a cycling assay and LC-MS/MS analysis. The participants were divided into four groups based on their NAD+ level quartiles. Multivariable logistic regression was used to evaluate the association of the whole blood NAD+ levels with MD.ResultsOf the 1,394 eligible participants, the average age was 43.2 years, and 74.3% had MD. In the top quartile of NAD+, the prevalence of MD and each of its components (hypertension, hyperlipidemia, diabetes, hyperuricemia, obesity, and NAFLD) were 87.9% 35.2%, 62.3%, 8.7%, 36.9%, 21.0%, and 60.5%, respectively. As compared with the lowest NAD+ quartile (≤29.4 μmol/L), the adjusted odds ratios and 95% confidence interval of the highest quartile were 3.01 (1.87-4.87) for MD, 2.48 (1.44-4.29) for 1 MD component, 2.74 (1.45-5.17) for 2 MD components, and 4.30 (2.32-7.98) for 3-6 MD components. The risk of MD began to increase at NAD+ levels of 31.0 μmol/L, as revealed by the gradient associations of NAD+ levels with MD. There was no significant interaction between age, sex, drinking, smoking, and NAD+ for MD (p for interaction ≥0.10).ConclusionsIncreased NAD+ was significantly associated with MD, as well as its individual components. Our findings provide new evidence for the relationship between blood NAD+ levels and MD.