Single-cell sequencing reveals distinct immune cell features in cutaneous lesions of pemphigus vulgaris and bullous pemphigoid.

Bullous pemphigoid (BP) and pemphigus vulgaris (PV) are two common subtypes of autoimmune bullous disease (AIBD). The key role of circulating autoreactive immune cells contributing to skin damage of AIBD has been widely recognized. Nevertheless, the immune characteristics in cutaneous lesions remain unclear. Here, we performed single-cell RNA sequencing (scRNA-seq) and single-cell VDJ sequencing (scRNA-seq) to generate transcriptional profiles for cells and T/B cell clonetype in skin lesions of BP and PV. We found that the proportions of NK&T, macrophages/ dendritic cells, B cells, and mast cells increased in BP and PV lesions. Then, BP and PV cells constituted over 75% of all myeloid cell subtypes, CD4+ T cell subtypes and CD8+ T cell subtypes. Strikingly, CD8+ Trm was identified to be expanded in PV, and located in the intermediate state of the pseudotime trajectory from CD8+ Tm to CD8+ Tem. Interestingly, CD8+ Tem and CD4+ Treg highly expressed exhaustion-related genes, especially in BP lesions. Moreover, the enhanced cell communication between stromal cells and immune cells like B cells and macrophages/ dendritic cells was also identified in BP and PV lesions. Finally, clone expansion was observed in T cells of BP and PV compared with HC, while CD8+ Trm represented the highest ratio of hyperexpanded TCR clones among all T cell subtypes. Our study generally depicts a large and comprehensive single-cell landscape of cutaneous lesions and highlights immune cell features in BP and PV. This offers potential research targets for further investigation.

Novel inhalation therapy in pulmonary fibrosis: principles, applications and prospects.

Pulmonary fibrosis (PF) threatens millions of people worldwide with its irreversible progression. Although the underlying pathogenesis of PF is not fully understood, there is evidence to suggest that the disease can be blocked at various stages. Inhalation therapy has been applied for lung diseases such as asthma and chronic obstructive pulmonary disease, and its application for treating PF is currently under consideration. New techniques in inhalation therapy, such as the application of microparticles and nanoparticles, traditional Chinese medicine monomers, gene therapy, inhibitors, or agonists of signaling pathways, extracellular vesicle interventions, and other specific drugs, are effective in treating PF. However, the safety and effectiveness of these therapeutic techniques are influenced by the properties of inhaled particles, biological and pathological barriers, and the type of inhalation device used. This review provides a comprehensive overview of the pharmacological, pharmaceutical, technical, preclinical, and clinical experimental aspects of novel inhalation therapy for treating PF and focus on therapeutic methods that significantly improve existing technologies or expand the range of drugs that can be administered via inhalation. Although inhalation therapy for PF has some limitations, the advantages are significant, and further research and innovation about new inhalation techniques and drugs are encouraged.

Traditional Chinese medicine inspired dual-drugs loaded inhalable nano-therapeutics alleviated idiopathic pulmonary fibrosis by targeting early inflammation and late fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a highly debilitating and fatal chronic lung disease that is difficult to cure clinically. IPF is characterized by a gradual decline in lung function, which leads to respiratory failure and severely affects patient quality of life and survival. Oxidative stress and chronic inflammation are believed to be important pathological mechanisms underlying the onset and progression of IPF, and the vicious cycle of NOX4-derived ROS, NLRP3 inflammasome activation, and p38 MAPK in pulmonary fibrogenesis explains the ineffectiveness of single-target or single-drug interventions. In this study, we combined astragaloside IV (AS-IV) and ligustrazine (LIG) based on the fundamental theory of traditional Chinese medicine (TCM) of "tonifying qi and activating blood" and loaded these drugs onto nanoparticles (AS_LIG@PPGC NPs) that were inhalable and could penetrate the mucosal barrier. Our results suggested that inhalation of AS_LIG@PPGC NPs significantly improved bleomycin-induced lung injury and fibrosis by regulating the NOX4-ROS-p38 MAPK and NOX4-NLRP3 pathways to treat and prevent IPF. This study not only demonstrated the superiority, feasibility, and safety of inhalation therapy for IPF intervention but also confirmed that breaking the vicious cycle of ROS and the NLRP3 inflammasome is a promising strategy for the successful treatment of IPF. Moreover, this successful nanoplatform is a good example of the integration of TCM and modern medicine.

m6A methyltransferase METTL3 programs CD4+ T-cell activation and effector T-cell differentiation in systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is an autoimmune disorder in which excessive CD4+ T-cell activation and imbalanced effector T-cell differentiation play critical roles. Recent studies have implied a potential association between posttranscriptional N6-methyladenosine (m6A) modification and CD4+ T-cell-mediated humoral immunity. However, how this biological process contributes to lupus is not well understood. In this work, we investigated the role of the m6A methyltransferase like 3 (METTL3) in CD4+ T-cell activation, differentiation, and SLE pathogenesis both in vitro and in vivo. METHODS: The expression of METTL3 was knocked down and METTL3 enzyme activity was inhibited using siRNA and catalytic inhibitor, respectively. In vivo evaluation of METTL3 inhibition on CD4+ T-cell activation, effector T-cell differentiation, and SLE pathogenesis was achieved using a sheep red blood cell (SRBC)-immunized mouse model and a chronic graft versus host disease (cGVHD) mouse model. RNA-seq was performed to identify pathways and gene signatures targeted by METTL3. m6A RNA-immunoprecipitation qPCR was applied to confirm the m6A modification of METTL3 targets. RESULTS: METTL3 was defective in the CD4+ T cells of SLE patients. METTL3 expression varied following CD4+ T-cell activation and effector T-cell differentiation in vitro. Pharmacological inhibition of METTL3 promoted the activation of CD4+ T cells and influenced the differentiation of effector T cells, predominantly Treg cells, in vivo. Moreover, METTL3 inhibition increased antibody production and aggravated the lupus-like phenotype in cGVHD mice. Further investigation revealed that catalytic inhibition of METTL3 reduced Foxp3 expression by enhancing Foxp3 mRNA decay in a m6A-dependent manner, hence suppressing Treg cell differentiation. CONCLUSION: In summary, our findings demonstrated that METTL3 was required for stabilizing Foxp3 mRNA via m6A modification to maintain the Treg differentiation program. METTL3 inhibition contributed to the pathogenesis of SLE by participating in the activation of CD4+ T cells and imbalance of effector T-cell differentiation, which could serve as a potential target for therapeutic intervention in SLE.

Dynamic Color-Switching of Hydrogel Micropillar Array under Ethanol Vapor for Optical Encryption.

Responsive structural colors from artificially engineered micro/nanostructures are critical to the development of anti-counterfeiting, optical encryption, and intelligent display. Herein, the responsive structural color of hydrogel micropillar array is demonstrated under the external stimulus of ethanol vapor. Micropillar arrays with full color are fabricated via femtosecond laser direct writing by controlling the height and diameter of the micropillars according to the FDTD simulation. Color-switching of the micropillar arrays is achieved in <1 s due to the formation of liquid film among micropillars. More importantly, the structural color blueshift of the micropillar arrays is sensitive to the micropillar diameter, instead of the micropillar height. The micropillar array with a diameter of 772 nm takes 400 ms to complete blueshift under ethanol vapor, while that with a diameter of 522 nm blueshifts at 2400 ms. Microscale patterns are realized by employing the size-dependent color-switching of designed micropillar arrays under ethanol vapor. Moreover, Morse code and directional blueshift of structural colors are realized in the micropillar arrays. The advantages of controllable color-switching of the hydrogel micropillar array would be prospective in the areas of optical encryption, dynamic display, and anti-counterfeiting.

Dual-Stimuli Cooperative Responsive Hydrogel Microactuators Via Two-Photon Lithography.

With the development of bionics as well as materials science, intelligent soft actuators have shown promising applications in many fields such as soft robotics, sensing, and remote manipulation. Microfabrication technologies have enabled the reduction of the size of responsive soft actuators to the micron level. However, it is still challenging to construct microscale actuators capable of responding to different external stimuli in complex and diverse conditions. Here, this work demonstrates a dual-stimuli cooperative responsive hydrogel microactuator by asymmetric fabrication via femtosecond laser direct writing. The dual response of the hydrogel microstructure is achieved by employing responsive hydrogel with functional monomer 2-(dimethylamino)ethyl methacrylate. Raman spectra of the hydrogel microstructures suggest that the pH and temperature response of the hydrogel is generated by the changes in tertiary amine groups and hydrogen bonds, respectively. The asymmetric hydrogel microstructures show opposite bending direction when being heated to high temperature or exposed to acid solution, and can independently accomplish the grasp of polystyrene microspheres. Moreover, this work depicts the cooperative response of the hydrogel microactuator to pH and temperature at the same time. The dual-stimuli cooperative responsive hydrogel microactuators will provide a strategy for designing and fabricating controllable microscale actuators with promising applications in microrobotics and microfluidics.

Cross-Scale Topography Achieved by MOPL with Positive Photoresist to Regulate the Cell Behavior.

Cross-scale micro-nano structures play an important role in semiconductors, MEMS, chemistry, and cell biology. Positive photoresist is widely used in lithography due to the advantages of high resolution and environmental friendliness. However, cross-scale micro-nano structures of positive photoresist are difficult to flexibly pattern, and the feature resolution is limited by the optical diffraction. Here, cross-scale patterned micro-nano structures are achieved using the positive photoresist based on the femtosecond laser maskless optical projection lithography (MOPL) technique. The dependence between exposure dose and groove width is comprehensively analyzed, and a feature size of 112 nm is obtained at 110 µW. Furthermore, large-area topography considering cell size is efficiently fabricated by the MOPL technique, which enables the regulation of cell behavior. The proposed protocol of achieving cross-scale structures with the exact size by MOPL of positive photoresist would provide new avenues for potential applications in nanoelectronics and tissue engineering.

Wetting of Cell Aggregates on Microdisk Topography Structures Achieved by Maskless Optical Projection Lithography.

Cell aggregates as a 3D culture model can effectively mimic the physiological processes such as embryonic development, immune response, and tissue renewal in vivo. Researches show that the topography of biomaterials plays an important role in regulating cell proliferation, adhesion, and differentiation. It is of great significance to understand how cell aggregates respond to surface topography. Herein, microdisk array structures with the optimized size are used to investigate the wetting of cell aggregates. Cell aggregates exhibit complete wetting with distinct wetting velocities on the microdisk array structures of different diameters. The wetting velocity of cell aggregates reaches a maximum of 293 µm h-1 on microdisk structures with a diameter of 2 µm and is a minimum of 247 µm h-1 on microdisk structures of 20 µm diameter, which suggests that the cell-substrates adhesion energy on the latter is smaller. Actin stress fibers, focal adhesions (FAs), and cell morphology are analyzed to reveal the mechanisms of variation of wetting velocity. Furthermore, it is demonstrated that cell aggregates adopt climb and detour wetting modes on small and large-sized microdisk structures, respectively. This work reveals the response of cell aggregates to micro-scale topography, providing guidance for better understanding of tissue infiltration.

A single-cell map of peripheral alterations after FMT treatment in patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is characterized by loss of self-tolerance and persistent self-aggression, sustained chronic inflammation, production of autoantibodies and multi-system damage, and is largely incurable to date. The gut microbiota and its metabolites, now recognized as crucial environmental triggers of local/systemic immune reactions, have been implicated in the development and progression of SLE. Fecal microbiota transplantation (FMT) is restoration of disturbed microbiota by transplanting foreign gut microbiota from healthy individuals into the gastrointestinal tract of diseased individuals. Our previous clinical trial suggests that FMT is a potentially safe and effective treatment for SLE. In order to elucidate the potential effect of FMT on peripheral immune cells of patients with SLE, we collected PBMCs (n = 30) of 13 SLE patients who participated in the clinical trial before and after the FMT-treatment, and performed single-cell RNA sequencing. The results first revealed that peripheral T lymphocytes of SLE patients decreased and NK cells increased after the FMT treatment. Then, sub-clustering analysis discovered that total CD4+ T cells highly expressed genes of IL7R, CD28, and CD8+ T cells highly expressed genes of GZMH and NKG7 after FMT treatment. Moreover, FMT treatment reduced the expression of interferon-related genes (IRGs) in CD4+ T, CD8+ T, DP, NK, and B cells of SLE patients. More importantly, interferon-related pathways were more enriched in cells of the FMT non-responder group, and further the interferon genes expression of lymphocytes and myeloid cells was negatively correlated with the efficiency of FMT treatment. Collectively, our data identified various immunophenotypic and associated gene set changes following FMT treatment, illustrating the heterogeneity of response to FMT treatment in SLE.

Effects of fecal microbiota transplant on DNA methylation in patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a highly heterogeneous autoimmune disease characterized by multiple organ damage accompanied by the over-production of autoantibodies. Decreased intestinal flora diversity and disruption of homeostasis have been proven to be associated with pathogenesis of SLE. In previous study, a clinical trial was conducted to verify the safety and effectiveness of fecal microbiota transplantation (FMT) in the treatment of SLE. To explore the mechanism of FMT in the treatment of SLE, we included 14 SLE patients participating in clinical trials, including 8 in responders group (Rs) and 6 in non-responders group (NRs), and collected peripheral blood DNA and serum. We found that the serum of S-adenosylmethionine (SAM), methylation group donor, was upregulated after FMT, accompanied by an increase in genome-wide DNA methylation level in Rs. We further showed that the methylation levels in promoter regions of Interferon-γ (IFN-γ), induced Helicase C Domain Containing Protein 1 (IFIH1), endoplasmic reticulum membrane protein complex 8 (EMC8), and Tripartite motif-containing protein 58 (TRIM58) increased after FMT treatment. On the contrary, there was no significant change in the methylation of IFIH1 promoter region in the NRs after FMT, and the methylation level of IFIH1 in the Rs was significantly higher than that in the NRs at week 0. We included 850 K methylation chip sequencing, combining previous data of metagenomic sequencing, and metabolomic sequencing for multi-omics analysis to discuss the relationship between flora-metabolite-methylation in FMT. Finally, we found that hexanoic acid treatment can up-regulate the global methylation of peripheral blood mononuclear cells in SLE patients. Overall, our results delineate changes in methylation level after FMT treatment of SLE and reveal possible mechanisms of FMT treatment in terms of the recovery of abnormal hypomethylation.

Fecal microbiota transplantation in the treatment of systemic lupus erythematosus: What we learnt from the explorative clinical trial.

Systemic lupus erythematosus (SLE) is an autoimmune disease with the characterized presence of autoantibodies and resulting in multiple organ damage, which is incurable and can be lethal. The current treatments are limited and less progress has been made in drug discovery for the last few decades. Researches imply that gut dysbiosis exists in both patients and murine models with SLE, taking part in the pathogenesis of SLE through multiple mechanisms such as microbiota translocation and molecular mimicry. Intestinal interventions on the gut microbiome by fecal transplantations to reconstitute the gut-immunity homeostasis serve as a novel therapeutic option for SLE patients. Fecal microbiota transplantation (FMT), which is usually used in intestinal diseases, has been firstly demonstrated to be safe and efficient in recovering gut microbiota structure of SLE patients and reducing lupus activity in our recent clinical trial, which is the first trial testing FMT therapy in SLE treatment. In this paper, we reviewed the results of the single-arm clinical trial and made recommendations on FMT practice in SLE treatment including therapeutic indications, screening items and dosage regimen, trying to provide references for future study and clinical practice. We also came up with the unanswered questions that need to be solved by the ongoing randomized controlled trial as well as the future expectations for the intestinal intervention strategies of SLE patients.

Exploring the repairing mechanisms of reduced graphene oxide (rGo) on the dysregulation of Xenopus Laevis larva hypothalamus-pituitary-thyroid (HPT) axis caused by chiral triazole fungicide metconazole.

Replacing chair fungicide racemate marketed product by its enantiomer with high activity and low environmental risk for application is a more environmentally friendly methods to control crop diseases. Moreover, carbon-based nanomaterials, with the desirable chemical and mechanical properties, exhibits latent reduce fungicide toxicity capability, while the mechanism is still poorly understood. Therefore, the present study characterized the toxicity of rac-metconazole (Mez; (1RS,5RS;1RS,5SR)-5-(4-chlorobenzyl)-2,2-dimethyl-1-(1H)) and its two cis-enantiomers as well as the repairing effect of reduced graphene oxide (rGo) on Xenopus Laevis larva by examining growth appearance indexes, Mez bioaccumulation, and hypothalamus-pituitary-thyroid (HPT) axis related hormone contents and gene expression after 14 and 28 days exposure. Compared with two cis-Mez, rac-Mez was preferentially bioaccumulated in tadpoles, and rac-Mez treatment showed a higher toxicity effect on tadpole including growth stage and body weight inhibition by dysregulating tadpole thyroid stimulating hormone (TSH) and thyroid hormone (TH) contents and related gene expression. Enantioselectivity was observed in two cis-Mez treatments. Compared with R,S-Mez, S,R-Mez treatment showed more severe damage on tadpole HPT axis related physiological and biochemical processes. rGo could effectively decrease the toxicity of Mez, especially shown the capacity of repairing the hormone dysregulation caused by R,S-Mez treatment. Moreover, the addition of rGo can decrease the bioaccumulation of Mez in tadpoles. Therefore, R,S-Mez is less toxic to Xenopus Laevis larva growth, and its toxicity could be effectively repaired by the addition of rGO.

Micropattern of Silver/Polyaniline Core-Shell Nanocomposite Achieved by Maskless Optical Projection Lithography.

With the development of device miniaturization, a flexible and fast preparation method is in demand for achieving microstructures with desired patterns. We develop a novel photoreduction-polymerization method for preparing conductive metal-polymer patterns. Ag/polyaniline (PANI) nanocomposites have been successfully synthesized by maskless optical projection lithography (MOPL) technology, which is based on multiphoton absorption and the localized surface plasmon resonance (LSPR) effect. The individualized design and synthesis of the nanocomposite patterns at the micro-nano scale are flexibly realized on a variety of substrates. The surface-enhanced Raman scattering (SERS) effect of Rhodamine 6G (R6G) is demonstrated on the microstructure of a square maze-shaped Ag/PANI nanocomposite. The electrical conductivity of the as-prepared nanocomposite is obtained. The preparation protocol proposed in this study opens up new avenues for the fabrication of micro-nano devices such as sensors and detectors.

Single-cell transcriptome reveals immunopathological cell composition of skin lesions in subacute cutaneous lupus erythematosus.

Subacute cutaneous lupus erythematosus (SCLE) is a clinical subtype of cutaneous lupus erythematosus with psoriatic-like or annular papules with scaly erythemas, the pathological mechanism of which is poorly understood. To investigate the immune pathogenesis of SCLE, we performed single-cell RNA sequencing (scRNA-seq) of SCLE skin lesions and integrated the scRNA-seq data from skin tissues of healthy controls (HCs). Our results identified expanded fibroblasts and keratinocytes subtypes, abnormally activated lymphocyte and inflammatory M1 macrophages in SCLE. In SCLE, stromal cells, such as keratinocytes and fibroblasts, showed enhanced chemotactic functions for recruiting immune cells. Importantly, interferon-related genes were identified as key intermediate genes in the potential trajectory of fibroblasts, keratinocytes, and B cells from HCs to SCLE. Our investigation provides a comprehensive description of cell composition in SCLE and highlights several important clues for understanding the pathogenesis of SCLE.

Consistent pattern printing of the gap structure in femtosecond laser DMD projection lithography.

Maskless lithography technologies have been developed and played an important role in the fabrication of functional micronano devices for microelectronics, biochips and photonics. Optical projection lithography based on digital micromirror device (DMD) is an efficient maskless lithography technology that can rapidly fabricate complex structures. The precise modulation of gap width by DMD maskless optical projection lithography (MOPL) using femtosecond laser becomes important for achieving micronano structures. Herein, we have investigated the relationship between the structure morphology and the light intensity distribution at the image plane by multi-slit diffraction model and Abbe imaging principle, and optimized the gap width more accurately by modulating exposure energy. The aperture diameter of the objective lens has a substantial effect on the pattern consistency. The continuously adjustable structural gap widths of 2144 nm, 2158 nm and 1703 nm corresponding to 6, 12, 24 pixels are obtained by varying the exposure energy in the home-built MOPL system. However, the ideal gap structure cannot be obtained only by adjusting the exposure energy when the gap width is small, such as 1 or 2 pixels. Furthermore, we have proposed an alternative way to achieve fine gap structures through the structural decomposition design and precise control of exposure energy in different regions without changing the MOPL optical system. This study would provide a promising protocol for fabricating gap microstructures with controllable configuration using MOPL technique.

Ultraviolet light induces HERV expression to activate RIG-I signalling pathway in keratinocytes.

Skin inflammation and photosensitivity are common in lupus erythematosus (LE) patients, and ultraviolet (UV) light is a known trigger of skin and possibly systemic inflammation in systemic lupus erythematosus (SLE) and discoid lupus erythematosus (DLE) patients. Type I interferons (IFN) are upregulated in LE skin after UV exposure; however, the mechanisms to explain UVB-induced inflammation remain unclear. Here, we demonstrated that UVB irradiation-induced activation of human endogenous retroviruses (HERVs) plays a major role in the immune response. UVB-induced HERV-associated dsRNA transcription and subsequent activation of the innate antiviral RIG-I/MDA5/IRF7 pathway led to downstream transcription of interferon-stimulated genes, which promotes UVB-induced apoptosis and proliferation inhibition in keratinocytes through RIG-I and MDA5 pathways. Our findings indicate that UVB irradiation induces HERV-dsRNA overexpression, and the dsRNA-sensing innate immunity pathway promotes type I IFN production, which may be a potential mechanism of skin inflammatory response and skin lesion of SLE/DLE.

Thymoquinone upregulates IL17RD in controlling the growth and metastasis of triple negative breast cancer cells in vitro.

BACKGROUND: Triple negative breast cancer (TNBC) is a molecular subtype of breast cancer, which is a major health burden of females worldwide. Thymoquinone (TQ), a natural compound, has been found to be effective against TNBC cells, and this study identified IL17RD as a novel target of TQ in TNBC cells. METHODS: We have performed chromatin immunoprecipitation Sequence (ChIP-Seq) by MBD1 (methyl-CpG binding domain protein 1) antibody to identify genome-wide methylated sites affected by TQ. ChIP-seq identified 136 genes, including the tumor suppressor IL17RD, as a novel target of TQ, which is epigenetically upregulated by TQ in TNBC cell lines BT-549 and MDA-MB-231. The IL17RD expression and survival outcomes were studied by Kaplan-Meier analysis. RESULTS: TQ treatment inhibited the growth, migration, and invasion of TNBC cells with or without IL17RD overexpression or knockdown, while the combination of IL17RD overexpression and TQ treatment were the most effective against TNBC cells. Moreover, higher expression of IL17RD is associated with longer survival in TNBC patients, indicating potential therapeutic roles of TQ and IL17RD against TNBC. CONCLUSIONS: Our data suggest that IL17RD might be epigenetically upregulated in TNBC cell lines by TQ, and this might be one of the mechanisms by which TQ exerts its anticancer and antimetastatic effects on TNBC cells.

λ/12 Super Resolution Achieved in Maskless Optical Projection Nanolithography for Efficient Cross-Scale Patterning.

The emerging demand for device miniaturization and integration prompts the patterning technique of micronano-cross-scale structures as an urgent desire. Lithography, as a sufficient patterning technique, has been playing an important role in achieving functional micronanoscale structures for decades. As a promising alternative, we have proposed and demonstrated the maskless optical projection nanolithography (MLOP-NL) technique for efficient cross-scale patterning. A minimum feature size of 32 nm, which is λ/12 super resolution breaking the optical diffraction limit, has been achieved by a single exposure. Furthermore, multiscale two-dimensional micronano-hybrid structures with the size over hundreds of micrometers and the precision at tens of nanometers have been fabricated by simply controlling the exposure conditions. The proposed MLOP-NL technique provides a powerful tool for achieving cross-scale patterning with both large-scale and precise configuration with high efficiency, which can be potentially used in the fabrication of multiscale integrated microsystems.

The deacetylase sirtuin 6 protects against kidney fibrosis by epigenetically blocking ß-catenin target gene expression.

Fibrosis is a common pathologic pathway of progressive kidney disease involving complex signaling networks. The deacetylase sirtuin 6 (sirt6) was recently implicated in kidney injury. However, it remains elusive whether and how sirt6 contributes to the regulation of kidney fibrosis. Here, we demonstrate that sirt6 protects against kidney interstitial fibrosis through epigenetic regulation of ß-catenin signaling. Sirt6 is markedly upregulated during fibrogenesis following obstructed nephropathy and kidney ischemia-reperfusion injury. Pharmacological inhibition of sirt6 deacetylase activity aggravates kidney fibrosis in obstructed nephropathy. Consistently, knockdown of sirt6 in mouse kidney proximal tubular epithelial cells aggravates transforming growth factor-ß-induced fibrosis in vitro. Mechanistically, sirt6 deficiency results in augmented expression of the downstream target proteins of ß-catenin signaling. We further show that sirt6 interacts with ß-catenin during transforming growth factor-ß treatment and binds to the promoters of ß-catenin target genes, resulting in the deacetylation of histone H3K56 to prevent the transcription of fibrosis-related genes. Thus, our data reveal the anti-fibrotic function of sirt6 by epigenetically attenuating ß-catenin target gene expression.

Nicotinamide reduces renal interstitial fibrosis by suppressing tubular injury and inflammation.

Renal interstitial fibrosis is a common pathological feature in progressive kidney diseases currently lacking effective treatment. Nicotinamide (NAM), a member of water-soluble vitamin B family, was recently suggested to have a therapeutic potential for acute kidney injury (AKI) in mice and humans. The effect of NAM on chronic kidney pathologies, including renal fibrosis, is unknown. Here we have tested the effects of NAM on renal interstitial fibrosis using in vivo and in vitro models. In vivo, unilateral urethral obstruction (UUO) induced renal interstitial fibrosis as indicated Masson trichrome staining and expression of pro-fibrotic proteins, which was inhibited by NAM. In UUO, NAM suppressed tubular atrophy and apoptosis. In addition, NAM suppressed UUO-associated T cell and macrophage infiltration and induction of pro-inflammatory cytokines, such as TNF-α and IL-1ß. In cultured mouse proximal tubule cells, NAM blocked TGF-ß-induced expression of fibrotic proteins, while it marginally suppressed the morphological changes induced by TGF-ß. NAM also suppressed the expression of pro-inflammatory cytokines (eg MCP-1 and IL-1ß) during TGF-ß treatment of these cells. Collectively, the results demonstrate an anti-fibrotic effect of NAM in kidneys, which may involve the suppression of tubular injury and inflammation.