Rationale for the use of sphingosine analogues in COVID-19 patients

Despite the recent announcement of promising drug candidates to treat COVID-19, there is currently no effective antiviral drug or vaccine. There is strong evidence that acute lung injury/acute respiratory distress syndrome (ALI/ARDS), likely triggered by a cytokine storm, is responsible for the severity of disease seen in COVID-19 patients. In support of this hypothesis, pilot studies using IL-6 receptor inhibitors such as tocilizumab have shown promising results. Therefore, the use of drugs or cocktails of drugs with broader ability to inhibit these cytokine receptors is likely to be effective. In this article, we propose the use of sphingosine analogues, which have been shown to mitigate acute lung damage in animal models of ALI/ARDS, as early adjuvant therapies to prevent and/or mitigate the cytokine response in COVID-19 patients. This proposal is based on the ability of these drugs to decrease the production of IL-6 and other cytokines. The potential application of fingolimod (FTY720), the oldest sphingosine analogue approved for the treatment of multiple sclerosis, in the early stages of COVID-19 is discussed in more detail as a prototype drug.

Monitoring human genotoxicity risk associated to urban and industrial Buenos Aires air pollution exposure

The quality of life in large megacities is directly affected by its air quality. In urban environments, suspended particles from anthropogenic origin is one of the main air contaminants identified as highly genotoxic, mutagenic, or carcinogenic. Atmospheric monitoring is therefore imperative, and bioassays to detect the effects of genotoxic agents give usually excellent results. Analysis of micronucleus (MN) in exfoliated oral mucosa cells is a sensitive non-invasive method for monitoring genetic damage in human populations. The first aim of this study was to analyze and characterize levels of volatile organic compounds (VOCs), particulate matter (PM), and polycyclic aromatic hydrocarbons (PAHs) in two areas from Buenos Aires: La Plata city, an urban (U) area and Ensenada, an industrial (I) area. Secondly, we evaluated the possible health risk of its inhabitants through a simple genotoxic assay on exfoliated oral mucosa cells. Whole blood cell count and nuclear abnormalities frequencies were evaluated in the exfoliated oral mucosa cells from urban and industrial inhabitants. Smoking habit represented a significant factor increasing MN percentage while, age did not increase the production of any of the nuclear aberrations assayed (micronuclei, binucleated, karyorrhexis) when the inhabitants from the urban and the industrial areas were compared. In addition, changes in MN and binucleated cell percentages in males and females were found to be area-dependent. We suggest that regardless PM concentration, PM-specific characteristics (size, shape, chemical elements, etc.) and VOCs levels could be responsible for the different harmful genotoxic effects seen in the two areas. Although this is a preliminary study, our results allowed to recognize that individuals living in both the urban and the industrial areas could be considered susceptible groups and should periodically undergo biological monitoring and appropriate care.

Hazardous effects of urban air particulate matter acute exposure on lung and extrapulmonary organs in mice

Air particulate matter (PM) can lead to extrapulmonary adverse reactions in organs such as liver and heart either by particle translocation from the lung to the systemic circulation or by the release of lung mediators. Young BALB/c mice were intranasal instilled with 1mg/BW of Urban Air Particles from Buenos Aires or Residual Oil Fly Ash. Histopathology, oxidative metabolism and inflammation on lungs and extrapulmonary organs and the systemic response were evaluated. Lung histophatological analysis supported the rise in the number of inflammatory cells in the bronchoalveolar lavage from PM-exposed animals. Also, both PM caused recruitment of inflammatory cells in the liver and heart parenchyma and IL-6 and transaminases augmentation in serum. We have shown that despite morphochemical differences, both urban air PM altered the lung and extrapulmonary organs. Therefore, exposure to urban air PM may distress body metabolism which, in turn could lead to the development and progression of multifactorial diseases.

Chronic exposure to urban air pollution from Buenos Aires: the ocular mucosa as an early biomarker

Air pollution represents a major health problem in megacities, bringing about 8 million deaths every year. The aim of the study was to evaluate in vivo the ocular and respiratory mucosa biological response after chronic exposure to urban air particles from Buenos Aires (UAP-BA). BALB/c mice were exposed to UAP-BA or filtered air for 1, 6, 9, and 12 months. After exposure, histology, histomorphometry, and IL-6 proinflammatory cytokine level were evaluated in the respiratory and ocular mucosa. Total cell number and differential cell count were determined in the brochoalveolar lavage fluid. In the lung, chronic exposure to UAP-BA induced reduction of the alveolar space, polymorhonuclear cell recruitment, and goblet cell hyperplasia. In the ocular surface, UAP-BA induced an initial mucin positive cells rise followed by a decline through time, while IL-6 level increased at the latest point-time assayed. Our results showed that the respiratory and the ocular mucosas respond differently to UAP-BA. Being that lung and ocular mucosa diseases may be triggered and/or exacerbated by chronic exposure to urban air PM, the inhabitants of Buenos Aires whom are chronically exposed to environmental urban air pollution may be considered a subpopulation at risk. Based on our results, we propose the ocular mucosa as a reliable and more accessible surrogate for pulmonary mucosa environmental toxicity that might also serve as an earlier biomarker for air pollution adverse impact on health.

Volcanic ash from Puyehue-Cordón Caulle Volcanic Complex and Calbuco promote a differential response of pro-inflammatory and oxidative stress mediators on human conjunctival epithelial cells

Volcanic ash could pose a hazard to the ocular surface as it is constantly exposed to environmental particles. We exposed conjunctival cells to Puyehue-Cordón Caulle volcanic complex (PCCVC) or Calbuco ash particles and evaluated proliferation, viability, apoptosis, MUC1 expression, pro-inflammatory cytokines, and oxidative stress markers. Ash particles from these volcanoes vary in size, composition, and morphology. Our results demonstrate that PCCVC but not Calbuco ash particles induce cytotoxicity on human conjunctival epithelial cells viewed as a decrease in cell proliferation and the transmembrane mucin MUC1 expression; a pro-inflammatory response mediated by IL-6 and IL-8; and an imbalance of the redox environment leading to protein oxidative damage. This is the first in vitro study that assesses the biological effect of volcanic ash particles on human conjunctival epithelial cells and the involvement of inflammatory mediators and oxidative stress as the mechanisms of damage. Our results could provide a better understanding of the ocular symptoms manifested by people living near volcanic areas.

Oxidative stress response to air particle pollution in a rat nutritional growth retardation model

Air pollution consisting of gases and particulate matter-(PM) represents a health problem in cities worldwide. However, air pollution does not impact equally all individuals, as children appear to be more vulnerable subpopulations. Air pollution and malnutrition are two distinct factors that have been associated with oxidative damage. Therefore, the interaction between environmental exposure and nutritional status in populations at risk needs to be explored. The aim of this study was to examine oxidative metabolism in lung, heart and liver in malnourished young rats exposed to residual oil fly ash (ROFA). A Nutritional Growth Retardation (NGR) model was developed in weanling male rats placed on a 20% restricted balanced diet for 4 weeks. Then, NGR and control rats were intranasally instilled with either ROFA (1mg/kg BW) or phosphate buffered saline (PBS). Twenty-four hr post-exposure lung, heart and liver were excised, and serum collected. ROFA induced lung and liver inflammation in control and NGR animals as evidenced by lung polymorphonuclear neutrophil (PMN) recruitment and alveolar space reduction accompanied by liver lymphocyte and binucleated hepatocyte level increase. In lung and liver, antioxidant defense mechanisms reduced lipoperoxidation. In contrast, only in NGR animals did ROFA exposure alter heart oxidative metabolism leading to lipid peroxidation. Although histological and biochemical tissue alterations were detected, no marked changes in serum liver and heart systemic biomarkers were observed. In conclusion, NGR animals responded differently to PM exposure than controls suggesting that nutritional status plays a key role in responsiveness to ambient air contaminants.

Evaluation of metabolic reactivity in macrophages from mice with chronic sodium arsenite intake and experimental carcinogenesis

 Arsenic is carcinogenic to human beings, and environmental exposure to arsenic is a public health issue that affects large populations around the world. Thus, studies are needed to determine the mode of action of arsenic and to prevent harmful effects that arise from arsenic intake. In particular, knowledge of the effects of arsenic exposure in individuals who are undergoing a carcinogenesis process is lacking. The present study was performed in mice to evaluate the effect of chronic As3+ administration on peritoneal and alveolar macrophages; the As3+ was administered in drinking water over 9 months and there was a two-stage carcinogenesis process. At the end of the experiment, the number of tumors stabilized to below the control values, but the tumors showed increased malignancy. Our objective was to evaluate the systemic effects of chronic As3+ingestion in a population of macrophages that was derived from the peritoneal cavity and the broncho-alveolar trunk of cancerized mice since they are the first line of defense in the immune system. The results showed that the macrophages under all conditions retained their ability to self-regulate their metabolic reactivity. This feature was more evident in peritoneal macrophages than in alveolar macrophages. Furthermore, an increase in the number of macrophages from animals receiving higher doses of As3+ compared to untreated animals was observed. These findings indicate that certain parameters associated with two-stage skin carcinogenesis are modified by the presence of As3+ in drinking water.

Evaluation of metabolic reactivity in macrophages from mice with chronic sodium arsenite intake and experimental carcinogenesis

 Arsenic is carcinogenic to human beings, and environmental exposure to arsenic is a public health issue that affects large populations around the world. Thus, studies are needed to determine the mode of action of arsenic and to prevent harmful effects that arise from arsenic intake. In particular, knowledge of the effects of arsenic exposure in individuals who are undergoing a carcinogenesis process is lacking. The present study was performed in mice to evaluate the effect of chronic As3+ administration on peritoneal and alveolar macrophages; the As3+ was administered in drinking water over 9 months and there was a two-stage carcinogenesis process. At the end of the experiment, the number of tumors stabilized to below the control values, but the tumors showed increased malignancy. Our objective was to evaluate the systemic effects of chronic As3+ingestion in a population of macrophages that was derived from the peritoneal cavity and the broncho-alveolar trunk of cancerized mice since they are the first line of defense in the immune system. The results showed that the macrophages under all conditions retained their ability to self-regulate their metabolic reactivity. This feature was more evident in peritoneal macrophages than in alveolar macrophages. Furthermore, an increase in the number of macrophages from animals receiving higher doses of As3+ compared to untreated animals was observed. These findings indicate that certain parameters associated with two-stage skin carcinogenesis are modified by the presence of As3+ in drinking water.

Titanium Nanoparticle Size Influences Trace Concentration Levels in Skin Appendages

As a result of biotribocorrosion, the surface of a titanium (Ti) biomedical device can be a potential source of systemic contamination with Ti nanoparticles (NPs). Although NPs can be chemically similar, differences in particle size may lead to different biological responses. The aim of this experimental study was to determine Ti trace levels in skin appendages and plasma and explore the influence of NP size on trace levels using a murine model. Results showed the presence of Ti traces in the nails, hair, and plasma. The concentration of the smallest NPs (5 Nm) was higher than that of 10 Nm NPs in all the studied samples. Irrespective of NP size, Ti levels were always lower in plasma than in skin appendages. Ti levels were higher in nails than in hair. Ti NPs size influenced trace concentration levels in hair/nails, suggesting that 5 Nm Ti particles are more easily eliminated through these skin appendages. Given that the nails showed the highest levels of Ti, and that these skin appendages are not exposed to agents that can leach out Ti, as occurs with hair, we propose the nails as the most suitable and reliable bioindicator for monitoring systemic contamination with Ti.

Active caspase-3 expression levels as bioindicator of individual radiosensitivity

Several molecules and events involved in cell response to radiation-induced damage have been investigated towards a personalized radiotherapy. Considering the importance of active caspase-3 in the proteolytic cascade that ensures radiation-induced apoptosis execution, this research was designed to evaluate the expression levels of this protein as a bioindicator of individual radiosensitivity. Peripheral blood samples of 10 healthy individuals were gamma-irradiated (cobalt-60 source) with 1, 2 and 4 Gy (control: non-irradiated samples), and active caspase-3 expression levels were measured in lymphocytes, by flow cytometry, ex vivo and after different times of in vitro incubation (24, 48 and 72 hours). Short-term incubation of 24 h was the most adequate condition to evidence correlations between dose radiation and active caspase-3 expression. For each radiation dose, it was observed a significant inter-individual variation in active caspase-3 expression intensity, suggesting that this parameter may be suitable for evidence individual radiosensitivity. The methodology presented and discussed in this work may help to predict healthy tissues response to radiation exposure toward the better patient outcome.

Acute exposure to Buenos Aires air particles (UAP-BA) induces local and systemic inflammatory response in middle-aged mice: A time course study

Exposure to air particulate matter (PM) is associated with increased cardiovascular morbimortality. However, PM doesn't affect equally to all people, being the old cohort the most susceptible and studied. We hypothesized that another specific life phase, the middle-aged subpopulation, may be negatively affected. Therefore, the aim of this study was to analyze in vivo the acute biological impact of two environmental particles, Urban Air Particles from Buenos Aires and Residual Oil Fly Ash, on the cardiorespiratory system of middle-aged mice, evaluating oxidative metabolism and inflammation. Both PM provoked a local and systemic inflammatory response, leading to a reduced alveolar area in the lung, an epicard inflammation in the heart, an increment of IL-6, and a reduction on PON 1 activity in serum of middle-aged animals. The positive correlation of local parameters with systemic markers of oxidative stress and inflammation could be responsible for associations of cardiovascular morbimortality in this subpopulation.

In vivo short-term exposure to residual oil fly ash impairs pulmonary innate immune response against environmental mycobacterium infection

Epidemiological studies have shown that pollution derived from industrial and vehicular transportation induces adverse health effects causing broad ambient respiratory diseases. Therefore, air pollution should be taken into account when microbial diseases are evaluated. Environmental mycobacteria (EM) are opportunist pathogens that can affect a variety of immune compromised patients, which impacts significantly on human morbidity and mortality. The aim of this study was to evaluate the effect of residual oil fly ash (ROFA) pre-exposure on the pulmonary response after challenge with opportunistic mycobacteria by means of an acute short-term in vivo experimental animal model. We exposed BALB/c mice to ROFA and observed a significant reduction on bacterial clearance at 24 h post infection. To study the basis of this impaired response four groups of animals were instilled with (a) saline solution (Control), (b) ROFA (1 mg kg(-1) BW), (c) ROFA and EM-infected (Mycobacterium phlei, 8 × 10(6) CFU), and (d) EM-infected. Animals were sacrificed 24 h postinfection and biomarkers of lung injury and proinflammatory madiators were examined in the bronchoalveolar lavage. Our results indicate that ROFA was able to produce an acute pulmonary injury characterized by an increase in bronchoalveolar polymorphonuclear (PMN) cells influx and a rise in O2 (-) generation. Exposure to ROFA before M. phlei infection reduced total cell number and caused a significant decline in PMN cells recruitment (p < 0.05), O2 (-) generation, TNFα (p < 0.001), and IL-6 (p < 0.001) levels. Hence, our results suggest that, in this animal model, the acute short-term pre-exposure to ROFA reduces early lung response to EM infection.

Pulmonary inflammation and cell death in mice after acute exposure to air particulate matter from an industrial region of Buenos Aires

Epidemiological studies have shown that air particulate matter (PM) can increase respiratory morbidity and mortality being the lungs the main target organ to PM body entrance. Even more, several in vivo and in vitro studies have shown that air PM has a wide toxicity spectra depending among other parameters, on its size, morphology, and chemical composition. The Reconquista River is the second most polluted river from Buenos Aires, and people living around its basin are constantly exposed to its contaminated water, soil and air. However, the air PM from the Reconquista River (RR-PMa) has not been characterized, and its biological impact on lung has yet not been assessed. Therefore, the present investigation was undertaken to study (1) RR-PMa morphochemical characteristic and (2) RR-PMa lung acute effects after intranasal instillation exposure through the analysis of three end points: oxidative stress, inflammation, and apoptosis. A single acute exposure of RR-PMa (1 mg/kg body weight) after 24 h caused significant (p < 0.05) enrichment in bronchoalveolar total cell number and polymorphonuclear (PNM) fraction, superoxide anion generation, production of pro-inflammatory cytokines TNF-α and IL-6, and induction of apoptosis. It was also observed that in lung homogenates, none of the antioxidant enzymes assayed showed differences between exposed RR-PMa and control mice. These data demonstrate that air PM from the Reconquista River induce lung oxidative stress, inflammation, and cell death therefore represents a potential hazard to human health.

In vitro age dependent response of macrophages to micro and nano titanium dioxide particles

As a result of corrosion, microparticles (MP) and/or nanoparticles (NP) can be released from the metallic implants surface into the bioenvironment. The biological response to these particles depends not only on the physico-chemical properties of the particles but also on host factors, such as age. Macrophages have attracted wide concern in biomedicine. The aim of this investigation was to study the age related biological response of macrophages to TiO2 -MP and NP in vitro. Alveolar macrophages (AM) obtained from young and senescent rats were cultured and exposed to TiO2 -MP and NP. Cell metabolism, superoxide anion (O2 (-) ) and nitric oxide (NO) generation, and cytokine release (IL-6, TNFα, IL-10) were measured. Cell metabolism was not affected by particle exposure. O2 (-) and NO generation increased in a dose dependent manner. A marked increase on IL-6 release was found in the young-AM subpopulation exposed to TiO2 -MP. Conversely, both particle sizes induced a dose dependent release of TNFα in senescent-AM. Only the highest concentration of TiO2 -particles caused a significant increase in IL-10 release in AM-cultures. These observations lend strong support to the suggestion that cellular response of macrophages to TiO2 -particles is age dependent. The biological effect of the particles would seem to be more deleterious in the senescent age-group.

Diesel exhaust particles selectively induce both proinflammatory cytokines and mucin production in cornea and conjunctiva human cell lines

PURPOSE

To evaluate the effect of diesel exhaust particles (DEP) on the viability, proliferation, apoptosis, secretion of cytokines (IL-6, IL-8, and TNF-α), and mucin gene transcription (MUC1, MUC5AC, and MUC16) in human epithelial cells of the cornea (HCLE) and conjunctiva (IOBA-NHC).

METHODS

HCLE and IOBA-NHC cells were incubated with DEP (10-500 μg/mL) for 24 hours. Cell proliferation was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptotic cells were measured by an annexin V-FITC and propidium iodide kit for flow cytometry. Proinflammatory cytokines were determined by an ELISA kit. Mucin gene transcription was quantified by real-time PCR.

RESULTS

DEP significantly decreased the viability, proliferation, and secretion of IL-8, but increased the secretion of IL-6 on both HCLE and IOBA-NHC cell lines in a dose-dependent manner. Neither cornea nor conjunctiva cells incubated with DEP released TNF-α. DEP induced a significant increase in the percentage of apoptotic cells in IOBA-NHC, whereas no changes were observed in HCLE. Finally, DEP significantly decreased the transcription levels of MUC1 and MUC16 in HCLE, but increased the transcription levels of MUC1, MUC5AC, and MUC16 in IOBA-NHC.

CONCLUSIONS

These findings suggest that human corneal and conjunctival epithelial cells incubated with DEP showed cytotoxicity and an inflammatory response mediated by IL-6, not by TNF-α or IL-8. Also, the decrease in mucin expression in the cornea cells might leave exposed areas in the cornea for contact with DEP. Finally, the increase in mucin expression in the conjunctiva cells might be involved at least in the clearance of DEP to protect the ocular epithelium.

Impact through time of different sized titanium dioxide particles on biochemical and histopathological parameters

Due to corrosion, a titanium implant surface can be a potential source for the release of micro (MPs) and nano-sized particles (NPs) into the biological environment. This work sought to evaluate the biokinetics of different sized titanium dioxide particles (TiO2 ) and their potential to cause cell damage. Wistar rats were intraperitoneally injected with 150 nm, 10 nm, or 5nm TiO2 particles. The presence of TiO2 particles was evaluated in histologic sections of the liver, lung, and kidney and in blood cells at 3 and 12 months. Ultrastructural analysis of liver and lung tissue was performed by TEM, deposit concentration in tissues was determined spectroscopically, and oxidative metabolism was assessed by determining oxidative membrane damage, generation of superoxide anion (O2(-)), and enzymatic and non-enzymatic antioxidants. TiO2 particles were observed inside mononuclear blood cells and in organ parenchyma at 3 and 12 months. TiO2 deposits were consistently larger in liver than in lung tissue. Alveolar macrophage O2(-) generation and average particle size correlated negatively (p < 0.05). NPs were more reactive and biopersistent in lung tissue than MPs. Antioxidant activity, particularly in the case of 5 nm particles, failed to compensate for membrane damage in liver cells; the damage was consistent with histological evidence of necrosis.

Bioaccessible heavy metals-sediment particles from Reconquista River induce lung inflammation in mice

The Reconquista River (RR), one of the most polluted watercourses in Argentina, receives effluent discharges from heavily industrialized and highly populated settlements. During winter and summer, the floodplain remains dry, producing the oxidation of sulfide and organic matter present in the sediment, making heavy metals more bioaccessible. Dispersion of this sediment occurs, and thus harmful effects on the pulmonary health of residents and workers inhabiting the RR bank may take place. The authors characterized the sediment particles of the RR (RR-PM) morphologically by scanning electron microscopy and its elemental composition by energy dispersive X-ray spectroscopy (EDX) and Community Bureau of Reference (BCR) sequential extraction. Furthermore, the authors evaluated its biological impact on the respiratory system of BALB/c mice, generating four groups: control healthy, sensibilized with ovalbumin, exposed to particles, and sensibilized and exposed to particles. Sediment particles of the Reconquista River contained fine particulate matter, with a high concentration of bioaccessible Cu and Zn. The authors found that animal exposure to RR-PM caused polymorphonuclear cell lung infiltration, augmentation of O2(-), increase of proinflammatory cytokines (tumor necrosis factor alpha [TNFα], interleukin-6 [IL-6]) and apoptosis. This adverse response was more dramatic in the sensibilized and exposed to particles group. Even more, they proved the bioaccessible fraction present in the RR-PM to be responsible for these harmful effects. The authors conclude that RR-PM produces an adverse biological impact on the airways of healthy animals, which is largely aggravated in previously sensibilized animals.

Uranyl nitrate-exposed rat alveolar macrophages cell death: influence of superoxide anion and TNF α mediators

Uranium compounds are widely used in the nuclear fuel cycle, military and many other diverse industrial processes. Health risks associated with uranium exposure include nephrotoxicity, cancer, respiratory, and immune disorders. Macrophages present in body tissues are the main cell type involved in the internalization of uranium particles. To better understand the pathological effects associated with depleted uranium (DU) inhalation, we examined the metabolic activity, phagocytosis, genotoxicity and inflammation on DU-exposed rat alveolar macrophages (12.5-200 μM). Stability and dissolution of DU could differ depending on the dissolvent and in turn alter its biological action. We dissolved DU in sodium bicarbonate (NaHCO₃ 100 mM) and in what we consider a more physiological vehicle resembling human internal media: sodium chloride (NaCl 0.9%). We demonstrate that uranyl nitrate in NaCl solubilizes, enters the cell, and elicits its cytotoxic effect similarly to when it is diluted in NaHCO₃. We show that irrespective of the dissolvent employed, uranyl nitrate impairs cell metabolism, and at low doses induces both phagocytosis and generation of superoxide anion (O₂⁻). At high doses it provokes the secretion of TNFα and through all the range of doses tested, apoptosis. We herein suggest that at DU low doses O₂⁻ may act as the principal mediator of DNA damage while at higher doses the signaling pathway mediated by O₂⁻ may be blocked, prevailing damage to DNA by the TNFα route. The study of macrophage functions after uranyl nitrate treatment could provide insights into the pathophysiology of uranium-related diseases.

Low levels of residual oil fly ash (ROFA) impair innate immune response against environmental mycobacteria infection in vitro

Epidemiological studies have shown that pollution derived from industrial and vehicular transportation provokes adverse health effects causing broad spectrum of ambient respiratory diseases. Therefore, air pollution should be taken into account when microbial diseases are evaluated. Environmental mycobacteria (EM) are opportunist pathogens in a variety of immunocompromised patients eliciting significant impact on human morbidity and mortality. The aim of this study was to evaluate the in vitro effects of residual oil fly ash (ROFA) on the alveolar macrophages (AMs) response to opportunistic bacteria. AMs from young Wistar rats were obtained by bronchoalveolar lavage and co-cultured with Mycobacterium phlei (MOI 10). We exposed AM cultures to ROFA to characterize the effect of low ROFA concentrations (0, 2.5, and 5μg/ml) and evaluated the response of pre-exposed AM against the bacilli. Low ROFA concentrations induced superoxide anion and nitrites production (p<0.001). Pre-exposure to ROFA (2.5 and 5μg/ml) caused a significant reduction on TNFα (p<0.001) and superoxide anion (p<0.001) production but, did not modify the nitrite production when AM were co-cultured with M. phlei. In addition, ROFA significantly diminished AM killing ability in culture (p<0.001). Hence, our results indicate that pre-exposure to low levels of ROFA modifies the innate pulmonary defence mechanisms against environmental mycobacteria.

Age-dependent changes in porcine alveolar macrophage function during the postnatal period of alveolarization

During early postnatal ontogeny in most mammals, the lung is structurally and functionally immature. In some species with relatively altricial lung morphology, there is evidence of a coupling between functional maturity of the pulmonary cellular immune system and alveolar maturation. Herein, we examine changes in alveolar macrophage (AM) number and function occurring during alveolarization in a more precocial species, the pig, to determine if heightened oxidative metabolism and phagocytic ability is similarly delayed until completion of lung morphogenesis. We assessed cell differential in lavage fluid and evaluated two main functional parameters of AM phagocytic response, the generation of reactive oxygen species (ROS), and particle internalization. AM functional maturation occurred mainly during the first postnatal week: the proportion of AMs, ROS generation, and phagocytosis all increased significantly. These results suggest maturational improvement of the impaired AM-based pulmonary immune system of the neonate piglet occurs during the postnatal period of rapid alveolarization.

Biodistribution of titanium dioxide from biologic compartments

The layer of titanium dioxide (TiO(2)) of the implant is chronically exposed to the internal electrolyte milieu in the peri-implant biological compartment. Corrosion results from electrochemical attack and ensuing gradual degradation of the metallic materials and is thus of biological interest when these biomaterials are employed in clinical implantology. Herein we evaluated and compared the chronic effect and the biodistribution of TiO(2) administered subcutaneously or intraperitoneally. We propose that the compartmentalization of titanium in the area of subcutaneous injection would reproduce the biological compartment of the implant and its microenvironment from which metal ions could be released and migrate systemically. Potential TiO(2) deposits were identified and characterized in skin, liver and lung by histological and EDX analyses. After both treatments, the skin, liver, and lungs exhibited histological evidence of TiO(2) deposits. In order to characterize in situ macrophage-like cells, tissue sections were immunohistochemically stained for CD68. Tissue specimens from all organs assayed showed positive staining for anti-macrophage monoclonal antibody CD68 (PGM1). Despite the compartmentalization of titanium within nodular areas in rats treated subcutaneously, systemic migration occurred. We concluded that systemic migration of TiO(2) occurred regardless of the administration route.

Biological response of tissues with macrophagic activity to titanium dioxide

The titanium dioxide layer is composed mainly of anatase and rutile. This layer is prone to break, releasing particles to the milieu. Therefore, corrosion may cause implant failure and body contamination. We have previously shown that commercial anatase-titanium dioxide (TiO(2)-anatase) is deposited in organs with macrophagic activity, transported in the blood by phagocytic-mononuclear cells, and induces an increase in the production of reactive oxygen species (ROS). In this study, we evaluated the effects of rutile-titanium dioxide (TiO(2)-rutile). Male Wistar rats were injected i.p. with a suspension of TiO(2)-rutile powder at a dose of 1.60 g/100 g b.w. Six months postinjection, the presence of Ti was assessed in serum, blood cells, liver, spleen, and lung. Titanium was found in phagocytic mononuclear cells, serum, and in the parenchyma of all the organs tested. TiO(2)-rutile generated a rise in the percentage of reactive cells, which was smaller than that observed when TiO(2)-anatase was employed in a previous study. Although TiO(2)-rutile provoked an augmentation of ROS, it failed to induce damage to membrane lipids, possibly due to an adaptive response. The present study reveals that TiO(2)-rutile is less bioreactive than TiO(2)-anatase.

Age-related lung cell response to urban Buenos Aires air particle soluble fraction

Exposure to particulate matter (PM) may alter lung homeostasis inducing changes in fluid balance and host defense. Bioavailability of soluble PM compounds like polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and transition metals has been shown to play a key role in lung injury. We have previously characterized the size, shape, and chemical components of urban air particles from Buenos Aires (UAP-BA) and their biological impact on lungs. Herein, we evaluate the possible toxic effect of UAP-BA-soluble fraction (UAP-BAsf) on pulmonary cells obtained from young (1-2 months old) and aged (9-12 months old) Wistar rats using phagocytosis, oxidant-antioxidant generation, and apoptosis as endpoints. UAP-BA were collected in downtown BA and residual oil fly ash (ROFA), employed as a positive control, was collected from Boston Edison Co., Mystic Power Plant, Mystic, CT, USA. Both particle-soluble fractions (sf) were employed at concentrations ranging from 0 to 100 microg/mL. UAP-BAsf and ROFAsf even at the lowest dose assayed (10 microg/mL) showed in both lung cell populations the ability to stimulate phagocytosis and increase superoxide anion (O(2)(-)) generation. Both types of air particles caused a marked intracellular oxidant stress in aged pulmonary cells that may contribute to subsequent cell activation and production of proinflammatory mediators, leading to cell dysfunction. These data suggest that the impact of UAP-BAsf on phagocytosis, oxidant radical generation, and apoptosis is clearly dependent on the maturational state of the animal and might have different mechanisms of action.

Oxidative metabolism of lung macrophages exposed to sodium arsenite

Arsenic pollution has become increasingly severe. It occurs as the result of geological processes and different human activities. Arsenic toxicity at the respiratory level occurs mainly by inhalation of products of coal combustion. The aim of this study was to evaluate sodium arsenite (As(3+)) toxicity in murine alveolar macrophages (AMs) in vitro and its association with the alterations in cell metabolism. No changes in viability, apoptosis or cell area were detected in AMs treated with As(3+) concentrations up to 2 microM for 24-96 h. A marked decrease in these end-points was observed for As(3+) concentrations ranging from 2.5 microM to 10 microM. Regarding the dynamics of the endo-exocytic process triggered by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell incorporation, no variations were detected for As(3+) concentrations lower than 2 microM while higher concentrations markedly modified this response. MTT specific activity, as a measure of cell metabolic activity, was not modified irrespective of the As(3+) concentration assayed. However, nitroblue tetrazolium (NBT) specific activity, as a measure of superoxide anion generation, is responsive but only to low As(3+) doses. Although this study focuses on lung macrophages, the effects of As(3+) described herein may also apply to the response of macrophages residing in other organs. Arsenite modifies the metabolic and the oxidative status of AMs in vitro. When macrophages are in an As(3+) rich medium, they exhibit a reduction in respiratory burst levels and lose their intrinsic capacity to respond to toxicants.

Ultrastructural and metabolic changes in osteoblasts exposed to uranyl nitrate

Exposure to uranium is an occupational hazard to workers who continually handle uranium and an environmental risk to the population at large. Since the cellular and molecular pathways of uranium toxicity in osteoblast cells are still unknown, the aim of the present work was to evaluate the adverse effects of uranyl nitrate (UN) on osteoblasts both in vivo and in vitro. Herein we studied the osteoblastic ultrastructural changes induced by UN in vivo and analyzed cell proliferation, generation of reactive oxygen species (ROS), apoptosis, and alkaline phosphatase (APh) activity in osteoblasts exposed to various UN concentrations (0.1, 1, 10, and 100 microM) in vitro. Cell proliferation was quantified by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, ROS was determined using the nitro blue tetrazolium test, apoptosis was morphologically determined using Hoechst 3332 and APh activity was assayed spectrophotometrically. Electron microscopy revealed that the ultrastructure of active and inactive osteoblasts exposed to uranium presented cytoplasmic and nuclear alterations. In vitro, 1-100 microM UN failed to modify cell proliferation ratio and to induce apoptosis. ROS generation increased in a dose-dependent manner in all tested doses. APh activity was found to decrease in 1-100 microM UN-treated cells vs. controls. Our results show that UN modifies osteoblast cell metabolism by increasing ROS generation and reducing APh activity, suggesting that ROS may play a more complex role in cell physiology than simply causing oxidative damage.

Effect of titanium dioxide on the oxidative metabolism of alveolar macrophages: An experimental study in rats

Metallic implants of titanium are used therapeutically in biomedicine because of its excellent biocompatibility. However, no metal or alloy is completely inert. We have previously shown that titanium oxide (TiO(2)) is transported in blood by phagocytic monocytes and deposited in organs such as liver, spleen, and lung 6 months after intraperitoneal injection (ip). Furthermore, it is well known that exposure to metal traces alters the cellular redox status. Thus, the aim of the present study was to determine the presence of titanium in target organs after chronic exposure, assess the potential structural alterations, and evaluate the oxidative metabolism of alveolar macrophages (AM) in the lung. Rats were ip injected with 1.60 g/100 g body wt of TiO(2) in saline solution. Organs (liver, spleen, lung) were processed for histological evaluation. Reactive oxygen species (ROS) in AM obtained by bronchoalveolar lavage (BAL) were evaluated using the nitroblue tetrazolium test and quantitative evaluation by digital image analysis. The histological analysis of organs revealed the presence of titanium in the parenchyma of these organs with no associated tissue damage. Although in lung alveolar macrophages TiO(2) induced a significant rise in ROS generation, it failed to cause tissue alteration. This finding may be attributed to an adaptive response.

Functional age-dependent changes in bronchoalveolar lavage rat cells

Alveolar macrophages (AM) are located at the first line of non-specific defense against inhaled antigens in the lower respiratory tract and therefore represent the major effector cell in antimicrobial defense. Since children under 2 years are known to manifest increased susceptibility to lung infections we used a rat model to study functional capacities of the AM during different stages of development We analyzed several steps of the phagocytic process (adherence, chemotaxis and ingestion) as well as two different mechanisms of cytotoxicity [antibody dependent cellular cytotoxicity (ADCC) and cytotoxicity triggered by immune complex (ICC)] and tumor necrosis factor (TNF-alpha) secretion. We used young (4-6 weeks old), intermediate (16-25 weeks old) and adult (36-45 weeks old) rats. Adherence and phagocytic capacities of AM were lower in young rats compared to intermediate and adult animals. Chemotaxis towards the C5a complement component was low in the first two months of life, then it increased in the intermediate group and fell again in adults. Bronchoalveolar lavage (BAL) cells from young rats did not produce detectable TNF-alpha levels even when stimulated with phorbol 12-myristate 13-acetate (PMA). When we studied two different cytotoxic mechanisms we found that ICC markedly declines from youth to adulthood while ADCC showed a steady increase from youth to adulthood. In conclusion, our data show differences that may help to explain in part the enhanced susceptibility to pulmonary infections found in young children.

Low energy proton irradiation effects on alveolar macrophages from young and aged rats

A prospective study was undertaken to assess the radiotoxicity of accelerated particles in pulmonary alveolar macrophages (AM). We evaluated the effects of a single dose (10-75 Gy) of an external low-energy (20 MeV) proton beam on cultured AM oxidative metabolism and phagocytic function. Macrophages are the first line of defense against invading pathogens and are known to generate superoxide anion (O2), nitric oxide (NO), and mediators of antimicrobial and antitumoral defense mechanisms. We obtained AM by bronchoalveolar lavage from young (1-2 month old) and aged (9-12 month old) male Wistar rats. Cell viability, phagocytosis, O2 and NO production in control and proton-irradiated cultured AM were evaluated The effect of proton irradiation on cell viability was dose-dependent The higher doses induced a dramatic decrease in viability in the aged population. Phagocytosis increased 1.3-1.4 fold inboth populations irrespective of the dose delivered. Generation of O2 was always higher in the aged population for all the doses assayed and showed no significant variation from the control values. In the young population a clear increase was observed with doses of 25 and 50 Gy. NO production in AM from young animals rose in a dose-dependent manner. Conversely, proton irradiation did not affect NO production in macrophages from aged animals. The results of this study demonstrate that AM isolated from young and aged rats are functionally different and show a distinct behavior when exposed to proton irradiation. These findings suggest that age may condition response and must be taken into account when accelerated particle-radiotherapy protocols are considered as a valid therapeutic option for the treatment of cancer. To the best of our knowledge, this is the first report comparing sham-irradiated and proton-irradiated young and aged AM.

Radiation effects on oxidative metabolism in young and aged rat alveolar macrophages

The effect of ionizing radiation on metabolic functions of alveolar macrophages (AM) have been well studied. However, variations associated to age have not been established yet. The aim of this work was to perform a comparative study on irradiated alveolar macrophages from young and aged rat lungs. Cell viability and occurrence of apoptosis as well as production of nitric oxide (NO), generation of superoxide anion (O2*-) and total antioxidant capacity were analyzed in vitro after exposure to gamma-irradiation with 10, 25, 50 and 75 Gy. Cell viability decreased only in the aged population at the higher doses. Morphological features of apoptosis were clearly evidenced in irradiated alveolar macrophages from aged animals although the DNA fragmentation assay for apoptosis showed no differences for either of the populations studied. NO production and total reactive antioxidant potential (TRAP) levels showed a dose-dependent modulation. Low radiation doses inhibited the production of NO and decreased TRAP levels whereas higher doses enhanced the NO production and increased the TRAP levels in both macrophage populations. Generation of O2*- was always higher in the aged population for all the doses assayed. We conclude that in vitro young alveolar macrophages exhibited higher radioresistance over the whole range of doses as compared to the aged macrophage population. Our results show that the aging process markedly affects the radioresistance of phagocytic cells. Therefore, immune defense and inflammatory response of lungs from aged patients should be considered when planning radiotherapy protocols.

Automated image analysis for monitoring oxidative burst in macrophages

OBJECTIVE

To evaluate oxidative bursts induced by phorbol myristate acetate in phagocytes at the single-cell level by automated image analysis.

STUDY DESIGN

The generation of reactive oxygen species was quantitatively expressed by means of histograms displaying the percentage of cells corresponding to each of the total optical densities measured.

RESULTS

Macrophage subpopulations were quantitatively defined. This method allows detailed analysis of the amount of formazan per cell and the sites of deposition of blue precipitate in each cell.

CONCLUSION

Image analysis is a reliable quantitative, single-cell assay for studying various cellular characteristics associated with macrophage functions.

Quantitative recovery of pulmonary intravascular macrophages from sheep lungs

Pulmonary intravascular macrophages (PIMs) adhere to the endothelium of lung capillaries and sequester circulating particles and pathogens from the blood. Iron oxide (gamma Fe2O3) 5 mg/kg, administered intravenously, specifically labeled PIMs in situ within the living sheep. Attempts to isolate gamma Fe2O3-labeled PIMs using vascular perfusion (VP) procedures yielded few cells. To improve recovery of PIMs, a proteolytic lung digestion (PLD) procedure was developed. Following PLD, gamma Fe2O3-containing PIMs were recovered by magnets and the amount of gamma Fe2O3 present measured by fluxgate magnetometry. Proteolytic lung digestion recovered 34% of the total gamma Fe2O3 in lung samples and yielded 2 x 10(5) PIMs/g lung with 95% viability. In contrast, VP recovered only 3% of the total gamma Fe2O3 in the lung; furthermore, less than 2% of the recovered gamma Fe2O3 was cell associated. Proteolytic lung digestion followed by magnetic separation is an effective way to recover viable sheep PIMs for in vitro study.

Regulation of cultured rat vaginal epithelial cells by 17 beta-estradiol and progesterone

We have previously described a technique to obtain short-term cultures of epithelial cells from Wistar rat vaginae. In order to improve the efficiency and life span of these cultures, in the present study we have cultured the vaginal cells with lethally irradiated 3T3 cell feeder layers. Under this condition, cells can grow for several weeks while retaining epithelial characteristics and can eventually be subcultured. The proliferative effect of the ovarian hormones in these cultures was studied using two different approaches, [Methyl-3H]Thymidine (3HTdr) incorporation and increase in cell number. Both assays indicated a proliferative effect of 17 beta-estradiol and progesterone at physiological concentrations. This proliferative effect was also shown in feeder layer-free cultures, ruling out an indirect effect through the mesodermal cells. The capacity of the hormones to modify terminal differentiation in the culture was also studied, using colony stratification as an indicator of differentiation. Progesterone and fetal calf serum had an inhibitory effect on terminal differentiation, whereas 17 beta-estradiol induced a stimulatory action. This culture model allowed us to show a direct effect of the ovarian hormones on vaginal cells in vitro and seems to be a useful model to study hormone-cell interactions in vitro.