Allograft rejection is a common immunological feature in renal transplantation and is associated with reduced graft survival. A mouse renal allograft rejection model was induced and single-cell RNA sequencing (scRNA-seq) data of CD45⁺leukocytes in kidney allografts on days 7 (D7) and 15 (D15) after operation was analyzed to reveal a full immunological profiling. We identified 20 immune cell types among 10,921 leukocytes. Macrophages and CD8⁺T cells constituted the main populations on both timepoints. In the process from acute rejection (AR) towards chronic rejection (CR), the proportion of proliferating and naïve CD8⁺T cells dropped significantly. Both B cells and neutrophils decreased by about 3 folds. On the contrary, the proportion of macrophages and dendritic cells (DCs) increased significantly, especially by about a 4.5-fold increase in Ly6c^loMrc1⁺macrophages and 2.6 folds increase in Ly6c^loEar2⁺macrophages. Moreover, myeloid cells harbored the richest ligand and receptor (LR) pairs with other cells, particularly for chemokine ligands such as Cxcl9, Cxcl10, Cxcl16 and Yars. However, macrophages with weak response to interferon gamma (IFNg) contributed to rejection chronicization. To conclude, reduction in CD8 T cells, B cells and neutrophils while increasing in Ly6c^loMrc1⁺macrophages and Ly6c^loEar2⁺macrophages, may contribute significantly to the progress from AR towards CR.

Previously, this study demonstrates the critical role of myeloid specific TLR4 in macrophage‐mediated progressive renal injury in anti‐glomerular basement membrane (anti‐GBM) crescentic glomerulonephritis (cGN); however, the underlying mechanism remains largely unknown. In this study, single‐cell RNA sequencing (scRNA‐seq), pseudotime trajectories reconstruction, and motif enrichment analysis are used, and macrophage diversity in anti‐GBM cGN under tight regulation of myeloid‐TLR4 is uncovered. Most significantly, a myeloid‐TLR4 deletion‐induced novel reparative macrophage phenotype (Nr4a1⁺Ear2+) with significant upregulated anti‐inflammatory and tissue repair‐related signaling is discovered, thereby suppressing the M1 proinflammatory responses in anti‐GBM cGN. This is further demonstrated in vitro that deletion of TLR4 from bone marrow‐derived macrophages (BMDMs) induces the Nr4a1/Ear2‐expressing anti‐inflammatory macrophages while blocking LPS‐stimulated M1 proinflammatory responses. Mechanistically, activation of the Nr4a1/Ear2‐axis is recognized as a key mechanism through which deletion of myeloid‐TLR4 promotes the anti‐inflammatory macrophage differentiation in vivo and in vitro. This is confirmed by specifically silencing macrophage Nr4a1 or Ear2 to reverse the anti‐inflammatory effects on TLR4 deficient BMDMs upon LPS stimulation. In conclusion, the findings decode a previously unidentified role for a myeloid‐TLR4 dependent Nr4a1/Ear2 negative feedback mechanism in macrophage‐mediated progressive renal injury, implying that activation of Nr4a1‐Ear2 axis can be a novel and effective immunotherapy for anti‐GBM cGN.

Transforming growth factor β (TGF-β) is a well-known key mediator for the progression and metastasis of lung carcinoma. However, cost-effective anti-TGF-β therapeutics for lung cancer remain to be explored. Specifically, the low efficacy in drug delivery greatly limits the clinical application of small molecular inhibitors of TGF-β. In the present study, specific inhibitor of Smad3 (SIS3) is developed into a self-carried nanodrug (SCND-SIS3) using the reprecipitation method, which largely improves its solubility and bioavailability while reduces its nephrotoxicity. Compared to unmodified-SIS3, SCND-SIS3 demonstrates better anti-cancer effects through inducing tumor cell apoptosis, inhibiting angiogenesis, and boosting NK cell-mediated immune responses in syngeneic Lewis Lung Cancer (LLC) mouse model. Better still, it could achieve comparable anti-cancer effect with just one-fifth the dose of unmodified-SIS3. Mechanistically, RNA-sequencing analysis and cytokine array results unveil a TGF-β/Smad3-dependent immunoregulatory landscape in NK cells. In particular, SCND-SIS3 promotes NK cell cytotoxicity by ameliorating Smad3-mediated transcriptional inhibition of Ndrg1. Furthermore, improved NK cell cytotoxicity by SCND-SIS3 is associated with higher expression of activation receptor Nkp46, and suppressed levels of Trib3 and TSP1 as compared with unmodified-SIS3. Taken together, SCND-SIS3 possesses superior anti-cancer effects with enhanced bioavailability and biocompatibility, therefore representing as a novel therapeutic strategy for lung carcinoma with promising clinical potential.

Angiotensin‐converting enzyme‐2 (ACE2) and Mas receptor are the major components of the ACE2/Ang 1‐7/Mas axis and have been shown to play a protective role in hypertension and hypertensive nephropathy individually. However, the effects of dual deficiency of ACE2 and Mas (ACE2/Mas) on Ang II‐induced hypertensive nephropathy remain unexplored, which was investigated in this study in a mouse model of hypertension induced in either ACE2 knockout (KO) or Mas KO mice and in double ACE2/Mas KO mice by subcutaneously chronic infusion of Ang II. Compared with wild‐type (WT) animals, mice lacking either ACE2 or Mas significantly increased blood pressure over 7‐28 days following a chronic Ang II infusion (P < .001), which was further exacerbated in double ACE2/Mas KO mice (P < .001). Furthermore, compared to a single ACE2 or Mas KO mice, mice lacking ACE2/Mas developed more severe renal injury including higher levels of serum creatinine and a further reduction in creatinine clearance, and progressive renal inflammation and fibrosis. Mechanistically, worsen hypertensive nephropathy in double ACE2/Mas KO mice was associated with markedly enhanced AT1‐ERK1/2‐Smad3 and NF‐κB signalling, thereby promoting renal fibrosis and renal inflammation in the hypertensive kidney. In conclusion, ACE2 and Mas play an additive protective role in Ang II‐induced hypertension and hypertensive nephropathy. Thus, restoring the ACE2/Ang1‐7/Mas axis may represent a novel therapy for hypertension and hypertensive nephropathy.

Transforming growth factor-β (TGF-β) is a crucial pathogenic mediator of inflammatory diseases. In tissue fibrosis, TGF-β regulates the pathogenic activity of infiltrated immunocytes and promotes extracellular matrix production via de novo myofibroblast generation and kidney cell activation. In cancer, TGF-β promotes cancer invasion and metastasis by enhancing the stemness and epithelial mesenchymal transition of cancer cells. However, TGF-β is highly pleiotropic in both tissue fibrosis and cancers, and thus, direct targeting of TGF-β may also block its protective anti-inflammatory and tumor-suppressive effects, resulting in undesirable outcomes. Increasing evidence suggests the involvement of long non-coding RNAs (lncRNAs) in TGF-β-driven tissue fibrosis and cancer progression with a high cell-type and disease specificity, serving as an ideal target for therapeutic development. In this review, the mechanism and translational potential of TGF-β-associated lncRNAs in tissue fibrosis and cancer will be discussed.

Myeloid cells and TLR4 play a critical role in acute kidney injury. This study investigated the regulatory role and mechanisms of myeloid TLR4 in experimental anti-glomerular basement membrane (GBM) glomerulonephritis (GN). Anti-GBM GN was induced intlr4^flox/floxandtlr4^{flox/flox−lysM−cre}mice by intravenous injection of the sheep anti-mouse GBM antibody. Compared to control mice, conditional disruption oftlr4from myeloid cells, largely macrophages (> 85%), suppressed glomerular crescent formation and attenuated progressive renal injury by lowering serum creatinine and 24-h urine protein excretion while improving creatinine clearance. Mechanistically, deletion of myeloidtlr4markedly inhibited renal infiltration of macrophages and T cells and resulted in a shift of infiltrating macrophages from F4/80⁺iNOS⁺M1 to F4/80⁺CD206⁺M2 phenotype and inhibited the upregulation of renal proinflammatory cytokines IL-1β and MCP-1. Importantly, deletion of myeloidtlr4suppressed T cell-mediated immune injury by shifting Th1 (CD4⁺IFNγ⁺) and Th17 (CD4⁺IL-17a⁺) to Treg (CD4⁺CD25⁺FoxP3⁺) immune responses. Transcriptome analysis also revealed that disrupted myeloid TLR4 largely downregulated genes involving immune and cytokine-related pathways. Thus, myeloid TLR4 plays a pivotal role in anti-GBM GN by immunological switching from M1 to M2 and from Th1/Th17 to Treg and targeting myeloid TLR4 may be a novel therapeutic strategy for immune-mediated kidney diseases.