Impact of metabolic dysfunction-associated fatty liver disease on the outcomes following laparoscopic hepatectomy for hepatocellular carcinoma.

BACKGROUND: The impact of metabolic dysfunction-associated fatty liver disease (MAFLD) on laparoscopic liver resection (LLR) for hepatocellular carcinoma (HCC) remains unclear. This study aimed to compare the outcomes of LLR for MAFLD-HCC and Non-MAFLD-HCC. METHODS: Patients with HCC who received LLR between October 2017 and July 2021 were enrolled. Inverse probability of treatment weighting (IPTW) was used to generate adjusted comparisons. Both short- and long-term outcomes were evaluated accordingly. RESULTS: A total of 887 patients were enrolled, with 140 in MAFLD group and 747 in Non-MAFLD group. After IPTW adjustment, baseline factors were well matched. The MAFLD group was associated with more blood loss (210 vs 150 ml, p = 0.022), but with similar postoperative hospital stays and complication rates. The 1- and 3-year overall survival rates were 97.4% and 92.5% in MAFLD group, and 97.5% and 88.3% in Non-MAFLD group, respectively (p = 0.14). The 1- and 3-year disease-free survival rates were 84.8% and 62.9% in MAFLD group, and 80.2% and 58.8% in Non-MAFLD group, respectively (p = 0.31). CONCLUSIONS: LLR for MAFLD-HCC was associated with more blood loss but with comparable postoperative recovery and long-term survival compared with Non-MAFLD-HCC patients. LLR is feasible and safe for HCC patients with MAFLD background.

Systemic conversion therapies for initially unresectable hepatocellular carcinoma: a systematic review and meta-analysis.

BACKGROUND: Systemic conversion therapy provides patients with initially unresectable hepatocellular carcinoma (HCC) the chance to salvage radical liver resection and superior survival outcomes, but the optimal conversion strategy is unclear. METHODS: A systematic literature search was conducted on PubMed, EMBASE, Web of Science, Scopus, and the Cochrane Library between 2007 and 2024 focusing on studies reporting conversion therapy for HCC. The treatment groups were divided into Tyrosine kinase inhibitors (TKI), TKI plus loco-regional therapy (LRT), TKI plus anti-PD-1 therapy (TKI + PD-1), TKI + PD-1 + LRT, immune checkpoint inhibitors (ICI) plus LRT, and Atezolizumab plus bevacizumab (A + T) groups. The conversion to surgery rate (CSR), objective response rate (ORR), grade ≥ 3 treatment-related adverse events (AEs), overall survival (OS) and progression-free survival (PFS) were analyzed. RESULTS: 38 studies and 4,042 patients were included. The pooled CSR were 8% (95% CI, 5-12%) in TKI group, 13% (95% CI, 8-19%) in TKI + LRT group, 28% (95% CI, 19-37%) in TKI + PD-1 group, 33% (95% CI, 25-41%) in TKI + PD-1 + LRT group, 23% (95% CI, 1-46%) in ICI + LRT group, and 5% (95% CI, 3-8%) in A + T group, respectively. The pooled HR for OS (0.45, 95% CI, 0.35-0.60) and PFS (0.49, 95% CI, 0.35-0.70) favored survival benefit of conversion surgery. Subgroup analysis revealed that lenvatinib + PD-1 + LRT conferred higher CSR of 35% (95% CI, 26-44%) and increased ORR of 70% (95% CI, 56-83%). CONCLUSIONS: The current study indicates that TKI + PD-1 + LRT, especially lenvatinib + PD-1 + LRT, may be the superior conversion therapy with a manageable safety profile for patients with initially unresectable HCC. The successful conversion therapy favors the superior OS and PFS compared with systemic treatment alone. TRIAL REGISTRATION: International prospective register of systematic reviews (PROSPERO) (registration code: CRD 42024495289).

Pulmonary actinomycosis masquerading as lung cancer.

Pulmonary actinomycosis is a rare chronic purulent granulomatous disease, which can be easily misdiagnosed as lung cancer, tuberculosis, and other diseases. However, diagnosis relies on histopathological evidence, and early diagnosis is conducive to the patient's recovery. In this study, a case of a 70-year-old man with a soft tissue density mass at the right lower lung was studied, with initial chest CT suggesting lung cancer, pulmonary actinomycosis was confirmed by subsequent pathological biopsy of lung tissues eventually. The patient responded well to antibiotics treatment. This paper is to explore the clinical characteristics of the disease, providing insight into the disease, and its diagnosis and treatment.

The influence of chlorination additives on metal separation during the pyrometallurgical recovery of spent lithium-ion batteries.

The difficulty of separating Li during pyrometallurgical smelting of spent lithium-ion batteries (LIBs) has limited the development of pyrometallurgical processes. Chlorination enables the conversion of Li from spent LIBs to the gas phase during the smelting process. In this paper, the effects of four solid chlorinating agents (KCl, NaCl, CaCl2 and MgCl2) on Li volatilization and metal (Co, Cu, Ni and Fe) recovery were investigated. The four solid chlorinating agents were systematically compared in terms of the direct chlorination capacities, indirect chlorination capacities, alloy physical losses and chemical losses in the slag. CaCl2 was better suited for use as a solid chlorinating agent to promote Li volatilization due to its excellent results in these indexes. The temperature required for the release of HCl from MgCl2, facilitated by CO2 and SiO2, was lower than 500 °C. The prematurely released HCl failed to participate in the chlorination reaction. This resulted in approximately 12 % less Li volatilization when MgCl2 was used as a chlorinating agent compared to when CaCl2 was used. In addition, the use of KCl as a chlorinating agent decreased the chemical dissolution loss of alloys in the slag. The performance of NaCl was mediocre. Finally, based on evaluations of the four indexes, recommendations for the selection and optimization of solid chlorinating agents were provided.

Exosomal mRNA in plasma serves as a predictive marker for microvascular invasion in hepatocellular carcinoma.

BACKGROUND AND AIM: There is a pressing need for non-invasive preoperative prediction of microvascular invasion (MVI) in hepatocellular carcinoma (HCC). This study investigates the potential of exosome-derived mRNA in plasma as a biomarker for diagnosing MVI. METHODS: Patients with suspected HCC undergoing hepatectomy were prospectively recruited for preoperative peripheral blood collection. Exosomal RNA profiling was conducted using RNA sequencing in the discovery cohort, followed by differential expression analysis to identify candidate targets. We employed multiplexed droplet digital PCR technology to efficiently validate them in a larger sample size cohort. RESULTS: A total of 131 HCC patients were ultimately enrolled, with 37 in the discovery cohort and 94 in the validation cohort. In the validation cohort, the expression levels of RSAD2, PRPSAP1, and HOXA2 were slightly elevated while CHMP4A showed a slight decrease in patients with MVI compared with those without MVI. These trends were consistent with the findings in the discovery cohort, although they did not reach statistical significance (P > 0.05). Notably, the expression level of exosomal PRPSAP1 in plasma was significantly higher in patients with more than 5 MVI than in those without MVI (0.147 vs 0.070, P = 0.035). CONCLUSION: This study unveils the potential of exosome-derived PRPSAP1 in plasma as a promising indicator for predicting MVI status preoperatively.

Robotic versus laparoscopic liver resection for posterosuperior segments: a systematic review and meta-analysis.

BACKGROUND: Minimally invasive hepatectomy for difficult lesions located in posterosuperior segments (segments I, IVa, VII and VIII) remains challenging. The value of robotic liver resection (RLR) compared with laparoscopic liver resection (LLR) for posterosuperior segments is controversial. Therefore, we performed this meta-analysis to validate the safety and efficacy of RLR in posterosuperior segments. METHODS: The Medline, Embase, Web of Science, and Cochrane Library electronic databases were searched to identify available research published up to October 2023. Statistical analysis was performed with RevMan software version 5.3. RESULTS: Six studies with a total of 2289 patients (RLR: n = 749; LLR: n = 1540) were included in this meta-analysis. The RLR group had less intraoperative blood loss (WMD = -119.54 ml, 95% CI: -178.89 to -60.19, P < 0.0001), fewer blood transfusions (OR = 0.56, 95% CI: 0.39 to 0.80, P = 0.001), a lower conversion rate (OR = 0.37, 95% CI: 0.23 to 0.61, P < 0.0001), and a shorter operative time (WMD = -27.16 min, 95% CI: -35.95 to -18.36, P < 0.00001). DISCUSSION: Compared with LLR, RLR for lesions in the posterosuperior segments could be safe and effective, and it has superior surgical outcomes.

Steric Hindrance-Mediated Enzymatic Reaction Enable Homogeneous Dual Fluorescence Indicators Aptasensing of Hepatocellular Carcinoma CTCs.

Circulating tumor cells (CTCs) serve as important biomarkers in the liquid biopsy of hepatocellular carcinoma (HCC). Herein, a homogeneous dual fluorescence indicators aptasensing strategy is described for CTCs in HCC, with the core assistance of a steric hindrance-mediated enzymatic reaction. CTCs in the sample could specifically bind to a 5'-biotin-modified glypican-3 (GPC3) aptamer and remove the steric hindrance formed by the biotin-streptavidin system. This influences the efficiency of the terminal deoxynucleotidyl transferase enzymatic reaction. Then, methylene blue (MB) was introduced to react with the main product poly cytosine (polyC) chain, and trivalent cerium ion (Ce3+) was added to react with the byproduct pyrophosphate to form fluorescent pyrophosphate cerium coordination polymeric nanoparticles. Finally, the CTCs were quantified by dual fluorescence indicators analysis. Under optimized conditions, the linear range was 5 to 104 cells/mL, and the limits of detection reached 2 cells/mL. Then, 40 clinical samples (15 healthy and 25 HCC patients) were analyzed. The receiver operating characteristic curve analysis revealed an area under the curve of 0.96, a sensitivity of 92%, and a specificity of 100%. Therefore, this study established a sensitive and accurate CTCs sensing system for clinical HCC patients, promoting early tumor diagnosis.

Caudo-dorsal approach combined with the occlusion of right hepatic vein and Pringle maneuver in laparoscopic anatomical resection of segment 7.

BACKGROUND: Laparoscopic anatomical resection of segment 7 (LARS7) remains a technically challenging procedure due to the deep anatomical location and the potential risk of injury to the right hepatic vein (RHV). Herein, we initiated an innovative technique of caudo-dorsal approach combined with the occlusion of the RHV and Pringle maneuver for LARS7 and presented the outcomes of our initial series. METHOD: Since January 2021, the patients who underwent LARS7 by using this novel technique were enrolled in this study. The critical aspect of this technique was the interruption of communication between the RHV and the inferior vena cava. Meanwhile, the Pringle maneuver was adopted to control the hepatic inflow. RESULT: A total of 11 patients underwent LARS7 by using this novel technique, which included 8 hepatocellular carcinoma, 2 bile duct adenocarcinoma and one focal nodular hyperplasia. The median operative time was 199 min (range of 151-318 min) and the median blood loss was 150 ml (range of 50-200 ml). The main trunk of the RHV was fully exposed on the cutting surface in all cases and no patient received perioperative blood transfusion. No procedure was converted to open surgery. Of note, no indications of CO2 gas embolism were observed in these cases after the introduction of double occlusion. Only one patient suffered from postoperative complications and healed after treatment. The median postoperative stay was 5 days (range of 4-7 days). The 90-day mortality was nil. At a median follow-up period of 19 months, all of the patients were alive without any evidence of tumor recurrence. CONCLUSION: The caudo-dorsal approach combined with the occlusion of RHV and the Pringle maneuver may be a feasible and expected technique for safe exposure of RHV in LARS7. Further validation of the feasibility and efficacy of this technique is needed.

Long-term surgical outcomes of bile duct tumor thrombus versus portal vein tumor thrombus for hepatocellular carcinoma: a propensity score matching analysis.

Background: Portal vein tumor thrombus (PVTT) seriously affects the prognosis of hepatocellular carcinoma (HCC). However, whether bile duct tumor thrombus (BDTT) significantly affects the prognosis of HCC as much as PVTT remains unclear. We aimed to compare the long-term surgical outcomes of HCC with macroscopic PVTT (macro-PVTT) and macroscopic BDTT (macro-BDTT). Methods: The data of HCC patients with macro-BDTT or macro-PVTT who underwent hemihepatectomy were retrospectively reviewed. A propensity score matching (PSM) analysis was performed to reduce the baseline imbalance. The recurrence-free survival (RFS) and overall survival (OS) rates were compared between the cohorts. Results: Before PSM, the PVTT group had worse RFS and OS rates than the BDTT group (P = 0.043 and P = 0.008, respectively). Multivariate analyses identified PVTT (hazard ratio [HR] = 1.835, P = 0.016) and large HCC (HR = 1.553, P = 0.039) as independent risk factors for poor OS and RFS, respectively. After PSM, the PVTT group had worse RFS and OS rates than the BDTT group (P = 0.037 and P = 0.004, respectively). The 3- and 5-year OS rates were significantly higher in the BDTT group (59.5% and 52.1%, respectively) than in the PVTT group (33.3% and 20.2%, respectively). Conclusion: Aggressive hemihepatectomy provides an acceptable prognosis for HCC patients with macro-BDTT. Furthermore, the long-term surgical outcomes of HCC patients with macro-BDTT were significantly better than those of HCC patients with macro-PVTT.

Laparoscopic liver resection or enucleation for giant hepatic hemangioma: how to choose?

BACKGROUND: Laparoscopic treatment has been increasingly adopted for giant hepatic hemangioma (HH), but the role of liver resection or enucleation remains uncertain. The aim of this study is to compare the laparoscopic resection (LR) with laparoscopic enucleation (LE) for HH, and to provide evidence on how to choose the most suitable approach for HH. METHODS: A retrospective analysis of HH patients underwent laparoscopic treatment between March 2015 and August 2022 was performed. Perioperative outcomes were compared based on the surgical approaches, and risk factors for increased blood loss was calculated by logistic regression analysis. RESULTS: A total of 127 patients in LR group and 287 patients in LE group were enrolled in this study. The median blood loss (300 vs. 200 mL, P < 0.001) was higher in LE group than that in LR group. Independent risk factors for blood loss higher than 400 mL were tumor size ≥ 10 cm, tumor adjacent to major vessels, tumor occupying right liver or caudate lobe, and the portal phase enhancement ratio (PER) ≥ 38.9%, respectively. Subgroup analysis showed that LR was associated with less blood loss (155 vs. 400 mL, P < 0.001) than LE procedure in patients with high PER value. Both LR and LE approaches exhibited similar perioperative outcomes in patients with low PER value. CONCLUSIONS: Laparoscopic treatment for HH could be feasibly and safely performed by both LE and LR. For patients with PER higher than 38.9%, the LR approach is recommended.

Accumulation of TOX high mobility group box family member 3 promotes the oncogenesis and development of hepatocellular carcinoma through the MAPK signaling pathway.

Microvascular invasion (MVI) has been widely valued in the field of liver surgery because MVI positivity indicates poor prognosis in hepatocellular carcinoma (HCC) patients. However, the potential molecular mechanism underlying the poor prognosis of MVI-positive HCC patients is unclear. Therefore, this study focused on identifying the key genes leading to poor prognosis in patients with a high degree of malignancy of HCC by examining the molecular signaling pathways in MVI-positive HCC patients. Through RNA sequencing, TOX high mobility group box family member 3 (TOX3) was demonstrated to be significantly highly expressed in MVI-positive HCC tissues, which was associated with poor prognosis. The results of in vivo and in vitro showed that TOX3 can promote the oncogenesis and development of HCC by targeting key molecules of the MAPK and EMT signaling pathways. The IP-MS results indicated that proteasome degradation of TOX3 in HCC cells is potentially mediated by a tripartite motif containing 56 (TRIM56, an E3 ligase) in HCC cells. Inhibiting TRIM56 enhances TOX3 protein levels. Overall, our study identified TOX3 as a key gene in the MAPK and EMT signaling pathways in HCC, and its overexpression confers significant proliferation and invasiveness to tumor cells.

Laparoscopic Anatomic Bi-segmentectomy (S5 and S6) Using Takasaki's Approach and Indocyanine Green Fluorescence Navigation.

BACKGROUND: To date, most laparoscopic anatomic bi-segmentectomy practices have been performed vertically, such as the resection of segments 6 and 7, segments 5 and 8, and segments 2 and 3;1-3 however, transversal hepatectomy may be more appropriate for certain lesions that are located in a specific area.4,5 Herein, we present a video of a pure laparoscopic anatomic bi-segmentectomy (S5 and S6) using Takasaki's approach and indocyanine green fluorescence navigation. METHOD: A 58-year-old male with hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) was admitted to our institution. The preoperative abdominal computed tomography (CT) scan showed a 5 × 4 cm tumor located between segments 5 and 6. Right hepatectomy was not adopted because of severe cirrhosis and portal hypertension. Therefore, laparoscopic anatomic bi-segmentectomy (5 and 6) was planned. After cholecystectomy, G5 and G6 were dissected and ligated using Takasaki's Glissonean pedicle approach.6 The ischemic line then appeared on the liver surface. An intraoperative ultrasound was used to confirm that the tumor was within the ischemic line. Afterwards, intraoperative fluorescence navigation (negative stained) was performed to detect the demarcation line and guide the transection of liver parenchymal. RESULTS: The operative time was 225 min and the estimated blood loss was 150 mL. The total Pringle time was 75 min. The postoperative course was uneventful and the patient was discharged on postoperative day 8. Pathology confirmed the diagnosis of HCC and the surgical margin was negative. CONCLUSIONS: Laparoscopic anatomic bi-segmentectomy (S5 and S6) is technically feasible and safe, which may be a beneficial alternative to formal right hepatectomy in some cases.

Pure Laparoscopic Anatomic Resection of Liver Segment 4 with Middle Hepatic Vein Involvement Using Indocyanine Green Fluorescence Staining.

BACKGROUND: Laparoscopic anatomic resection of liver segment 4 is a technically challenging operation, which is rarely reported owing to the difficulty of defining the demarcation of a hepatic segment 4 on a monitor.1 The portal territory staining method is technically feasible to identify tumors and segment boundaries during hepatectomy.2 Herein, we describe the laparoscopic hepatectomy of segment 4 using the fluorescent-positive staining method. METHODS: A 72-year-old man recurred colorectal liver metastases after colectomy, positron emission tomography (PET)/computed tomography (CT) showed metastases located in segment 4 with involvement of the middle hepatic vein (MHV) and caudate lobe; no other organ metastasis or recurrence occurred. We performed an anatomical hepatectomy 4 with MHV and parenchymal resection of segment 1 (H1'/4-MHV).3 The key point of the procedure was dividing and clamping Glisson's branches for segment 2 and segment 3 using the hepatic round ligament approach; the G2 and G3 were dissected along the right side of round ligament via the extrahepatic Glissonian approach, then the left hepatic artery (LHA) was divided and injected with ICG in the left portal vein (LPV). Finally, transection was performed along the fluorescent stain location line and ischemic demarcation line. RESULTS: The operation time was 263 min; the Pringle lasted 110 min, and the estimated blood loss was 400 g. The patient was discharged on postoperative day 5 without complications. Sigmoid carcinoma and R0 margin were confirmed by histopathology. CONCLUSIONS: Laparoscopic anatomic hepatectomy 4 with middle hepatic vein invasion using indocyanine green (ICG) fluorescence staining is a feasible and effective technique.

Approaches of laparoscopic anatomical liver resection of segment 8 for hepatocellular carcinoma: a retrospective cohort study of short-term results at multiple centers in China.

BACKGROUND: Laparoscopic anatomical liver resection of segment 8 (LALR-S8) remains a challenge for anatomical laparoscopic segmentectomy. Most current reports on LALR-S8 are case series using one surgical approach, and there is a lack of multicenter data on identifying intersegmental planes using different approaches. In this study, the authors aimed to elucidate the short-term results of three different approaches for LALR-S8 for hepatocellular carcinoma (HCC), focusing on intersegmental plane determination, and to reflect on current practice regarding different approaches at multiple centers in China. MATERIALS AND METHODS: The clinical cohort data of 122 patients who underwent LALR-S8 for HCC at seven leading centers in China were retrospectively analyzed. The surgical procedures of all approaches were summarized and standardized according to the method of the Glissonean pedicle of segment 8 identification. The postoperative short-term outcomes and oncological results of the three approaches were evaluated and compared. RESULTS: Three approaches were used: laparoscopic ultrasonography-guided indocyanine green fluorescent positive staining approach (11/122, 9.02%), hepatic vein-guided approach (99/122, 81.15%), and Glissonean indocyanine green fluorescent negative staining approach (12/122, 9.83%). Seven (5.73%) patients experienced complications according to the Clavien-Dindo classification, and the rate of grade ≥IIIa complications was 2.46%. The R0 resection rates among the groups (margin >1 mm) and the margin width showed no statistical difference. CONCLUSION: LALR-S8 is safe and feasible for treating HCC under standardized surgical techniques and appropriate surgical approaches. The three reported approaches had comparable short-term oncological outcomes, while the hepatic vein-guided approach was most commonly used.

Preoperative dexamethasone administration in hepatectomy of 25-min intermittent Pringle's maneuver for hepatocellular carcinoma: a randomized controlled trial.

BACKGROUND: A previous randomized controlled trial demonstrated that intermittent Pringle's maneuver (IPM) with a 25-min ischemic interval could be applied safely and efficiently in hepatectomy for patients with hepatocellular carcinoma (HCC). But prolonging the hepatic inflow clamping time will inevitably aggravate the ischemia-reperfusion injury. Therefore, we aimed to evaluate the effect of prophylactic dexamethasone on alleviating surgical stress for HCC patients with a 25-min ischemic interval. METHODS: From December 2022 to April 2023, patients who met the inclusion criteria were randomly assigned to the dexamethasone group or control group. Perioperative data and short-term survival outcomes between the two groups were recorded and compared, and subgroup analysis was performed. RESULTS: Two hundred and seventy patients were allocated to the dexamethasone group ( n =135) and control group ( n =135). Patients in the dexamethasone group had lower area under the curve of serial alanine aminotransferase (AUC ALT ) ( P =0.043) and aspartate aminotransferase (AUC AST ) ( P =0.009), total bilirubin (TB) ( P =0.018), procalcitonin (PCT) ( P =0.012), interleukin-6 (IL-6) ( P =0.006), incidence of major complication ( P =0.031) and shorter postoperative hospital stay ( P =0.046) than those in the control group. Subgroup analysis showed that the dexamethasone group experienced milder hepatocellular injury than the control group for patients with cirrhosis, and for patients without cirrhosis, the dexamethasone group experienced milder inflammatory response. Moreover, the dexamethasone group preserved better liver function and experienced milder inflammatory response for patients undergoing major hepatectomy, although the hepatocellular injury was not significantly improved. CONCLUSION: Preoperative dexamethasone administration can help improve perioperative outcomes for HCC patients when applying IPM with a 25-min ischemic interval in hepatectomy.

Reconstruction of Inferior Vena Cava by Autologous Great Saphenous Vein Grafts in Liver Surgery.

BACKGROUND: To secure surgical margin for hepatic lesion with involvement of the inferior vena cava (IVC), combined radical liver resection and IVC replacement are required. A novel method of replacing IVC by newly customized autologous great saphenous vein (GSV) grafts was introduced by this study. This study aimed at reporting the feasibility and outcome of this novel technique. METHODS: From January 2014 to January 2021, all consecutive patients who underwent concomitant hepatectomy and IVC replacement by autogenous GSV graft were enrolled in this study. Technical insights, intraoperative details, demographic data, postoperative complication, graft patency and survival data were collected and analyzed. RESULTS: Concomitant hepatectomy/autotransplantation (ERAT) with IVC replacement by autogenous GSV graft was successful in 47 patients and there was no 30-day mortality. There were 8 out of the 47 patients whose retrohepatic venae cavae were completely invaded by the lesion and their reconstructed IVCs were totally made from GSV grafts. The other 39 patients whose IVCs were partially invaded had their IVCs reconstructed by both the unaffected part of the IVC wall and newly customized GSV graft. Postoperative complications classified as Clavien-Dindo grade II, III A and III B were observed in 10, 7 and 3 patients, respectively. The median follow-up months were 35 months (29-80 months). No patient developed thrombosis of the graft and 100% patency of the IVC was observed throughout the study. CONCLUSION: In selected patients, hepatectomy/ERAT with IVC replacement by autogenous GSV graft is safe and feasible. The newly customized autologous GVS graft was ideal for reconstruction of the IVC in liver surgery.

Intermedin (adrenomedullin 2) plays a protective role in sepsis by regulating T- and B-cell proliferation and activity.

BACKGROUND: Sepsis is the major cause of death in intensive care units. We previously found that intermedin (IMD), a calcitonin family peptide, can protect against sepsis by dynamically repairing vascular endothelial junctions and can ameliorate the inflammatory response by inhibiting the infiltration of macrophages in peripheral tissues. The effects of IMD on inflammatory and immune responses indicate that IMD may play a role in immunity. However, whether IMD affects immune cell development, differentiation and response to infection remains unclear. METHODS: IMD-knockout (Adm2-/-) mice were generated in our previous work. Wild-type and IMD-KO mice were subjected to sham or cecal ligation and puncture (CLP) surgery, and bone marrow cells were obtained for RNA sequencing (RNA-Seq) analysis. The RNA-Seq results were verified by real-time RT-PCR. The effect of IMD KO or IMD rescue on the septic mice was explored using mild and severe infection models induced by CLP surgery at different levels of severity, and the survival outcomes were analyzed using Kaplan-Meier curves and the log-rank test. The mechanism underlying the effects of IMD in T/B cell proliferation and differentiation were investigated by PCR, Western blot (WB), and cell proliferation assays and flow cytometry analysis. RESULTS: RNA-Seq showed that IMD-KO mice exhibited a primary immunosuppression phenotype characterized by a marked decrease in the expression of T- and B-cell function-related genes. This immunosuppression made the IMD-KO mice vulnerable to pathogenic invasion, and even mild infection killed nearly half of the IMD-KO mice. Supplementation with the IMD peptide restored the expression of T/B-cell-related genes and significantly reduced the mortality rate of the IMD-KO mice. IMD is likely to directly promote T- and B-cell proliferation through ERK1/2 phosphorylation, stimulate T-cell differentiation via Ilr7/Rag1/2-controled T cell receptor (TCR) recombination, and activate B cells via Pax5, a transcription factor that activates at least 170 genes needed for B-cell functions. CONCLUSION: Together with previous findings, our results indicate that IMD may play a protective role in sepsis via three mechanisms: protecting the vascular endothelium, reducing the inflammatory response, and activating T/B-cell proliferation and differentiation. Our study may provide the first identification of IMD as a calcitonin peptide that plays an important role in the adaptive immune response by activating T/B cells and provides translational opportunities for the design of immunotherapies for sepsis and other diseases associated with primary immunodeficiency.