Severe burns and trauma frequently lead to the skin barrier disruption and development of moist burn wound, which can trigger sepsis, septic shock, and even death. Immunodysfunction is closely associated with poor prognosis. In-depth research on the mechanisms of natural and adaptive immune dysfunction can help reveal the essence of the disease. Currently, elucidating the underlying mechanisms of immune dysfunction has become a critical research priority. Such investigations may provide fundamental insights into disease pathogenesis. Besides, accurate immune function assessment holds significant value for early detection of immune dysfunction, judgment of the severity of the condition, precise prediction of the prognosis, and guidance of clinical treatment. Implementing immunomodulatory treatment based on the pathophysiological mechanisms and evaluation results is a necessary approach to restoring the immune function, reducing mortality rate, and improving the prognosis of the patients with sepsis following severe burns and trauma. To this end, the authors systematically examined the characteristics and mechanisms of immune dysfunction, immune assessment as well as classification, and corresponding therapeutics in sepsis following severe burns and trauma, thereby providing a reference for the development of precise diagnosis and treatment strategies for immune dysfunction management.

Objective:To investigate the effects of thioredoxin reductase 1 (TXNRD1) on ferroptosis and immune function of dendritic cells (DCs) in septic mice, and to provide a basis for improving the immunosuppression in sepsis caused by wound infection.Methods:This study was an experimental research. Sixty male C57BL/6J mice aged 6-8 weeks were subjected to cecal ligation and puncture (CLP) to establish sepsis models. Ten mice were selected at 0 (immediately), 6, 12, 24, 48, and 72 h after CLP surgery, respectively, according to the random number table method. Mouse splenic DCs were isolated using CD11c-positive magnetic beads. The protein expressions of TXNRD1, and anti-ferroptosis proteins solute carrier family 7 member 11 (SLC7A11), and glutathione peroxidase 4 (GPX4) in the cells were detected by Western blotting, the reduced glutathione (GSH) content in the cells was measured by colorimetric assay, the lipid peroxidation level was assessed via live-cell imaging technology, and the levels of major histocompatibility complex class Ⅱ subtype I-A/I-E and leukocyte differentiation antigens CD80 and CD86 were detected by flow cytometry. Another 100 male C57BL/6J mice aged 6-8 weeks were divided into corn oil+sham injury group, corn oil+CLP group, inhibitor+sham injury group, and inhibitor+CLP group according to the random number table method, with 25 mice in each group. Mice in the two inhibitor groups were intraperitoneally injected with TXNRD1 inhibitor auranofin, while mice in the two corn oil groups were intraperitoneally injected with corn oil. One hour later, mice in the two CLP groups underwent CLP surgery to establish sepsis models, while mice in the two sham injury groups underwent sham surgery. Twenty mice from each group were selected to observe survival within 7 d post-surgery, and the survival rate was calculated. At 24 h post-surgery, mouse splenic DCs from the remaining 5 mice in each group were collected for corresponding assays as above.Results:Compared with those at 0 h after CLP surgery, the protein expressions of TXNRD1, GPX4, and SLC7A11 in mouse cells at 24 h after CLP surgery and the protein expression of TXNRD1 in mouse cells at 48 h after CLP surgery were significantly decreased ( P<0.05), the GSH content in mouse cells was significantly decreased at 24 and 48 h after CLP surgery ( P<0.05). The lipid peroxidation level in mouse cells was low at 0, 6, and 12 h after CLP surgery, slightly lower than that at 72 h after CLP surgery; the lipid peroxidation levels in mouse cells at 24 and 48 h after CLP surgery were significantly higher than those at 0, 6, 12, and 72 h after CLP surgery. Compared with those at 0 h after CLP surgery, the levels of I-A/I-E and CD80 in mouse cells at 6, 12, 24, 48, and 72 h after CLP surgery and the levels of CD86 in mouse cells at 12, 24, and 48 h after CLP surgery were significantly increased ( P<0.05). At 24 h post-surgery, the protein expressions of TXNRD1, SLC7A11, and GPX4 in mouse cells in corn oil+CLP group were significantly lower than those in corn oil+sham injury group ( P<0.05), while the protein expressions of TXNRD1, SLC7A11, and GPX4 in mouse cells in inhibitor+CLP group were significantly lower than those in corn oil+CLP group and inhibitor+sham injury group ( P<0.05). At 24 h post-surgery, the content of GSH in mouse cells in corn oil+CLP group was (239±32) μg/mg, which was significantly lower than (366±59) μg/mg in corn oil +sham injury group ( P<0.05); the content of GSH in mouse cells in inhibitor+CLP group was (134±19) μg/mg, which was significantly lower than (355±31) μg/mg in inhibitor+sham injury group and that in corn oil+CLP group (with both P values <0.05). At 24 h post-surgery, the lipid peroxidation level of mouse cells in inhibitor+CLP group was significantly higher than that in the other three groups ( P<0.05). At 24 h post-surgery, the levels of I-A/I-E, CD80, and CD86 in mouse cells in corn oil+CLP group were significantly higher than those in corn oil+sham injury group ( P<0.05), while the levels of I-A/I-E and CD80 in mouse cells in inhibitor+CLP group were significantly higher than those in inhibitor+sham injury group ( P<0.05) but significantly lower than those in corn oil+CLP group ( P<0.05); the level of CD86 in mouse cells in inhibitor+sham injury group was significantly higher than that in corn oil+sham injury group ( P<0.05). Within 7 d post-surgery, the survival rate of mice in inhibitor+CLP group was significantly lower than that in inhibitor+sham injury group and corn oil+CLP group (with χ2 values of 31.19 and 3.91, respectively, both P values <0.05). Conclusions:In septic mice, the expression of TXNRD1 in DCs is reduced, cell ferroptosis is enhanced, and immune function is weakened. The inhibition of TXNRD1 in DCs will exacerbate cell ferroptosis and immune function suppression, and is closely related to the poor prognosis of sepsis.

The pathophysiological mechanisms underlying sepsis is complex, mainly involving excessive inflammatory response and immune dysfunction. The development of nanobiomaterial technology has brought brand-new options for the treatment of sepsis. In the current paper, we discuss the current application status and potential of nanobiomaterials in treatment of sepsis from aspects of antibacterial, anti-inflammatory, targeted regulation of immune cell function, and multi-target combined regulation, pointing out new direction for the future development of therapeutic strategies for sepsis based on nanobiomaterials.

Objective To investigate programmed death including necroptosis,apoptosis,autophagy,ferroptosis,and pyroptosis in bone marrow megakaryocytes of mice during sepsis and its impact on platelet production capacity and coagulation function in mice.Methods C57BL/6J mice were randomly divided into a sham operation group(sham group)and a sepsis model group(CLP group).Peripheral blood platelets and coagulation function were measured by abdominal aortic blood sampling at 24 h postoperatively in both sham and CLP groups.After the mice were sacrificed,long bones of both lower limbs were taken,and bone marrow megakaryocytes were extracted using megakaryocyte separation solution and immunomagnetic bead separation.Laser confocal microscopy was used to observe the activation of programmed death-related marker molecules in mouse bone marrow megakaryocytes.Flow cytometry was used to detect programmed death rate,platelet production phenotype,and platelet surface markers(CD41,CD42b,CD61)of megakaryocytes.Western blotting was used to detect the expression of programmed death-related proteins in megakaryocytes.Results Compared with the sham group,the CLP group showed significant decreases in the number of platelets during acute sepsis(24 h)(P<0.000 1),significant increases in platelet distri-bution width(PDW)and mean platelet volume(MPV)(P<0.01),significant prolonging of thrombin time(TT),prothrombin time(PT),and activated partial thromboplastin time(APTT)(P<0.000 1,P<0.001,P<0.01),and significant reduction in fibrinogen(Fib)(P<0.000 1).Compared with the Con/sham group,the LPS/CLP group exhibited significant increases in the platelet production phenotype of megakaryocyte,the number of PLP in the supernatant,and the expression levels of platelet surface markers(CD41,CD42b,CD61).The rates of megakaryocyte necroptosis/apoptosis,pyroptosis,and ferroptosis were significantly elevated at 24 h post-CLP surgery.Laser confo-cal microscopy showed significant activation of LC3,P-MLKL,Caspase-1,and Fe2+in megakaryocytes of mice after CLP surgery.Western blotting results revealed that the CLP group exhibited a significant increase in the activa-tion rate of necroptosis-related protein P-MLKL(P<0.001),a significant increase in the cleavage of pyroptosis-related proteins GSDMD and GSDMD-N(P<0.01,P<0.001,respectively),a significant increase in the expres-sion of ferroptosis-related protein ACSL4(P<0.01),and a significant decrease in the expression of GPX4(P<0.01)compared to the sham group.Additionally,the CLP group demonstrated significant increases in the expression of apoptosis-related protein Bax,the cleavage of autophagy-related protein LC3B-Ⅱ,and the expression of P62(P<0.05,P<0.001,P<0.001,respectively).Inhibition of apoptosis with programmed cell death inhibitors decreased platelet production function of megakaryocyte,while inhibition of necroptosis and pyroptosis had limited effects on platelet production function of megakaryocyte.Inhibition of ferroptosis and autophagy enhanced platelet production function of megakaryocyte.Conclusion Significant programmed death of megakaryocytes was observed during the acute phase of sepsis(24 h).Among those megakaryocytes,apoptosis is an important mechanism for the differentia-tion of platelet production phenotype and increased platelet production capacity of megakaryocyte.Overactive autophagy and ferroptosis in megakaryocytes lead to megakaryocyte dysfunction,which is an important mechanism for coagulation abnormalities in sepsis.

Currently,aging is a major public health topic globally.Infectious diseases exhibit high incidence and mortality among the elderly,which seriously affect the quality of life of the elderly and cause a heavy economic bur-den.The changes of immune function in the elderly are complicated.Their immune response and clinical immune regulation methods after infection need further clarification.This expert consensus summarizes the immune charac-teristics of the elderly and the inherent connection with infections,the application of glucocorticoids,the use of re-lated immune modulators,as well as diagnosis and treatment under specific conditions,providing high-quality recommendations for clinical practice.

Objective To investigate programmed death including necroptosis,apoptosis,autophagy,ferroptosis,and pyroptosis in bone marrow megakaryocytes of mice during sepsis and its impact on platelet production capacity and coagulation function in mice.Methods C57BL/6J mice were randomly divided into a sham operation group(sham group)and a sepsis model group(CLP group).Peripheral blood platelets and coagulation function were measured by abdominal aortic blood sampling at 24 h postoperatively in both sham and CLP groups.After the mice were sacrificed,long bones of both lower limbs were taken,and bone marrow megakaryocytes were extracted using megakaryocyte separation solution and immunomagnetic bead separation.Laser confocal microscopy was used to observe the activation of programmed death-related marker molecules in mouse bone marrow megakaryocytes.Flow cytometry was used to detect programmed death rate,platelet production phenotype,and platelet surface markers(CD41,CD42b,CD61)of megakaryocytes.Western blotting was used to detect the expression of programmed death-related proteins in megakaryocytes.Results Compared with the sham group,the CLP group showed significant decreases in the number of platelets during acute sepsis(24 h)(P<0.000 1),significant increases in platelet distri-bution width(PDW)and mean platelet volume(MPV)(P<0.01),significant prolonging of thrombin time(TT),prothrombin time(PT),and activated partial thromboplastin time(APTT)(P<0.000 1,P<0.001,P<0.01),and significant reduction in fibrinogen(Fib)(P<0.000 1).Compared with the Con/sham group,the LPS/CLP group exhibited significant increases in the platelet production phenotype of megakaryocyte,the number of PLP in the supernatant,and the expression levels of platelet surface markers(CD41,CD42b,CD61).The rates of megakaryocyte necroptosis/apoptosis,pyroptosis,and ferroptosis were significantly elevated at 24 h post-CLP surgery.Laser confo-cal microscopy showed significant activation of LC3,P-MLKL,Caspase-1,and Fe2+in megakaryocytes of mice after CLP surgery.Western blotting results revealed that the CLP group exhibited a significant increase in the activa-tion rate of necroptosis-related protein P-MLKL(P<0.001),a significant increase in the cleavage of pyroptosis-related proteins GSDMD and GSDMD-N(P<0.01,P<0.001,respectively),a significant increase in the expres-sion of ferroptosis-related protein ACSL4(P<0.01),and a significant decrease in the expression of GPX4(P<0.01)compared to the sham group.Additionally,the CLP group demonstrated significant increases in the expression of apoptosis-related protein Bax,the cleavage of autophagy-related protein LC3B-Ⅱ,and the expression of P62(P<0.05,P<0.001,P<0.001,respectively).Inhibition of apoptosis with programmed cell death inhibitors decreased platelet production function of megakaryocyte,while inhibition of necroptosis and pyroptosis had limited effects on platelet production function of megakaryocyte.Inhibition of ferroptosis and autophagy enhanced platelet production function of megakaryocyte.Conclusion Significant programmed death of megakaryocytes was observed during the acute phase of sepsis(24 h).Among those megakaryocytes,apoptosis is an important mechanism for the differentia-tion of platelet production phenotype and increased platelet production capacity of megakaryocyte.Overactive autophagy and ferroptosis in megakaryocytes lead to megakaryocyte dysfunction,which is an important mechanism for coagulation abnormalities in sepsis.

Currently,aging is a major public health topic globally.Infectious diseases exhibit high incidence and mortality among the elderly,which seriously affect the quality of life of the elderly and cause a heavy economic bur-den.The changes of immune function in the elderly are complicated.Their immune response and clinical immune regulation methods after infection need further clarification.This expert consensus summarizes the immune charac-teristics of the elderly and the inherent connection with infections,the application of glucocorticoids,the use of re-lated immune modulators,as well as diagnosis and treatment under specific conditions,providing high-quality recommendations for clinical practice.

Severe burns and trauma frequently lead to the skin barrier disruption and development of moist burn wound, which can trigger sepsis, septic shock, and even death. Immunodysfunction is closely associated with poor prognosis. In-depth research on the mechanisms of natural and adaptive immune dysfunction can help reveal the essence of the disease. Currently, elucidating the underlying mechanisms of immune dysfunction has become a critical research priority. Such investigations may provide fundamental insights into disease pathogenesis. Besides, accurate immune function assessment holds significant value for early detection of immune dysfunction, judgment of the severity of the condition, precise prediction of the prognosis, and guidance of clinical treatment. Implementing immunomodulatory treatment based on the pathophysiological mechanisms and evaluation results is a necessary approach to restoring the immune function, reducing mortality rate, and improving the prognosis of the patients with sepsis following severe burns and trauma. To this end, the authors systematically examined the characteristics and mechanisms of immune dysfunction, immune assessment as well as classification, and corresponding therapeutics in sepsis following severe burns and trauma, thereby providing a reference for the development of precise diagnosis and treatment strategies for immune dysfunction management.

Objective:To investigate the effects of thioredoxin reductase 1 (TXNRD1) on ferroptosis and immune function of dendritic cells (DCs) in septic mice, and to provide a basis for improving the immunosuppression in sepsis caused by wound infection.Methods:This study was an experimental research. Sixty male C57BL/6J mice aged 6-8 weeks were subjected to cecal ligation and puncture (CLP) to establish sepsis models. Ten mice were selected at 0 (immediately), 6, 12, 24, 48, and 72 h after CLP surgery, respectively, according to the random number table method. Mouse splenic DCs were isolated using CD11c-positive magnetic beads. The protein expressions of TXNRD1, and anti-ferroptosis proteins solute carrier family 7 member 11 (SLC7A11), and glutathione peroxidase 4 (GPX4) in the cells were detected by Western blotting, the reduced glutathione (GSH) content in the cells was measured by colorimetric assay, the lipid peroxidation level was assessed via live-cell imaging technology, and the levels of major histocompatibility complex class Ⅱ subtype I-A/I-E and leukocyte differentiation antigens CD80 and CD86 were detected by flow cytometry. Another 100 male C57BL/6J mice aged 6-8 weeks were divided into corn oil+sham injury group, corn oil+CLP group, inhibitor+sham injury group, and inhibitor+CLP group according to the random number table method, with 25 mice in each group. Mice in the two inhibitor groups were intraperitoneally injected with TXNRD1 inhibitor auranofin, while mice in the two corn oil groups were intraperitoneally injected with corn oil. One hour later, mice in the two CLP groups underwent CLP surgery to establish sepsis models, while mice in the two sham injury groups underwent sham surgery. Twenty mice from each group were selected to observe survival within 7 d post-surgery, and the survival rate was calculated. At 24 h post-surgery, mouse splenic DCs from the remaining 5 mice in each group were collected for corresponding assays as above.Results:Compared with those at 0 h after CLP surgery, the protein expressions of TXNRD1, GPX4, and SLC7A11 in mouse cells at 24 h after CLP surgery and the protein expression of TXNRD1 in mouse cells at 48 h after CLP surgery were significantly decreased ( P<0.05), the GSH content in mouse cells was significantly decreased at 24 and 48 h after CLP surgery ( P<0.05). The lipid peroxidation level in mouse cells was low at 0, 6, and 12 h after CLP surgery, slightly lower than that at 72 h after CLP surgery; the lipid peroxidation levels in mouse cells at 24 and 48 h after CLP surgery were significantly higher than those at 0, 6, 12, and 72 h after CLP surgery. Compared with those at 0 h after CLP surgery, the levels of I-A/I-E and CD80 in mouse cells at 6, 12, 24, 48, and 72 h after CLP surgery and the levels of CD86 in mouse cells at 12, 24, and 48 h after CLP surgery were significantly increased ( P<0.05). At 24 h post-surgery, the protein expressions of TXNRD1, SLC7A11, and GPX4 in mouse cells in corn oil+CLP group were significantly lower than those in corn oil+sham injury group ( P<0.05), while the protein expressions of TXNRD1, SLC7A11, and GPX4 in mouse cells in inhibitor+CLP group were significantly lower than those in corn oil+CLP group and inhibitor+sham injury group ( P<0.05). At 24 h post-surgery, the content of GSH in mouse cells in corn oil+CLP group was (239±32) μg/mg, which was significantly lower than (366±59) μg/mg in corn oil +sham injury group ( P<0.05); the content of GSH in mouse cells in inhibitor+CLP group was (134±19) μg/mg, which was significantly lower than (355±31) μg/mg in inhibitor+sham injury group and that in corn oil+CLP group (with both P values <0.05). At 24 h post-surgery, the lipid peroxidation level of mouse cells in inhibitor+CLP group was significantly higher than that in the other three groups ( P<0.05). At 24 h post-surgery, the levels of I-A/I-E, CD80, and CD86 in mouse cells in corn oil+CLP group were significantly higher than those in corn oil+sham injury group ( P<0.05), while the levels of I-A/I-E and CD80 in mouse cells in inhibitor+CLP group were significantly higher than those in inhibitor+sham injury group ( P<0.05) but significantly lower than those in corn oil+CLP group ( P<0.05); the level of CD86 in mouse cells in inhibitor+sham injury group was significantly higher than that in corn oil+sham injury group ( P<0.05). Within 7 d post-surgery, the survival rate of mice in inhibitor+CLP group was significantly lower than that in inhibitor+sham injury group and corn oil+CLP group (with χ2 values of 31.19 and 3.91, respectively, both P values <0.05). Conclusions:In septic mice, the expression of TXNRD1 in DCs is reduced, cell ferroptosis is enhanced, and immune function is weakened. The inhibition of TXNRD1 in DCs will exacerbate cell ferroptosis and immune function suppression, and is closely related to the poor prognosis of sepsis.