Prmt5 deficient mouse B cells display RNA processing complexity and slower colorectal tumor progression.

Protein arginine methyltransferase 5 (Prmt5) is essential for normal B-cell development; however, the roles of Prmt5 in tumor-infiltrating B cells in tumor therapy have not been well elucidated. Here, we revealed that CD19-cre-Prmt5fl/fl (Prmt5cko) mice showed smaller tumor weights and volumes in the colorectal cancer mouse model; B cells expressed higher levels of Ccl22 and Il12a, which attracted T cells to the tumor site. Furthermore, we used direct RNA sequencing to comprehensively profile RNA processes in Prmt5 deletion B cells to explore underline mechanisms. We found significantly differentially expressed isoforms, mRNA splicing, poly(A) tail lengths, and m6A modification changes between the Prmt5cko and control groups. Cd74 isoform expressions might be regulated by mRNA splicing; the expression of two novel Cd74 isoforms was decreased, while one isoform was elevated in the Prmt5cko group, but the Cd74 gene expression showed no changes. We observed Ccl22, Ighg1, and Il12a expression was significantly increased in the Prmt5cko group, whereas Jak3 and Stat5b expression was decreased. Ccl22 and Ighg1 expression might be associated with poly(A) tail length, Jak3, Stat5b, and Il12a expression might be modulated by m6A modification. Our study demonstrated that Prmt5 regulates B-cell function through different mechanisms and supported the development of Prmt5-targeted antitumor treatments.

PRMT5 Deficiency Enforces the Transcriptional and Epigenetic Programs of Klrg1+CD8+ Terminal Effector T Cells and Promotes Cancer Development.

Protein arginine methyltransferase 5 (PRMT5) participates in the symmetric dimethylation of arginine residues of proteins and contributes to a wide range of biological processes. However, how PRMT5 affects the transcriptional and epigenetic programs involved in the establishment and maintenance of T cell subset differentiation and roles in antitumor immunity is still incompletely understood. In this study, using single-cell RNA and chromatin immunoprecipitation sequencing, we found that mouse T cell-specific deletion of PRMT5 had greater effects on CD8+ than CD4+ T cell development, enforcing CD8+ T cell differentiation into Klrg1+ terminal effector cells. Mechanistically, T cell deficiency of PRMT5 activated Prdm1 by decreasing H4R3me2s and H3R8me2s deposition on its loci, which promoted the differentiation of Klrg1+CD8+ T cells. Furthermore, effector CD8+ T cells that transited to memory precursor cells were decreased in PRMT5-deficient T cells, thus causing dramatic CD8+ T cell death. In addition, in a mouse lung cancer cell line-transplanted tumor mouse model, the percentage of CD8+ T cells from T cell-specific deletion of PRMT5 mice was dramatically lost, but CD8+Foxp3+ and CD8+PDL1+ regulatory T cells were increased compared with the control group, thus accelerating tumor progression. We further verified these results in a mouse colon cancer cell line-transplanted tumor mouse model. Our study validated the importance of targeting PRMT5 in tumor treatment, because PRMT5 deficiency enforced Klrg1+ terminal CD8+ T cell development and eliminated antitumor activity.

Prmt5 deficiency inhibits CD4+ T-cell Klf2/S1pr1 expression and ameliorates EAE disease.

BACKGROUND: Protein arginine methyltransferase 5 (Prmt5) is the main type II methyltransferase, catalyzes protein arginine residue symmetric dimethylation, and modulates normal cellular physiology and disease progression. Prmt5 inhibition or deletion in CD4+ T cells has been reported to ameliorate experimental autoimmune encephalomyelitis (EAE), but the detailed molecular mechanisms have not yet been elucidated. METHODS: EAE was induced by administration of myelin oligodendrocyte glycoprotein (MOG35-55) in T cells Prmt5 conditional knockout (CD4-cre-Prmt5fl/fl, Prmt5cko) and Prmt5fl/fl (WT) mice. Flow cytometry, single-cell RNA sequencing, ATAC sequencing and chromatin immunoprecipitation assay (ChIP) approaches were used to explore the detail mechanisms. RESULTS: We find that Prmt5cko mice are resistant to EAE; infiltrating inflammatory CD4+ T cells in the central nervous system (CNS) are greatly reduced. However, in Prmt5cko mice, T cells in the spleen show much more proliferation and activation properties, the total number of CD4+ T cells in the spleen is not reduced, and the percentage of Rora+ CD4+ T cells is elevated. Also, CD4+ T cells express lower levels of S1pr1 and Klf2 than WT mice, which may influence pathogenic CD4+ T-cell egress from the spleen and migration to the CNS. Moreover, the single-cell ATAC sequence and ChIP assay reveal that the transcription factor Klf2 is enriched at the S1pr1 promoter and that Klf2 motif activity is reduced in Prmt5cko mice. CONCLUSIONS: Our study delineates the undiscovered role of Prmt5 in T-cell biology in which Prmt5 may inhibit Klf2-S1pr1 pathway to ameliorate EAE disease. Controlling T-cell Prmt5 expression may be helpful for the treatment of autoimmune diseases.

The efficacy of addition of Tenofovir Disoproxil Fumarate to Peg-IFNα-2b is superior to the addition of Entecavir in HBeAg positive CHB patients with a poor response after 12 weeks of Peg-IFNα-2b treatment alone.

Background: There are limited data regarding the efficacy of addition of entecavir (ETV) or tenofovir disoproxil fumarate (TDF) to Peg-IFNα-2b in HBeAg positive chronic hepatitis B (CHB) patients without early response to Peg-IFNα-2b. In this study, we aimed to evaluate the efficacy of ETV and TDF in HBeAg positive CHB patients who had a poor response to Peg-INFα-2b at the end of 12 weeks of monotherapy. Methods: A total of 40 HBeAg-positive CHB patients who were naive to antiviral therapy were recruited. The patients received a subcutaneous injection of Peg-IFNα-2b (180 µg) once a week for 12 weeks. However, the patients had a poor response to Peg-INFα-2b at the end of the 12-week-period monotherapy. The patients were then divided into two therapeutic protocol groups: (1) Group A: Patients received Peg-IFNα-2b (180 µg) subcutaneously weekly and ETV (0.5 mg) orally once daily for 48 weeks; (2) Group B: Patients received Peg-IFNα-2b (180 µg) subcutaneously weekly and TDF (300 mg) orally once daily for 48 weeks. The therapeutic efficacy was evaluated. Blood samples were collected at baseline and every 12 weeks. Routine biochemical tests including ALT, AST, etc. were measured by automated biochemical technique. HBV DNA was quantified using the TaqMan PCR assay. The levels of HBsAg, HBsAb, HBeAg, HBeAb and HBcAb were measured using a commercial chemiluminescent microparticle immunoassay. Results: The HBsAg level declined rapidly in both two treatment groups during the first 12 weeks and declined gradually in the next 36 weeks. At week 48, the mean ΔHBsAg level in Peg-IFNα-2b+TDF group was significantly higher than that in Peg-IFNα-2b +ETV group (-1.799 ± 0.3063 vs. -1.078 ± 0.2028, P=0.0491). The HBeAg loss rate was significantly higher in TDF add-on group than that in ETV add-on group at week 48 (40% vs. 10%, P=0.028). At week 48, the proportions of patients with undetectable HBV DNA (<500 IU/mL) were 80% (16 out of 20) and 95% (19 out of 20) in Peg-IFNα-2b+ETV group and Peg-IFNα-2b+TDF group, respectively. Conclusions: This real world study demonstrated that the efficacy of addition of TDF to Peg-IFNα-2b is superior to the efficacy of addition of ETV to Peg-IFNα-2b in HBeAg positive CHB patients with a poor response after 12 weeks of Peg-IFNα-2b treatment alone. However, this present study also requires a larger sample size study to verify in the future.

PRMT5 Inhibition Promotes PD-L1 Expression and Immuno-Resistance in Lung Cancer.

Protein arginine transferase 5 (PRMT5) has been implicated as an important modulator of tumorigenesis as it promotes tumor cell proliferation, invasion, and metastasis. Studies have largely focused on PRMT5 regulating intrinsic changes in tumors; however, the effects of PRMT5 on the tumor microenvironment and particularly immune cells are largely unknown. Here we found that targeting PRMT5 by genetic or pharmacological inhibition reduced lung tumor progression in immunocompromised mice; however, the effects were weakened in immunocompetent mice. PRMT5 inhibition not only decreased tumor cell survival but also increased the tumor cell expression of CD274 in vitro and in vivo, which activated the PD1/PD-L1 axis and eliminated CD8+T cell antitumor immunity. Mechanistically, PRMT5 regulated CD274 gene expression through symmetric dimethylation of histone H4R3, increased deposition of H3R4me2s on CD274 promoter loci, and inhibition of CD274 gene expression. Targeting PRMT5 reduced this inhibitory effect and promoted CD274 expression in lung cancer. However, PRMT5 inhibitors represent a double-edged sword as they may selectively kill cancer cells but may also disrupt the antitumor immune response. The combination of PRMT5 inhibition and ani-PD-L1 therapy resulted in an increase in the number and enhanced the function of tumor-infiltrating T cells. Our findings address an unmet clinical need in which combining PRMT5 inhibition with anti-PD-L1 therapy could be a promising strategy for lung cancer treatment.