The signaling suppressor CIS controls proallergic T cell development and allergic airway inflammation.

Transcription factors of the STAT family are critical in the cytokine-mediated functional differentiation of CD4(+) helper T cells. Signaling inhibitors of the SOCS family negatively regulate the activation of STAT proteins; however, their roles in the differentiation and function of helper T cells are not well understood. Here we found that the SOCS protein CIS, which was substantially induced by interleukin 4 (IL-4), negatively regulated the activation of STAT3, STAT5 and STAT6 in T cells. CIS-deficient mice spontaneously developed airway inflammation, and CIS deficiency in T cells led to greater susceptibility to experimental allergic asthma. CIS-deficient T cells showed enhanced differentiation into the TH2 and TH9 subsets of helper T cells. STAT5 and STAT6 regulated IL-9 expression by directly binding to the Il9 promoter. Our data thus demonstrate a critical role for CIS in controlling the proallergic generation of helper T cells.

The MicroRNA-183-96-182 Cluster Promotes T Helper 17 Cell Pathogenicity by Negatively Regulating Transcription Factor Foxo1 Expression.

T helper 17 (Th17) cells are key players in autoimmune diseases. However, the roles of non-coding RNAs in Th17 cell development and function are largely unknown. We found that deletion of the endoribonuclease-encoding Dicer1 specifically in Th17 cells protected mice from experimental autoimmune encephalomyelitis. We found that the Dicer1-regulated microRNA (miR)-183-96-182 cluster (miR-183C) was highly expressed in Th17 cells and was induced by cytokine IL-6-STAT3 signaling. miR-183C expression enhanced pathogenic cytokine production from Th17 cells during their development and promoted autoimmunity. Mechanistically, miR-183C in Th17 cells directly repressed expression of the transcription factor Foxo1. Foxo1 negatively regulated the pathogenicity of Th17 cells in part by inhibiting expression of cytokine receptor IL-1R1. These findings indicate that the miR-183C drives Th17 pathogenicity in autoimmune diseases via inhibition of Foxo1 and present promising therapeutic targets.

The methylcytosine dioxygenase Tet2 promotes DNA demethylation and activation of cytokine gene expression in T cells.

Epigenetic regulation of lineage-specific genes is important for the differentiation and function of T cells. Ten-eleven translocation (Tet) proteins catalyze 5-methylcytosine (5 mC) conversion to 5-hydroxymethylcytosine (5 hmC) to mediate DNA demethylation. However, the roles of Tet proteins in the immune response are unknown. Here, we characterized the genome-wide distribution of 5 hmC in CD4(+) T cells and found that 5 hmC marks putative regulatory elements in signature genes associated with effector cell differentiation. Moreover, Tet2 protein was recruited to 5 hmC-containing regions, dependent on lineage-specific transcription factors. Deletion of Tet2 in T cells decreased their cytokine expression, associated with reduced p300 recruitment. In vivo, Tet2 plays a critical role in the control of cytokine gene expression in autoimmune disease. Collectively, our findings suggest that Tet2 promotes DNA demethylation and activation of cytokine gene expression in T cells.

STAT3 Decoy Oligodeoxynucleotides Suppress Liver Inflammation and Fibrosis in Liver Cancer Cells and a DDC-Induced Liver Injury Mouse Model.

Liver damage caused by various factors results in fibrosis and inflammation, leading to cirrhosis and cancer. Fibrosis results in the accumulation of extracellular matrix components. The role of STAT proteins in mediating liver inflammation and fibrosis has been well documented; however, approved therapies targeting STAT3 inhibition against liver disease are lacking. This study investigated the anti-fibrotic and anti-inflammatory effects of STAT3 decoy oligodeoxynucleotides (ODN) in hepatocytes and liver fibrosis mouse models. STAT3 decoy ODN were delivered into cells using liposomes and hydrodynamic tail vein injection into 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed mice in which liver injury was induced. STAT3 target gene expression changes were verified using qPCR and Western blotting. Liver tissue fibrosis and bile duct proliferation were assessed in animal experiments using staining techniques, and macrophage and inflammatory cytokine distribution was verified using immunohistochemistry. STAT3 decoy ODN reduced fibrosis and inflammatory factors in liver cancer cell lines and DDC-induced liver injury mouse model. These results suggest that STAT3 decoy ODN may effectively treat liver fibrosis and must be clinically investigated.

IL-27 confers a protumorigenic activity of regulatory T cells via CD39.

Expression of ectonucleotidase CD39 contributes to the suppressive activity of Foxp3+ regulatory T cells (Tregs) by hydrolyzing immunogenic ATP into AMP. The molecular mechanism that drives CD39 expression on Tregs remains elusive. We found that tumor-infiltrating Tregs (Ti-Tregs) failed to up-regulate CD39 in mice lacking EBI3 subunit of IL-27 or IL-27Ra. Mixed bone marrow chimera and in vitro studies showed that IL-27 signaling in Tregs directly drives CD39 expression on Ti-Tregs in a STAT1-dependent, but STAT3- and T-bet-independent, manner. Tregs stimulated with IL-27 showed enhanced suppressive activities against CD8+ T cell responses in vitro. Moreover, IL-27Ra-deficient Tregs and STAT1-deficient Tregs were less efficient than WT Tregs in suppressing antitumor immunity in vivo. CD39 inhibition significantly abolished IL-27-induced suppressive activities of Tregs. Thus, IL-27 signaling in Tregs critically contributes to protumorigenic properties of Tregs via up-regulation of CD39.

Differentiation of c-Kit+ CD24+ natural killer cells into myeloid cells in a GATA-2-dependent manner.

Myeloid progenitor cells have generally been considered the predominant source of myeloid cells under steady-state conditions. Here we show that NK cells contributed to a myeloid cell lineage pool in naïve and tumor-bearing mice. Using fate tracing of NKp46+ cells, we found that myeloid cells could be derived from NK cells. Notably, among mature CD11b+ CD27+ NK cells, c-Kit+ CD24+ NK cells were capable of differentiating into a range of myeloid lineages in vitro and produced neutrophils and monocytes in vivo. The differentiation was completely inhibited by NK-stimulating cytokines. In addition to the potential for differentiation into myeloid cells, c-Kit+ CD24+ NK cells retained NK cell phenotypes and effector functions. Mechanistically, GATA-2 was necessary for the differentiation of c-Kit+ CD24+ NK cells. Therefore, we discovered that GATA-2-dependent differentiation of c-Kit+ CD24+ NK cells contributes to myeloid cell development and identified a novel pathway for myeloid lineage commitment under physiological conditions.

Modulation of the adsorption chemistry of a precursor in atomic layer deposition to enhance the growth per cycle of a TiO2 thin film.

Atomic layer deposition (ALD) has scarcely been utilized in large-scale manufacturing and industrial processes due to its low productivity, even though it possesses several advantages for improving the device performance. The major cause of its low productivity is the slow growth rate, which is determined by the amount of chemisorbed precursor. The slow growth rate of ALD has become even more critical due to the introduction of heteroleptic-based precursors for achieving a higher thermal stability. In this study, we investigated the theoretical and experimental chemisorption characteristics of the Ti(CpMe5)(OMe)3 precursor during the ALD of TiO2. By density functional theory calculations, the relationship between the steric hindrance effect and the chemistry of a chemisorbed precursor was revealed. Based on the calculation result, a way for improving the growth per cycle by 50% was proposed and demonstrated, successfully.

Changing Trends in Liver Cirrhosis Etiology and Severity in Korea: the Increasing Impact of Alcohol.

BACKGROUND: Chronic hepatitis B is the most common cause of liver cirrhosis in South Korea. However, alcoholic liver disease has shown an increasing trend. Although the clinical implications surrounding liver cirrhosis have been changing over the years, few studies have recently examined cirrhosis epidemiology. Therefore, we aimed to investigate changes in liver cirrhosis etiology and severity in Korea. METHODS: We retrospectively reviewed 16,888 records of cirrhotic patients from six tertiary hospitals in Korea from 2008 to 2017. Continuous and non-continuous variables were processed via linear and Poisson regression, expressed as beta (B) coefficients and as exponentiated values of coefficients (Exp[B]), respectively. RESULTS: Chronic hepatitis B showed a decreasing trend (Exp[B] = 0.975, P < 0.001), whereas alcohol showed an increasing trend (Exp[B] = 1.013, P = 0.003), occupying the most common etiology in 2017. The Child-Turcotte-Pugh (CTP) score and decompensated liver cirrhosis prevalence did not change over the 10-year period. The incidence of variceal bleeding, severe ascites, hepatic encephalopathy, and spontaneous bacterial peritonitis significantly decreased from 12.3% to 7.7%, 7.8% to 4.1%, 1.0% to 0.5%, and 1.9% to 1.1%, respectively (P < 0.05 for all). In the subgroup analysis, the chronic hepatitis B group showed improving CTP scores (B = -0.025, P < 0.001) and decreasing decompensated liver cirrhosis rates (Exp[B] = 0.977, P = 0.016), whereas the alcohol group demonstrated increasing CTP class C (Exp[B] = 1.031, P = 0.005) and model for end-stage liver disease scores (B = 0.081, P = 0.005) over 10 years. CONCLUSION: The chronic hepatitis B group exhibited improved results, whereas the alcohol group still presented poor liver functions and outcomes. Future national policies and systematic approaches addressing the incidence, prevention, and treatment of alcoholic liver cirrhosis are indispensable.

Child-Pugh, MELD, MELD-Na, and ALBI scores: which liver function models best predicts prognosis for HCC patient with ascites?

OBJECTIVE: It remains controversial whether certain treatments should apply to HCC patients with ascites due to concerns about worsening liver function. The objective of the present study is to compare the prognostic performance of 4 liver function models currently in use for HCC patients with ascites. METHODS: A total of 437 treatment-naïve, newly diagnosed HCC patients were analyzed. The predictive performance of Child-Pugh, MELD, MELD-Na, and ALBI scores were examined using ROC curve analysis. RESULTS: MELD-Na score showed good performance in predicting 1-, 2-, and 3-year mortality, particularly 1-year mortality. MELD-Na score significantly increased at 30 days after treatment in cases initially receiving best supportive care (14-17, p < .001), TACE (9-11, p < .001), and other treatment (radiotherapy, sorafenib, or systemic chemotherapy) (9-11, p = .021). For patients with advanced tumor stage and MELD-Na score ≥12, HCC-specific treatment did not offer significantly better prognosis compared with only the best supportive care (median survival: 2.2 vs. 1.8 months for HCC-specific treatment vs. best supportive care, p = .15). CONCLUSION: MELD-Na can effectively identify liver functional reserve and prognosis in HCC patients with ascites. MELD-Na, together with the tumor stage, may help establish a therapeutic strategy for them.

Changes in Characteristics of Patients with Liver Cirrhosis Visiting a Tertiary Hospital over 15 Years: a Retrospective Multi-Center Study in Korea.

BACKGROUND: Liver cirrhosis has become a heavy burden not only for patients, but also for our society. However, little is known about the recent changes in clinical outcomes and characteristics of patients with cirrhosis-related complications in Korea. Therefore, we aimed to evaluate changes in characteristics of patients with liver cirrhosis in Daegu-Gyeongbuk province in Korea over the past 15 years. METHODS: We retrospectively reviewed the medical records of 15,716 liver cirrhotic patients from 5 university hospitals in Daegu-Gyeongbuk province from 2000 to 2014. The Korean Standard Classification of Diseases-6 code associated with cirrhosis was investigated through medical records and classified according to the year of first visit. RESULTS: A total of 15,716 patients was diagnosed with cirrhosis. A number of patients newly diagnosed with cirrhosis has decreased each year. In 2000, patients were most likely to be diagnosed with hepatitis B virus (HBV) cirrhosis, followed by alcoholic cirrhosis. There was a significant decrease in HBV (P < 0.001), but alcohol, hepatitis C virus (HCV), and non-alcoholic fatty liver disease (NAFLD) showed a significant increase during the study period (alcohol, P = 0.036; HCV, P = 0.001; NAFLD, P = 0.001). At the time of initial diagnosis, the ratio of Child-Turcotte-Pugh (CTP) class A gradually increased from 23.1% to 32.9% (P < 0.001). The most common cause of liver-related hospitalization in 2000 was hepatocellular carcinoma (HCC) (25.5%); in 2014, gastrointestinal bleeding with esophageal and gastric varices (21.4%) was the most common cause. Cases of hospitalization with liver-related complication represented 76.4% of all cases in 2000 but 70.9% in 2014. Incidence rate of HCC has recently increased. In addition, HCC-free survival was significantly lower in CTP class A than in classes B and C. Finally, there was significant difference in HCC occurrence according to causes (P < 0.001). HBV and HCV cirrhosis had lower HCC-free survival than alcoholic and NAFLD cirrhosis. CONCLUSION: In recent years, the overall number of cirrhosis patients has decreased. This study confirmed the recent trend in decrease of cirrhosis, especially of cirrhosis due to HBV, and the increase of HCV, alcoholic and NAFLD cirrhosis. Targeted screening for at-risk patients will facilitate early detection of liver diseases allowing effective intervention and may have decreased the development of cirrhosis and its complications.

Fibrinogen cleavage products and Toll-like receptor 4 promote the generation of programmed cell death 1 ligand 2-positive dendritic cells in allergic asthma.

BACKGROUND: Inhaled protease allergens preferentially trigger TH2-mediated inflammation in allergic asthma. The role of dendritic cells (DCs) on induction of TH2 cell responses in allergic asthma has been well documented; however, the mechanism by which protease allergens induce TH2-favorable DCs in the airway remains unclear. OBJECTIVE: We sought to determine a subset of DCs responsible for TH2 cell responses in allergic asthma and the mechanism by which protease allergens induce the DC subset in the airway. METHODS: Mice were challenged intranasally with protease allergens or fibrinogen cleavage products (FCPs) to induce allergic airway inflammation. DCs isolated from mediastinal lymph nodes were analyzed for surface phenotype and T-cell stimulatory function. Anti-Thy1.2 and Mas-TRECK mice were used to deplete innate lymphoid cells and mast cells, respectively. Adoptive cell transfer, bone marrow DC culture, anti-IL-13, and Toll-like receptor (TLR) 4-deficient mice were used for further mechanistic studies. RESULTS: Protease allergens induced a remarkable accumulation of TH2-favorable programmed cell death 1 ligand 2 (PD-L2)+ DCs in mediastinal lymph nodes, which was significantly abolished in mice depleted of mast cells and, to a lesser extent, innate lymphoid cells. Mechanistically, FCPs generated by protease allergens triggered IL-13 production from wild-type mast cells but not from TLR4-deficient mast cells, which resulted in an increase in the number of PD-L2+ DCs. Intranasal administration of FCPs induced an increase in numbers of PD-L2+ DCs in the airway, which was significantly abolished in TLR4- and mast cell-deficient mice. Injection of IL-13 restored the PD-L2+ DC population in mice lacking mast cells. CONCLUSION: Our findings unveil the "protease-FCP-TLR4-mast cell-IL-13" axis as a molecular mechanism for generation of TH2-favorable PD-L2+ DCs in allergic asthma and suggest that targeting the PD-L2+ DC pathway might be effective in suppressing allergic T-cell responses in the airway.

Reduced risk of hepatocellular carcinoma by achieving a subcirrhotic liver stiffness through antiviral agents in hepatitis B virus-related advanced fibrosis or cirrhosis.

BACKGROUND AND AIM: A subcirrhotic range of liver stiffness (sc-LS), assessed by transient elastography, is associated with better outcomes in patients with chronic hepatitis B (CHB). We investigated whether the achievement of sc-LS by antiviral therapy (AVT) reduced the risk of developing hepatocellular carcinoma (HCC) in patients with CHB-related advanced fibrosis or cirrhosis. METHODS: In total, 209 patients with CHB-related advanced fibrosis or cirrhosis, who received paired transient elastography examinations during AVT between 2007 and 2012, were enrolled. The cut-off LS value for ultrasonographic cirrhosis was defined as 11.6 kPa. RESULTS: The median age of the study population was 51 years, with males predominating (n = 138, 66.0%). The median LS value at enrollment was 14.1 kPa (interquartile range: 9.5-24.1 kPa). After 2 years of AVT, 140 (67.0%) patients achieved sc-LS. During the study period, 28 (13.4%) patients developed HCC after 2 years of AVT. On multivariate analysis, the achievement of sc-LS after AVT was independently associated with a decreased risk of HCC development (hazard ratio [HR] = 0.485, P = 0.047), whereas older age (HR = 1.071) and male gender (HR = 3.704) were independently associated with an increased HCC risk (both P < 0.05). Patients with a cirrhotic range of LS value after 2 years of AVT were at a higher risk of HCC development than those with sc-LS (log-rank test, P = 0.020). CONCLUSIONS: The achievement of sc-LS after AVT can reduce the risk of HCC development in patients with CHB, even when advanced fibrosis or cirrhosis is apparent on starting AVT.

Transplantation with autologous bone marrow-derived mesenchymal stem cells for alcoholic cirrhosis: Phase 2 trial.

Bone marrow-derived mesenchymal stem cell (BM-MSC) transplantation has been suggested as an effective therapy for liver cirrhosis. The efficacy and safety of autologous BM-MSC transplantation in the treatment of alcoholic cirrhosis were investigated. Seventy-two patients with baseline biopsy-proven alcoholic cirrhosis who had been alcohol-abstinent for more than 6 months underwent a multicenter, randomized, open-label, phase 2 trial. Patients were randomly assigned to three groups: one control group and two autologous BM-MSC groups that underwent either one-time or two-time hepatic arterial injections of 5 × 107 BM-MSCs 30 days after BM aspiration. A follow-up biopsy was performed 6 months after enrollment, and adverse events were monitored for 12 months. The primary endpoint was improvement in fibrosis quantification based on picrosirius red staining. The secondary endpoints included liver function tests, Child-Pugh score, and Model for End-stage Liver Disease score. Outcomes were analyzed by per-protocol analysis. In terms of fibrosis quantification (before versus after), the one-time and two-time BM-MSC groups were associated with 25% (19.5 ± 9.5% versus 14.5 ± 7.1%) and 37% (21.1 ± 8.9% versus 13.2 ± 6.7%) reductions in the proportion of collagen, respectively (P < 0.001). In the intergroup comparison, two-time BM-MSC transplantation in comparison with one-time BM-MSC transplantation was not associated with improved results in fibrosis quantification (P > 0.05). The Child-Pugh scores of both BM-MSC groups (one-time 7.6 ± 1.0 versus 6.3 ± 1.3 and two-time 7.8 ± 1.2 versus 6.8 ± 1.6) were also significantly improved following BM-MSC transplantation (P < 0.05). The proportion of patients with adverse events did not differ among the three groups. CONCLUSION: Autologous BM-MSC transplantation safely improved histologic fibrosis and liver function in patients with alcoholic cirrhosis. (Hepatology 2016;64:2185-2197).

Epstein Barr virus-induced 3 (EBI3) together with IL-12 negatively regulates T helper 17-mediated immunity to Listeria monocytogenes infection.

Although the protective functions by T helper 17 (Th17) cytokines against extracellular bacterial and fungal infection have been well documented, their importance against intracellular bacterial infection remains unclear. Here, we investigated the contribution of Th17 responses to host defense against intracellular bacteria Listeria monocytogenes and found that Th17 cell generation was suppressed in this model. Unexpectedly, mice lacking both p35 and EBI3 cleared L. monocytogenes as efficiently as wild-type mice, whereas p35-deficient mice failed to do so. Furthermore, both innate cells and pathogen-specific T cells from double-deficient mice produced significantly higher IL-17 and IL-22 compared to wild-type mice. The bacterial burden in the liver of double-deficient mice treated with anti-IL-17 was significantly increased compared to those receiving a control Ab. Transfer of Th17 cells specific for listeriolysin O as well as administration of IL-17 and IL-22 significantly suppressed bacterial growth in p35-deficient mice, indicating the critical contribution of Th17 responses to host defense against the intracellular pathogen in the absence of IL-12 and proper Th1 responses. Our findings unveil a novel immune evasion mechanism whereby the intracellular bacteria exploit IL-27EBI3 to suppress Th17-mediated protective immunity.

Accuracy of transient elastography in assessing liver fibrosis in chronic viral hepatitis: A multicentre, retrospective study.

BACKGROUND/AIMS: Transient elastography (TE) has become an alternative to liver biopsy (LB). This study investigated the diagnostic performance of liver stiffness (LS) measurement using TE in Korean patients with chronic hepatitis B and C (CHB and CHC). METHODS: From April 2006 to June 2014, 916 patients (567 CHB and 349 CHC) who underwent LB and TE at 15 centres were analyzed. The Batts and Ludwig scoring system was used for histologic assessment. Aspartate aminotransferase (AST)-to-platelet ratio indexes (APRI) were calculated. Area under the receiver operating characteristic curve (AUROC) was used. RESULTS: The median age, LS value, and APRI score were 45 years, 8.8 kPa, and 0.61, respectively, in CHB patients vs. 51 years, 6.8 kPa and 0.55, respectively, in CHC patients. TE was significantly superior to APRI in CHB patients (AUROC 0.774 vs. 0.72 for ≥F2, 0.849 vs. 0.812 for ≥F3, and 0.902 vs. 0.707 for F4, respectively; all P < 0.05). Furthermore, TE was significantly superior for predicting ≥ F3 stage (AUROC 0.865 vs. 0.840, P = 0.009) whereas it was similar for predicting ≥ F2 and F4 stage (AUROC 0.822 vs. 0.796; 0.910 vs. 0.884; all P > 0.05) in CHC patients. In CHB patients, optimal cut-off LS values were 7.8 kPa for ≥F2, 8.2 kPa for ≥ F3, and 11.6 kPa for F4, vs. 6.8 kPa, 8.6 kPa, and 14.5 kPa, respectively, in CHC patients. CONCLUSIONS: TE can accurately assess the degree of liver fibrosis in Korean patients with CVH. TE was superior to APRI for predicting each fibrosis stage.

IL-17 and IL-21: Their Immunobiology and Therapeutic Potentials.

Studies over the last 2 decades have identified IL-17 and IL-21 as key cytokines in the modulation of a wide range of immune responses. IL-17 serves as a critical defender against bacterial and fungal pathogens, while maintaining symbiotic relationships with commensal microbiota. However, alterations in its levels can lead to chronic inflammation and autoimmunity. IL-21, on the other hand, bridges the adaptive and innate immune responses, and its imbalance is implicated in autoimmune diseases and cancer, highlighting its important role in both health and disease. Delving into the intricacies of these cytokines not only opens new avenues for understanding the immune system, but also promises innovative advances in the development of therapeutic strategies for numerous diseases. In this review, we will discuss an updated view of the immunobiology and therapeutic potential of IL-17 and IL-21.

The Clinical Significance of Myosteatosis in Survival Outcomes in Patients with Hepatocellular Carcinoma Treated with Sorafenib.

The role of body composition parameters in sorafenib-treated hepatocellular carcinoma (HCC) patients is still not fully elucidated. Here, we aimed to evaluate the impact of computed tomography (CT)-based body composition parameters on the survival of such patients. In this multicenter study, we analyzed the data of 245 sorafenib-treated HCC patients from January 2008 to December 2019. Sarcopenia, visceral obesity, and myosteatosis were defined by using cross-sectional CT images at the third lumbar vertebra level. The effects of these parameters on overall survival (OS) and progression-free survival (PFS) were evaluated. The median age was 67.0 years (interquartile range: 61.0-78.0 year), and 211 patients (86.1%) were male. The median OS and PFS were 7.9 months and 4.8 months, respectively. Vascular invasion (hazard ratio (HR), 1.727; 95% confidence interval (CI), 1.258-2.371; p = 0.001), extrahepatic metastasis (HR, 1.401; 95% CI, 1.028-1.908; p = 0.033), alpha-fetoprotein level > 200 ng/mL (HR, 1.559; 95% CI, 1.105-2.201; p = 0.012), and myosteatosis (HR, 1.814; 95% CI, 1.112-2.960; p = 0.017) were associated with OS. Patient mortality was significantly higher in the group with two or more risk factors than in the group with fewer risk factors. In conclusion, myosteatosis may be a novel prognostic CT-based radiological biomarker in sorafenib-treated HCC patients.

Boosting with variant-matched adenovirus-based vaccines promotes neutralizing antibody responses against SARS-CoV-2 Omicron sublineages in mice.

Global spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) Omicron subvariants, such as BA.4, BA.5 and XBB.1.5, has been leading the recent wave of coronavirus disease 2019 (COVID-19). Unique mutations in the spike proteins of these emerging Omicron subvariants caused immune evasion from the pre-existing protective immunity induced by vaccination or natural infection. Previously, we developed AdCLD-CoV19-1, a non-replicating recombinant adenoviral vector that encodes the receptor binding domain of the spike protein of the ancestral SARS-CoV-2 strain. Based on the same recombinant adenoviral vector platform, updated vaccines that cover unique mutations found in each Omicron subvariant, including BA.1, BA.2, BA.4.1 and BA.5, were constructed. Preclinical studies revealed that each updated vaccine as a booster shot following primary vaccination targeting the ancestral strain improved neutralizing antibody responses against the pseudovirus of its respective strain most effectively. Of note, boosting with a vaccine targeting the BA.1 or BA.2 Omicron subvariant was most effective in neutralization against the pseudovirus of the BA.2.75 strain, whereas BA.4.1/5-adapted booster shots were most effective in neutralization against the BQ.1, BQ1.1 and BF.7 strains. Therefore, it is imperative to develop a vaccination strategy that can cover the unique spike mutations of currently circulating Omicron subvariants in order to prevent the next wave of COVID-19.