Evidence for a lipofibroblast-to- Cthrc1 + myofibroblast reversible switch during the development and resolution of lung fibrosis in young mice.

BACKGROUND: Fibrosis is often associated with aberrant repair mechanisms that ultimately lead to organ failure. In the lung, idiopathic pulmonary fibrosis (IPF) is a fatal form of interstitial lung disease (ILD) to which there is currently no curative therapy. From the cell biology point of view, the cell of origin and eventual fate of activated myofibroblasts (aMYFs) have taken center stage as these cells are believed to drive structural remodeling and lung function impairment. While aMYFs are now widely believed to originate from resident fibroblasts, the heterogeneity of aMYFs and ultimate fate during fibrosis resolution remain elusive. We have previously shown that aMYFs dedifferentiation and acquisition of a lipofibroblast (LIF)-like phenotype represent a route of fibrosis resolution. METHODS: In this study, we combined genetic lineage tracing and single-cell transcriptomics in mice, and data mining of human IPF datasets to decipher the heterogeneity of aMYFs and investigate differentiation trajectories during fibrosis resolution. Furthermore, organoid cultures were utilized as a functional readout for the alveolar mesenchymal niche activity during various phases of injury and repair in mice. RESULTS: Our data demonstrate that aMYFs consist of four subclusters displaying unique pro-alveologenic versus profibrotic profiles. Alveolar fibroblasts displaying a high LIF-like signature largely constitute both the origin and fate of aMYFs during fibrogenesis and resolution respectively. The heterogeneity of aMYFs is conserved in humans and a significant proportion of human aMYFs displays a high LIF signature. CONCLUSION: Our work identifies a subcluster of aMYFs that is potentially relevant for future management of IPF.

FGF10 Triggers De Novo Alveologenesis in a Bronchopulmonary Dysplasia Model: Impact on Resident Mesenchymal Niche Cells.

Bronchopulmonary dysplasia (BPD) is a neonatal lung disease developing in premature babies characterized by arrested alveologenesis and associated with decreased Fibroblast growth factor 10 (FGF10) expression. One-week hyperoxia (HYX) exposure of newborn mice leads to a permanent arrest in alveologenesis. To test the role of Fgf10 signaling to promote de novo alveologenesis following hyperoxia, we used transgenic mice allowing inducible expression of Fgf10 and recombinant FGF10 (rFGF10) protein delivered intraperitoneally. We carried out morphometry analysis, and IF on day 45. Alveolospheres assays were performed co-culturing AT2s from normoxia (NOX) with FACS-isolated Sca1Pos resident mesenchymal cells (rMC) from animals exposed to NOX, HYX-PBS, or HYX-FGF10. scRNAseq between rMC-Sca1Pos isolated from NOX and HYX-PBS was also carried out. Transgenic overexpression of Fgf10 and rFGF10 administration rescued the alveologenesis defects following HYX. Alveolosphere assays indicate that the activity of rMC-Sca1Pos is negatively impacted by HYX and partially rescued by rFGF10 treatment. Analysis by IF demonstrates a significant impact of rFGF10 on the activity of resident mesenchymal cells. scRNAseq results identified clusters expressing Fgf10, Fgf7, Pdgfra, and Axin2, which could represent the rMC niche cells for the AT2 stem cells. In conclusion, we demonstrate that rFGF10 administration is able to induce de novo alveologenesis in a BPD mouse model and identified subpopulations of rMC-Sca1Pos niche cells potentially representing its cellular target.

Addition of intravitreal carboplatin with melphalan for management of vitreous seeding in retinoblastoma.

PURPOSE: To evaluate the efficacy and toxicity of intravitreal carboplatin plus melphalan for the treatment of vitreous seeds in eyes with retinoblastoma (RB). METHODS: This retrospective series at a tertiary referral center included 22 consecutive RB patients who had received intravitreal carboplatin (16 µg per 0.05 ml) combined with melphalan (30 µg in 0.03 ml) [IVi (Ca-Me)] for treatment of vitreous seeds. Tumor control and drug toxicities were recorded. RESULTS: There were 22 eyes of 22 patients, divided into primary group (n = 13) without history of previous intravitreal chemotherapy (IViC) and refractory group (n = 9) with history of previous IViC using melphalan and/or topotecan. The demographics and clinical findings of the primary and refractory groups did not differ significantly. The 6-month follow-up revealed complete vitreous seed control (77% vs. 89%, p = 0.47). Vitreous seed recurrence was detected in 1 eye of each group at 6 months. During the next 18-month follow-up period, no recurrence of seed was observed. The response to IVi (Ca-Me) was not significantly influenced by previous IViC (p = 0.70), primary systemic or intra-arterial chemotherapy (p = 0.45), or the type of regression (p = 0.35). The most common tumor treatment complications were retinal detachment (RD) (n = 2), early hypotony (n = 2) and late hypotony (n = 4, unrelated), cataract (n = 2), and severe pigment dispersion (n = 1). Enucleation was performed in 8 eyes, for total RD (n = 1), phthisis bulbi (n = 5), and extensive solid tumor recurrence (n = 2). There was no case of orbital invasion, systemic metastasis, or death. CONCLUSION: Based on this interventional case series for primary and refractory vitreous RB seeds, carboplatin plus melphalan therapy may be effective with few toxic side effects.

KRAS, NRAS, BRAF, and PIK3CA mutation rates, clinicopathological association, and their prognostic value in Iranian colorectal cancer patients.

AIM: Mutations in KRAS, NRAS, BRAF, and PIK3CA genes are critical factors in clinical evaluation of colorectal cancer (CRC) development and progression. In Iran, however, the data regarding genetic profile of CRC patients is limited except for KRAS exon2 and BRAF V600F mutations. This study aimed to investigate the mutational spectrum and prognostic effects of these genes and explore the relationship between these mutations and clinicopathological features of CRC. METHOD: To achieve these objectives, mutations in KRAS (exons 2, 3, and 4), NRAS (exons 2, 3, and 4), PIK3CA (exons 9 and 20), and BRAF (exon 15) was determined using PCR and pyrosequencing in a total of 151 patients with colorectal cancer. RESULTS: KRAS, BRAF, NRAS, and PIK3CA mutations were identified in 41%, 5.96%, 3.97%, and 13.24% of the cases, respectively. There were some significant correlations between clinicopathological features and KRAS, PIK3CA, BRAF, and NRAS mutations. Mutations in KRAS and PIK3CA were shown to be independent risk factors for poor survival of the patients at stage I-IV (p < 0.0001 and p = 0.001, respectively). No significant impact on prognosis was observed in patients with BRAF mutations. CONCLUSION: Our study revealed the prevalence of CRC biomarkers mutations in Iranian patients and emphasized the role of KRAS and PIK3CA on shorter overall survival rates in this population.

Characterization in mice of the resident mesenchymal niche maintaining AT2 stem cell proliferation in homeostasis and disease.

Resident mesenchymal cells (rMCs defined as Cd31Neg Cd45Neg EpcamNeg ) control the proliferation and differentiation of alveolar epithelial type 2 (AT2) stem cells in vitro. The identity of these rMCs is still elusive. Among them, Axin2Pos mesenchymal alveolar niche cells (MANCs), which are expressing Fgf7, have been previously described. We propose that an additional population of rMCs, expressing Fgf10 (called rMC-Sca1Pos Fgf10Pos ) are equally important to maintain AT2 stem cell proliferation. The alveolosphere model, based on the AT2-rMC co-culture in growth factor-reduced Matrigel, was used to test the efficiency of different rMC subpopulations isolated by FACS from adult murine lung to sustain the proliferation and differentiation of AT2 stem cells. We demonstrate that rMC-Sca1Pos Fgf10Pos cells are efficient to promote the proliferation and differentiation of AT2 stem cells. Co-staining of adult lung for Fgf10 mRNA and Sftpc protein respectively, indicate that 28% of Fgf10Pos cells are located close to AT2 cells. Co-ISH for Fgf7 and Fgf10 indicate that these two populations do not significantly overlap. Gene arrays comparing rMC-Sca1Pos Axin2Pos and rMC-Sca1Pos Fgf10Pos support that these two cell subsets express differential markers. In addition, rMC function is decreased in obese ob/ob mutant compared to WT mice with a much stronger loss of function in males compared to females. In conclusion, rMC-Sca1Pos Fgf10Pos cells play important role in supporting AT2 stem cells proliferation and differentiation. This result sheds a new light on the subpopulations of rMCs contributing to the AT2 stem cell niche in homeostasis and in the context of pre-existing metabolic diseases.

Targeting p16INK4a Promotes Lipofibroblasts and Alveolar Regeneration after Early-Life Injury.

Rationale: Promoting endogenous pulmonary regeneration is crucial after damage to restore normal lungs and prevent the onset of chronic adult lung diseases.Objectives: To investigate whether the cell-cycle inhibitor p16INK4a limits lung regeneration after newborn bronchopulmonary dysplasia (BPD), a condition characterized by the arrest of alveolar development, leading to adult sequelae.Methods: We exposed p16INK4a-/- and p16INK4aATTAC (apoptosis through targeted activation of caspase 8) transgenic mice to postnatal hyperoxia, followed by pneumonectomy of the p16INK4a-/- mice. We measured p16INK4a in blood mononuclear cells of preterm newborns, 7- to 15-year-old survivors of BPD, and the lungs of patients with BPD.Measurements and Main Results: p16INK4a concentrations increased in lung fibroblasts after hyperoxia-induced BPD in mice and persisted into adulthood. p16INK4a deficiency did not protect against hyperoxic lesions in newborn pups but promoted restoration of the lung architecture by adulthood. Curative clearance of p16INK4a-positive cells once hyperoxic lung lesions were established restored normal lungs by adulthood. p16INK4a deficiency increased neutral lipid synthesis and promoted lipofibroblast and alveolar type 2 (AT2) cell development within the stem-cell niche. Besides, lipofibroblasts support self-renewal of AT2 cells into alveolospheres. Induction with a PPARγ (peroxisome proliferator-activated receptor γ) agonist after hyperoxia also increased lipofibroblast and AT2 cell numbers and restored alveolar architecture in hyperoxia-exposed mice. After pneumonectomy, p16INK4a deficiency again led to an increase in lipofibroblast and AT2 cell numbers in the contralateral lung. Finally, we observed p16INK4a mRNA overexpression in the blood and lungs of preterm newborns, which persisted in the blood of older survivors of BPD.Conclusions: These data demonstrate the potential of targeting p16INK4a and promoting lipofibroblast development to stimulate alveolar regeneration from childhood to adulthood.

Use of three-dimensional organoids and lung-on-a-chip methods to study lung development, regeneration and disease.

Differences in lung anatomy between mice and humans, as well as frequently disappointing results when using animal models for drug discovery, emphasise the unmet need for in vitro models that can complement animal studies and improve our understanding of human lung physiology, regeneration and disease. Recent papers have highlighted the use of three-dimensional organoids and organs-on-a-chip to mimic tissue morphogenesis and function in vitro Here, we focus on the respiratory system and provide an overview of these in vitro models, which can be derived from primary lung cells and pluripotent stem cells, as well as healthy or diseased lungs. We emphasise their potential application in studies of respiratory development, regeneration and disease modelling.

MicroRNA-142 is a multifaceted regulator in organogenesis, homeostasis, and disease.

Over the past decade, microRNA-142 (miR-142) is emerging as a major regulator of cell fate decision in the hematopoietic system. However, miR-142 is expressed in many other tissues, and recent evidence suggests that it may play a more pleiotropic role during embryonic development. In addition, miR-142 has been shown to play important functions in disease. miR-142 displays a functional role in cancer, virus infection, inflammation, and immune tolerance. Both a guide strand (miR-142-3p) and passenger strand (miR-142-5p) are generated from the miR-142 hairpin. miR-142-3p and -5p display overlapping but also independent target genes. Loss of function mouse models (genetrap, global knock out [KO], and conditional KO) have been reported and support the important role of miR-142 in different biological processes. This review will summarize the abundant literature already available for miR-142 and will lay the foundation for future works on this important microRNA. Developmental Dynamics 246:285-290, 2017. © 2016 Wiley Periodicals, Inc.

Genetic Variants in the Fat Mass and Obesity-Associated Gene and Risk of Obesity/Overweight in Children and Adolescents: A Systematic Review and Meta-Analysis.

OBJECTIVE: The variations in the single-nucleotide polymorphisms (SNPs) of the fat mass and obesity (FTO)-associated gene have been linked to being overweight or obese in children. In this research a thorough examination was performed to elucidate the connection between various FTO gene SNPs and overweight or obesity in children and adolescents. METHOD: We searched PubMed, Google scholar, Web of Science and Scopus until January 2024 to find studies that investigate the association between different SNPs of FTO gene and the risk of overweight/obesity in children and adolescents. After filtering the relevant studies, meta-analysis was used to quantify the association of FTO gene SNPs within different genetic inheritance models. RESULTS: We have identified 32 eligible studies with 14,930 obese/overweight cases and 24,765 healthy controls. Our recessive model showed a significant association with rs9939609 (OR: 1.56, 95% CI: 1.20; 2.02, p < 0.01) and rs1421085 (OR: 1.77, 95% CI: 1.14; 2.75, p < 0.01). Besides, in the homozygote model, rs1421085 showed the highest association (OR: 2.32, 95% CI: 1.38; 3.89, p < 0.01) with the risk of obesity in a population of children and adolescents. Moreover, there are other SNPs of FTO genes, such as rs9921255, rs9928094 and rs9930333, which showed a positive association with obesity and overweight. However, their effects were evaluated in very few numbers of studies. CONCLUSION: In this study, we have found that the FTO rs9939609 and rs1421085 are associated to an increased risk of obesity among children and adolescents. Besides, the findings of this study further reaffirmed the established link between rs9939609 and obesity in children and adolescents.

Familial primary calcific band-shaped keratopathy with late onset systemic disease: a case series and review of the literature.

BACKGROUND: Familial calcific band-shaped keratopathy (BSK) is a very rare disease, with no underlying cause. There is no underlying disease in this form of the disease. This article introduces a family with seven children, three of whom were diagnosed with familial primary calcific BSK. One of them developed a systemic disease 38 years after ocular manifestation. CASE PRESENTATION: In this case report, three Iranian siblings from a family with familial calcific band-shaped keratopathy (BSK) are introduced. Systemic and ocular examinations performed on these patients indicated the occurrence of chronic kidney disease in the older child, a 41-year-old woman, 38 years after ocular manifestation. The examinations conducted on the other two siblings revealed no pathological findings. The 41-year-old sister and 37-year-old brother underwent unilateral deep anterior lamellar keratoplasty (DALK), while the 33-year-old sister underwent bilateral superficial keratectomy (SK). CONCLUSION: Considering the late onset of systemic disease in one of the siblings diagnosed with familial calcific band-shaped keratopathy (BSK), it is crucial to emphasize the necessity of long-term follow-up for these patients and their families.

Highlighting fibroblast plasticity in lung fibrosis: the WI-38 cell line as a model for investigating the myofibroblast and lipofibroblast switch.

Background: Myofibroblasts (MYFs) are generally considered the principal culprits in excessive extracellular matrix deposition and scar formation in the pathogenesis of lung fibrosis. Lipofibroblasts (LIFs), on the other hand, are defined by their lipid-storing capacity and are predominantly found in the alveolar regions of the lung. They have been proposed to play a protective role in lung fibrosis. We previously reported that a LIF to MYF reversible differentiation switch occurred during fibrosis formation and resolution. In this study, we tested whether WI-38 cells, a human embryonic lung fibroblast cell line, could be used to study fibroblast differentiation towards the LIF or MYF phenotype and whether this could be relevant for idiopathic pulmonary fibrosis (IPF). Methods: Using WI-38 cells, Fibroblast (FIB) to MYF differentiation was triggered using TGF-ß1 treatment and FIB to LIF differentiation using Metformin treatment. We also analyzed the MYF to LIF and LIF to MYF differentiation by pre-treating the WI-38 cells with TGF-ß1 or Metformin respectively. We used IF, qPCR and bulk RNA-Seq to analyze the phenotypic and transcriptomic changes in the cells. We correlated our in vitro transcriptome data from WI-38 cells (obtained via bulk RNA sequencing) with the transcriptomic signature of LIFs and MYFs derived from the IPF cell atlas as well as with our own single-cell transcriptomic data from IPF patients-derived lung fibroblasts (LF-IPF) cultured in vitro. We also carried out alveolosphere assays to evaluate the ability of the proposed LIF and MYF cells to support the growth of alveolar epithelial type 2 cells. Results: WI-38 cells and LF-IPF display similar phenotypical and gene expression responses to TGF-ß1 and Metformin treatment. Bulk RNA-Seq analysis of WI-38 cells and LF-IPF treated with TGF-ß1, or Metformin indicate similar transcriptomic changes. We also show the partial conservation of the LIF and MYF signature extracted from the Habermann et al. scRNA-seq dataset in WI-38 cells treated with Metformin or TGF-ß1, respectively. Alveolosphere assays indicate that LIFs enhance organoid growth, while MYFs inhibit organoid growth. Finally, we provide evidence supporting the MYF to LIF and LIF to MYF reversible switch using WI-38 cells. Conclusions: WI-38 cells represent a versatile and reliable model to study the intricate dynamics of fibroblast differentiation towards the MYF or LIF phenotype associated with lung fibrosis formation and resolution, providing valuable insights to drive future research.

Massive Uveal Relapse of Retinoblastoma Presumed to Be Choroidal Tumorous Involvement: Case Series.

We report the choroidal and ciliary body invasion by retinoblastoma (RB) in a salvaged eye after complete and successful primary treatment. Case 1: A 25-month-old boy was referred due to group B RB lesions based on the International Classification of RB (ICRB; groups A-E) in the right eye (OD). His left eye (OS) was enucleated because of advanced group E RB. After 47 months of uneventful follow-up (F/U), a new lesion recurred and was treated with transpupillary thermotherapy. Four months later, a fast-growing pigmented subretinal mass was detected that was treated by brachytherapy with the apical dose of 80 Gy. Three weeks later, the lesion regressed completely, and no recurrence happened after 6 years of F/U. Case 2: A 4-month-old girl with a deletion in chromosome 13 was referred for bilateral RB. OD was enucleated because of unresponsive RB and anterior segment involvement. In OS, group B lesions had multiple recurrences after systemic chemotherapy. After a while, a single mass appeared in the nasal periphery which was controlled well with brachytherapy. Four months later, AC involvement was controlled with IAC, intravitreal, and intracameral chemotherapy, but posterior synechia and cataract appeared later. One year after the last treatment, UBM showed a ring-shaped ciliary body mass. Her parents refused enucleation again, and she received intravenous chemotherapy. Two years later, magnetic resonance imaging showed orbital and optic canal involvement with a deformed globe. In conclusion, RB recurrence can appear as local choroidal and ciliary body involvement even after a time of complete remission. The role of B-scan and UBM in early diagnosis and successful treatment is valuable.

A Novel Missense Mutation in the TGF-ß-binding Protein-Like Domain 3 of FBN1 Causes Weill-Marchesani Syndrome with Intellectual Disability.

Background: Weill-Marchesani syndrome (WMS) is a rare connective tissue disorder characterized by locus heterogeneity and variable expressivity. Patients suffering from WMS are described by short stature, brachydactyly, joint stiffness, congenital heart defects, and eye abnormalities. This disorder is inherited in two different modes; the autosomal dominant form of the disease occurs due to a mutation in FBN1, and the recessive form results from mutations in ADAMTS10, ADAMTS17, or LTP2 genes. Materials and Methods: The family recruited in this study was a consanguineous Iranian family with an intellectually disabled girl referred to the Sadra Genetics laboratory, Shahrekord, Iran. The clinical history of family members was investigated. Whole-Exome Sequencing (WES) for the proband was performed. Sanger sequencing was used to assess the segregation of candidate variants in the other family members. Results: Whole-exome sequencing analysis revealed a novel heterozygote mutation in the proband located at the third TGF-ß-binding protein-like (TB) domain of the FBN1 gene (NM000138: c.2066A>G: (p. Glu689Gly), NP_000129.3, in exon 17 of the gene). Co-segregation analysis with Sanger sequencing confirmed this mutation in the affected members of the pedigree. Conclusion: Our findings represent an autosomal dominant form of specific WMS resulting from a substitution mutation in the FBN1 gene. In addition to the typical manifestations of the disorder, mild intellectual disability (ID) was identified in the 8-year-old proband. Given the fact that ID is primarily reported in ADAMTS10 mutated cases, this family was clinically and genetically a novel case.

Validation of a Novel Fgf10 Cre-ERT2 Knock-in Mouse Line Targeting FGF10Pos Cells Postnatally.

Fgf10 is a key gene during development, homeostasis and repair after injury. We previously reported a knock-in Fgf10 Cre-ERT2 line (with the Cre-ERT2 cassette inserted in frame with the start codon of exon 1), called thereafter Fgf10 Ki-v1, to target FGF10Pos cells. While this line allowed fairly efficient and specific labeling of FGF10Pos cells during the embryonic stage, it failed to target these cells after birth, particularly in the postnatal lung, which has been the focus of our research. We report here the generation and validation of a new knock-in Fgf10 Cre-ERT2 line (called thereafter Fgf10 Ki-v2) with the insertion of the expression cassette in frame with the stop codon of exon 3. Fgf10 Ki-v2/+ heterozygous mice exhibited comparable Fgf10 expression levels to wild type animals. However, a mismatch between Fgf10 and Cre expression levels was observed in Fgf10 Ki-v2/+ lungs. In addition, lung and limb agenesis were observed in homozygous embryos suggesting a loss of Fgf10 functional allele in Fgf10 Ki-v2 mice. Bioinformatic analysis shows that the 3'UTR, where the Cre-ERT2 cassette is inserted, contains numerous putative transcription factor binding sites. By crossing this line with tdTomato reporter line, we demonstrated that tdTomato expression faithfully recapitulated Fgf10 expression during development. Importantly, Fgf10 Ki-v2 mouse is capable of significantly targeting FGF10Pos cells in the adult lung. Therefore, despite the aforementioned limitations, this new Fgf10 Ki-v2 line opens the way for future mechanistic experiments involving the postnatal lung.

Potential Impact of Diabetes and Obesity on Alveolar Type 2 (AT2)-Lipofibroblast (LIF) Interactions After COVID-19 Infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a new emerging respiratory virus, caused evolving pneumonia outbreak around the world. In SARS-Cov-2 infected patients, diabetes mellitus (DM) and obesity are two metabolic diseases associated with higher severity of SARS-CoV-2 related complications, characterized by acute lung injury requiring assisted ventilation as well as fibrosis development in surviving patients. Different factors are potentially responsible for this exacerbated response to SARS-CoV-2 infection. In patients with DM, base-line increase in inflammation and oxidative stress represent preexisting risk factors for virus-induced damages. Such factors are also likely to be found in obese patients. In addition, it has been proposed that massive injury to the alveolar epithelial type 2 (AT2) cells, which express the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2), leads to the activation of their stromal niches represented by the Lipofibroblasts (LIF). LIF are instrumental in maintaining the self-renewal of AT2 stem cells. LIF have been proposed to transdifferentiate into Myofibroblast (MYF) following injury to AT2 cells, thereby contributing to fibrosis. We hypothesized that LIF's activity could be impacted by DM or obesity in an age- and gender-dependent manner, rendering them more prone to transition toward the profibrotic MYF status in the context of severe COVID-19 pneumonia. Understanding the cumulative effects of DM and/or obesity in the context of SARS-CoV-2 infection at the cellular level will be crucial for efficient therapeutic solutions.

Molecular Diagnosis of Hereditary Neuropathies by Whole Exome Sequencing and Expanding the Phenotype Spectrum.

BACKGROUND: Inherited peripheral neuropathies (IPNs) are a group of neuropathies affecting peripheral motor and sensory neurons. Charcot-Marie-Tooth (CMT) disease is the most common disease in this group. With recent advances in next-generation sequencing (NGS) technologies, more than 100 genes have been implicated for different types of CMT and other clinically and genetically inherited neuropathies. There are also a number of genes where neuropathy is a major feature of the disease such as spinocerebellar ataxia (SCA) and hereditary spastic paraplegia (HSP). We aimed to determine the genetic causes underlying IPNs in Iranian families. METHODS: We performed whole exome sequencing (WES) for 58 PMP22 deletion-/duplication-negative unrelated Iranian patients with a spectrum of phenotypes and with a preliminary diagnosis of hereditary neuropathies. RESULTS: Twenty-seven (46.6%) of the cases were genetically diagnosed with pathogenic or likely pathogenic variants. In this study, we identified genetically strong variants within genes not previously linked to any established disease phenotype in five (8.6%) patients. CONCLUSION: Our results highlight the advantage of using WES for genetic diagnosis in highly heterogeneous diseases such as IPNs. Moreover, functional analysis is required for novel and uncertain variants.

Fgf10 Signaling-Based Evidence for the Existence of an Embryonic Stage Distinct From the Pseudoglandular Stage During Mouse Lung Development.

The existence during mouse lung development of an embryonic stage temporally and functionally distinct from the subsequent pseudoglandular stage has been proposed but never demonstrated; while studies in human embryonic lung tissue fail to recapitulate the molecular control of branching found in mice. Lung development in mice starts officially at embryonic day (E) 9.5 when on the ventral side of the primary foregut tube, both the trachea and the two primary lung buds emerge and elongate to form a completely separate structure from the foregut by E10. In the subsequent 6 days, the primary lung buds undergo an intense process of branching to form a ramified tree by E16.5. We used transgenic mice allowing to transiently inhibit endogenous fibroblast growth factor 10 (Fgf10) activity in mutant embryos at E9, E9.5, and E11 upon intraperitoneal exposure to doxycycline and examined the resulting lung phenotype at later developmental stages. We also determined using gene arrays the transcriptomic response of flow cytometry-isolated human alveolar epithelial progenitor cells derived from hESC or hiPSC, grown in vitro for 12 or 24 h, in the presence or absence of recombinant FGF10. Following injection at E9, the corresponding mutant lungs at E18.5 appear almost normal in size and shape but close up examination indicate failure of the right lung to undergo lobar septation. At E9.5, the lungs are slightly hypoplastic but display normal differentiation and functionality. However, at E11, the lungs show impaired branching and are no longer functional. Using gene array data, we report only a partial overlap between human and mouse in the genes previously shown to be regulated by Fgf10 at E12.5. This study supports the existence of an embryonic stage of lung development where Fgf10 signaling does not play a function in the branching process but rather in lobar septation. It also posits that functional comparisons between mouse and human organogenesis must account for these distinct stages.

Evaluation of chromosomal aberrations caused by air pollutants in some taxi drivers from two polluted districts of urban Tehran and its comparison with drivers from rural areas of Lahijan: a pilot study.

BACKGROUND: Chromosome instability is the most common form of genomic instability. Genomic instability can lead to tumorogenesis. High level of chromosomal aberrations in peripheral blood lymphocytes can be used as a biomarker for cancer. Air pollution is one of the most important factors that cause chromosomal instability (CIN). In this comparative study we used classic Cytogenetic technique to analyze the effects of air pollutants on chromosome stability. We collected peripheral blood from 30 taxi drivers of two polluted districts (districts 6 and 7) in Tehran and 30 taxi drivers from rural areas of Lahijan, north of Iran. RESULTS: Comparison of the level of chromosome breakage in the two groups showed an increased level of chromosome breakage in the drivers from polluted districts of Tehran, although not significant, using Fisher exact test (p-value = 0.300). However, the overall chromosome aberration rate (including both chromosome and chromatid gaps), the difference was significant using Chi-square test (p-value = 0.012). CONCLUSION: An increased level of chromosome aberration was present in the drivers from polluted districts of Tehran compared to drivers from non-polluted areas in Lahijan.