Peculiar Ca2+ Homeostasis, ER Stress, Autophagy, and TG2 Modulation in Celiac Disease Patient-Derived Cells.

Celiac disease (CD) is an inflammatory intestinal disease caused by the ingestion of gluten-containing cereals by genetically predisposed individuals. Constitutive differences between cells from CD patients and control subjects, including levels of protein phosphorylation, alterations of vesicular trafficking, and regulation of type 2 transglutaminase (TG2), have been reported. In the present work, we investigated how skin-derived fibroblasts from CD and control subjects responded to thapsigargin, an endoplasmic reticulum ER stress inducer, in an attempt to contribute to the comprehension of molecular features of the CD cellular phenotype. We analyzed Ca2+ levels by single-cell video-imaging and TG2 activity by a microplate assay. Western blots and PCR analyses were employed to monitor TG2 levels and markers of ER stress and autophagy. We found that the cytosolic and ER Ca2+ level of CD cells was lower than in control cells. Treatments with thapsigargin differently activated TG2 in control and CD cells, as well as caused slightly different responses regarding the activation of ER stress and the expression of autophagic markers. On the whole, our findings identified further molecular features of the celiac cellular phenotype and highlighted that CD cells appeared less capable of adapting to a stress condition and responding in a physiological way.

Advance in hyperbaric oxygen therapy in spinal cord injury.

Spinal cord injury (SCI) is a severe lesion comporting various motor, sensory and sphincter dysfunctions, abnormal muscle tone and pathological reflex, resulting in a severe and permanent lifetime disability. The primary injury is the immediate effect of trauma and includes compression, contusion, and shear injury to the spinal cord. A secondary and progressive injury usually follows, beginning within minutes and evolving over several hours after the first ones. Because ischemia is one of the most important mechanisms involved in secondary injury, a treatment to increase the oxygen tension of the injured site, such as hyperbaric oxygen therapy, should theoretically help recovery. Although a meta-analysis concluded that hyperbaric oxygen therapy might be helpful for clinical treatment as a safe, promising and effective choice to limit secondary injury when appropriately started, useful and well-defined protocols/guidelines still need to be created, and its application is influenced by local/national practice. The topic is not a secondary issue because a well-designed randomized controlled trial requires a proper sample size to demonstrate the clinical efficacy of a treatment, and the absence of a common practice guideline represents a limit for results generalization. This narrative review aims to reassemble the evidence on hyperbaric oxygen therapy to treat SCI, focusing on adopted protocols in the studies and underlining the critical issues. Furthermore, we tried to elaborate on a protocol with a flowchart for an evidence-based hyperbaric oxygen therapy treatment. In conclusion, a rationale and shared protocol to standardize as much as possible is needed for the population to be studied, the treatment to be adopted, and the outcomes to be evaluated. Further studies, above all, well-designed randomized controlled trials, are needed to clarify the role of hyperbaric oxygen therapy as a strategic tool to prevent/reduce secondary injury in SCI and evaluate its effectiveness based on an evidence-based treatment protocol. We hope that adopting the proposed protocol can reduce the risk of bias and drive future studies.

Type 2 Transglutaminase in Coeliac Disease: A Key Player in Pathogenesis, Diagnosis and Therapy.

Type 2 transglutaminase (TG2) is the main autoantigen in coeliac disease (CD), a widespread inflammatory enteropathy caused by the ingestion of gluten-containing cereals in genetically predisposed individuals. As a consequence, serum antibodies to TG2 represent a very useful marker in CD diagnosis. However, TG2 is also an important player in CD pathogenesis, for its ability to deamidate some Gln residues of gluten peptides, which become more immunogenic in CD intestinal mucosa. Given the importance of TG2 enzymatic activities in CD, several studies have sought to discover specific and potent inhibitors that could be employed in new therapeutical approaches for CD, as alternatives to a lifelong gluten-free diet. In this review, we summarise all the aspects regarding TG2 involvement in CD, including its enzymatic reactions in pathogenesis, the role of anti-TG2 antibodies in disease management, and the exploration of recent strategies to reduce deamidation or to use transamidation to detoxify gluten.

Pro-Apoptotic and Pro-Autophagic Properties of Cardenolides from Aerial Parts of Pergularia tomentosa

Pergularia tomentosa L., a milkweed tropical plant belonging to the family Asclepiadaceae, is a rich source of unusual cardiac glycosides, characterised by transfused A/B rings and a sugar moiety linked by a double link, generating a dioxanoid structure. In the present report, five cardenolides isolated from the aerial parts of the plant (calactin, calotropin, 12ß-hydroxycalactin, 12ß,6'-dihydroxycalotropin, and 16α-hydroxycalotropin) were investigated for their biological effects on a human hepatocarcinoma cell line. Cell viability was monitored by an MTT assay. The occurrence of apoptosis was evaluated by detecting caspase-3 activation and chromatin fragmentation. The ability of these compounds to induce autophagy was analysed by monitoring two markers of the autophagic process, LC3 and p62. Our results indicated that all cardenolides had cytotoxic effects, with IC50 ranging from 0.127 to 6.285 µM. All compounds were able to induce apoptosis and autophagy, calactin being the most active one. Some of them also caused a reduction in cell migration and a partial block of the cell cycle into the S-phase. The present study suggests that selected cardenolides from aerial parts of P. tomentosa, particularly calactin, possess potentially desirable properties for further investigation as anticancer agents.

Incidence of malignant mesothelioma and asbestos exposure in the Emilia-Romagna region, Italy.

BACKGROUND: The aim of this study is to describe the incidence of malignant mesothelioma (MM) and asbestos exposure in an Italian region in the period 1996-June 2021. METHODS: The study included cases with microscopic confirmation and those with instrumental confirmation. For each case, information on sex, age, tumour site, morphology and date of diagnosis was collected, along with details of exposure to asbestos. RESULTS: 3,097 cases of MM (2,233 males and 864 females) were registered: 90.8% with microscopic confirmation. A total of 2,840 cases involved the pleura (92%), 230 cases the peritoneum (7%), and a small number of cases the pericardium and testis (9 and 18, respectively). Most cases (78.0%) occurred after 65 years of age, while only 1.5% concerned individuals with age < 45 years. The standardized incidence rate for the entire period (adjusted to the 2000 Italian standard population and calculated per 100,000 person-years) was equal to 3.9 in males and 1.4 in females, and the trend showed an increase with age in both sexes. Concerning asbestos exposure, 79.7% of cases were exposed (86.7% males and 60.1% females). In 70.3%, exposure was occupational (83.4% males and 33.2% females), while 20.7% of females and 0.8% of males had familial exposure. Building construction, rolling stock manufacture/repair and metalworking were the most prevalent economic activities associated with occupational exposure. CONCLUSIONS: This study offers an overview of MM in an Italian region characterized by high incidence and high exposure due to its particular production activities.

The mechanism of cytotoxicity of 4-nonylphenol in a human hepatic cell line involves ER-stress, apoptosis, and mitochondrial dysfunction.

4-Nonylphenol (4-NP) is an emerging environmental pollutant widely diffused in waters and sediments. It mainly derives from the degradation of alkyl phenol ethoxylates, compounds commonly employed as industrial surfactants. 4-NP strongly contaminates foods and waters for human use; thus, it displays a wide range of toxic effects not only for aquatic organisms but also for mammals and humans. After ingestion through the diet, it tends to accumulate in body fluids and tissues. One of the main organs where 4-NP and its metabolites are concentrated is the liver, where it causes, even at low doses, oxidative stress and apoptosis. In the present study, we analyzed the effects of 4-NP on a human hepatic cell line (HepG2) to deepen the knowledge of its cytotoxic mechanism. We found that 4-NP, in a range of concentration from 50 to 100 µM, significantly reduced cell viability; it caused a partial block of proliferation and induced apoptosis with activation of caspase-3 and overexpression of p53. Moreover, 4-NP induced-apoptosis seemed to involve both an ER-stress response, with the appearance of high level of GRP78, CHOP and the spliced XBP1, and a dysregulation of mitochondrial physiology, characterized by an overexpression of main markers of mitochondrial dynamics. Our data support the idea that a daily consumption of 4-NP-contaminated foods may lead to local damages at the level of gastrointestinal system, including liver, with negative consequences for the organ physiology.

The epidemiological surveillance of malignant mesothelioma in Italy (1993-2015): methods, findings, and research perspectives.

BACKGROUND: as a legacy of the large asbestos consumption until the definitive ban in 1992, Italy had to tackle a real epidemic of asbestos related diseases. The Italian National Registry of Malignant Mesotheliomas (ReNaM) is a permanent surveillance system of mesothelioma incidence, with a regional structure. Aims, assignments and territorial network of ReNaM are described, as well as data collection, recording and coding procedures. OBJECTIVES: to describe the Italian epidemiological surveillance system of mesothelioma incidence, to provide updated data about occurrence of malignant mesothelioma in Italy, and to discuss goals, attainments, and expectations of registering occupational cancer. DESIGN: analysis of data by malignant mesothelioma incident cases surveillance system. SETTING AND PARTICIPANTS: Italy, network of regional surveillance system, all Italian regions. MAIN OUTCOME MEASURES: a Regional Operating Centre (COR) is currently established in all the Italian regions, actively searching incident malignant mesothelioma cases from health care institutions. Occupational history, lifestyle habits, and residential history are obtained using a standardized questionnaire, administered to the subject or to the next of kin by a trained interviewer. The extent of dataset, epidemiological parameters, and occupations involved are reported updated at 31.12.2016, and standardized incidence rates are calculated. RESULTS: at December 2016, ReNaM has collected 27,356 malignant mesothelioma cases, referring to the period of incidence between 1993 and 2015. The modalities of exposure to asbestos have been investigated for 21,387 (78%) and an occupational exposure has been defined for around 70% of defined cases (14,818). CONCLUSIONS: the Italian experience shows that epidemiological systematic surveillance of asbestos related diseases incidence has a key importance for assessing and monitoring the public health impact of occupational and/or environmental hazards, programming preventive interventions, including remediation plans and information campaigns, and supporting the efficiency of insurance and welfare system. Monitoring the incidence of malignant mesothelioma through a specialized cancer registry is essential to follow-up the health effects of changing modalities and extent of occupational exposures over years and of environmental contamination. Such consolidated surveillance system is recommended also for occupational cancers with low aetiological fraction.

The epidemiology of malignant mesothelioma in women: gender differences and modalities of asbestos exposure.

INTRODUCTION: The epidemiology of gender differences for mesothelioma incidence has been rarely discussed in national case lists. In Italy an epidemiological surveillance system (ReNaM) is working by the means of a national register. METHODS: Incident malignant mesothelioma (MM) cases in the period 1993 to 2012 were retrieved from ReNaM. Gender ratio by age class, period of diagnosis, diagnostic certainty, morphology and modalities of asbestos exposure has been analysed using exact tests for proportion. Economic activity sectors, jobs and territorial distribution of mesothelioma cases in women have been described and discussed. To perform international comparative analyses, the gender ratio of mesothelioma deaths was calculated by country from the WHO database and the correlation with the mortality rates estimated. RESULTS: In the period of study a case list of 21 463 MMs has been registered and the modalities of asbestos exposure have been investigated for 16 458 (76.7%) of them. The gender ratio (F/M) was 0.38 and 0.70 (0.14 and 0.30 for occupationally exposed subjects only) for pleural and peritoneal cases respectively. Occupational exposures for female MM cases occurred in the chemical and plastic industry, and mainly in the non-asbestos textile sector. Gender ratio proved to be inversely correlated with mortality rate among countries. CONCLUSIONS: The consistent proportion of mesothelioma cases in women in Italy is mainly due to the relevant role of non-occupational asbestos exposures and the historical presence of the female workforce in several industrial settings. Enhancing the awareness of mesothelioma aetiology in women could support the effectiveness of welfare system and prevention policies.

The effects of improving the mesothelioma surveillance network on sensitivity, timeliness in reporting and asbestos exposure assessment.

BACKGROUND: In Italy, Mesothelioma Registries (MRs) have been established by law for the epidemiological surveillance of occupational cancers. MRs collect information about asbestos exposure of incident cases, through interviews. In the Emilia-Romagna region, MR was implemented in 1996 and extended its network of health professionals who report suspected mesothelioma in 2001 and 2007. OBJECTIVES: This study evaluated the impact of the extension of the network on MR sensitivity and timeliness. METHODS: Mesothelioma cases were analysed in three subsequent periods: 1996-2001 (before any network extension), 2002-2007 (after first extension) and 2008-2014 (after second extension). Sensitivity was evaluated by the proportion of cases directly reported by the network out of the total number of incident cases; reporting and interview timeliness were assessed by median times between diagnosis and, respectively, reporting and interview. Pleural mesothelioma reporting timeliness was also evaluated by use of quantile regression models, stratified by diagnostic certainty and adjusted by sex and age. RESULTS: Sensitivity increased from 79.4% (1996-2001), to 89.0% (2002-2007) and to 91.4% (2008-2013). For mesothelioma with diagnostic certainty, we recorded considerably reduced reporting times from the 50th percentile on, whereas for uncertain mesothelioma relevant reductions were observed also in the lower percentiles. A reduced time to interview was observed too, which was more significant for uncertain cases. The proportion of patients directly interviewed increased from 33.5% (1996-2001), to 39.1% (2002-2007), to 49.5% (2008-2014). CONCLUSIONS: The extended network improved the MR sensitivity and allowed shorter reporting and interview times and more frequent patient interviews, thus improving accuracy of exposure definition.

Inference on germline BAP1 mutations and asbestos exposure from the analysis of familial and sporadic mesothelioma in a high-risk area.

Inherited loss-of-function mutations in the BAP1 oncosuppressor gene are responsible for an inherited syndrome with predisposition to malignant mesothelioma (MM), uveal and keratinocytic melanoma, and other malignancies. Germline mutations that were inherited in an autosomal dominant fashion were identified in nine families with multiplex MM cases and 25 families with multiple melanoma, renal cell carcinoma, and other tumors. Germline mutations were also identified in sporadic MM cases, suggesting that germline mutations in BAP1 occur frequently. In this article, we report the analysis of BAP1 in five multiplex MM families and in 103 sporadic cases of MM. One family carried a new truncating germline mutation. Using immunohistochemistry, we show that BAP1 is not expressed in tumor tissue, which is in accordance with Knudson's two hits hypothesis. Interestingly, whereas the three individuals who were possibly exposed to asbestos developed MM, the individual who was not exposed developed a different tumor type, that is, mucoepidermoid carcinoma. This finding suggests that the type of carcinogen exposure may be important for the cancer type that is developed by mutation carriers. On the contrary, the other families or the 103 sporadic patients did not show germline mutations in BAP1. Our data show that BAP1 mutations are very rare in patients with sporadic MM, and we report a new BAP1 mutation, extend the cancer types associated with these mutations, and suggest the existence of other yet unknown genes in the pathogenesis of familial MM.

Epidemiological patterns of asbestos exposure and spatial clusters of incident cases of malignant mesothelioma from the Italian national registry.

BACKGROUND: Previous ecological spatial studies of malignant mesothelioma cases, mostly based on mortality data, lack reliable data on individual exposure to asbestos, thus failing to assess the contribution of different occupational and environmental sources in the determination of risk excess in specific areas. This study aims to identify territorial clusters of malignant mesothelioma through a Bayesian spatial analysis and to characterize them by the integrated use of asbestos exposure information retrieved from the Italian national mesothelioma registry (ReNaM). METHODS: In the period 1993 to 2008, 15,322 incident cases of all-site malignant mesothelioma were recorded and 11,852 occupational, residential and familial histories were obtained by individual interviews. Observed cases were assigned to the municipality of residence at the time of diagnosis and compared to those expected based on the age-specific rates of the respective geographical area. A spatial cluster analysis was performed for each area applying a Bayesian hierarchical model. Information about modalities and economic sectors of asbestos exposure was analyzed for each cluster. RESULTS: Thirty-two clusters of malignant mesothelioma were identified and characterized using the exposure data. Asbestos cement manufacturing industries and shipbuilding and repair facilities represented the main sources of asbestos exposure, but a major contribution to asbestos exposure was also provided by sectors with no direct use of asbestos, such as non-asbestos textile industries, metal engineering and construction. A high proportion of cases with environmental exposure was found in clusters where asbestos cement plants were located or a natural source of asbestos (or asbestos-like) fibers was identifiable. Differences in type and sources of exposure can also explain the varying percentage of cases occurring in women among clusters. CONCLUSIONS: Our study demonstrates shared exposure patterns in territorial clusters of malignant mesothelioma due to single or multiple industrial sources, with major implications for public health policies, health surveillance, compensation procedures and site remediation programs.

Malignant mesothelioma due to non-occupational asbestos exposure from the Italian national surveillance system (ReNaM): epidemiology and public health issues.

INTRODUCTION: Italy produced and imported a large amount of raw asbestos, up to the ban in 1992, with a peak in the period between 1976 and 1980 at about 160,000 tons/year. The National Register of Mesotheliomas (ReNaM, "Registro Nazionale dei Mesoteliomi" in Italian), a surveillance system of mesothelioma incidence, has been active since 2002, operating through a regional structure. METHODS: The Operating Regional Center (COR) actively researches cases and defines asbestos exposure on the basis of national guidelines. Diagnostic, demographic and exposure characteristics of non-occupationally exposed cases are analysed and described with respect to occupationally exposed cases. RESULTS: Standardised incidence rates for pleural mesothelioma in 2008 were 3.84 (per 100,000) for men and 1.45 for women, respectively. Among the 15,845 mesothelioma cases registered between 1993 and 2008, exposure to asbestos fibres was investigated for 12,065 individuals (76.1%), identifying 530 (4.4%) with familial exposure (they lived with an occupationally exposed cohabitant), 514 (4.3%) with environmental exposure to asbestos (they lived near sources of asbestos pollution and were never occupationally exposed) and 188 (1.6%) exposed through hobby-related or other leisure activities. Clusters of cases due to environmental exposure are mainly related to the presence of asbestos-cement industry plants (Casale Monferrato, Broni, Bari), to shipbuilding and repair activities (Monfalcone, Trieste, La Spezia, Genova) and soil contamination (Biancavilla in Sicily). CONCLUSIONS: Asbestos pollution outside the workplace contributes significantly to the burden of asbestos-related diseases, suggesting the need to prevent exposures and to discuss how to deal with compensation rights for malignant mesothelioma cases induced by non-occupational exposure to asbestos.

[Epidemiologic surveillance of mesothelioma for the prevention of asbestos exposure also in non-traditional settings]. / Sorveglianza epidemiologica dei mesoteliomi per la prevenzione dell'esposizione ad amianto anche in attività non tradizionalmente coinvolte.

OBJECTIVE: To show how malignant mesothelioma (MM) surveillance not only identifies settings of exposure representing past industrial history, but it may also detect conditions of current exposure relevant for the prevention, if the wide spectrum of asbestos uses is considered. DESIGN: Active search of MM cases and exposure assessment at individual level through a questionnaire; identification of exposure circumstances relevant for prevention. SETTING AND PARTICIPANTS: Italy, all the Regions where a Regional Operating Centre (COR) is established to identify all MM cases diagnosed in the population and analyze their occupational, residential, household and environmental histories. Period of diagnosis: 1993-2008. MAIN OUTCOME MEASURES: Descriptive analysis of MM cases and of asbestos exposures. RESULTS: ReNaM includes 15,845 cases of MM diagnosed between 1993 and 2008.The male/female ratio is 2.5. Mean age at diagnosis is 69 years. Pleural MMs represent 93% of all cases. Exposures have been investigated in 12,065 cases (76%). The median latency time is 46 years. In addition to clusters of MM cases in activities well known to entail asbestos use, different current exposure circumstances requiring intervention have been evidenced. CONCLUSIONS: On the basis of this experience, epidemiological surveillance of all occupational cancers should be implemented to foster synergies with the compensation system and the Local Health Authorities' occupational safety and health services, as required by the Italian Legislative Decree N. 81/2008.

Pleural mesothelioma: epidemiological and public health issues. Report from the Second Italian Consensus Conference on Pleural Mesothelioma.

Malignant mesothelioma is closely connected to asbestos exposure, with epidemiological patterns closely reshaping the geography and history of asbestos exposure. Mechanisms of causation and of interaction of asbestos fibres with pleura are complex and currently not yet completely understood. Curative efforts so far provided little results. Italy shows one of the highest incidence of MM and developed a network of specialized cancer registries in order to monitor disease occurrence and describe its epidemiology in details. The second Italian Consensus Conference on Pleural Mesothelioma convened in Torino on November 24th-25th, 2011. Besides the main consensus report summarizing the contribution of the different expertises, that was published elsewhere, the participants in 'Public Health and Epidemiology' section decided to report in major details the evidence and the conclusions regarding epidemiology, causative mechanisms and the public health impact of the disease.

Pleural mesothelioma risk in the construction industry: a case-control study in Italy, 2000-2018.

OBJECTIVES: Workers in the construction industry have been exposed to asbestos in various occupations. In Italy, a National Mesothelioma Registry has been implemented more than 20 years ago. Using cases selected from this registry and exploiting existing control data sets, we estimated relative risks for pleural mesothelioma (PM) among construction workers. DESIGN: Case-control study. SETTING: Cases from the National Mesothelioma Registry (2000-2018), controls from three previous case-control studies. METHODS: We selected male PM incident cases diagnosed in 2000-2018. Population controls were taken from three studies performed in six Italian regions within two periods (2002-2004 and 2012-2016). Age-adjusted and period-adjusted unconditional logistic regression models were fitted to estimate odds ratios (OR) for occupations in the construction industry. We followed two approaches, one (primary) excluding and the other (secondary) including subjects employed in other non-construction blue collar occupations for >5 years. For both approaches, we performed an overall analysis including all cases and, given the incomplete temporal and geographic overlap of cases and controls, three time or/and space restricted sensitivity analyses. RESULTS: The whole data set included 15 592 cases and 2210 controls. With the primary approach (4797 cases and 1085 controls), OR was 3.64 (2181 cases) for subjects ever employed in construction. We found elevated risks for blue-collar occupations (1993 cases, OR 4.52), including bricklayers (988 cases, OR 7.05), general construction workers (320 cases, OR 4.66), plumbers and pipe fitters (305 cases, OR 9.13), painters (104 cases, OR 2.17) and several others. Sensitivity analyses yielded very similar findings. Using the secondary approach, we observed similar patterns, but ORs were remarkably lower. CONCLUSIONS: We found markedly increased PM risks for most occupations in the construction industry. These findings are relevant for compensation of subjects affected with mesothelioma in the construction industry.

Pleural malignant mesothelioma epidemic: incidence, modalities of asbestos exposure and occupations involved from the Italian National Register.

Due to the large scale use of asbestos (more than 3.5 million tons produced or imported until its definitive banning in 1992), a specific national surveillance system of mesothelioma incident cases is active in Italy, with direct and individual anamnestic etiological investigation. In the period between 1993 and 2004, a case-list of 8,868 pleural MM was recorded by the Italian National Register (ReNaM) and the modalities of exposure to asbestos fibres have been investigated for 6,603 of them. Standardized incidence rates are 3.49 (per 100,000 inhabitants) for men and 1.25 for women, with a wide regional variability. Occupational asbestos exposure was in 69.3% of interviewed subjects (N = 4,577 cases), while 4.4% was due to cohabitation with someone (generally, the husband) occupationally exposed, 4.7% by environmental exposure from living near a contamination source and 1.6% during a leisure activity. In the male group, 81.5% of interviewed subjects exhibit an occupational exposure. In the exposed workers, the median year of first exposure was 1957, and mean latency was 43.7 years. The analysis of exposures by industrial sector focuses on a decreasing trend for those traditionally signaled as "at risk" (asbestos-cement industry, shipbuilding and repair and railway carriages maintenance) and an increasing trend for the building construction sector. The systematic mesothelioma surveillance system is relevant for the prevention of the disease and for supporting an efficient compensation system. The existing experience on all-too-predictable asbestos effects should be transferred to developing countries where asbestos use is spreading.

Extravascular lung water index, pulmonary vascular permeability index, and global end-diastolic volume index in mechanically ventilated COVID-19 patients requiring prone position ventilation: a preliminary retrospective study.

BACKGROUND: There is a lack of data on extravascular lung water index (EVLWi), pulmonary vascular permeability index (PVPi), and global end-diastolic volume index (GEDVi) during prone position ventilation (PPV) in coronavirus disease 2019 (COVID-19) patients. The objectives of this study were to analyze trends in EVLWi, PVPi, and GEDVi during PPV and the relationships between these parameters and PaO2/FiO2. METHODS: In this preliminary retrospective observational study, we performed transpulmonary thermodilution (TPTD) in seven mechanically ventilated COVID-19 patients without cardiac and pulmonary comorbidities requiring PPV for 18 hours, at specific times (30 minutes pre-PPV, 18 hours after PPV, and 3 hours after supination). EVLWi, PVPi and GEDVi were measured. The relationships between PaO2/FiO2 and EVLWi, and PVPi and GEDVi values, in the supine position were analyzed by linear regression. Correlation and determination coefficients were calculated. RESULTS: EVLWi was significantly different between three time points (analysis of variance, P=0.004). After 18 hours in PPV, EVLWi was lower compared with values before PPV (12.7±0.9 ml/kg vs. 15.3±1.5 ml/kg, P=0.002). Linear regression showed that only EVLWi was correlated with PaO2/FiO2 (ß =-5.757; 95% confidence interval, -10.835 to -0.679; r=-0.58; R2 =0.34; F-test P=0.029). CONCLUSIONS: EVLWi was significantly reduced after 18 hours in PPV and values measured in supine positions were correlated with PaO2/FiO2. This relationship can help clinicians discriminate whether deterioration in gas exchange is related to fluid overload or disease progression. Further clinical research should evaluate the role of TPTD parameters as markers to stratify disease severity and guide clinical management.