Tamoxifen citrate: a glimmer of hope for silicosis

From Basic Research to Clinical Practice: Considerations for Treatment Drugs for Silicosis

Silicosis, characterized by irreversible pulmonary fibrosis, remains a major global public health problem. Nowadays, cumulative studies are focusing on elucidating the pathogenesis of silicosis in order to identify preventive or therapeutic antifibrotic agents. However, the existing research on the mechanism of silica-dust-induced pulmonary fibrosis is only the tip of the iceberg and lags far behind clinical needs. Idiopathic pulmonary fibrosis (IPF), as a pulmonary fibrosis disease, also has the same problem. In this study, we examined the relationship between silicosis and IPF from the perspective of their pathogenesis and fibrotic characteristics, further discussing current drug research and limitations of clinical application in silicosis. Overall, this review provided novel insights for clinical treatment of silicosis with the hope of bridging the gap between research and practice in silicosis.

Tamoxifen Prevents Peritendinous Adhesions: A Preliminary Report

Background

Scarless healing comprises the ultimate goal after an injury. Since tendon healing results in a fibrotic scar, an injured tendon can never regain the mechanical potential and strength of its uninjured form. A wide variety of studies focus on the tendon healing with an absent or minimal peritendinous adhesions. However, no simple method has managed it at all. Possible complex actions and peritendinous environmental events take place during the tendon healing process. Tamoxifen (TAM), besides its breast cancer-related usage, is a potent antifibrotic drug. Here, we aimed to reduce the peritendinous adhesion with TAM administration.

Methods

Achilles tendons of 44 Wistar albino rats were randomly distributed in 4 groups. In group 1, bilateral lower extremities were used as control and sham. Groups 2 and 3 were comprised of low-dose (1 mg/kg) and high-dose (40 mg/kg) systemic administration of TAM, respectively. Group 4 included local administration (1 mg/kg) of TAM. Biomechanical, macroscopical, and histopathological analyses were done and compared statistically. Biomechanically, the maximum force that led to tendon rupture was determined, and tensile force data were recorded via tensile testing device. Macroscopical and histopathological analysis were composed of the quantity, quality, and grade of peritendinous adhesions.

Results

Macroscopic and histopathologic findings revealed that groups 2 and 3 had a variety of values ranging between slight to severe adhesions. In group 2, almost half of the animals had moderate adhesions, whereas in group 3, the majority of the animals had moderate adhesions. There were no animals with moderate or severe adhesions in group 4. Statistically significant values were calculated between sham and control groups. Biomechanically, group 2 showed the most significant result. The tendons in group 2 had the highest stiffness when maximal force was applied to rupture the tendons. Henceforth, all these consequences were proven statistically.

Conclusion

We achieved less peritendinous adhesion with the local administration of TAM when compared to systemic administration of TAM. A better understanding of the peritendinous environmental process will reveal to develop new therapies in the prevention of peritendinous adhesions.

Cell tracing reveals the transdifferentiation fate of mouse lung epithelial cells during pulmonary fibrosis in vivo

Idiopathic pulmonary fibrosis (IPF) is a progressive and devastating interstitial lung disease. The origin of myofibroblasts is still to be elucidated and the existence of epithelial-mesenchymal transition (EMT) in IPF remains controversial. Hence, it is important to clarify the origin of fibroblasts by improving modeling and labeling methods and analyzing the differentiation pathway of alveolar epithelial cells (AEC) in pulmonary fibrosis with cell tracking technology. In the present study, adult transgenic mice with SPC-rtTA^+/-/tetO₇-CMV-Cre^+/-/mTmG^+/- were induced with doxycycline for 15 days. The gene knockout phenomenon occurred in type II AECs in the lung and the reporter gene cell membrane-localized enhanced green fluorescence protein (mEGFP) was expressed in the cell membrane. The expression of Cre recombinase and SPC was analyzed using immunohistochemical (IHC) staining to detect the labeling efficiency. A repetitive intraperitoneal bleomycin-induced pulmonary fibrosis model was established, and the mice were sacrificed on day 28. The co-localization of mEGFP and mesenchymal markers α-smooth muscle actin (α-SMA) and S100 calcium binding protein A4 (S100A4) were detected by multiple IHC staining. The results revealed that Cre was expressed in the airway and AECs in the lung tissue of adult transgenic mice with SPC-rtTA^+/-/tetO₇-CMV-Cre^+/-/mTmG^+/- induced by doxycycline; the labeling efficiency in the peripheral lung tissue was 63.27±7.51%. mEGFP was expressed on the membrane of type II AECs and their differentiated form of type I AECs. Expression of mEGFP was mainly observed in the fibrotic region in bleomycin-induced pulmonary fibrosis; 1.94±0.08% of α-SMA-positive cells were mEGFP-positive and 9.68±2.06% of S100A4-positive cells were mEGFP-positive in bleomycin-induced pulmonary fibrosis. In conclusion, the present results suggested that while EMT contributes to the pathogenesis of pulmonary fibrosis, it is not the major causative factor of this condition.

Evaluation of Dynamic Disulphide/Thiol Homeostasis in Silica Exposed Workers

BACKGROUND

Oxidative stress is implicated as one of the main molecular mechanism underlying silicosis.

AIMS

In this study, our aim was to asses the redox status in occupationally silica-exposed workers, by evaluating the dynamic thiol-disulphide homeostasis.

STUDY DESIGN

Case-control study.

METHODS

Thirty-six male workers occupationally exposed to silica particles and 30 healthy volunteers, working as office workers were included to the study. Posteroanterior chest radiographs and pulmonary function tests of both groups were evaluated. Also serum thiol disulphide levels were measured using the spectrophotometric method described by Erel and Neşelioğlu.

RESULTS

Among the 36 workers that underwent pulmonary function tests 6 (17%) had obstructive, 7 (19%) had restrictive, 6 (17%) had obstructive and restrictive signs whereas 17 (47%) had no signs. The mean PFTs results of silica-exposed workers were significantly lower than control subjects. The serum disulphide levels of silica-exposed workers were significantly higher than control subjects (23.84±5.89 μmol/L and 21.18±3.44 μmol/L, respectively p=0.02).

CONCLUSION

The serum disulphide levels, a biomarker of oxidative stress, are found to be higher in silica-exposed workers.

A Novel Technique for Conjunctivoplasty in a Rabbit Model: Platelet-Rich Fibrin Membrane Grafting

Purpose. To investigate the effect of platelet-rich fibrin (PRF) membrane on wound healing. Methods. Twenty-four right eyes of 24 New Zealand rabbits equally divided into 2 groups for the study design. After the creation of 5 × 5 mm conjunctival damage, it was secured with PRF membrane, which was generated from the rabbit's whole blood samples in PRF membrane group, whereas damage was left unsutured in the control group. Three animals were sacrificed in each group on the 1st, 3rd, 7th, and 28th postoperative days. Immunohistochemical (IHC) stainings and biomicroscopic evaluation were performed and compared between groups. Results. PRF membrane generated significant expressions of vascular endothelial growth factor (VEGF), transforming growth factor-beta (TGF-β), and platelet-derived growth factor (PDGF) in the early postoperative period. However, the IHC evaluation allowed showing the excessive staining at day 28, in control group. Biomicroscopic evaluation revealed complete epithelialization in PRF membrane group, but none of the cases showed complete healing in the control group. Conclusions. This experimental study showed us the beneficial effects of the PRF membrane on conjunctival healing. Besides its chemical effects, it provides mechanical support as a scaffold for the migrating cells that are important for ocular surface regeneration. These overall results encourage us to apply autologous PRF membrane as a growth factor-enriched endogenous scaffold for ocular surface reconstruction.

Baicalin Alleviates Silica-Induced Lung Inflammation and Fibrosis by Inhibiting the Th17 Response in C57BL/6 Mice

Silicosis is an inflammatory and fibrotic lung disease caused by inhalation of silica. Th17 cells play a key role in causing silica-induced lung inflammation and fibrosis. Baicalin, a compound isolated from the Chinese herb Huangqin, could suppress the differentiation of Th17 cells and alleviate inflammation. However, there are very few reports of the immunoregulatory mechanisms of baicalin in experimental silica-induced lung inflammation and fibrosis. In our study, mice were exposed to silica by intratracheal instillation, and in this way we established an experimental silicosis model. To elucidate the effects and mechanisms of baicalin in silica-induced inflammation and fibrosis, we used baicalin to treat the developed mouse model of silicosis. Treatment with baicalin attenuated the accumulation of inflammatory cells and led to milder pathological inflammatory and fibrotic changes in lung tissues. Baicalin affected the immunological balance between Th17 and Treg responses. Therefore, baicalin caused a decrease in Th17 cells by stimulating Treg cells and by inhibiting IL-6 and IL-23. We further demonstrated that silica-induced Th1 and Th2 immune responses were both inhibited by increased Treg activation, which was promoted by baicalin. Our findings confirmed the potential functions of baicalin in inhibiting the Th17 response and reducing silica-induced inflammation and fibrosis.