Inhalation of welding fumes reduced sperm counts and high fat diet reduced testosterone levels; differential effects in Sprague Dawley and Brown Norway rats.

BACKGROUND: Previous studies have shown that inhalation of welding fumes may induce pulmonary and systemic inflammation and organ accumulation of metal, to which spermatogenesis and endocrine function may be sensitive. Also obesity may induce low-grade systemic inflammation. This study aimed to investigate the effects on sperm production of inhaled metal nanoparticles from stainless steel welding, and the potential exacerbation by intake of a high fat diet. Both the inbred Brown Norway and the outbred Sprague Dawley rat strains were included to study the influence of strain on the detection of toxicity. Rats were fed regular or high fat (HF) diet for 24 weeks and were exposed to 20 mg/m3 of gas metal arc-stainless steel (GMA-SS) welding fumes or filtered air for 3 h/day, 4 days/week for 5 weeks, during weeks 7-12. Outcomes were assessed upon termination of exposure (week 12) and after recovery (week 24). RESULTS: At week 12, the GMA-SS exposure induced pulmonary inflammation in both strains, without consistent changes in markers of systemic inflammation (CRP, MCP-1, IL-6 and TNFα). GMA-SS exposure lowered daily sperm production compared to air controls in Sprague Dawley rats, but only in GMA-SS Brown Norway rats also fed the HF diet. Overall, HF diet rats had lower serum testosterone levels compared to rats on regular diet. Metal content in the testes was assessed in a limited number of samples in Brown Norway rats, but no increase was obsedrved. At week 24, bronchoalveolar lavage cell counts had returned to background levels for GMA-SS exposed Sprague Dawley rats but remained elevated in Brown Norway rats. GMA-SS did not affect daily sperm production statistically significantly at this time point, but testicular weights were lowered in GMA-SS Sprague Dawley rats. Serum testosterone remained lowered in Sprague Dawley rats fed the HF diet. CONCLUSION: Exposure to GMA-SS welding fumes lowered sperm production in two strains of rats, whereas high fat diet lowered serum testosterone. The effect on sperm counts was likely not mediated by inflammation or lowered testosterone levels. The studied reproductive outcomes seemed more prone to disruption in the Sprague Dawley compared to the Brown Norway strain.

Effects of maternal inhalation of carbon black nanoparticles on reproductive and fertility parameters in a four-generation study of male mice.

BACKGROUND: Previous findings indicate that in utero exposure to nanoparticles may affect the reproductive system in male offspring. Effects such as decreased sperm counts and testicular structural changes in F1 males have been reported following maternal airway exposure to carbon black during gestation. In addition, a previous study in our laboratory suggested that the effects of in utero exposure of nanoparticles may span further than the first generation, as sperm content per gram of testis was significantly lowered in F2 males. In the present study we assessed male fertility parameters following in utero inhalation exposure to carbon black in four generations of mice. RESULTS: Filter measurements demonstrated that the time-mated females were exposed to a mean total suspended particle mass concentration of 4.79 ± 1.86 or 33.87 ± 14.77 mg/m3 for the low and high exposure, respectively. The control exposure was below the detection limit (LOD 0.08 mg/m3). Exposure did not affect gestation and litter parameters in any generation. No significant changes were observed in body and reproductive organ weights, epididymal sperm parameters, daily sperm production, plasma testosterone or fertility. CONCLUSION: In utero exposure to carbon black nanoparticles, at occupationally relevant exposure levels, via maternal whole body inhalation did not affect male-specific reproductive, fertility and litter parameters in four generations of mice.

Pulmonary exposure to carbonaceous nanomaterials and sperm quality.

BACKGROUND: Semen quality parameters are potentially affected by nanomaterials in several ways: Inhaled nanosized particles are potent inducers of pulmonary inflammation, leading to the release of inflammatory mediators. Small amounts of particles may translocate from the lungs into the lung capillaries, enter the systemic circulation and ultimately reach the testes. Both the inflammatory response and the particles may induce oxidative stress which can directly affect spermatogenesis. Furthermore, spermatogenesis may be indirectly affected by changes in the hormonal milieu as systemic inflammation is a potential modulator of endocrine function. The aim of this study was to investigate the effects of pulmonary exposure to carbonaceous nanomaterials on sperm quality parameters in an experimental mouse model. METHODS: Effects on sperm quality after pulmonary inflammation induced by carbonaceous nanomaterials were investigated by intratracheally instilling sexually mature male NMRI mice with four different carbonaceous nanomaterials dispersed in nanopure water: graphene oxide (18 µg/mouse/i.t.), Flammruss 101, Printex 90 and SRM1650b (0.1 mg/mouse/i.t. each) weekly for seven consecutive weeks. Pulmonary inflammation was determined by differential cell count in bronchoalveolar lavage fluid. Epididymal sperm concentration and motility were measured by computer-assisted sperm analysis. Epididymal sperm viability and morphological abnormalities were assessed manually using Hoechst 33,342/PI flourescent and Spermac staining, respectively. Epididymal sperm were assessed with regard to sperm DNA integrity (damage). Daily sperm production was measured in the testis, and testosterone levels were measured in blood plasma by ELISA. RESULTS: Neutrophil numbers in the bronchoalveolar fluid showed sustained inflammatory response in the nanoparticle-exposed groups one week after the last instillation. No significant changes in epididymal sperm parameters, daily sperm production or plasma testosterone levels were found. CONCLUSION: Despite the sustained pulmonary inflammatory response, an eight week exposure to graphene oxide, Flammruss 101, Printex 90 and the diesel particle SRM1650b in the present study did not appear to affect semen parameters, daily sperm production or testosterone concentration in male NMRI mice.

Atherosclerosis and vasomotor dysfunction in arteries of animals after exposure to combustion-derived particulate matter or nanomaterials.

Exposure to particulate matter (PM) from traffic vehicles is hazardous to the vascular system, leading to clinical manifestations and mortality due to ischemic heart disease. By analogy, nanomaterials may also be associated with the same outcomes. Here, the effects of exposure to PM from ambient air, diesel exhaust and certain nanomaterials on atherosclerosis and vasomotor function in animals have been assessed. The majority of studies have used pulmonary exposure by inhalation or instillation, although there are some studies on non-pulmonary routes such as the gastrointestinal tract. Airway exposure to air pollution particles and nanomaterials is associated with similar effects on atherosclerosis progression, augmented vasoconstriction and blunted vasorelaxation responses in arteries, whereas exposure to diesel exhaust is associated with lower responses. At present, there is no convincing evidence of dose-dependent effects across studies. Oxidative stress and inflammation have been observed in the arterial wall of PM-exposed animals with vasomotor dysfunction or plaque progression. From the data, it is evident that pulmonary and systemic inflammation does not seem to be necessary for these vascular effects to occur. Furthermore, there is inconsistent evidence with regard to altered plasma lipid profile and systemic inflammation as a key step in vasomotor dysfunction and progression of atherosclerosis in PM-exposed animals. In summary, the results show that certain nanomaterials, including TiO2, carbon black and carbon nanotubes, have similar hazards to the vascular system as combustion-derived PM.

Airway exposure to TiO2 nanoparticles and quartz and effects on sperm counts and testosterone levels in male mice.

Several types of engineered nanoparticles (ENP) have been shown to adversely affect male reproduction in rodent studies, but the airway route of exposure has been little investigated. This precludes adequate risk assessment of ENP exposure in occupational settings. Titanium dioxide nanoparticles (TiO2 NP) have been shown to affect total sperm count in adult male mice after intravenous and oral administration. This study aimed to investigate whether also airway exposure would affect sperm counts in male mice. Mature C57BL/6J mice were intratracheally instilled with 63 µg of rutile nanosized TiO2, once weekly for seven weeks. Respirable α-quartz (SRM1878a) was included at a similar dose level as a positive control for pulmonary inflammation. BALF cell composition showed neutrophil granulocyte influx as indication of pulmonary inflammation in animals exposed to TiO2 NP and α-quartz, but none of the particle exposures affected weight of testes or the epididymis, sperm counts or plasma testosterone when assessed at termination of the study.

Lung inflammation and genotoxicity in mice lungs after pulmonary exposure to candle light combustion particles.

Candle burning produces a large amount of particles that contribute substantially to the exposure to indoor particulate matter. The exposures to various types of combustion particles, such as diesel exhaust particles, have been associated with increased risk of lung cancer by mechanisms that involve oxidative stress, inflammation and genotoxicity. The aim of this study was to compare pulmonary effects of candle light combustion particles (CP) with two benchmark diesel exhaust particles (A-DEP and SRM2975). Intratracheal (i.t.) instillation of CP (5mg/kg bodyweight) in C57BL/6n mice produced a significant influx of alveolar macrophages and polymorphonuclear leukocytes and increased concentrations of proteins and lactate dehydrogenase activity in bronchoalveolar fluid. Lower levels of these markers of inflammation and cytotoxicity were observed after i.t. instillation of the same dose of A-DEP or SRM2975. The i.t. instillation of CP did not generate oxidative damage to DNA in lung tissue, measured as DNA strand breaks and human 8-oxoguanine glycosylase-sensitive sites by the comet assay. The lack of genotoxic response was confirmed in lung epithelial (A549) cells, although the exposure to CP increased intracellular levels of reactive oxygen species. In conclusion, pulmonary exposure to particles from burning candles is associated with inflammation and cytotoxicity in the lungs.

Automobile diesel exhaust particles induce lipid droplet formation in macrophages in vitro.

Exposure to diesel exhaust particles (DEP) has been associated with adverse cardiopulmonary health effects, which may be related to dysregulation of lipid metabolism and formation of macrophage foam cells. In this study, THP-1 derived macrophages were exposed to an automobile generated DEP (A-DEP) for 24h to study lipid droplet formation and possible mechanisms. The results show that A-DEP did not induce cytotoxicity. The production of reactive oxygen species was only significantly increased after exposure for 3h, but not 24h. Intracellular level of reduced glutathione was increased after 24h exposure. These results combined indicate an adaptive response to oxidative stress. Exposure to A-DEP was associated with significantly increased formation of lipid droplets, as well as changes in lysosomal function, assessed as reduced LysoTracker staining. In conclusion, these results indicated that exposure to A-DEP may induce formation of lipid droplets in macrophages in vitro possibly via lysosomal dysfunction.