Salzmann's Nodular Degeneration in Refractive Surgery: The Earlier Hit Hypothesis of EBM Injury-Related Fibrosis of the Subepithelial Space and Deeper Corneal Extension.

PURPOSE: To review the atypical development of Salzmann's nodular degeneration (SND) after two cases of laser in situ keratomileusis (LASIK) and one case of photorefractive keratomileusis (PRK), and to highlight the pathophysiology of SND and its treatment. METHODS: Three cases of SND (two following LASIK performed with microkeratomes and one following PRK) were reviewed and Pubmed.gov and internet searches were performed. RESULTS: SND is myofibroblast-generated fibrosis in the subepithelial space between the epithelium and Bowman's layer that develops years or decades after traumatic, surgical, infectious, or inflammatory injuries to the cornea in which the epithelial basement membrane is damaged in one or more locations and does not fully regenerate. It is hypothesized based on these cases, and the previous immunohistochemistry of other investigators, that myofibroblast precursors, such as fibrocytes or corneal fibroblasts, that enter the subepithelial space are driven to develop into myofibroblasts, which slowly proliferate and extend the fibrosis, by transforming growth factor-beta from epithelium and tears that passes through the defective epithelial basement membrane. These myofibroblasts and the disordered collagens, and other extracellular matrix components they produce, make up the subepithelial opacity characteristic of SND. Nodules are larger accumulations of myofibroblasts and disordered extracellular matrix. If the injury is associated with damage to the underlying Bowman's layer and stroma, as in LASIK flap generation, then the myofibroblasts and fibrosis can extend into Bowman's layer and the underlying anterior stroma. CONCLUSIONS: SND fibrosis often extends into Bowman's layer and the anterior stroma if there are associated Bowman's defects, such as incisions or lacerations. In the latter cases, SND frequently cannot be removed by simple scrape and peel, as typically performed for most common SND cases, but can be trimmed to remove the offending tissue. This condition is more accurately termed Salzmann's subepithelial fibrosis. [J Refract Surg. 2024;40(5):e279-e290.].

Assessment of the association of myofibroblasts and structural components of the extracellular matrix with histopathological parameters of actinic cheilitis and lower lip squamous cell carcinoma.

BACKGROUND: To evaluate the presence of myofibroblasts (MFs) in the development of lip carcinogenesis, through the correlation of clinical, histomorphometric and immunohistochemical parameters, in actinic cheilitis (ACs) and lower lip squamous cell carcinomas (LLSCCs). METHODS: Samples of ACs, LLSCCs, and control group (CG) were prepared by tissue microarray (TMA) for immunohistochemical TGF-ß, α-SMA, and Ki-67 and histochemical hematoxylin and eosin, picrosirius red, and verhoeff van gieson reactions. Clinical and microscopic data were associated using the Mann-Whitney, Kruskal-Wallis/Dunn, and Spearman correlation tests (SPSS, p < 0.05). RESULTS: ACs showed higher number of α-SMA+ MFs when compared to CG (p = 0.034), and these cells were associated with the vertical expansion of solar elastosis (SE) itself (p = 0.027). Areas of SE had lower deposits of collagen (p < 0.001), immunostaining for TGF-ß (p < 0.001), and higher density of elastic fibers (p < 0.05) when compared to areas without SE. A positive correlation was observed between high-risk epithelial dysplasia (ED) and the proximity of SE to the dysplastic epithelium (p = 0.027). LLSCCs showed a higher number of α-SMA+ MFs about CG (p = 0.034), as well as a reduction in the deposition of total collagen (p = 0.009) in relation to ACs and CG. There was also a negative correlation between the amount of α-SMA+ cells and the accumulation of total collagen (p = 0.041). Collagen and elastic density loss was higher in larger tumors (p = 0.045) with nodal invasion (p = 0.047). CONCLUSIONS: Our findings show the possible role of MFs, collagen fibers, and elastosis areas in the lip carcinogenesis process.

Noncanonical WNT5A controls the activation of latent TGF-ß to drive fibroblast activation and tissue fibrosis.

Transforming growth factor ß (TGF-ß) signaling is a core pathway of fibrosis, but the molecular regulation of the activation of latent TGF-ß remains incompletely understood. Here, we demonstrate a crucial role of WNT5A/JNK/ROCK signaling that rapidly coordinates the activation of latent TGF-ß in fibrotic diseases. WNT5A was identified as a predominant noncanonical WNT ligand in fibrotic diseases such as systemic sclerosis, sclerodermatous chronic graft-versus-host disease, and idiopathic pulmonary fibrosis, stimulating fibroblast-to-myofibroblast transition and tissue fibrosis by activation of latent TGF-ß. The activation of latent TGF-ß requires rapid JNK- and ROCK-dependent cytoskeletal rearrangements and integrin αV (ITGAV). Conditional ablation of WNT5A or its downstream targets prevented activation of latent TGF-ß, rebalanced TGF-ß signaling, and ameliorated experimental fibrosis. We thus uncovered what we believe to be a novel mechanism for the aberrant activation of latent TGF-ß in fibrotic diseases and provided evidence for targeting WNT5A/JNK/ROCK signaling in fibrotic diseases as a new therapeutic approach.

Taurine attenuates activation of hepatic stellate cells by inhibiting autophagy and inducing ferroptosis.

BACKGROUND: Liver fibrosis is a compensatory response during the tissue repair process in chronic liver injury, and finally leads to liver cirrhosis or even hepatocellular carcinoma. The pathogenesis of hepatic fibrosis is associated with the progressive accumulation of activated hepatic stellate cells (HSCs), which can transdifferentiate into myofibroblasts to produce an excess of the extracellular matrix (ECM). Myofibroblasts are the main source of the excessive ECM responsible for hepatic fibrosis. Therefore, activated hepatic stellate cells (aHSCs), the principal ECM producing cells in the injured liver, are a promising therapeutic target for the treatment of hepatic fibrosis. AIM: To explore the effect of taurine on aHSC proliferation and the mechanisms involved. METHODS: Human HSCs (LX-2) were randomly divided into five groups: Normal control group, platelet-derived growth factor-BB (PDGF-BB) (20 ng/mL) treated group, and low, medium, and high dosage of taurine (10 mmol/L, 50 mmol/L, and 100 mmol/L, respectively) with PDGF-BB (20 ng/mL) treated group. Cell Counting Kit-8 method was performed to evaluate the effect of taurine on the viability of aHSCs. Enzyme-linked immunosorbent assay was used to estimate the effect of taurine on the levels of reactive oxygen species (ROS), malondialdehyde, glutathione, and iron concentration. Transmission electron microscopy was applied to observe the effect of taurine on the autophagosomes and ferroptosis features in aHSCs. Quantitative real-time polymerase chain reaction and Western blot analysis were performed to detect the effect of taurine on the expression of α-SMA, Collagen I, Fibronectin 1, LC3B, ATG5, Beclin 1, PTGS2, SLC7A11, and p62. RESULTS: Taurine promoted the death of aHSCs and reduced the deposition of the ECM. Treatment with taurine could alleviate autophagy in HSCs to inhibit their activation, by decreasing autophagosome formation, downregulating LC3B and Beclin 1 protein expression, and upregulating p62 protein expression. Meanwhile, treatment with taurine triggered ferroptosis and ferritinophagy to eliminate aHSCs characterized by iron overload, lipid ROS accumulation, glutathione depletion, and lipid peroxidation. Furthermore, bioinformatics analysis demonstrated that taurine had a direct targeting effect on nuclear receptor coactivator 4, exhibiting the best average binding affinity of -20.99 kcal/mol. CONCLUSION: Taurine exerts therapeutic effects on liver fibrosis via mechanisms that involve inhibition of autophagy and trigger of ferroptosis and ferritinophagy in HSCs to eliminate aHSCs.

The c-Abl-RACK1-FAK signaling axis promotes renal fibrosis in mice through regulating fibroblast-myofibroblast transition.

BACKGROUND: Renal fibrosis is a prevalent manifestation of chronic kidney disease (CKD), and effective treatments for this disease are currently lacking. Myofibroblasts, which originate from interstitial fibroblasts, aggregate in the renal interstitium, leading to significant accumulation of extracellular matrix and impairment of renal function. The nonreceptor tyrosine kinase c-Abl (encoded by the Abl1 gene) has been implicated in the development of renal fibrosis. However, the precise role of c-Abl in this process and its involvement in fibroblast-myofibroblast transition (FMT) remain poorly understood. METHODS: To investigate the effect of c-Abl in FMT during renal fibrosis, we investigated the expression of c-Abl in fibrotic renal tissues of patients with CKD and mouse models. We studied the phenotypic changes in fibroblast or myofibroblast-specific c-Abl conditional knockout mice. We explored the potential targets of c-Abl in NRK-49F fibroblasts. RESULTS: In this study, fibrotic mouse and cell models demonstrated that c-Abl deficiency in fibroblasts mitigated fibrosis by suppressing fibroblast activation, fibroblast-myofibroblast transition, and extracellular matrix deposition. Mechanistically, c-Abl maintains the stability of the RACK1 protein, which serves as a scaffold for proteins such as c-Abl and focal adhesion kinase at focal adhesions, driving fibroblast activation and differentiation during renal fibrosis. Moreover, specifically targeting c-Abl deletion in renal myofibroblasts could prove beneficial in established kidney fibrosis by reducing RACK1 expression and diminishing the extent of fibrosis. CONCLUSIONS: Our findings suggest that c-Abl plays a pathogenic role in interstitial fibrosis through the regulation of RACK1 protein stabilization and myofibroblast differentiation, suggesting a promising strategy for the treatment of CKD.

Evaluation of stromal myofibroblasts in oral submucous fibrosis and its malignant transformation: An immunohistochemical study.

BACKGROUND: Oral submucous fibrosis (OSF) is a precancerous lesion, with oral squamous cell carcinoma (OSCC) being the most prevalent malignancy affecting the oral mucosa. The malignant transformation of OSF into OSCC is estimated to occur in 7-13% of cases. Myofibroblasts (MFs) play pivotal roles in both physiological and pathological processes, such as wound healing and tumorigenesis, respectively. This study aimed to explore the involvement of MFs in the progression of OSF and its malignant transformation. MATERIALS AND METHODS: In total, 94 formalin-fixed paraffin-embedded tissue blocks were collected, including normal oral mucosa (NOM; n = 10), early-moderate OSF (EMOSF; n = 29), advanced OSF (AOSF; n = 29), paracancerous OSF (POSF; n = 21), and OSCC (n = 5) samples. Alpha-smooth muscle actin was used for the immunohistochemical identification of MFs. RESULTS: NOM exhibited infrequent expression of MFs. A higher staining index of MFs was found in AOSF, followed by EMOSF and NOM. Additionally, a significant increase in the staining index of MFs was found from EMOSF to POSF and OSCC. The staining index of MFs in NOM, EMOSF, AOSF, POSF, and OSCC was 0.14 ± 0.2, 1.69 ± 1.4, 2.47 ± 1.2, 3.57 ± 2.6, and 8.86 ± 1.4, respectively. All results were statistically significant (P < 0.05). CONCLUSIONS: The expression of MFs exhibited a gradual increase as the disease progressed from mild to malignant transformation, indicating the contributory role of MFs in the fibrogenesis and potential tumorigenesis associated with OSF.

PBX/Knotted 1 homeobox-2 (PKNOX2) is a novel regulator of myocardial fibrosis.

Much effort has been made to uncover the cellular heterogeneities of human hearts by single-nucleus RNA sequencing. However, the cardiac transcriptional regulation networks have not been systematically described because of the limitations in detecting transcription factors. In this study, we optimized a pipeline for isolating nuclei and conducting single-nucleus RNA sequencing targeted to detect a higher number of cell signal genes and an optimal number of transcription factors. With this unbiased protocol, we characterized the cellular composition of healthy human hearts and investigated the transcriptional regulation networks involved in determining the cellular identities and functions of the main cardiac cell subtypes. Particularly in fibroblasts, a novel regulator, PKNOX2, was identified as being associated with physiological fibroblast activation in healthy hearts. To validate the roles of these transcription factors in maintaining homeostasis, we used single-nucleus RNA-sequencing analysis of transplanted failing hearts focusing on fibroblast remodelling. The trajectory analysis suggested that PKNOX2 was abnormally decreased from fibroblast activation to pathological myofibroblast formation. Both gain- and loss-of-function in vitro experiments demonstrated the inhibitory role of PKNOX2 in pathological fibrosis remodelling. Moreover, fibroblast-specific overexpression and knockout of PKNOX2 in a heart failure mouse model induced by transverse aortic constriction surgery significantly improved and aggravated myocardial fibrosis, respectively. In summary, this study established a high-quality pipeline for single-nucleus RNA-sequencing analysis of heart muscle. With this optimized protocol, we described the transcriptional regulation networks of the main cardiac cell subtypes and identified PKNOX2 as a novel regulator in suppressing fibrosis and a potential therapeutic target for future translational studies.

Naringenin nanoparticles targeting cyclin B1 suppress the progression of rheumatoid arthritis-associated lung cancer by inhibiting fibroblast-to-myofibroblast transition.

There is growing evidence of an elevated risk of lung cancer in patients with rheumatoid arthritis. The poor prognosis of rheumatoid arthritis-associated lung cancer and the lack of therapeutic options pose an even greater challenge to the clinical management of patients. This study aimed to identify potential molecular targets associated with the progression of rheumatoid arthritis-associated lung cancer and examine the efficacy of naringenin nanoparticles targeting cyclin B1. Mendelian randomizatio analysis revealed that rheumatoid arthritis has a positive correlation with the risk of lung cancer. Cyclin B1 was significantly upregulated in patients with rheumatoid arthritis-associated lung cancer and was significantly overexpressed in synovial tissue fibroblasts. Furthermore, the overexpression of cyclin B1 in rheumatoid arthritis fibroblast-like synoviocytes, which promotes their proliferation and fibroblast-to-myofibroblast transition, can significantly contribute to the growth and infiltration of lung cancer cells. Importantly, our prepared naringenin nanoparticles targeting cyclin B1 effectively attenuated proliferation and fibroblast-to-myofibroblast transition by blocking cells at the G2/M phase. In vivo experiments, naringenin nanoparticles targeting cyclin B1 significantly alleviated the development of collagen-induced arthritis and lung orthotopic tumors. Collectively, our results reveal that naringenin nanoparticles targeting cyclin B1 can suppress the progression of rheumatoid arthritis-associated lung cancer by inhibiting fibroblast-to-myofibroblast transition. These findings provide new insights into the treatment of rheumatoid arthritis-associated lung cancer therapy.

Myofibroblast and pro-fibrotic cytokines in fibrosis of IgG4-related disease (IgG4-RD) patients from South Asia: preliminary data.

INTRODUCTION: Fibrosis is a typical pathological characteristic in IgG4-RD patients and often irreversible. There exists a lack of suitable markers for detection of earlier onset of fibrosis in various organs in IgG4-RD patients. Hence, this study aims at analysing ambispectively the myofibroblasts and the pro-fibrotic cytokines, IFN gamma and IL-33 involved in IgG4-RD associated fibrosis in South Asian patients. METHOD: Archived biopsy samples of definite/probable/possible cases of IgG4-RD, classified according to diagnostic criteria, taken from patients who attended the OPD and IPD of our tertiary care centre during January 2015-January 2020 were chosen for this study. The paraffin sections were examined qualitatively for fibrosis and the excessive collagen deposition by Hematoxylin & Eosin and Masson's Trichrome staining. Also, the presence of alpha-Smooth muscle actin (α-SMA) expressing myofibroblasts and the involvement of pro-fibrotic cytokines (IFN-gamma, IL-33) were assessed by Immunohistochemistry and scored semi-quantitatively (+mild, ++moderate, +++ severe). Serum IL-33 levels were analysed by indirect Elisa (R & D Systems). RESULTS: Myofibroblasts were present in 10/12 biopsy samples, in moderate levels in 4 (33%) and very high levels (+++) in 3 (25%) of the patients. IFN-gamma was expressed at low levels in 6 (50%) and absent in 6 (50%). All patients showed IL-33 expression with very high levels in tissue (6, 50%), as well as in serum samples. CONCLUSION: The findings of this study reinforce the role of myofibroblasts and profibrotic cytokines like IL-33 in fibrosis of Ig4-RD patients, pointing to their potential as earlier predictive markers of onset and extent of fibrosis.

Ocular inflammatory myofibroblastic tumor in a pediatric patient.

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm that rarely metastasizes and is more commonly seen in children, adolescents, and young adults than older adults. These tumors, composed of myofibroblasts and inflammatory cells, are often confused for a local infection due to the inflammatory cell infiltration, and they form in mucosal surfaces but rarely arise in the orbit. We present the case of a 6-year-old girl with excisional biopsy-confirmed conjunctival stromal IMT. There was no evidence of recurrence 2 years following resection with no subsequent medical therapy.

A novel mechanoeffector role of fibroblast S100A4 in myofibroblast transdifferentiation and fibrosis.

Fibroblast to myofibroblast transdifferentiation mediates numerous fibrotic disorders, such as idiopathic pulmonary fibrosis (IPF). We have previously demonstrated that non-muscle myosin II (NMII) is activated in response to fibrotic lung extracellular matrix, thereby mediating myofibroblast transdifferentiation. NMII-A is known to interact with the calcium-binding protein S100A4, but the mechanism by which S100A4 regulates fibrotic disorders is unclear. In this study, we show that fibroblast S100A4 is a calcium-dependent, mechanoeffector protein that is uniquely sensitive to pathophysiologic-range lung stiffness (8-25 kPa) and thereby mediates myofibroblast transdifferentiation. Re-expression of endogenous fibroblast S100A4 rescues the myofibroblastic phenotype in S100A4 KO fibroblasts. Analysis of NMII-A/actin dynamics reveals that S100A4 mediates the unraveling and redistribution of peripheral actomyosin to a central location, resulting in a contractile myofibroblast. Furthermore, S100A4 loss protects against murine in vivo pulmonary fibrosis, and S100A4 expression is dysregulated in IPF. Our data reveal a novel mechanosensor/effector role for endogenous fibroblast S100A4 in inducing cytoskeletal redistribution in fibrotic disorders such as IPF.

Mechanisms of kidney fibrosis and routes towards therapy.

Kidney fibrosis is the final common pathway of virtually all chronic kidney diseases (CKDs) and is therefore considered to be a promising therapeutic target for these conditions. However, despite great progress in recent years, no targeted antifibrotic therapies for the kidney have been approved, likely because the complex mechanisms that initiate and drive fibrosis are not yet completely understood. Recent single-cell genomic approaches have allowed novel insights into kidney fibrosis mechanisms in mouse and human, particularly the heterogeneity and differentiation processes of myofibroblasts, the role of injured epithelial cells and immune cells, and their crosstalk mechanisms. In this review we summarize the key mechanisms that drive kidney fibrosis, including recent advances in understanding the mechanisms, as well as potential routes for developing novel targeted antifibrotic therapeutics.

Mechanical stiffness promotes skin fibrosis through FAPα-AKT signaling pathway.

BACKGROUND: Myofibroblasts contribute to the excessive production, remodeling and cross-linking of the extracellular matrix that characterizes the progression of skin fibrosis. An important insight into the pathogenesis of tissue fibrosis has been the discovery that increased matrix stiffness during fibrosis progression is involved in myofibroblast activation. However, mechanistic basis for this phenomenon remains elusive. OBJECTIVE: To explore the role of fibroblast activation protein-α (FAPα) in mechanical stiffness-induced skin fibrosis progression. METHODS: RNA-seq was performed to compare differential genes of mouse dermal fibroblasts (MDFs) grown on low or high stiffness plates. This process identified FAPα, which is a membrane protein usually overexpressed in activated fibroblasts, as a suitable candidate. In vitro assay, we investigate the role of FAPα in mechanical stiffness-induced MDFs activation and downstream pathway. By establishing mouse skin fibrosis model and intradermally administrating FAPα adeno-associated virus (AAV) or a selective Fap inhibitor FAPi, we explore the role of FAPα in skin fibrosis in vivo. RESULTS: We show that FAPα, a membrane protein highly expressed in myofibroblasts of skin fibrotic tissues, is regulated by increased matrix stiffness. Genetic deletion or pharmacological inhibition of FAPα significantly inhibits mechanical stiffness-induced activation of myofibroblasts in vitro. Mechanistically, FAPα promotes myofibroblast activation by stimulating the PI3K-Akt pathway. Furthermore, we showed that administration of the inhibitor FAPi or FAPα targeted knockdown ameliorated the progression of skin fibrosis. CONCLUSION: Taken together, we identify FAPα as an important driver of mechanical stiffness-induced skin fibrosis and a potential therapeutic target for the treatment of skin fibrosis.

EGFR-activated myofibroblasts promote metastasis of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. Cancer-associated fibroblasts (CAFs) are recognized potential therapeutic targets, but poor understanding of these heterogeneous cell populations has limited the development of effective treatment strategies. We previously identified transforming growth factor beta (TGF-ß) as a main driver of myofibroblastic CAFs (myCAFs). Here, we show that epidermal growth factor receptor/Erb-B2 receptor (EGFR/ERBB2) signaling is induced by TGF-ß in myCAFs through an autocrine process mediated by amphiregulin. Inhibition of this EGFR/ERBB2-signaling network in PDAC organoid-derived cultures and mouse models differentially impacts distinct CAF subtypes, providing insights into mechanisms underpinning their heterogeneity. Remarkably, EGFR-activated myCAFs promote PDAC metastasis in mice, unmasking functional significance in myCAF heterogeneity. Finally, analyses of other cancer datasets suggest that these processes might operate in other malignancies. These data provide functional relevance to myCAF heterogeneity and identify a candidate target for preventing tumor invasion in PDAC.

Role of macrophage-to-myofibroblast transition in chronic liver injury and liver fibrosis.

BACKGROUND: Chronic liver injury contributes to liver fibrosis, which is characterized by the excessive deposition of extracellular matrix (ECM) components. ECM is mainly composed of myofibroblasts. Recently, macrophage-to-myofibroblasts transition (MMT), has been identified as a novel origin for myofibroblasts. However, the potential functions of MMT in chronic liver injury and liver fibrosis remain unknown. METHODS: To clarify the transformation of fibrotic cells in hepatic fibrosis, liver specimens were collected from people at different stages in the progression of hepatic fibrosis and stained with immunofluorescence. Models of hepatic fibrosis such as the CCL4 model, HFD-induced NAFLD model, MCD-induced NAFLD model and ethanol-induced AFLD model were demonstrated and were stained with immunofluorescence. RESULTS: Here, we uncovered macrophages underwent MMT in clinical liver fibrosis tissue samples and multiple animal models of chronic liver injury. MMT cells were found in specimens from patients with liver fibrosis on the basis of co-expression of macrophage (CD68) and myofibroblast (a-SMA) markers. Moreover, macrophages could transform into myofibroblasts in CCL4-induced liver fibrosis model, high-fat diet (HFD) and methionine-choline-deficient diet (MCD)-induced nonalcoholic fatty liver diseases (NAFLD) model, and ethanol-induced alcoholic fatty liver diseases (AFLD) model. In addition, we highlighted that MMT cells mainly had a predominant M2 phenotype in both human and experimental chronic liver injury. CONCLUSIONS: Taken together, MMT acts a crucial role in chronic liver injury and liver fibrosis.

STAT6 promoting oxalate crystal deposition-induced renal fibrosis by mediating macrophage-to-myofibroblast transition via inhibiting fatty acid oxidation.

OBJECTIVE AND DESIGN: Kidney stones commonly occur with a 50% recurrence rate within 5 years, and can elevate the risk of chronic kidney disease. Macrophage-to-myofibroblast transition (MMT) is a newly discovered mechanism that leads to progressive fibrosis in different forms of kidney disease. In this study, we aimed to investigate the role of MMT in renal fibrosis in glyoxylate-induced kidney stone mice and the mechanism by which signal transducer and activator of transcription 6 (STAT6) regulates MMT. METHODS: We collected non-functioning kidneys from patients with stones, established glyoxylate-induced calcium oxalate stone mice model and treated AS1517499 every other day in the treatment group, and constructed a STAT6-knockout RAW264.7 cell line. We first screened the enrichment pathway of the model by transcriptome sequencing; detected renal injury and fibrosis by hematoxylin eosin staining, Von Kossa staining and Sirius red staining; detected MMT levels by multiplexed immunofluorescence and flow cytometry; and verified the binding site of STAT6 at the PPARα promoter by chromatin immunoprecipitation. Fatty acid oxidation (FAO) and fibrosis-related genes were detected by western blot and real-time quantitative polymerase chain reaction. RESULTS: In this study, we found that FAO was downregulated, macrophages converted to myofibroblasts, and STAT6 expression was elevated in stone patients and glyoxylate-induced kidney stone mice. The promotion of FAO in macrophages attenuated MMT and upregulated fibrosis-related genes induced by calcium oxalate treatment. Further, inhibition of peroxisome proliferator-activated receptor-α (PPARα) eliminated the effect of STAT6 deletion on FAO and fibrosis-associated protein expression. Pharmacological inhibition of STAT6 also prevented the development of renal injury, lipid accumulation, MMT, and renal fibrosis. Mechanistically, STAT6 transcriptionally represses PPARα and FAO through cis-inducible elements located in the promoter region of the gene, thereby promoting MMT and renal fibrosis. CONCLUSIONS: These findings establish a role for STAT6 in kidney stone injury-induced renal fibrosis, and suggest that STAT6 may be a therapeutic target for progressive renal fibrosis in patients with nephrolithiasis.

Infantile inflammatory myofibroblastic tumour of the sigmoid colon: a diagnostic dilemma.

An inflammatory myofibroblastic tumour (IMT) is an uncommon neoplasm composed of inflammatory cells and myofibroblasts in a fibrous stroma. They are mostly seen in the lungs and rarely involve the gastrointestinal tract. An 8-month-old infant presented with a history of lower abdominal lump for 2 months. Her CT scan confirmed a large, lobulated mass in the retroperitoneum arising from the pelvis. The mass was found to be arising from the sigmoid colon on laparotomy which was excised. Histopathology showed a cellular tumour composed of spindle cells and inflammatory lymphocytic infiltrate. Immunohistochemistry revealed positive staining for anaplastic lymphoma kinase and smooth muscle actin, confirming the diagnosis of IMT. The patient is doing well at her 6-month follow-up. Ours is the youngest case of sigmoid IMT among the only other series of eight cases reported in the literature indicating its rarity.

Low-Grade Myofibroblastic Sarcoma of the Oral and Maxillofacial Region: An International Clinicopathologic Study of 13 Cases and Literature Review.

Low-grade myofibroblastic sarcoma (LGMS) represents an atypical tumor composed of myofibroblasts with a variety of histological patterns and with a high tendency to local recurrence and a low probability of distant metastases. LGMS has predilection for the head and neck regions, especially the oral cavity. This study aimed to report 13 new cases of LGMS arising in the oral and maxillofacial region. This study included LGMS cases from five oral and maxillofacial pathology laboratories in four different countries (Brazil, Peru, Guatemala, and South Africa). Their clinical, radiographic, histopathological, and immunohistochemical findings were evaluated. In this current international case series, most patients were females with a mean age of 38.7 years, and commonly presenting a nodular lesion in maxilla. Microscopically, all cases showed a neoplasm formed by oval to spindle cells in a fibrous stroma with myxoid and dense areas, some atypical mitoses, and prominent nucleoli. The immunohistochemical panel showed positivity for smooth muscle actin (12 of 13 cases), HHF35 (2 of 4 cases), ß-catenin (3 of 5 cases), desmin (3 of 11 cases), and Ki-67 (range from 5 to 50%). H-caldesmon was negative for all cases. The diagnosis of LGMS was confirmed in all cases. LGMS shows predominance in young adults, with a slight predilection for the female sex, and maxillary region. LGMS should be a differential diagnosis of myofibroblastic lesions that show a proliferation of spindle cells in a fibrous stroma with myxoid and dense areas and some atypical mitoses, supporting the diagnosis with a complementary immunohistochemical study. Complete surgical excision with clear margins is the treatment of choice. However, long-term follow-up information is required before definitive conclusions can be drawn regarding the incidence of recurrence and the possibility of metastasis.

Role of myofibroblasts in oral plasma cell granuloma: Immunohistochemical evaluation of α-SMA and ALK in a retrospective study of 30 cases.

INTRODUCTION: Oral plasma cell granuloma (OPCG) is a rare reactive lesion with generally benign yet occasionally aggressive behavior. Myofibroblasts are important in many physiologic, and pathologic conditions. The role of myofibroblasts in the clinical behavior of OPCG was assessed as well as its usefulness in differentiating this lesion from the inflammatory myofibroblastic tumor mimicking plasma cell granuloma. MATERIAL AND METHODS: This retrospective study included 30 paraffin blocks of OPCG. Immunohistochemical evaluation of alpha-smooth muscle actin (α-SMA) and Anaplastic lymphoma kinase (ALK) antibodies was performed. The mean area of positive expression was calculated and scored semiquantitatively with clinicopathologic correlations. RESULTS: Most of the cases were clinically non-aggressive. Alveolar bone resorption was observed in nine cases, two of them showed severe resorption and stromal fibrosis. Negative α-SMA was observed in 70% of cases showing a predominance of plasma cells in the stroma. All cases of stromal fibrosis revealed positive α-SMA of a weak percentage. A statistically significant difference was observed between α-SMA expression and the clinicopathologic variables. Negative ALK expression was noted in all cases. DISCUSSION: Myofibroblasts were infrequently found in OPCG. Remarkably, the aggressive behavior in cases with intense fibrosis was related to the existence of myofibroblasts even of non-neoplastic nature and minimal amount. The number of myofibroblasts and their nature assessed via α-SMA and ALK immunohistochemical expression respectively might be valuable in predicting the biological behavior of OPCG and may hold diagnostic significance in challenging OPCG cases that might mimic inflammatory myofibroblastic tumor.

Imunoexpressão de clic4, α-sma, e-caderina e vimentina em lesões odontogênicas epitelias benígnas / Immunoexpression of clic4, α-sma, e-cadherin and vimentin in benign epithelial odontogenic lesions

As lesões odontogênicas epiteliais benignas constituem um grupo heterogêneo de lesões. A proteína CLIC4 atua na regulação dos processos de parada de crescimento e apoptose, participando também do processo de transdiferenciação dos fibroblastos em miofibroblastos que passam a expressar α-SMA. Além disso, a expressão de CLIC4 pode interferir no processo de transição epitélio-mesenquima (TEM) em neoplasias. Este trabalho avaliou a imunoexpressão de CLIC4, α-SMA, E-caderina e Vimentina em ameloblastomas (AM) (n = 16), ceratocistos odontogênicos (n = 20) e tumores odontogênicos adenomatóides (TOA) (n = 8). A análise da expressão imunoistoquímica das proteínas CLIC4, E-caderina e vimentina no componente epitelial das lesões e de CLIC4 e α-SMA no tecido conjuntivo foi realizada de forma semi-quantitativa por um avaliador previamente calibrado. A expressão no componente epitelial de CLIC4 foi analisada separadamente no núcleo e no citoplasma, bem como a marcação de E-caderina que foi avaliada na membrana e no citoplasma. As comparações dos percentuais de imunorreatividade em relação aos grupos estudados foram realizadas por meio dos testes não paramétricos de Kruskal-Wallis e Mann-Whitney. Possíveis correlações entre a expressão de CLIC4, α-SMA, E-caderina e Vimentina foram avaliadas por meio do teste de correlação de Spearman. O nível de significância foi estabelecido em 5% (p < 0,05). Foram observados diferentes padrões de marcação entre os grupos analisados, observando-se que a imunoexpressão exclusivamente citoplasmática da CLIC4 no componente epitelial dos AM (p < 0,001) e TOA (p < 0,001) foi significativamente superior a dos CO, não demonstrarando significância estatística entre os AM e TOA. A imunoexpressão (nuclear e citoplasmática) da CLIC4 no revestimento epitelial CO foi significativamente superior à encontrada no componente epitelial dos AM (p < 0,001) e dos TOA (p < 0,001). A imunoexpressão estromal de CLIC4 foi significativamente superior nos AM (p = 0,009) e CO (p = 0,004) quando comparados aos TOA. A imunoexpressao de α-SMA significativamente maior em AM (p = 0,016) e CO (p = 0,034) quando comparados aos TOA. Para a imunoexpressão membranar da E-caderina em CO foi significativamente superior em comparação à encontrada nos AM (p = 0,009) e nos TOA (p = 0,024). Foi observada maior imunoexpressão de E-caderina (membranar e citoplasmática) nos COs, quando comparados aos AM (p < 0,001) e aos TOAs (p < 0,001). A expressão de Ecaderina citoplasmática foi significativamente maior nos AM e TOA (p < 0,001) quando comparados aos CO. Observou-se diferença estatisticamente significativa na imunoexpressão de vimentina entre os casos de AM e os casos de TOA (p = 0,038) e CO (p < 0,001), bem como entre o TOA e CO (p < 0,001). As correlações testadas entre os escores das proteínas estudadas evidenciou que no grupo dos AM foi possível evidenciar moderada correlação positiva e estatisticamente significativa (r = 0,527; p = 0,036) entre a expressão citoplasmática da CLIC4 e a expressão citoplasmática da E-caderina. Também foi verificada fraca correlação negativa e estatisticamente significativa (r = -0,499; p = 0,049) entre a expressão núcleo-citoplasmática da CLIC4 e a expressão citoplasmática da E-caderina nos AM. Além disso, uma moderada correlação positiva e estatisticamente significativa entre a expressão estromal da CLIC4 e a expressão da α-SMA nos AM (r = 0,648; p = 0,007) e nos CO (r = 0,541; p = 0,014). Foi observada forte correlação negativa e estatisticamente significativa (r = -0,813; p < 0,001) entre a expressão da E-caderina e a expressão da vimentina nos AM. Os resultados deste estudo sugerem um potencial envolvimento de CLIC4 no processo de transdiferenciação de miofibroblastos, e que a presença destas células é mais frequentemente associada a lesões de comportamento biológico mais agressivo como os AM e CO, além de uma possível atuação desta proteína na regulação do ciclo celular e na TEM nas lesões estudadas (AU).

Benign epithelial odontogenic lesions constitute a heterogeneous group of lesions. the CLIC4 protein acts in the regulation of growth arrest and apoptosis processes, also participating in the process of transdifferentiation of fibroblasts Into myofibroblasts that begin to express α-SMA. Furthermore, CLIC4 expression can interfere with the epithelialmesenchymal transition (EMT) process in neoplasms. This work evaluated the immunoexpression of CLIC4, α-SMA, e-cadherin and vimentin in ameloblastomas (AM) (n = 16), odontogenic keratocysts (OK) (n = 20) and adenomatoid odontogenic tumors (AOT) (n = 8). The analysis of the immunohistochemical expression of the proteins CLIC4, ecadherin and vimentin in the epithelial component of the lesions and of CLIC4 and α-SMA in the connective tissue was carried out in a semi-quantitative way by a previously calibrated evaluator. Expression in the epithelial component of CLIC4 was analyzed separately in the nucleus and cytoplasm, as well as e-cadherin labeling, which was evaluated in the membrane and cytoplasm. Comparisons of the percentages of immunoreactivity in relation to the studied groups were carried out using the nonparametric kruskal-wallis and mann-whitney tests. Possible correlations between the expression of CLIC4, α-SMA, e-cadherin and vimentin were evaluated using the spearman correlation test. The significance level was set at 5% (p < 0.05). Different staining patterns were observed between the groups analyzed, observing that the exclusively cytoplasmic immunoexpression of CLIC4 in the epithelial component of AM (p < 0.001) and AOT (p < 0.001) was significantly higher than that of OK, not demonstrating statistical significance between the AM and AOT. The immunoexpression (nuclear and cytoplasmic) of CLIC4 in the co epithelial lining was significantly higher than that found in the epithelial component of AM (p < 0.001) and AOT (p < 0.001). Stromal CLIC4 immunoexpression was significantly higher in AM (p = 0.009) and OK (p = 0.004) when compared to AOT. The immunoexpression of α-SMA is significantly higher in AM (p = 0.016) and OK (p = 0.034) when compared to AOT. For e-cadherin membrane immunoexpression in co was significantly higher compared to that found in AM (p = 0.009) and AOT (p = 0.024). Greater immunoexpression of e-cadherin (membrane and cytoplasmic) was observed in OK, when compared to AM (p < 0.001) and AOT (p < 0.001). Cytoplasmic ecadherin expression was significantly higher in AM and AOT (p < 0.001) when compared to OK. A statistically significant difference in vimentin immunoexpression was observed between cases of AM and cases of AOT (p = 0.038) and OK (p < 0.001), as well as between AOT and OK (p < 0.001). The correlations tested between the scores of the proteins studied showed that in the am group it was possible to demonstrate a moderate positive and statistically significant correlation (r = 0.527; p = 0.036) between the cytoplasmic expression of clic4 and the cytoplasmic expression of e-cadherin. A weak and statistically significant negative correlation (r = -0.499; p = 0.049) was also found between the nucleus-cytoplasmic expression of clic4 and the cytoplasmic expression of e- cadherin in AM. Furthermore, a moderate positive and statistically significant correlation between the stromal expression of CLIC4 and the expression of α-SMA in AM (r = 0.648; p = 0.007) and OK (r = 0.541; p = 0.014). Additionally, a strong negative and statistically significant correlation (r = -0.813; p < 0.001) was observed between the expression of ecadherin and the expression of vimentin in AM. The results of this study suggest a potential involvement of CLIC4 in the myofibroblast transdifferentiation process, and that the presence of these cells is more frequently associated with lesions with more aggressive biological behavior such as AM and OK, in addition to a possible role of this protein in the regulation of cell cycle and EMT in the lesions studied (AU).