Quercetin Alleviates Pulmonary Fibrosis in Silicotic Mice by Inhibiting Macrophage Transition and TGF-ß-Smad2/3 Pathway.

Silicosis is a pulmonary disease caused by the inhalation of silica. There is a lack of early and effective prevention, diagnosis, and treatment methods, and addressing silicotic fibrosis is crucial. Quercetin, a flavonoid with anti-carcinogenic, anti-inflammatory, and antiviral properties, is known to have a suppressive effect on fibrosis. The present study aimed to determine the therapeutic effect of quercetin on silicotic mice and macrophage polarity. We found that quercetin suppressed silicosis in mice. It was observed that SiO2 activated macrophage polarity and the macrophage-to-myofibroblast transition (MMT) by transforming the growth factor-ß (TGF-ß)-Smad2/3 signaling pathway in silicotic mice and MH-S cells. Quercetin also attenuated the MMT and the TGF-ß-Smad2/3 signaling pathway in vivo and in vitro. The present study demonstrated that quercetin is a potential therapeutic agent for silicosis, which acts by regulating macrophage polarity and the MMT through the TGF-ß-Smad2/3 signaling pathway.

Matrix stiffness regulates α-TAT1-mediated acetylation of α-tubulin and promotes silica-induced epithelial-mesenchymal transition via DNA damage.

Silicosis is characterized by silica exposure-induced lung interstitial fibrosis and formation of silicotic nodules, resulting in lung stiffening. The acetylation of microtubules mediated by α-tubulin N-acetyltransferase 1 (α-TAT1) is a posttranslational modification that promotes microtubule stability in response to mechanical stimulation. α-TAT1 and downstream acetylated α-tubulin (Ac-α-Tub) are decreased in silicosis, promoting the epithelial-mesenchymal transition (EMT); however, the underlying mechanisms are unknown. We found that silica, matrix stiffening or their combination triggered Ac-α-Tub downregulation in alveolar epithelial cells, followed by DNA damage and replication stress. α-TAT1 elevated Ac-α-Tub to limit replication stress and the EMT via trafficking of p53-binding protein 1 (53BP1, also known as TP53BP1). The results provide evidence that α-TAT1 and Ac-α-Tub inhibit the EMT and silicosis fibrosis by preventing 53BP1 mislocalization and relieving DNA damage. This study provides insight into how the cell cycle is regulated during the EMT and why the decrease in α-TAT1 and Ac-α-Tub promotes silicosis fibrosis.This article has an associated First Person interview with the first authors of the paper.

Effectiveness of Pentavalent Rotavirus Vaccine in Shanghai, China: A Test-Negative Design Study.

OBJECTIVE: To evaluate vaccine effectiveness (VE) of a live oral pentavalent rotavirus vaccine (RotaTeq, RV5) among young children in Shanghai, China, via a test-negative design study. STUDY DESIGN: We consecutively recruited children visiting a tertiary children's hospital for acute diarrhea from November 2021 to February 2022. Information on clinical data and rotavirus vaccination was collected. Fresh fecal samples were obtained for rotavirus detection and genotyping. To evaluate VE of RV5 against rotavirus gastroenteritis among young children, unconditional logistic regression models were conducted to compare ORs for vaccination between rotavirus-positive cases and test-negative controls. RESULTS: A total of 390 eligible children with acute diarrhea were enrolled, including 45 (11.54%) rotavirus-positive cases and 345 (88.46%) test-negative controls. After excluding 4 cases (8.89%) and 55 controls (15.94%) who had received the Lanzhou lamb rotavirus vaccine, 41 cases (12.39%) and 290 controls (87.61%) were included for the evaluation of RV5 VE. After adjustment for potential confounders, the 3-dose RV5 vaccination showed 85% (95% CI, 50%-95%) VE against mild to moderate rotavirus gastroenteritis among children aged 14 weeks to ≤4 years and 97% (95% CI, 83%-100%) VE among children aged 14 weeks to ≤2 years with genotypes G8P8, G9P8, and G2P4 represented 78.95%, 18.42%, and 2.63% of circulation strains, respectively. CONCLUSIONS: A 3-dose vaccination of RV5 is highly protective against rotavirus gastroenteritis among young children in Shanghai. The G8P8 genotype prevailled in Shanghai after RV5 introduction.

Effect of Sex Differences in Silicotic Mice.

Mechanisms of silicosis, caused by the inhalation of silica are still unclear, and the effect of sex on silicosis has rarely been reported. The purpose of this study was to investigate whether sex affects the silicotic lesions and the progressive fibrotic responses in silicosis. Our study showed that sex had no significant effect on the area of silicon nodules and the collagen deposition after a one-time bronchial perfusion of silica. Immunohistochemical staining showed that CD68 and the transforming growth factor-ß1 (TGF-ß1) were positive in male and female silicotic mice. In addition, the western blot results showed that the fibrosis-related factors type I collagen (COL I), α-smooth muscle actin (α-SMA), vimentin, TGF-ß1, p-SMAD2/3, inflammatory-related factors interleukin 6 (IL 6), interleukin 1ß (IL 1ß), and senescence-related factors p16 and p21 were up-regulated in silicotic mice and there was no difference between female or male mice exposed to silica. The expression of TGF-ß1, p-SMAD2/3, p16, and p21 were downregulated in the early stage of female silicotic mice, compared to the males. Thus, despite differences in the expression of certain factors, there was no overall difference in the progressive fibrosis between female and male mice in silicosis. These results thus provide a new perspective for studying the pathological development of silicosis.

MicroRNA-411-3p inhibits bleomycin-induced skin fibrosis by regulating transforming growth factor-ß/Smad ubiquitin regulatory factor-2 signalling.

Skin fibrosis, which is characterized by fibroblast proliferation and increased extracellular matrix, has no effective treatment. An increasing number of studies have shown that microRNAs (miRNAs/miRs) participate in the mechanism of skin fibrosis, such as in limited cutaneous systemic sclerosis and pathological scarring. The objective of the present study was to determine the role of miR-411-3p in bleomycin (BLM)-induced skin fibrosis and skin fibroblast transformation. Using Western blot analysis and real-time quantitative polymerase chain reaction assess the expression levels of miR-411-3p, collagen (COLI) and transforming growth factor (TGF)-ß/Smad ubiquitin regulatory factor (Smurf)-2/Smad signalling factors both in vitro and in vivo with or without BLM. To explore the regulatory relationship between miR-411-3p and Smurf2, we used the luciferase reporter assay. Furthermore, miR-411-3p overexpression was identified in vitro and in vivo via transfection with Lipofectamine 2000 reagent and injection. Finally, we tested the dermal layer of the skin using haematoxylin and eosin and Van Gieson's staining. We found that miR-411-3p expression was decreased in bleomycin (BLM)-induced skin fibrosis and fibroblasts. However, BLM accelerated transforming growth factor (TGF)-ß signalling and collagen production. Overexpression of miR-411-3p inhibited the expression of collagen, F-actin and the TGF-ß/Smad signalling pathway factors in BLM-induced skin fibrosis and fibroblasts. In addition, miR-411-3p inhibited the target Smad ubiquitin regulatory factor (Smurf)-2. Furthermore, Smurf2 was silenced, which attenuated the expression of collagen via suppression of the TGF-ß/Smad signalling pathway. We demonstrated that miR-411-3p exerts antifibrotic effects by inhibiting the TGF-ß/Smad signalling pathway via targeting of Smurf2 in skin fibrosis.

MiR-411-3p alleviates Silica-induced pulmonary fibrosis by regulating Smurf2/TGF-ß signaling.

Occupational exposure to silica dust particles was the major cause of pulmonary fibrosis, and many miRNAs have been demonstrated to regulate target mRNAs in silicosis. In the present study, we found that a decreasing level of miR-411-3p in silicosis rats and lung fibroblasts induced by TGF-ß1. Enlargement of miR-411-3p could inhibit the cell proliferation and migration in lung fibroblasts with TGF-ß1 treatment and attenuate lung fibrosis in silicotic mice. In addition, a mechanistic study showed that miR-411-3p exert its inhibitory effect on Smad ubiquitination regulatory factor 2 (Smurf2) expression and decrease ubiquitination degradation of Smad7 regulated by smurf2, result in blocking of TGF-ß/Smad signaling. We proposed that increased expression of miR-411-3p abrogates silicosis by blocking activation of TGF-ß/Smad signaling through decreasing ubiquitination degradation effect of smurf2 on Smad7.

N-Acetyl-Seryl-Asparyl-Lysyl-Proline regulates lung renin angiotensin system to inhibit epithelial-mesenchymal transition in silicotic mice.

Silicosis is a major public health concern with various contributing factors. The renin-angiotensin system (RAS)is a critical regulator in the pathogenesis of this disease. We focused on two key RAS enzymes, angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2), to elucidate the activation of the ACE-angiotensin II (Ang II)-angiotensin II receptor 1 (AT1) axis and the inhibition of the ACE2-angiotensin-(1-7) [Ang-(1-7)]-Mas receptor axis in C57BL/6mice following SiO2 treatment. Silica exposure caused nodule formation, pulmonary interstitial fibrosis, epithelial-mesenchymal transition (EMT), abnormal deposition of extracellular matrix, and impaired lung function in mice. These effects were attenuated by the inhibition of ACE (captopril), blockade of the AT1(losartan), or systemic knockdown of the Ace gene. These effects were exacerbated by the inhibition of ACE2 (MLN-4760), blockade of the Mas (A779), or knockdown of the Ace2 gene. N-Acetyl-Seryl-Asparyl-Lysyl-Proline (Ac-SDKP), an anti-fibrotic peptide, ameliorated the silica-exposure-induced pathological changes by targeting the RAS system by activating the protective ACE2-Ang-(1-7)-Mas axis and inhibiting the deleterious ACE-Ang II-AT1 axis, thereby exerting a protective effect. This was confirmed in mouse lung type II epithelial cells (MLE-12) pretreated with Ang II and/or gene silencing separately targeting Ace and Ace2.The effects of Ac-SDKP were similar to those produced by Ace gene silencing and were partly attenuated by Ace2 deficiency. These findings suggested that RAS plays critical roles in the pathomechanism of silicosis fibrosis and that Ac-SDKP regulates lung RAS to inhibit EMT in silicotic mice and MLE-12 cells.

Rho GDP dissociation inhibitor α silencing attenuates silicosis by inhibiting RhoA/Rho kinase signalling.

Transforming growth factor-ß1 (TGF-ß1) alters the fibroblast phenotype by promoting transdifferentiation into myofibroblasts, which exhibit the ability to promote collagen synthesis and extracellular matrix (ECM) deposition, thereby playing a significant role in the pathology of silicosis. In this study, we investigated the regulatory mechanisms involved in myofibroblast transdifferentiation. Two-dimensional gel electrophoresis showed that Rho GDP-dissociation inhibitor α (RhoGDIα) was upregulated following myofibroblast transdifferentiation stimulated by TGF-ß1. We hypothesised that RhoGDIα may induce myofibroblast transdifferentiation and thus result in silicosis. Accordingly, the biological significance of RhoGDIα in cell proliferation and apoptosis was investigated by deletion of RhoGDIα in MRC-5 cells. In addition, a mechanistic study showed that fasudil, an inhibitor of the RhoA/Rho kinase (ROCK) signalling pathway, reduced the levels of RhoGDIα, RhoA, and phospho-myosin phosphatase （phospho-MYPT） in MRC-5 cells and silicosis model rats. Knockdown of RhoGDIα inhibited myofibroblast transdifferentiation and collagen deposition through RhoGDIα/RhoA/ROCK signalling in silicosis model mice. Overall, downregulation of RhoGDIα may significantly promote cell apoptosis and inhibit cell growth, resulting in reversal of myofibroblast transdifferentiation by RhoA/ROCK in vitro and in vivo. These data will facilitate further exploration of the potential use of RhoGDIα as a target for silicosis therapy.

Interaction of N-acetyl-seryl-aspartyl-lysyl-proline with the angiotensin-converting enzyme 2-angiotensin-(1-7)-Mas axis attenuates pulmonary fibrosis in silicotic rats.

NEW FINDINGS: What is the central question of this study? What are the effects of the antifibrotic peptide acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) on the angiotensin-converting enzyme 2 (ACE2)-angiotensin-(1-7)-Mas axis during the occurrence and progression of silicosis? What is the main finding and its importance? Ac-SDKP inhibited lung fibrosis in rats exposed to silica by activation of the ACE2-angiotensin-(1-7)-Mas axis. Angiotensin-(1-7) potentially promotes Ac-SDKP by increasing the level of meprin α, the major synthetase of Ac-SDKP. Thus, the interaction Ac-SDKP and angiotesin-(1-7) in silicosis could provide a new therapeutic strategy. ABSTRACT: The central role of angiotensin-converting enzyme (ACE) in the occurrence and progression of silicosis has been established. The antifibrotic peptide acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) can be degraded by ACE. The ACE2-angiotensin-(1-7)-Mas axis is protective and acts to counterbalance the detrimental effects of ACE-angiotensin II (Ang II)-Ang II type 1 receptor and exerts antifibrotic effects. Here, we demonstrate an interaction between Ac-SDKP and Ang-(1-7) in the inhibition of collagen deposition and myofibroblast differentiation in rats exposed to silica. Treatment with Ac-SDKP increased the level of ACE2-Ang-(1-7)-Mas in rats or in cultured fibroblasts and decreased the levels of collagen type I and α-smooth muscle actin. Furthermore, exogenous Ang-(1-7) had similar antifibrotic effects and increased the level of meprin α, a major Ac-SDKP synthetase, both in vivo and in vitro. Compared with non-silicotic patients exposed to silica, the level of serum ACE was increased in patients with silicosis phase III; the levels of Ang II and Ang-(1-7) were high in patients with silicosis phase II; and the level of Ac-SDKP was high in the silicosis phase III group. These data imply that Ac-SDKP and Ang-(1-7) have an interactive effect as regulatory peptides of the renin-angiotensin system and exert antifibrotic effects.

N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) attenuates silicotic fibrosis by suppressing apoptosis of alveolar type II epithelial cells via mediation of endoplasmic reticulum stress.

Damage to alveolar epithelial cells (AECs) caused by long-term inhalation of large amounts of silica dust plays a significant role in the pathology of silicosis. The present study was undertaken to investigate the regulatory mechanism(s) involved in type II AEC damage from silicon dioxide (SiO2) as well as the mechanism(s) related to the prevention of silicosis by the antifibrotic tetra peptide, N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP). The 2-DE results showed that SiO2 induced endoplasmic reticulum (ER) stress in A549 cells. In addition, typical apoptotic characteristics were observed using a transmission electron microscope (TEM) in A549 cells stimulated by SiO2 and in type II AECs from silicotic rats. Mechanistic study showed that both Ac-SDKP and 4-phenylbutyrate (4-PBA), an inhibiter of ER stress, attenuated GRP78, phosphor-PERK, phosphor-eIF2α, CHOP and Caspase-12 protein expression in A549 cells stimulated by SiO2 and in type II AECs from silicotic rats. Treatment with Ac-SDKP and 4-PBA in vivo effectively inhibited collagen deposition in the lungs of silicotic rats. In summary, ER stress is involved in the apoptosis of type II AECs both in vitro and in vivo. Ac-SDKP effectively suppresses SiO2-induced apoptosis in type II AECs by attenuating the Caspase-12 and PERK/eIF2α/CHOP pathway activation caused by ER stress, thus preventing silicotic fibrosis.

Dibutyryl-cAMP attenuates pulmonary fibrosis by blocking myofibroblast differentiation via PKA/CREB/CBP signaling in rats with silicosis.

BACKGROUND: Myofibroblasts play a major role in the synthesis of extracellular matrix (ECM) and the stimulation of these cells is thought to play an important role in the development of silicosis. The present study was undertaken to investigate the anti-fibrotic effects of dibutyryl-cAMP (db-cAMP) on rats induced by silica. METHODS: A HOPE MED 8050 exposure control apparatus was used to create the silicosis model. Rats were randomly divided into 4 groups: 1)controls for 16 w; 2)silicosis for 16 w; 3)db-cAMP pre-treatment; 4) db-cAMP post-treatment. Rat pulmonary fibroblasts were cultured in vitro and divided into 4 groups as follows: 1) controls; 2) 10-7mol/L angiotensin II (Ang II); 3) Ang II +10-4 mol/L db-cAMP; and 4) Ang II + db-cAMP+ 10-6 mol/L H89. Hematoxylin-eosin (HE), Van Gieson staining and immunohistochemistry (IHC) were performed to observe the histomorphology of lung tissue. The levels of cAMP were detected by enzyme immunoassay. Double-labeling for α-SMA with Gαi3, protein kinase A (PKA), phosphorylated cAMP-response element-binding protein (p-CREB), and p-Smad2/3 was identified by immunofluorescence staining. Protein levels were detected by Western blot analysis. The interaction between CREB-binding protein (CBP) and Smad2/3 and p-CREB were measured by co-immunoprecipitation (Co-IP). RESULTS: Db-cAMP treatment reduced the number and size of silicosis nodules, inhibited myofibroblast differentiation, and extracellular matrix deposition in vitro and in vivo. In addition, db-cAMP regulated Gαs protein and inhibited expression of Gαi protein, which increased endogenous cAMP. Db-cAMP increased phosphorylated cAMP-response element-binding protein (p-CREB) via protein kinase A (PKA) signaling, and decreased nuclear p-Smad2/3 binding with CREB binding protein (CBP), which reduced activation of p-Smads in fibroblasts induced by Ang II. CONCLUSIONS: This study showed an anti-silicotic effect of db-cAMP that was mediated via PKA/p-CREB/CBP signaling. Furthermore, the findings offer novel insight into the potential use of cAMP signaling for therapeutic strategies to treat silicosis.

[Transforming growth factor-ß1 induced cellular proliferation and collagen synthesis was mediated by reactive oxygen species in pulmonary fibroblasts].

OBJECTIVE: This study will explore whether reactive oxygen species (ROS) is involved in TGF-ß1-induced JNK activation, pulmonary fibroblast proliferation and collagen type I and III synthesis. METHODS: Pulmonary fibroblasts were randomly divided into control (0.4% serum) and TGF-ß1 (5 µg/L) groups to detect whether TGF-ß1 could induce pulmonary fibroblast proliferation, synthesis of collagen I and III, phosphorylated-JNK (p-JNK) and 8-OHdG (indicator of ROS); while in the part to explore whether NAC (N-acetyl-L-cysteine, antioxidants) has the inhibitory role in TGF-ß1-induced pulmonary fibroblast, it did control (0.4% serum), H2O2 (0.1 mmol/L, positive control), H2O2+NAC (10 mmol/L), TGF-ß1 (5 µg/L), TGF-ß1+NAC groups. Pulmonary fibroblast proliferation, 8-OHdG levels, expressions of JNK and collagen I and III were used by MTT assay, immunofluorescence and western blot respectively. RESULTS: In the experiments to detect the effect of TGF-ß1 on pulmonary fibroblasts, compared with control, TGF-ß1 significantly stimulated pulmonary fibroblast proliferation and increased collagen I and III protein, p-JNK and 8-OHdG levels. In the next experiments to explore whether NAC has the inhibitory role in TGF-ß1-induced pulmonary fibroblasts, compared with control, pulmonary fibroblast proliferation and the levels of collagen I and II, p-JNK, 8-OHdG were all significantly increased in H2O2 and TGF-ß1 groups; while these changes were markedly blocked with the treatment of NAC. CONCLUSION: TGF-ß1 induces pulmonary fibroblasts to generate ROS, which contributes to JNK activation and pulmonary fibroblast proliferation as well as collagen synthesis, while ROS inhibition suppresses this effet of TGF-ß1 in pulmonary fibroblasts.

[Inhibition effect of N-acetyl-seryl-aspartyl-lysyl-proline on myofibroblast differentiation by regulating acetylated tubulin α in silicotic rat model].

OBJECTIVE: To explore the inhibition effect and mechanism of N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP)on myofibroblast differentiation via regulating acetylated tubulin α (Ac-Tub α)in vivo and in vitro. METHODS: Silicotic model were made by SiO2 douched and divided into 6 groups as follows: control (4w, 8w)group, silicotic model (4w, 8w)group and post-or pre-treatment by Ac-SDKP group. Pulmonary fibroblasts were divided into 5 groups: (1) control; (2) Ang II; (3) Ang II+Ac-SDKP; (4) Ang II+Valsartan; (5) Ang II+TCS histone deacetylase (HDAC)6 20b. The localization of Ac-Tub α and α-smooth muscle actin (SMA) were observed by immunohistochemical (IHC) and immunofluorescence staining. The protein levels of Ac-Tub α, α-SMA, collagen type I (col I) and HDAC6 were measured by western blot. RESULTS: In silicotic nodules and interstitial fibrosis area, positive expression of α-SMA, a classical marker of myofibroblast, was ob-served by IHC, accompanied with absence expression of Ac-Tub α. Furthermore, Ac-SDKP post-treatment could attenuate the levels of col I, α-SMA and HDAC6 to 48.39%, 52.63% and 70.18% compared with the silicotic 8w group respectively. And in Ac-SDKP pre-treatment group, compared with the silicotic 8w group, these protein levels were decreased to 32.26%, 64.91% and 54.39% respectively (P<0.05). The up-regulation of Ac-Tub α was found in Ac-SDKP post-and pre-treatment and increased to 3.00 and 2.90 folds compared with the silicotic 8w group. Compared with control group, the levels of α-SMA, HDAC6 and col I in Ang II group were up-regulated to 1.66, 3.56 and 4.00 folds accompanied with down-regulation of Ac-Tub by 44.44% (P<0.05). Pre-treatment with Valsartan, TCS HDAC6 20b or Ac-SDKP could inhibited all this changes induced by Ang II in vitro. CONCLUSION: Ac-SDKP can inhibit the myofibroblast differentiation and collagen deposition via sup-press HDAC6 and up-regulate the expression of Ac-Tub α in vivo and in vitro.

[Comparative proteomic analysis on anti-fibrotic effect of N-acetyl-seryl-aspartyl-lysyl-proline in rats with silicosis].

OBJECTIVE: To perform a comparative proteomic analysis for identification of pulmonary proteins related to the progression of silicosis and anti-fibrotic effect of N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP). METHODS: Bronchial instillation of SiO2powder (for 4 or 8 weeks) was applied in rats to establish a silicosis model. Ac-SDKP treatment was performed before (prevention group) or after (treatment group) SiO2instillation. The control group was treated by bronchial instillation of sodium chloride solution of the same volume as SiO2powder for 4 or 8 weeks. Proteins in lung tissue were separated by two-dimensional gel electrophoresis and stained with colloidal Coomassie brilliant blue. The gel images were scanned with the Lab Scan III system and analyzed with Imagemaster 6.0. The protein spots with significant differences between two groups (i.e., P value was less than 0.05 in One-way ANOVA) and with a change in volume over 30% were defined as differential proteins. Comparison was performed between the silicosis group and control group after 4 or 8 weeks, between the Ac-SDKP treatment group and silicosis group after 8 weeks, and between the Ac-SDKP prevention group and silicosis group after 8 weeks. The differentially expressed proteins were subjected to in-gel digestion with trypsin and MALDI-TOF-MS and Mascot search engine analysis to identify these proteins. RESULTS: Thirty-three differential proteins were identified. In comparison with the control group (4 weeks), the silicosis group (4 weeks) had 17 up-regulated proteins and 11 down-regulated proteins. In comparison with the control group (8 weeks), the silicosis group (8 weeks) had 16 up-regulated proteins and 12 down-regulated proteins. In comparison with the silicosis group (8 weeks), the Ac-SDKP treatment group had 5 up-regulated proteins and 6 down-regulated proteins, and the Ac-SDKP prevention group had 8 up-regulated proteins and 10 down-regulated proteins. CONCLUSION: Critical regulatory proteins related to silicotic fibrosis and anti-silicotic effect of Ac-SDKP have been identified. These proteins may play an important role in proliferation, apoptosis, inflammation, epithelial-mesenchymal transition, and signal transduction in silicosis.

[Anti-fibrotic role of AcSDKP through inhibition of P38MAPK pathway activity mediated transforming growth beta receptors in rat with silicosis].

OBJECTIVE: To investigate the distribution and expression of transforming growth factor beta (TGF-ß) receptors I and II, p38 mitogen-activated protein kinase (p38 MAPK), and type I and type III collagen in the lungs of rats with silicosis and cultured pulmonary fibroblasts, and to investigate the relationship of the anti-fibrosis effect of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) with its inhibition of TGF-ß receptor-mediated p38 MAPK pathway activity. METHODS: Rats were randomly divided into control group, silicosis model group, and AcSDKP treatment group (n = 10 for each group). For the model group and AcSDKP treatment group, rats were intratracheally instilled with silica to establish a silicosis model. Cultured pulmonary fibroblasts from neonatal rats were divided into control group, TGF-ß1 stimulation group, TGF-ß receptor inhibition group, p38 MAPK pathway inhibition group, and AcSDKP treatment group. The protein expression of TGF-ß receptors I and II, p38 MAPK, and type I and type III collagen were determined by immunohistochemistry and Western blot. The mRNA expression of TGF-ß receptors I and II were determined by real-time PCR. The distribution and nuclear translocation of phospho-p38 MAPK in cultured fibroblasts were determined by laser scanner confocal microscopy. RESULTS: In the AcSDKP treatment group, AcSDKP reduced the expression of TGF-ß receptors I and II, phospho-p38 MAPK, and type I and type III collagen to 86.12%, 41.01%, 42.63%, 89.05%, and 52.71%, respectively, of those of the silicosis model group (P < 0.05). In cultured fibroblasts, AcSDKP reduced the mRNA expression of TGF-ß receptors I and II to 42.26% and 54.33%, respectively, of those of the TGF-ß1 stimulation group; the protein expression of TGF-ß receptors I and II, phospho-p38 MAPK, and type 1 and type III collagen was reduced to 58.14%, 51.40%, 45.6%, 58.04%, and 44.74%, respectively, of those of the TGF-ß1 stimulation group. The phospho-p38 MAPK translocation from plasma to the nucleus was also inhibited; the nucleus/plasma ratio of p38 MAPK and the protein expression of type I and type III collagen were reduced to 68.60%, 58.04%, and 44.74%, respectively, of those of the TGF-ß stimulation group (P < 0.05). CONCLUSION: AcSDKP can inhibit the expression of collagen through inhibition of TGF-ß receptor-mediated p38 MAPK pathway activity, and is thus able to exert anti-fibrosis effect in rats with silicosis.

[Inhibition effect of N-acetyl-seryl-aspartyl-lysyl-proline on myofibroblast differentiation of MRC-5 human fetal lung fibroblasts inuced by Ang II].

OBJECTIVE: To explore the inhibition effect of N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) on myofibroblast differentiation of MRC-5 human fetal lung fibroblasts induced by angiotensin (Ang) II. METHODS: The study was divided into 2 step: (1) MRC-5 human fetal lung fibroblasts was induced for 48 h at different dose of Ang II and at different time point by 100 nmol/L Ang II. Then the expression of collagen type I and α-smooth muscle actin (α-SMA) were mesaured by western blot. (2) MRC-5 human fetal lung fibroblasts were divided into 4 group: (1) control, (2) Ang II, (3) Ang II+Ac-SDKP, (4) Ang II+8-Me-cAMP (a specific activator of Epac). The α-SMA expression was observed by immnocytochemical stain. The protein expression of collagen type I, α-SMA, serum response factor (SRF), myocardin-related transcription factor (MRTF)-A, exchange protein directly activated by cAMP (Epac) 1, 2 were measured by Westen blot. RESULTS: Myofibroblast differentiation could be induced by Ang II from MRC-5 cells with a dose- and time-dependent manner. The up-regulation of SRF and MRTF-A were observed in MRC-5 cells induced by Ang II and accompanied with collagen I and α-SMA increased. Pre-treatment with 8-Me-cAMP or Ac-SDKP could attenuated all this changes induced by Ang II, and promoted the expression of Epac1. CONCLUSION: Ac-SDKP can inhibit the myofibroblast differentiation of MRC-5 cells induced by Ang II via Epac1 activating.

Paeoniflorin mitigates MMP-12 inflammation in silicosis via Yang-Yin-Qing-Fei Decoction in murine models.

BACKGROUND: Silicosis presents a significant clinical challenges and economic burdens, with Traditional Chinese Medicine (TCM) emerging as a potential therapeutic avenue. However, the precise effects and mechanisms of TCM in treating silicosis remain uncertain and subject to debate. OBJECTIVE: The study aims to elucidate the therapeutic role and mechanisms of the Yang-Yin-Qing-Fei Decoction (YYQFD) and its key component, paeoniflorin, in silicosis using a murine model. METHODS: Silicotic mice were treated with YYQFD, pirfenidone (PFD), or paeoniflorin. RAW264.7 cells and mouse lung fibroblasts (MLF) were stimulated with silica, matrix metalloproteinase-12 (MMP-12), or TGF-ß1, followed by treatment with paeoniflorin, PFD, or relevant inhibitors. YYQFD constituents were characterized using High-Performance Liquid Chromatography (HPLC). Lung fibrosis severity was assessed via histopathological examination, micro-CT imaging, lung functions, and Western blot analysis. Transcriptome sequencing and bioinformatics analysis were employed to delineate the gene expression profile and target genes modulated by YYQFD in silicosis. RESULTS: Treatment with YYQFD ameliorated silica-induced lung fibrosis. Transcriptome sequencing identified MMP-12 as a potential common target of YYQFD and PFD. Additionally, a potential pro-inflammatory role of MMP-12, regulated by silica-induced TLR4 signaling pathways, was revealed. Paeoniflorin, one of the most distinctive compounds in YYQFD, attenuated silica-induced MMP-12 increase and its derived inflammatory factors in macrophages through a direct binding effect. Notably, paeoniflorin treatment exerted anti-fibrotic effects by inhibiting MMP-12-derived inflammatory factors and TGF-ß1-induced myofibroblast differentiation in silica-exposed mice. CONCLUSIONS: This study underscores paeoniflorin as one of the most principal bioactive compounds in YYQFD, highlighting its capacity to attenuate lung inflammation driven by macrophage-derived MMP-12 and reduce lung fibrosis both in vivo and in vitro.

Effect of macrophage-to-myofibroblast transition on silicosis.

BACKGROUND: The aim was to explore the effect of macrophage polarization and macrophage-to-myofibroblast transition (MMT) in silicosis. METHODS: Male Wistar rats were divided into a control group and a silicosis group developed using a HOPE MED 8050 dynamic automatic dusting system. Murine macrophage MH-S cells were randomly divided into a control group and an SiO2 group. The pathological changes in lung tissue were observed using hematoxylin and eosin (HE) and Van Gieson (VG) staining. The distribution and location of macrophage marker (F4/80), M1 macrophage marker (iNOS), M2 macrophage marker (CD206), and myofibroblast marker (α-smooth muscle actin [α-SMA]) were detected using immunohistochemical and immunofluorescent staining. The expression changes in iNOS, Arg, α-SMA, vimentin, and type I collagen (Col I) were measured using Western blot. RESULTS: The results of HE and VG staining showed obvious silicon nodule formation and the distribution of thick collagen fibers in the lung tissue of the silicosis group. Macrophage marker F4/80 increased gradually from 8 to 32 weeks after exposure to silica. Immunohistochemical and immunofluorescent staining results revealed that there were more iNOS-positive cells and some CD206-positive cells in the lung tissue of the silicosis group at 8 weeks. More CD206-positive cells were found in the silicon nodules of the lung tissues in the silicosis group at 32 weeks. Western blot analysis showed that the expressions of Inducible nitric oxide synthase and Arg protein in the lung tissues of the silicosis group were upregulated compared with those of the control group. The results of immunofluorescence staining showed the co-expression of F4/80, α-SMA, and Col I, and CD206 and α-SMA were co-expressed in the lung tissue of the silicosis group. The extracted rat alveolar lavage fluid revealed F4/80+α-SMA+, CD206+α-SMA+, and F4/80+α-SMA+Col I+ cells using immunofluorescence staining. Similar results were also found in MH-S cells induced by SiO2. CONCLUSIONS: The development of silicosis is accompanied by macrophage polarization and MMT.

[Effect of N-acetyl-seryl-aspartyl-lysyl-proline on differentiation from pulmonary fibroblast to myofibroblast mediated by Rho-associated coiled-coil forming protein kinase pathway].

OBJECTIVE: To investigate whether N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) can inhibit the differentiation of pulmonary fibroblasts into myofibroblasts by regulating Rho-associated coiled-coil forming protein kinase (ROCK) pathway mediated by transforming growth factor-ß1 (TGF-ß1). METHODS: Primary culture of pulmonary fibroblasts was performed by trypsinization method. Four generations of pulmonary fibroblasts were divided into control group, TGF-ß-induced differentiation group, Y-27632 treatment group, and Ac-SDKP treatment group. The intracellular distributions of ROCK, serum response factor (SRF), and α-smooth muscle actin (α-SMA) were observed by confocal laser scanning microscopy. The protein expression of ROCK, SFR, α-SMA, and type I and type III collagen in pulmonary fibroblasts was measured by Western blot. The mRNA expression of ROCK, SFR, and α-SMA was measured by real-time quantitative PCR. RESULTS: Compared with the control group, the pulmonary fibroblasts stimulated by TGF-ß1 had a lot of α-SMA antibody-labeled myofilaments in parallel or cross arrangement, as observed by confocal laser scanning microscopy, and the mRNA and protein expression of ROCK, SRF, and α-SMA and protein expression of type I and type III collagen increased significantly after 6, 12, and 24 h of stimulation (P < 0.05). Compared with the TGF-ß1-induced differentiation group, the Y-27632 treatment group and Ac-SDKP treatment group had significantly decreased mRNA and protein expression of ROCK, SRF, and α-SMA and protein expression of type I and type III collagen at the same time point (P < 0.05). CONCLUSION: Ac-SDKP can inhibit the differentiation of pulmonary fibroblasts into myofibroblasts and the synthesis of collagen in rats by regulating the ROCK pathway mediated by TGF-ß1. That may be one of the mechanisms by which Ac-SDKP acts against (silicotic) pulmonary fibrosis.

[Regulating effect of N-acetyl-seryl-aspartyl-lysyl-proline on activation of c-jun N-terminal kinase pathway in rats with silicosis].

OBJECTIVE: To investigate the regulatory effect of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) on the activation of c-jun N-terminal kinase (JNK) signal transduction pathway and its role in silicotic fibrosis. METHODS: A rat model of silicosis was developed by intratracheal instillation. Sixty rats were randomly divided into 4-week control group (n = 10), 8-week control group (n = 10), 4-week silicosis model group (n = 10), 8-week silicosis model group (n = 10), AcSDKP treatment group (n = 10), and AcSDKP prevention group (n = 10). The content of hydroxyproline in lung tissue was measured using a p-dimethylaminoben-zaldehyde reagent; the expression levels of transforming growth factor (TGF)-beta 1 (TGF-ß1), phospho-JNK, JNK, and c-jun in lung tissue were measured by Western blot. The lung fibroblasts from neonatal rats were cultured, and the 4th generation of cells were used in the experiment; these cells were divided into control group, TGF-ß1 stimulation group, SP600125 intervention group, and AcSDKP intervention group. The distributions of phospho-JNK and c-jun in lung fibroblasts were observed by immunocytochemistry; the expression levels of type I collagen and type III collagen in lung fibroblasts were measured by Western blot. RESULTS: The expression levels of TGF-ß1, phospho-JNK, and c-jun and the content of hydroxyproline in the AcSDKP treatment group were 70.60%, 78.03%, 79.85%, and 71.28%, respectively, of those in the 4-week silicosis model group (P < 0.05) and 77.99%, 66.73%, 69.94%, and 64.82%, respectively, of those in the 8-week silicosis model group (P < 0.05); the expression levels of TGF-ß1, phospho-JNK, and c-jun and the content of hydroxyproline in the AcSDKP prevention group were 84.56%, 61.18%, 64.73%, and 74.96%, respectively, of those in the 8-week silicosis model group (P < 0.05). The expression levels of phospho-JNK and c-jun in the AcSDKP intervention group were 54.59% and 55.56%, respectively, of those in the TGF-ß1 stimulation group; the expression levels of type I collagen and type III collagen in the AcSDKP intervention group were 79.9% and 84.4%, respectively, of those in the TGF-ß1 stimulation group (P < 0.05). CONCLUSION: AcSDKP exerts anti-silicotic fibrosis effect probably by inhibiting the activation of JNK signal transduction pathway mediated by TGF-ß1 and the deposition of interstitial collagen.