A preliminary survey for cases treated with intravenous immunoglobulin (IVIG) for Antibody-mediated rejection (AMR) in Japan was performed in 2022. Three cases treated with IVIG were reported. A secondary survey on the three cases was conducted in this study.

Intestine transplantation was performed in 42 cases from 2001 to 2022 in Japan, and IVIG was used in 3 of these cases (7%) for AMR that developed after transplantation. Five g of IVIG per dose was administrated, and the duration of administration was 6-10 days.

IVIG administration may be necessary as a therapeutic agent in intestine transplantation because of the high incidence of chronic rejection and its significant impact on prognosis. Therefore, we hope for national insurance coverage for IVIG.

【Objective】 Serum procalcitonin (PCT) levels transiently elevate during the first few days after both living donor liver transplantation (LDLT) and deceased donor liver transplantation (DDLT). Although the impact of early-phase serum PCT levels on DDLTs has been researched in other literature, that on LDLTs is still not well clarified.

【Design】 A single-institutional retrospective cohort.

【Methods】 A total of 233 adult primary liver transplantations (205 LDLTs and 28 DDLTs) between 2013 and 2022 were analyzed. Thirty-seven cases were excluded due to the lack of data. We evaluated the first-week transition in serum PCT levels. The impact of serum PCT levels on positive blood cultures of gut microbiota and 1-year graft survival was also analyzed.

【Results】 Pre-transplant serum PCT levels were significantly correlated with the Model for End-Stage Liver Disease score. Serum PCT levels peaked at postoperative day (POD) 2, and the average serum PCT levels at PODs 1-3 were higher in DDLTs (1.99 vs. 11.02 ng/mL, p<0.01). LDLT recipients with high average serum PCT levels at PODs 1-3 (>10 ng/mL) had a lower positive blood culture-free survival within 14 days (70.6 vs. 94.3%, p<0.01). The high average serum PCT levels at PODs 1-3 (>10 ng/mL) were also a significant factor in 1-year graft loss in LDLTs (hazard ratio = 4.17, p=0.03).

【Conclusion】 High serum PCT levels at PODs 1-3 may be a potential predictor of short-term positive blood cultures and graft loss in LDLTs.

【Introduction】 Therapeutic strategies for antibody mediated rejection (AMR) after liver transplantation are gradually being established; however, the efficacy of intravenous immunoglobulin (IVIg) therapy as a treatment for AMR after liver transplantation is not clear. The purpose of this multicenter, retrospective, observational study was to clarify the actual status of AMR treatment using IVIg in Japan, and the efficacy and safety of IVIg therapy.

【Methods】 Sixty-one liver transplant recipients diagnosed with AMR and treated with IVIg between April 2001 and March 2022 were analyzed. Sixty-one patients in the secondary survey who were treated with IVIG were analyzed for efficacy and safety in a retrospective study.

【Results】 Acute AMR was observed in 86.0% of adult cases, and 94.4% of pediatric cases. Acute T cell-mediated rejection (TCMR) was also concomitant with AMR in 48.8% of adult patients and 22.2% of pediatric patients. When AMR develops after liver transplantation, IVIg + PE and IVIg + steroid pulse therapy was the most common treatment in adult patients (27.9%). In pediatric cases, IVIg therapy alone was the most commonly used, at 38.9%. Patient survival and graft survival rates at 6 months after AMR treatment including IVIg in adult patients were 69.8% and 69.8%, respectively and were 94.4% and 88.9% in pediatric patients, respectively.

Serious adverse events, including those with unknown causal relationship, were observed in 7.0% of adult cases and 5.6% of pediatric cases.

【Conclusion】 AMR treatment including IVIg is safe and has sufficient therapeutic effect and may be one of the effective treatment modalities for the development of AMR after liver transplantation.

We retrospectively surveyed the status of IVIg use in the treatment for antibody-mediated rejection (AMR) in pediatric kidney transplant recipients in Japan between 2001 and 2022. We collected clinical information in 17 recipients from 9 institutes. The median dose of IVIg was 0.74 g/kg, and the range was widely distributed from 0.10 g/kg to 2.06 g/kg. The graft survival at 6 months and 12 months after the administration of IVIg was 100 and 93.3%. Fifteen patients were treated with IVIg and other treatment options, and in most cases, IVIg was considered as the first-line or second-line treatment for AMR. Among 16 donor-specific anti-HLA antibodies (DSAs) which were followed before and after the treatment, the MFI of 12 DSAs was markedly decreased after the administration of IVIg. No adverse events related to thrombotic complications were reported from this survey. From this survey, it was suggested that IVIg treatment for AMR in Japanese pediatric kidney transplant recipients was effective in terms of allograft survival and decreased MFI of DSAs.

【Objective】 Postoperative prolonged ascites is a common complication after living-donor liver transplantation (LDLT). However, there is little evidence regarding the circulatory indicators as risk factors for ascites after LDLT. The aim was to evaluate the impact of trans tricuspid pressure gradient (TRPG) on postoperative prolonged ascites.

【Design】 Case-series.

【Method】 We collected data from 268 recipients who underwent LDLT for liver failure between 2008 and 2022. We excluded 7 recipients who died within 30 days after LDLT and divided the remainer into two groups by TRPG value.

【Results】 Of the 261 patients with liver failure, 98 (37.7%) were classified as the high TRPG group and 163 (62.3%) comprised the low TRPG group. There was a significant difference in the rate of intractable ascites between the two groups, but no significant difference in overall survival (OS). After PSM, univariate analysis detected two risk factors, high TRPG value and ascites at laparotomy ≥5000 mL. In the multivariate analysis, high TRPG value (P=0.0345, OR=11.4, 95% CI 1.19-108) and ascites at laparotomy ≥5000 (mL) (P=0.0067, OR=10.2, 95% CI 1.91-54.8) were identified as independent risk factors.

【Conclusion】 Preoperative TRPG elevation is a risk for prolonged ascites after LDLT, and it can be valuable to measure TRPG in the preoperative condition assessment.

Extracellular vesicles (EVs) are emerging as a new field of interest in the study of liver diseases. EVs are involved in intercellular communication and contain various bioactive molecules. In liver transplantation (LT), EVs are attractive materials because they could be involved in many physiological and pathological processes, such as immunomodulation and tissue repair. They could play a multifaceted role in organ rejection and immune modulation, with further research possibly paving the way for advancements in diagnosis and treatment. EVs hold great promise for mitigating ischemia-reperfusion injury (IRI), potentially addressing organ shortage by enabling the regeneration of currently discarded organs. However, standardization of EV isolation and purification techniques, establishment of quantitative criteria, enhancement of EV yield while maintaining homogeneity, ensuring proper storage, and rigorous assessment of safety are all critical steps before clinical application of EV-based therapies in LT. Despite their costly nature in an already expensive procedure, future research efforts have the potential to maximize the potential of EVs in LT, ultimately contributing to improved patient outcomes and shaping the future of personalized medicine. This review highlights the role of EVs in LT, particularly their potential roles as biomarkers and therapeutic agents, as well as current insights into immunological response.