In vivo quantification of programmed death-ligand-1 expression heterogeneity in tumors using fluorescence lifetime imaging.

Cancer patient selection for immunotherapy is often based on programmed death-ligand-1 (PD-L1) expression as a biomarker. PD-L1 expression is currently quantified using immunohistochemistry, which can only provide snapshots of PD-L1 expression status in microscopic regions of ex vivo specimens. In vivo imaging using targeted agents can capture dynamic variations of PD-L1 expression in entire tumors within and across multiple subjects. Towards this goal, several PD-L1 targeted molecular imaging probes have been evaluated in murine models and humans. However, clinical translation of these probes has been limited due to a significant non-specific accumulation of the imaging probes and the inability of conventional imaging modalities to provide quantitative readouts that can be compared across multiple subjects. Here we report that in vivo time-domain (TD) fluorescence imaging can provide quantitative estimates of baseline tumor PD-L1 heterogeneity across untreated mice and variations in PD-L1 expression across mice undergoing clinically relevant anti-PD1 treatment. This approach relies on a significantly longer fluorescence lifetime (FLT) of PD-L1 specific anti-PD-L1 antibody tagged to IRDye 800CW (αPDL1-800) compared to nonspecific αPDL1-800. Leveraging this unique FLT contrast, we show that PD-L1 expression can be quantified across mice both in superficial breast tumors using planar FLT imaging, and in deep-seated liver tumors (>5 mm depth) using the asymptotic TD algorithm for fluorescence tomography. Our results suggest that FLT contrast can accelerate the preclinical investigation and clinical translation of novel molecular imaging probes by providing robust quantitative readouts of receptor expression that can be readily compared across subjects.

Laser speckle simulation tool based on stochastic differential equations for bio imaging applications.

Laser speckle-based blood flow imaging is a well-accepted and widely used method for pre-clinical and clinical applications. Although it was introduced as a method to measure only superficial blood flow (< 1mm depth), several recently introduced variants resulted in measuring deep tissue blood flow (a few cm) as well. A means of simulating laser speckles is often necessary for the analysis and development of these imaging modalities, as evident from many such attempts towards developing simulation tools in the past. Such methods often employ Fourier transforms or statistical tools to simulate speckles with desired statistical properties. We present the first method to use a stochastic differential equation to generate laser speckles with a pre-determined probability density function and a temporal auto-correlation. The method allows the choice of apriori gamma distribution along with simple exponential or more complex temporal auto-correlation statistics for simulated speckles, making it suitable for different blood flow profiles. In contrast to the existing methods that often generate speckles associated with superficial flow, we simulate both superficial and diffuse speckles leading to applications in deep tissue blood flow imaging. In addition, we have also incorporated appropriate models for noise associated with the detectors to simulate realistic speckles. We have validated our model by comparing the simulated speckles with those obtained from in-vivo studies in mice and healthy human subject.

MUC1, CK20, and CDX2 immunohistochemical markers can sub-classify periampullary carcinomas into pancreaticobiliary, intestinal, and mixed subtypes.

INTRODUCTION: Pancreaticobiliary subtype of Periampullary carcinoma (PAC) has a poor prognosis in comparison to the intestinal subtype. We assessed the potential of cytokeratins and mucin markers to classify the sub-types of periampullary tumors and compared them with the survival data to identify markers that may predict prognosis. METHODOLOGY: PAC tumor tissues were obtained from 94 patients undergoing Whipples Pancreaticoduodenectomy. Paraffin-embedded tissues were immunostained with cytokeratins CK7, CK20), mucins (MUC1, MUC2, MUC5Ac), and CDX2 antibodies. The survival status of patients was obtained as follow-up up to 5-years of surgery. The Receiver Operating Character Curve (ROC) analysis was used for detecting sensitivity and specificity. The survival data were analyzed using the Kaplan-Meier survival curve. RESULTS: Tumors were initially categorized on the basis of histological classification as pancreaticobiliary (n = 46), intestinal (n = 35) and indeterminate (n = 13). Further, using immunohistochemical markers (MUC1, CK20, and CDX2), we gave systematic classification of IHC-PB (n = 51), IHC-Int (n = 30) and IHC-Mixed (n = 13). The interobserver analysis showed good agreement between histologic and IHC type with a kappa value of 0.554. Combined expression of CK20, MUC1 and CDX2 accurately classify the mixed type of tumor. Overall survival rate and duration were 74.4% and 44.95 ± 2.29 months. Survival analysis for subtypes reveal, pancreaticobiliary tumors have low survival (27.9 ± 1.63 months) than mixed type (35.5 ± 0.45 months) and intestinal-type (52.92 ± 2.18 months). Among these, intestinal-type have better survival. Only TNM Stage III (tumor staging as per American Joint Committee on Cancer classification) and perineural invasion have been associated with predicting poor survival in PAC patients. CONCLUSION: Our results suggest that the combined expression of MUC1, CK20 and CDX2 could serve as markers to diagnose histological inconclusive specimens as mixed subtype tumors.

Does bony increased-offset reverse shoulder arthroplasty decrease scapular notching?

BACKGROUND: The purpose of this cohort study was to compare scapular notching rates, range of motion, and functional outcomes between patients who underwent a standard Grammont-style reverse shoulder arthroplasty (RSA) and patients who underwent bony increased-offset reverse shoulder arthroplasty (BIO-RSA) at a minimum of 2 years' follow-up. We hypothesized that the BIO-RSA cohort would have lower notching rates and improved rotational range of motion; however, validated outcome scores between cohorts would be no different. METHODS: A comparative cohort study was designed after a sample size calculation. A total of 40 patients were studied with 20 in each cohort (RSA vs BIO-RSA). All patients underwent an interview and physical examination. Outcomes included range of motion; shoulder strength; Disabilities of the Arm, Shoulder and Hand (DASH) score; American Shoulder and Elbow Surgeons score; Simple Shoulder Test score; Constant score; and Global Rating of Change scale score. Radiographs were obtained for all patients and examined for scapular notching. RESULTS: When we compared demographic characteristics between the standard RSA and BIO-RSA cohorts, including age, sex, and follow-up duration, there were no significant differences between groups (P > .05). In addition, there were no significant differences between cohorts when we compared forward elevation (P = .418); external rotation (P = .999); internal rotation (P = .071); strength (P > .376); Disabilities of the Arm, Shoulder and Hand score (P = .229); American Shoulder and Elbow Surgeons score (P = .579); Simple Shoulder Test score (P = .522); Constant score (P = .917); or Global Rating of Change scale score (P = .167). The frequency of scapular notching, however, was significantly higher (P = .022) in the RSA cohort than in the BIO-RSA cohort: 75% versus 40%. CONCLUSIONS: Although the scapular notching rate was significantly higher in the standard RSA group, no other outcome measures were statistically different, including range of motion, strength, and validated outcome scores.

CASA derived human sperm abnormalities: correlation with chromatin packing and DNA fragmentation.

PURPOSE: The present study was undertaken to evaluate the effects of morphokinetic abnormalities of human spermatozoa on chromatin packing and DNA integrity and possible beneficial effects of sperm selection in ICSI. METHODS: Semen samples from 1002 patients were analysed for morphology and motility using CASA. Protamine status and DNA fragmentation were analysed by chromomycin A3 staining and sperm chromatin dispersion assay respectively. RESULTS: Sperms with elongated, thin, round, pyri, amorphous, micro and macro forms were significantly higher in teratozoospermic and oligoasthenoteratozoospermic groups. Significant difference in chromatin packing and DNA fragmentation index was observed in these abnormal groups compared with normal. Similarly significant correlation was also seen between abnormal motility parameters and DNA fragmentation index in asthenozoospermic group compared with normal. CONCLUSIONS: Specific abnormal morphological forms have higher incidence of chromatin packing abnormalities and DNA fragmentation. Using these sperms in ICSI might have an impact on fertilization, embryo development and abortion rates. These can be selectively avoided during ICSI procedure to improve ART outcome.

Advances in the Continuum of Care of SCD: Wearable Defibrillators as a Bridge to ICD Implantation

Atividade de educação médica continuada onde Bruce D. Lindsay (moderador), Mina K. Chung (palestrante) e Srinivas Murali (palestrante) discorrem sobre a morte cardíaca súbita e o uso de desfibriladores implantáveis . Há a possibilidade de assistir ao vídeo, ler a transcrição das falas com slides e fazer o download do áudio. Também traz a possibilidade de realizar o teste de educação médica continuada da atividade e informação de como obter créditos pela mesma. Necessário estar cadastrado no site www.theheart.org para acesso ao material.

The methoxychlor metabolite, HPTE, inhibits rat luteal cell progesterone production.

UNLABELLED: The methoxychlor metabolite, HPTE, was shown to inhibit P450-cholesterol side-chain cleavage (P450scc) activity resulting in decreased progesterone production by cultured ovarian follicular cells in previous studies. It is not known whether HPTE has any effect on progesterone formation by the corpus luteum. RESULTS: Exposure to 100 nM HPTE reduced progesterone production by luteal cells with progressive declines to <22% of control at 500 nM HPTE. Similarly, HPTE progressively inhibited progesterone formation and P450scc catalytic activity of hCG- or 8 Br-cAMP-stimulated luteal cells. However, HPTE did not alter mRNA and protein levels of P450scc. Compounds acting as estrogen (17 ß-estradiol, bisphenol-A or octylphenol), antiestrogen (ICI) or antiandrogen (monobutyl phthalate, flutamide or M-2) added alone to luteal cells did not mimic the action of HPTE on progesterone and P450scc activity. These results suggest that HPTE directly inhibits P450scc catalytic activity resulting in reduced progesterone formation, and this action was not mediated through estrogen or androgen receptors.

Evaluation of local MCP-1 and IL-12 nanocoatings for infection prevention in open fractures.

The increasing incidence of bacterial infection and the appearance of Staphylococcus aureus (S. aureus) strains that are resistant to commonly used antibiotics has made it important to develop non-antibiotic approaches for infection prevention. The aim of this study was to develop local monocyte chemoattractant protein-1 (MCP-1) and interleukin-12 p70 (IL-12 p70) therapies to prevent S. aureus infection by enhancing the recruitment and activation of macrophages, which are believed to play an important role in infection prevention as the first line of defense against invading pathogens. Nanocoating systems for MCP-1 and IL-12 p70 deliveries were prepared, and their release characteristics desirable for infection prevention in open fractures were explored. Local MCP-1 therapy reduced S. aureus infection and influenced white blood cell populations, and local IL-12 p70 treatment had a more profound effect on preventing S. aureus infection. No synergistic relationship in decreasing S. aureus infection was observed when MCP-1 and IL-12 p70 treatments were combined. This reported new approach may reduce antibiotic use and antibiotic resistance.

Vitrification of human early cavitating and deflated expanded blastocysts: clinical outcome of 474 cycles.

PURPOSE: The present study was undertaken to evaluate and compare the post thaw survival, implantation and pregnancy rates of vitrified human early cavitating blastocysts with deflated expanded blastocysts. MATERIAL AND METHODS: Supernumerary blastocysts were vitrified in 30% ethylene glycol-dimethyl sulphoxide based solution using cryoloop. Fully expanded blastocysts were deflated by gentle aspiration of the blastocoelic fluid using a micromanipulator until the cavity collapses prior to vitrification. RESULTS: Of the 576 vitrified blastocysts, 545 (94.61%) survived thawing in the early cavitating blastocyst group which was significantly higher than deflated expanded blastocyst group, in which only 370 survived thawing out of 459 (80.62%). However, no significant difference was observed in implantation and pregnancy rates between early cavitating and deflated expanded blastocyst groups. CONCLUSIONS: Early cavitating blastocyst would be the ideal stage for cryopreservation of human blastocysts as it has higher survival rate and avoids additional invasive procedures like deflation of the blastocoele.

Electroporation of adult zebrafish.

We generated transient transgenic zebrafish by applying electrical pulses subsequent to injection of DNA into muscle tissue of 3-6-month old adult zebrafish. Electroporation parameters, such as number of pulses, voltage, and amount of plasmid DNA, were optimized and found that 6 pulses of 40 V/cm at 15 mug/fish increased the luciferase expression by 10-fold compared with those in controls. By measuring the expression of luciferase, in vivo by electroporation in adult zebrafish and in vitro using fish cell line (Xiphophorus xiphidium A2 cells), the strength of three promoters (CMV, human EF-1alpha, and Xenopus EF-1alpha) was compared. Subsequent to electroporation after injecting DNA in the mid region of zebrafish, expression of green fluorescent protein was found far away from the site of injection in the head and the tail sections. Thus, electroporation in adult zebrafish provides a rapid way of testing the behavior of gene sequences in the whole organism.

The methoxychlor metabolite, HPTE, directly inhibits the catalytic activity of cholesterol side-chain cleavage (P450scc) in cultured rat ovarian cells.

Exposure to the pesticide methoxychlor in rodents is linked to impaired steroid production, ovarian atrophy and reduced fertility. Following in vivo administration, it is rapidly converted by the liver to 2,2-bis-(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), the reported active metabolite. Both methoxychlor and HPTE have weak estrogenic and antiandrogenic activities, and these effects are thought to be mediated through the estrogen and androgen receptors, respectively. Previous in vivo studies on methoxychlor exposure to female animals have demonstrated decreased progesterone production but no change in serum estrogen levels. We recently showed that HPTE specifically inhibits the P450 cholesterol side-chain cleavage (P450scc, CYP11A1) step resulting in decreased androgen production by cultured rat testicular Leydig cells. The current studies examined the mechanism of action of HPTE on progesterone production by cultured ovarian cells (granulosa and theca-interstitial) from pregnant mare serum gonadotropin-primed immature rats. In addition, we evaluated whether the effects of HPTE on rat ovarian cell progesterone biosynthesis were mediated through the estrogen or androgen receptors. Exposure to HPTE (0, 10, 50 or 100nM) alone progressively inhibited progesterone formation in cultured theca-interstitial and granulosa cells and the P450scc catalytic activity in theca-interstitial cells in a dose-dependent manner with significant declines starting at 50nM. However, HPTE did not change mRNA levels of the P450scc system (P450scc, adrenodoxin reductase and adrenodoxin) as well as P450scc protein levels. Of interest, estradiol, xenoestrogens (bisphenol-A or 4-tert-octylphenol), a pure antiestrogen (ICI 182,780), or antiandrogens (4-hydroxyflutamide or the vinclozolin metabolite M-2), had no effect on progesterone production even at 1000nM. Co-treatment of HPTE with ICI 182,780 did not block the effect of HPTE on progesterone formation. These studies suggest that the decline in progesterone formation following exposure to HPTE in cultured ovarian cells is associated with the inhibition of catalytic activity of P450scc at least in theca-interstitial cells. This action does not appear to be mediated through the estrogen or androgen receptor signaling pathways, and other chemicals exhibiting estrogenic, antiestrogenic or antiandrogenic properties do not mimic its effect on ovarian steroid production.

Proteomic analysis of bronchoalveolar lavage fluid: effect of acute exposure to diesel exhaust particles in rats.

BACKGROUND: Inhalation of diesel exhaust particles (DEPs) is characterized by lung injury and inflammation, with significant increases in the numbers of polymorphonuclear leukocytes and alveolar macrophages. This influx of cellular infiltrates is associated with the activation of multiple genes, including cytokines and chemokines, and the production of reactive oxygen species. OBJECTIVE: The pathogenesis of the lung injury is not fully understood, but alterations in the presence or abundance of a number of proteins in the lung have been observed. Our objective in this study was to further characterize these changes and to ask whether additional changes could be discerned using modern proteomic techniques. METHODS: The present study investigates global alterations in the proteome of bronchoalveolar lavage fluid taken from rats 1, 7, or 30 days after exposure to 5, 35, or 50 mg/kg of animal weight of DEPs. RESULTS: Analysis by surface-enhanced laser desorption/ionization-time of flight mass spectrometry identified two distinct peaks that appeared as an acute response postexposure at all doses in all animals. We identified these two peaks, with mass to charge ratios (m/z) of 9,100 and 10,100, as anaphylatoxin C3a and calgranulin A by additional mass spectral investigation using liquid chromatography coupled to mass spectrometry. CONCLUSIONS: With this approach, we found a number of inflammatory response proteins that may be associated with the early phases of inflammation in response to DEP exposure. Further studies are warranted to determine whether serum levels of these proteins could be markers of diesel exhaust exposure in workers.

Exposure in vivo to silica or lipopolysaccharide produces transient or sustained upregulation, respectively, of PYPAF7 and MEFV genes in bronchoalveolar lavage cells in rats.

A family of proteins containing PAAD [for PYRIN, AIM (absent in melanoma), apoptosis-associated protein speck-like protein containing a caspase recruitment domain, and death domain] domain was found to be involved in modulating inflammatory responses, by its ability to regulate nuclear factor (NF)-kappaB and procaspase-1 activation. In this study, intratracheal instillation of silica in rats was found to produce transient upregulation of mRNA levels of the PAAD family of proteins, PYPAF7 (PYRIN containing Apaf1-like protein; Apaf stands for apoptosis activating factor) and MEFV (for Mediterranean fever), in bronchoalveolar lavage (BAL) cells. The levels were markedly elevated at 4 h, returning to basal levels by 24 h. In contrast, intratracheal instillation of LPS produced a sustained upregulation of the two genes in BAL cells. In vitro exposure of BAL cells to silica or lipopolysaccharide (LPS) produced no changes in the expression of these genes, indicating that silica or LPS exposure in vivo induces some factors that are responsible for the upregulation of PYPAF7 and MEFV. The mRNA levels of these two genes in peripheral blood monocytes and PMN following LPS exposure did not change, indicating that AM and peripheral blood cells show similar response to LPS exposure in vitro. This study provides the basis for a physiological model to study the effects of these two genes in modulating the inflammatory response after particle exposure.

Systemic microvascular dysfunction and inflammation after pulmonary particulate matter exposure.

The epidemiologic association between pulmonary exposure to ambient particulate matter (PM) and cardiovascular dysfunction is well known, but the systemic mechanisms that drive this effect remain unclear. We have previously shown that acute pulmonary exposure to PM impairs or abolishes endothelium-dependent arteriolar dilation in the rat spinotrapezius muscle. The purpose of this study was to further characterize the effect of pulmonary PM exposure on systemic microvascular function and to identify local inflammatory events that may contribute to these effects. Rats were intratracheally instilled with residual oil fly ash (ROFA) or titanium dioxide at 0.1 or 0.25 mg/rat 24 hr before measurement of pulmonary and systemic microvascular responses. In vivo microscopy of the spinotrapezius muscle was used to study systemic arteriolar responses to intraluminal infusion of the Ca2+ ionophore A23187 or iontophoretic abluminal application of the adrenergic agonist phenylephrine (PHE). Leukocyte rolling and adhesion were quantified in venules paired with the studied arterioles. Histologic techniques were used to assess pulmonary inflammation, characterize the adherence of leukocytes to systemic venules, verify the presence of myeloperoxidase (MPO) in the systemic microvascular wall, and quantify systemic microvascular oxidative stress. In the lungs of rats exposed to ROFA or TiO2, changes in some bronchoalveolar lavage markers of inflammation were noted, but an indication of cellular damage was not found. In rats exposed to 0.1 mg ROFA, focal alveolitis was evident, particularly at sites of particle deposition. Exposure to either ROFA or TiO2 caused a dose-dependent impairment of endothelium-dependent arteriolar dilation. However, exposure to these particles did not affect microvascular constriction in response to PHE. ROFA and TiO2 exposure significantly increased leukocyte rolling and adhesion in paired venules, and these cells were positively identified as polymorphonuclear leukocytes (PMNLs). In ROFA- and TiO2-exposed rats, MPO was found in PMNLs adhering to the systemic microvascular wall. Evidence suggests that some of this MPO had been deposited in the microvascular wall. There was also evidence for oxidative stress in the microvascular wall. These results indicate that after PM exposure, the impairment of endothelium-dependent dilation in the systemic microcirculation coincides with PMNL adhesion, MPO deposition, and local oxidative stress. Collectively, these microvascular observations are consistent with events that contribute to the disruption of the control of peripheral resistance and/or cardiac dysfunction associated with PM exposure.

Resistance training increases heat shock protein levels in skeletal muscle of young and old rats.

Heat shock proteins (HSP) HSP72, HSC70 and HSP25 protein levels and mRNA levels of HSP72 genes (Hsp72-1, Hsp72-2, Hsp72-3) and HSC70 were examined in tibialis anterior muscles from young and old rats following 4.5 weeks of heavy resistance exercise. Young (3 months) (n=10) and old (30 months) (n=9) rats were subjected to 14 sessions of electrically evoked resistance training using stretch-shortening contractions of the left limb that activated the dorsiflexor muscle group, including the tibialis anterior muscle, while the right side served as the intra-animal control. Muscle wet weight of the left tibialis anterior increased by 15.6% in young animals compared to the untrained right side, while the aged rats demonstrated no significant hypertrophy based on muscle wet weight. There were no differences in mRNA expression between the control and experimental muscles in either the old or the young animals for any of the four genes examined. On the other hand, HSP72 levels as determined by Western blots were significantly (p<0.01) higher (968.8 and 409.1%) in the trained as compared to the contralateral control muscle in young and old animals, respectively. HSP25 expression was increased significantly (p<0.01) by training in muscles of young rats (943.1%) and old rats (420.3%). Moreover, there was no training by age interaction for HSP72, while a significant age and training by age effects were found in muscles for HSP25. There was no change in HSC70 protein expression in response to the training intervention in either age group. SOD-1 enzyme level increased by 66.6% in the trained muscles of the young rats, while this enzyme was 33% lower in trained muscles compared to the untrained control side in old rats. Moreover, a significant (p<0.05) training by age interaction was found for SOD-1 enzyme levels. This study suggests that fast contracting muscles in young and old animals are capable of increasing HSP expression in response to high intensity contractile stress. Furthermore, the data are consistent with the hypothesis that higher levels of oxidative stress in muscles of old animals limit HSP levels and/or function in response to high intensity contractile stress.

Hemoglobin is expressed by alveolar epithelial cells.

Hemoglobin gene expression in non-erythroid cells has been previously reported in activated macrophages from adult mice and lens cells, and recent studies indicate that alveolar epithelial cells can be derived from hematopoietic stem cells. Our laboratory has now produced strong evidence that hemoglobin is expressed by alveolar type II (ATII) cells and Clara cells, the primary producers of pulmonary surfactant. ATII cells are also closely involved in innate immunity within the lung and are stem cells that differentiate into alveolar type I cells. Reverse transcriptase-PCR was used to measure the expression of transcripts from the alpha- and beta-globin gene clusters in several human and rodent pulmonary epithelial cells. Surprisingly, the two major globin mRNAs characteristic of adult erythroid precursor cells were clearly expressed in human A549 and H441 cell lines, mouse MLE-15 cells, and primary ATII cells isolated from normal rat and mouse lungs. DNA sequencing verified that these PCR products were indeed the result of specific amplification of globin gene cDNAs. These alveolar epithelial cells also expressed the corresponding hemoglobin protein subunits as determined by Western blotting, and tandem mass spectrometry sequencing was used to verify the presence of both alpha- and beta-globin polypeptides in rat primary ATII cells. The function of hemoglobin expression by cells of the pulmonary epithelium will be determined by future studies, but this novel finding could potentially have important implications for the physiology and pathology of the lung.

Efficient expression of transgenes in adult zebrafish by electroporation.

BACKGROUND: Expression of transgenes in muscle by injection of naked DNA is widely practiced. Application of electrical pulses at the site of injection was demonstrated to improve transgene expression in muscle tissue. Zebrafish is a precious model to investigate developmental biology in vertebrates. In this study we investigated the effect of electroporation on expression of transgenes in 3-6 month old adult zebrafish. RESULTS: Electroporation parameters such as number of pulses, voltage and amount of plasmid DNA were optimized and it was found that 6 pulses of 40 V.cm(-1) at 15 microg of plasmid DNA per fish increased the luciferase expression 10-fold compared to controls. Similar enhancement in transgene expression was also observed in Indian carp (Labeo rohita). To establish the utility of adult zebrafish as a system for transient transfections, the strength of the promoters was compared in A2 cells and adult zebrafish after electroporation. The relative strengths of the promoters were found to be similar in cell lines and in adult zebrafish. GFP fluorescence in tissues after electroporation was also studied by fluorescence microscopy. CONCLUSION: Electroporation after DNA injection enhances gene expression 10-fold in adult zebrafish. Electroporation parameters for optimum transfection of adult zebrafish with tweezer type electrode were presented. Enhanced reporter gene expression upon electroporation allowed comparison of strengths of the promoters in vivo in zebrafish.

Time course of gene expression of inflammatory mediators in rat lung after diesel exhaust particle exposure.

Diesel exhaust particles (DEPs) at three concentrations (5, 35, and 50 mg/kg body weight) were instilled into rats intratracheally. We studied gene expression at 1, 7, and 30 days postexposure in cells obtained by bronchoalveolar lavage (BAL) and in lung tissue. Using real-time reverse transcriptase-polymerase chain reaction (RT-PCR), we measured the mRNA levels of eight genes [interleukin (IL)-1beta, IL-6, IL-10, iNOS (inducible nitric oxide synthase), MCP-1 (monocyte chemoattractant protein-1), MIP-2 (macrophage inflammatory protein-2), TGF-beta1 (transforming growth factor-beta1), and TNF-alpha (tumor necrosis factor-alpha )] in BAL cells and four genes [IL-6, ICAM-1 (intercellular adhesion molecule-1), GM-CSF (granulocyte/macrophage-colony stimulating factor), and RANTES (regulated upon activation normal T cell expressed and secreted)] in lung tissue. In BAL cells on day 1, high-dose exposure induced a significant up-regulation of IL-1beta, iNOS, MCP-1, and MIP-2 but no change in IL-6, IL-10, TGF-beta1, and TNF-alpha mRNA levels. There was no change in the mRNA levels of IL-6, RANTES, ICAM-1, and GM-CSF in lung tissue. Nitric oxide production and levels of MCP-1 and MIP-2 were increased in the 24-hr culture media of alveolar macrophages (AMs) obtained on day 1. IL-6, MCP-1, and MIP-2 levels were also elevated in the BAL fluid. BAL fluid also showed increases in albumin and lactate dehydrogenase. The cellular content in BAL fluid increased at all doses and at all time periods, mainly due to an increase in polymorphonuclear leukocytes. In vitro studies in AMs and cultured lung fibroblasts showed that lung fibroblasts are a significant source of IL-6 and MCP-1 in the lung.

The sources of inflammatory mediators in the lung after silica exposure.

The expression of 10 genes implicated in regulation of the inflammatory processes in the lung was studied after exposure of alveolar macrophages (AMs) to silica in vitro or in vivo. Exposure of AMs to silica in vitro up-regulated the messenger RNA (mRNA) levels of three genes [interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2 (MIP-2)] without a concomitant increase in the protein levels. AMs isolated after intratracheal instillation of silica up-regulated mRNA levels of four additional genes [granulocyte/macrophage-colony stimulating factor (GM-CSF), IL-1beta, IL-10, and inducible nitric oxide synthase]. IL-6, MCP-1, and MIP-2 protein levels were elevated in bronchoalveolar lavage fluid. Fibroblasts under basal culture conditions express much higher levels of IL-6 and GM-CSF compared with AMs. Coculture of AMs and alveolar type II cells, or coculture of AMs and lung fibroblasts, in contact cultures or Transwell chambers, revealed no synergistic effect. Therefore, such interaction does not explain the effects seen in vivo. Identification of the intercellular communication in vivo is still unresolved. However, fibroblasts appear to be an important source of inflammatory mediators in the lung.