Silica - A trace geogenic element with emerging nephrotoxic potential

A critical review of a hidden epidemic: examining the occupational and environmental risk factors of chronic kidney disease of unknown etiology (CKDu)

A form of chronic kidney disease has been described in people without any known risk factors. These cases are referred to as chronic kidney disease of an unknown etiology (CKDu).

The role of mitochondrial dysfunction in macrophages on SiO2 -induced pulmonary fibrosis: A review

Several epidemiologic and toxicological studies have widely regarded that mitochondrial dysfunction is a popular molecular event in the process of silicosis from different perspectives, but the details have not been systematically summarized yet. Thus, it is necessary to investigate how silica dust leads to pulmonary fibrosis by damaging the mitochondria of macrophages. In this review, we first introduce the molecular mechanisms that silica dust induce mitochondrial morphological and functional abnormalities and then introduce the main molecular mechanisms that silica-damaged mitochondria induce pulmonary fibrosis. Finally, we conclude that the mitochondrial abnormalities of alveolar macrophages caused by silica dust are involved deeply in the pathogenesis of silicosis through these two sequential mechanisms. Therefore, reducing the silica-damaged mitochondria will prevent the potential occurrence and fatality of the disease in the future.

Occupational Silica Exposure as a Potential Risk for Microscopic Polyangiitis

Microscopic polyangiitis is an important and common component of cytoplasmic antibody-associated vasculitides that can lead to serious morbidity and even death. A clear causative etiology has not been identified. Although silica is well known to produce lung damage, the negative renal effects of silica exposure should not be overlooked. We present a case of renal dysfunction associated with silica exposure, its diagnosis by renal biopsy, and the treatment method used. Environmental or occupational silica exposure can cause microscopic polyangiitis. Working in occupations with increased risk of silica exposure may result in serious medical problems.

Cyanidin-3-galactoside from Aronia melanocarpa ameliorates silica-induced pulmonary fibrosis by modulating the TGF-β/mTOR and NRF2/HO-1 pathways

Cyanidin-3-galactoside (C3G), the most abundant anthocyanin in Aronia melanocarpa, has many beneficial health effects, such as antioxidation. C3G was extracted from A. melanocarpa and applied (100, 200, and 400 mg/kg body weight) to 50-μl silica particles (SP) solution-exposed mice to research its antifibrotic properties using histological analysis, hydroxyproline assay, quantitative real-time polymerase chain reaction, and western blot analysis. The results showed that C3G treatment significantly ameliorated pulmonary fibrosis and cell infiltration into the lungs of mice. It also relieved SP-induced epithelial-mesenchymal transition (EMT), 400 mg/kg C3G treatment increasing epithelial-cadherin mRNA expression and decreasing α-smooth muscle actin mRNA expression to the level of that in the control group. Western blot analysis showed that exposure to SP increased the production of transforming growth factor-β1 (TGF-β1) and phosphorylated mammalian target of rapamycin (mTOR) by 4.71- and 4.15-fold, respectively, in the lungs of mice, which were significantly inhibited by C3G treatment. Moreover, 400 mg/kg C3G treatment up-regulated two important antioxidant mediators, nuclear factor erythroid-2-related factor 2 (NRF2; 4.91-fold) and heme oxygenase-1 (HO-1; 4.81-fold). The mechanism study indicated that C3G might inhibit the TGF-β/mTOR signaling via the NRF2/HO-1 pathway and that SP-induced pulmonary EMT was ameliorated by inhibiting the TGF-β/mTOR signaling pathway. Our findings could provide new avenues for C3G as a functional food for preventing or mediating the progression of SP-induced pulmonary fibrosis.

Lung-kidney interactions and their role in chronic kidney disease-associated pulmonary diseases

Chronic illnesses rarely present in a vacuum, devoid of other complications, and chronic kidney disease is hardly an exception. Comorbidities associated with chronic kidney disease lead to faster disease progression, expedited dialysis dependency, and a higher mortality rate. Although chronic kidney disease is most commonly accompanied by cardiovascular diseases and diabetes, there is clear cross talk between the lungs and kidneys pH balance, phosphate metabolism, and immune system regulation. Our present understanding of the exact underlying mechanisms that contribute to chronic kidney disease-related pulmonary disease is poor. This review summarizes the current research on kidney-pulmonary interorgan cross talk in the context of chronic kidney disease, highlighting various acute and chronic pulmonary diseases that lead to further complications in patient care. Treatment options for patients presenting with chronic kidney disease and lung disease are explored by assessing activated molecular pathways and the body's compensatory response mechanisms following homeostatic imbalance. Understanding the link between the lungs and kidneys will potentially improve health outcomes for patients and guide healthcare professionals to better understand how and when to treat each of the pulmonary comorbidities that can present with chronic kidney disease.

Nanomaterials and hepatic disease: toxicokinetics, disease types, intrinsic mechanisms, liver susceptibility, and influencing factors

The widespread use of nanomaterials (NMs) has raised concerns that exposure to them may introduce potential risks to the human body and environment. The liver is the main target organ for NMs. Hepatotoxic effects caused by NMs have been observed in recent studies but have not been linked to liver disease, and the intrinsic mechanisms are poorly elucidated. Additionally, NMs exhibit varied toxicokinetics and induce enhanced toxic effects in susceptible livers; however, thus far, this issue has not been thoroughly reviewed. This review provides an overview of the toxicokinetics of NMs. We highlight the possibility that NMs induce hepatic diseases, including nonalcoholic steatohepatitis (NASH), fibrosis, liver cancer, and metabolic disorders, and explore the underlying intrinsic mechanisms. Additionally, NM toxicokinetics and the potential induced risks in the livers of susceptible individuals, including subjects with liver disease, obese individuals, aging individuals and individuals of both sexes, are summarized. To understand how NM type affect their toxicity, the influences of the physicochemical and morphological (PCM) properties of NMs on their toxicokinetics and toxicity are also explored. This review provides guidance for further toxicological studies on NMs and will be important for the further development of NMs for applications in various fields.

Silicosis: An Update and Guide for Clinicians

This overview provides an update on silicosis epidemiology with review of exposures and emerging trends in acute and accelerated silicosis in the twenty-first century. The silicosis epidemics in mining, denim sandblasting, and engineering stone industries are highlighted. Clinical presentations of silicosis and silica-related conditions such as autoimmune, kidney, and mycobacterial disease, as well as lung cancer, are discussed. Important aspects of the new OSHA 2017 Silica Standard are presented. This review also includes practical guidance for clinicians to address questions that may arise when evaluating silica-exposed patients and to the public health responses needed following a diagnosis of silica-related disease.

Sodium tanshinone IIA sulfonate attenuates silica-induced pulmonary fibrosis in rats via activation of the Nrf2 and thioredoxin system

Silicosis is characterized by pulmonary fibrosis due to long-term inhalation of silica particles. Although the cause of this serious disease is known, its pathogenesis remains unclear and there are currently no specific treatments. Recent studies have shown that the anti-oxidant transcription factor Nrf2 is expressed at reduced levels in fibrotic foci, which may be related to disease progression. However, the molecular mechanisms by which this might occur have yet to be elucidated. Sodium tanshinone IIA sulfonate (STS), an extract of Salvia miltiorrhiza, is used in traditional Chinese medicine in the treatment of coronary heart disease. STS has been shown to play a strong anti-oxidative role in various organs. Here, we employed a rat model to explore the effects of STS on oxidative stress and the progression of fibrosis in silicosis. STS significantly reduced collagen deposition in the lungs, thereby antagonising silicosis. Immunohistochemical and immunofluorescence staining showed that Nrf2 was differentially expressed in lung cells during silica induced fibrosis, and chromatin immunoprecipitation-sequencing experiments demonstrated that Nrf2 promoted the expression of the antioxidant proteins thioredoxin and thioredoxin reductase. Our results suggest that the anti-fibrotic effects of STS may be related to upregulation of Nrf2 nuclear expression, especially in fibrotic lesions, and the promotion of thioredoxin and thioredoxin reductase expression. Our findings may open up new avenues for the development of STS as a treatment for silicosis.

A Pilot Study to Assess Inhalation Exposures among Sugarcane Workers in Guatemala: Implications for Chronic Kidney Disease of Unknown Origin

Background: Sugarcane workers in Central America experience a heavy burden of chronic kidney disease of unknown origin. We conducted a pilot study among worker proxies in Guatemala to characterize exposures to particulate matter, silica, heavy metals, and glyphosate, as well as to examine potential nephrotoxic exposures. Methods: Air, soil, and ash samples were collected and analyzed using scanning electron microscopy, X-ray diffraction, inductively coupled plasma mass spectrometry, and an enzyme-linked immunosorbent assay. Results: The average mass concentration for particulate matter (PM)_2.5 and PM₁₀₀ exposures were 360 µg/m³ (range: 32 to 1500 µg/m³) and 555 µg/m³ (range: 229 to 1170 µg/m³), respectively. The elemental composition of particles was largely silicon. The amount of crystalline silica was below 5 μg, yet the percentage of total silica was ~17% by weight. Putatively, the silica was in the amorphous form. Concentrations of aluminum and calcium ranged from 2–7 μg/m³. Glyphosate was not detectable in analyzed air samples but was detectable at concentrations ranging from 81–165 ppb in soil samples. Conclusion: Sugarcane workers are exposed to high concentrations of particulate matter. Future studies should investigate the potential role of silica, heavy metals, and agrochemicals in the etiology of chronic kidney disease in this population.

Renal involvement in a silicosis patient - case report and literature review

A 43-year-old Chinese man with a silicosis history was admitted to our hospital due to bilateral lower extremity edema for 1 year, exacerbating with hematuria for 2 months. He started working as a coal miner 30 years ago, and was diagnosed as silicosis 3 months ago. Lab tests revealed hematuria 3+, proteinuria 3+, and a serum creatinine value 2.47 mg/dl on routine check. He was diagnosed with focal proliferative IgA nephropathy (IgAN) and acute tubulo-interstitial nephritis by renal biopsy. He was treated with corticosteroids and got a remission 4 months later. Immunohistochemical staining showed the deposition of macrophage receptor with collagenous structure (MARCO), nod-like receptor pyrin domain-containing-3 (NLRP3), Caspase-1, apoptosis-associated speck (ASC), interleukin (IL)-1β, and IL-18 in both glomerular and tubulo-interstitial areas. We proposed that the silicon exposure could be related to his kidney disease in the patient and NLRP3 mediated inflammation might be involved in its pathogenesis which needs further explorations.