Pathophysiology of the pleura

Clinical overview of the physiology and pathophysiology of pleural fluid movement: a narrative review

In physiological conditions, the pleural space couples the lung with the chest wall and contains a small amount of fluid in continuous turnover. The volume of pleural fluid is the result from the balance between the entry of fluid through the pleural capillaries and drainage by the lymphatics in the most dependent areas of the parietal pleura. Fluid filtration is governed by Starling forces, determined by the hydrostatic and oncotic pressures of the capillaries and the pleural space. The reabsorption rate is 28 times greater than the rate of pleural fluid production. The mesothelial layer of the inner lining of the pleural space is metabolically active and also plays a role in the production and reabsorption of pleural fluid. Pleural effusion occurs when the balance between the amount of fluid that enters the pleural space and the amount that is reabsorbed is disrupted. Alterations in hydrostatic or oncotic pressure produce a transudate, but they do not cause any structural damage to the pleura. In contrast, disturbances in fluid flow (increased filtration or decreased reabsorption) produce an exudate via several mechanisms that cause damage to pleural layers. Thus, cellular processes and the inflammatory and immune reactions they induce determine the composition of pleural fluid. Understanding the underlying pathophysiological processes of pleural effusion, especially cellular processes, can be useful in establishing its aetiology.

Medical thoracoscopy with talc pleurodesis for refractory hepatic hydrothorax: A case series of three successes

Medical thoracoscopy with chemical pleurodesis is a last resort for managing patients who suffer. from recurrent hepatic hydrothorax. However, despite pleurodesis, the rapid fluid build-up can hinder the successful apposition of the pleural surfaces. To improve the chances of success, we investigated the effectiveness of abdominal paracentesis before chemical pleurodesis via medical thoracoscopy to reduce significant fluid shifts from the peritoneal to the pleural cavity. We present a series of three patients with liver cirrhosis complicated by hepatic hydrothorax who underwent medical thoracoscopy with talc pleurodesis. Before the procedure, we optimised medical treatment, and if needed, we performed large-volume paracentesis to prevent rapid reaccumulation of pleural fluid. All study subjects achieved treatment success, defined as relief of breathlessness and absence of pleural effusion at 12 months. Complications related to the treatment included hepatic encephalopathy and acute kidney injury, which were managed conservatively. To manage symptomatic and recurrent hepatic hydrothorax, medical thoracoscopy with talc pleurodesis, preceded by the evacuation of ascites, can be considered as a treatment option. This procedure should be considered early for those who do not respond to medical management and are not suitable candidates for TIPS or liver transplantation.

Time-Sequential Monitoring of the Early Mesothelial Reaction in the Pleura after Cryoinjury

(1) Background: An early mesothelial reaction of the pleura, leading to fibrosis, has been reported in animals after chemical or heavy metal exposure. However, the visual monitoring of early time-sequential mesothelial reaction-associated cryoinjury has not been fully investigated. Therefore, this study aimed to evaluate and visualize the early mesothelial reactions seen following cryoinjury using rabbit pleura. (2) Methods: We monitored the early mesothelial reaction in rabbit pleurae after cryoinjury using optical coherence tomography (OCT), in real-time, which was then compared with pathological images. Due to the penetration limit of OCT, we made a thoracic window to image the parietal and visceral pleurae in vivo. We also used an innovative technique for capturing the microstructure in vivo, employing a computer-controlled intermittent iso-pressure breath hold to reduce respiratory motion, increasing the resolution of OCT. We organized three sample groups: the normal group, the sham group with just a thoracic window, and the experimental group with a thoracic window and cryotherapy. In the experimental group, localized cryoinjury was performed. The mesothelial cells at the level of pleura of the cryotherapy-injured site were visualized by OCT within the first 30 min and then again after 2 days at the same site. (3) Results: In the experimental group, focal thickening of the parietal pleura was observed at the site of cryoinjury using OCT after the first injury, and it was then confirmed pathologically as focal mesothelial cell proliferation. Two days after cryoinjury, diffuse mesothelial cell proliferation in the parietal pleura was noted on the reverse side around the cryoinjured site in the same rabbit. In the sham group, no pleural reaction was found. The OCT and pathological examinations revealed different patterns of mesothelial cell reactions between the parietal and visceral pleurae: the focal proliferation of mesothelial cells was found in the parietal pleura, while only a morphological change from flat cells to cuboidal cells and a thickened monolayer without proliferation of mesothelial cells were found in the visceral pleural. (4) Conclusions: An early mesothelial reaction occurs following cryoinjury to the parietal and visceral pleurae.

Diagnostic value of soluble biomarkers for parapneumonic pleural effusion

Parapneumonic pleural effusion (PPE) is a common complication in patients with pneumonia. Timely and accurate diagnosis of PPE is of great value for its management. Measurement of biomarkers in circulating and pleural fluid have the advantages of easy accessibility, short turn-around time, objectiveness and low cost and thus have utility for PPE diagnosis and stratification. To date, many biomarkers have been reported to be of value for the management of PPE. Here, we review the values of pleural fluid and circulating biomarkers for the diagnosis and stratification PPE. The biomarkers discussed are C-reactive protein, procalcitonin, presepsin, soluble triggering receptor expressed on myeloid cells 1, lipopolysaccharide-binding protein, inflammatory markers, serum amyloid A, soluble urokinase plasminogen activator receptor, matrix metalloproteinases, pentraxin-3 and cell-free DNA. We found that none of the available biomarkers has adequate performance for diagnosing and stratifying PPE. Therefore, further work is needed to identify and validate novel biomarkers, and their combinations, for the management of PPE.

Mesothelium-Derived Factors Shape GATA6-Positive Large Cavity Macrophages

The local microenvironment shapes macrophage differentiation in each tissue. We hypothesized that in the peritoneum, local factors in addition to retinoic acid can support GATA6-driven differentiation and function of peritoneal large cavity macrophages (LCMs). We found that soluble proteins produced by mesothelial cells lining the peritoneal cavity maintained GATA6 expression in cultured LCMs. Analysis of global gene expression of isolated mesothelial cells highlighted mesothelin (Msln) and its binding partner mucin 16 (Muc16) as candidate secreted ligands that potentially regulate GATA6 expression in peritoneal LCMs. Mice deficient for either of these molecules showed diminished GATA6 expression in peritoneal and pleural LCMs that was most prominent in aged mice. The more robust phenotype in older mice suggested that monocyte-derived macrophages were the target of Msln and Muc16. Cell transfer and bone marrow chimera experiments supported this hypothesis. We found that lethally irradiated Msln−/− and Muc16−/− mice reconstituted with wild-type bone marrow had lower levels of GATA6 expression in peritoneal and pleural LCMs. Similarly, during the resolution of zymosan-induced inflammation, repopulated peritoneal LCMs lacking expression of Msln or Muc16 expressed diminished GATA6. These data support a role for mesothelial cell–produced Msln and Muc16 in local macrophage differentiation within large cavity spaces such as the peritoneum. The effect appears to be most prominent on monocyte-derived macrophages that enter into this location as the host ages and also in response to infection.

Cytologic manifestations of Hodgkin lymphoma in serous effusions

Serous effusions occur in a small group of patients with classic Hodgkin lymphoma (cHL). Most effusions are benign inflammatory fluids. Malignant effusions predominantly in patients with treated relapsed diseases or rarely as a primary manifestation are diagnostically challenging to cytopathologists. Established cases of cHL with effusions were retrieved. Cytology slides were screened looking for Reed-Sternberg-Hodgkin (RSH) cells and patterns of background inflammatory cells. Cellblocks and their corresponding immunocytochemistry (ICC) slides were examined. The cytologic findings were correlated with nodal biopsy histopathologic and immunohistochemical features. We found six cases of benign and malignant pleural and pericardial effusions in patients with mediastinal nodular sclerosis-type cHL. Various cytomorphologic patterns were observed. Slides revealed sparsely scattered either isolated or aggregated mononuclear, binucleated and multinucleated RSH-like cells. Some may have been either disregarded as reactive mesothelial or histiocytic cells, or confused with other RSH-like malignant cells. The background varied between characteristic mixed inflammatory milieu, predominantly small lymphocytic or lymphohistiocytic with or without reactive mesothelial cells. Cytologic examination showed three positive cases (two cases with RSH cells confirmed by cellblock section ICC, one case with a mixed inflammatory infiltrate), and three benign effusions (one case with atypical RSH-like reactive mesothelial cells confirmed by ICC). Effusions associated with cHL exhibit different cytologic patterns. A high level of vigilance with utility of ICC has an important role in suspecting primary cases and confirming recurrences in known cases. The various cytologic patterns of cHL-associated benign and malignant effusions might reflect parallel pathophysiologic mechanisms.

Linseed, Baru, and Coconut Oils: NMR-Based Metabolomics, Leukocyte Infiltration Potential In Vivo, and Their Oil Characterization. Are There Still Controversies?

Different fatty acid proportions produce potential inflammatory and metabolic changes in organisms. However, the evidence for how each fatty acid mediates the metabolic pathway, and its lipid stability remains controversial. To resolve this controversy, the present study investigated the metabolic effects of cold-pressed linseed (LG), coconut (CG), and baru (BG) oils in comparison to those of soybean oil (SG) in mice, in terms of their oil characterization and stability. The quality analysis showed less oxidative behavior among PUFA-rich oils (SO, BO, and LO, with induction periods lower than 2 h compared to 39.8 h for CG), besides the high contents of tocopherols and carotenoids in SG and LG. In the experimental study, CG presented higher triglyceride (257.93 ± 72.30) and VLDL-cholesterol levels (51.59 ± 14.46, p < 0.05), while LG reduced LDL levels (59.29 ± 7.56, p < 0.05) when compared to SG (183.14 ± 22.06, 36.63 ± 4.41 and 131.63 ± 29.0, respectively). For visceral fats, the adiposity index was lower for BG (7.32 ± 3.13) and CG (9.58 ± 1.02, p < 0.05) in relation to SG (12.53 ± 2.80), and for leukocyte recruitment, CG presented lower polymorphonuclear (PMN) (p < 0.0001) and mononuclear (MN) (p < 0.05) cell infiltration, demonstrating anti-inflammatory potential. In NMR-based metabolomics, although CG presented higher values for the glucose, lactate, and LDL/VLDL ratio, this group also evidenced high levels of choline, a lipotropic metabolite. Our study emphasized the controversies of saturated fatty acids, which impair serum lipids, while alfa-linolenic acid presented cardioprotective effects. However, coconut oil also has a positive immunomodulatory pathway and was found to reduce visceral bodyfat in mice. Therefore, for future applications, we suggest a combination of lauric and al-fa-linolenic acid sources, which are present in coconut and linseed oil, respectively. This combination could be less obesogenic and inflammatory and exert cardioprotective action.

The significance of Fas, tumor necrosis factor-related apoptosis-inducing ligand and fibrinolytic factors in the assessment of malignant pleural effusion

Few studies have examined the usefulness of soluble apoptotic markers for the screening of pleural effusion. This study aimed to investigate the significance of Fas, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and fibrinolytic factors for the assessment of patients with malignant pleural effusion. A total of 137 patients with pleural effusion were evaluated. Soluble Fas, TRAIL, tissue-type plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), D-dimers and lactate dehydrogenase (LD) levels were measured. Pleural fluid/blood ratios (P/B) of fibrinolytic factors were calculated. Fas and TRAIL levels were significantly higher in patients with malignant effusion than in those with non-malignant effusion. Malignant effusion was 1.6-fold more prevalent in patients with elevated Fas than in those without (48.5% vs 30.4%, P=0.031). The P/B ratio of tPA was 2.5-fold higher in malignant effusion than in non-malignant effusion (4.65 vs 1.83, P<0.001). Fas was positively correlated with tPA and D-dimers, but not with biochemical parameters. The ability of Fas to identify malignant effusions was significantly greater than those of tPA and LD. In conclusion, measurements of Fas and TRAIL in conjunction with fibrinolytic factors may provide information useful for monitoring patients with suspected malignant pleural effusion.

Pleural Effusion Revealing a Diagnosis of Ewing Sarcoma

Pleural effusion can rarely present as an initial manifestation of Ewing sarcoma. We illustrate a case of a young male adult who was admitted with pleural effusion that led to the diagnosis of Ewing sarcoma.

The Role of Peritoneal Macrophages in Endometriosis

Endometriosis is an estrogen-dependent gynecological disorder, defined as the growth of endometrial stromal cells and glands at extrauterine sites. Endometriotic lesions are more frequently located into the abdominal cavity, although they can also be implanted in distant places. Among its etiological factors, the presence of immune dysregulation occupies a prominent place, pointing out the beneficial and harmful outcomes of macrophages in the pathogenesis of this disease. Macrophages are tissue-resident cells that connect innate and adaptive immunity, playing a key role in maintaining local homeostasis in healthy conditions and being critical in the development and sustainment of many inflammatory diseases. Macrophages accumulate in the peritoneal cavity of women with endometriosis, but their ability to clear migrated endometrial fragments seems to be inefficient. Hence, the characteristics of the peritoneal immune system in endometriosis must be further studied to facilitate the search for new diagnostic and therapeutic tools. In this review, we summarize recent relevant advances obtained in both mouse, as the main animal model used to study endometriosis, and human, focusing on peritoneal macrophages obtained from endometriotic patients and healthy donors, under the perspective of its future clinical translation to the role that these cells play on this pathology.

Anaphylatoxins orchestrate Th17 response via interactions between CD16+ monocytes and pleural mesothelial cells in tuberculous pleural effusion

The complement system is activated in tuberculous pleural effusion (TPE), with increased levels of the anaphylatoxins stimulating pleural mesothelial cells (PMCs) to secrete chemokines, which recruit nonclassical monocytes to the pleural cavity. The differentiation and recruitment of naive CD4⁺ T cells are induced by pleural cytokines and PMC-produced chemokines in TPE. However, it is unclear whether anaphylatoxins orchestrate CD4⁺ T cell response via interactions between PMCs and monocytes in TPE. In this study, CD16⁺ and CD16^- monocytes isolated from TPE patients were cocultured with PMCs pretreated with anaphylatoxins. After removing the PMCs, the conditioned monocytes were cocultured with CD4⁺ T cells. The levels of the cytokines were measured in PMCs and monocyte subsets treated separately with anaphylatoxins. The costimulatory molecules were assessed in conditioned monocyte subsets. Furthermore, CD4⁺ T cell response was evaluated in different coculture systems. The results indicated that anaphylatoxins induced PMCs and CD16⁺ monocytes to secrete abundant cytokines capable of only inducing Th17 expansion, but Th1 was feeble. In addition, costimulatory molecules were more highly expressed in CD16⁺ than in CD16⁻ monocytes isolated from TPE. The interactions between monocytes and PMCs enhanced the ability of PMCs and monocytes to produce cytokines and that of monocytes to express HLA-DR, CD40, CD80 and CD86, which synergistically induced Th17 expansion. In the above process, anaphylatoxins enhanced the interactions between monocytes and PMCs by increasing the level of the cytokines IL-1β, IL-6, IL-23 and upregulating the phenotype of CD40 and CD80 in CD16⁺ monocytes. Collectively, these data indicate that anaphylatoxins play a central role in orchestrating Th17 response mainly via interactions between CD16⁺ monocytes and PMCs in TPE.

Tuberculous pleural effusion is characterized by intense chronic accumulations of fluid and lymphocyte cells and monocytes/macrophages in the pleural space. Complement mediators play important roles in providing protection against Mycobacterium tuberculosis. Our results demonstrated that Mycobacterium tuberculosis infection induced the amplification of complement activation in TPE. Complement activation produces anaphylatoxins that induce PMCs and CD16⁺ monocytes to secrete abundant cytokines capable of only inducing Th17 expansion, but Th1 was feeble. In addition, costimulatory molecules were more highly expressed in CD16⁺ than in CD16⁻ monocytes isolated from TPE. The interactions between monocytes and PMCs enhanced the ability of PMCs and monocytes to produce cytokines and that of monocytes to express HLA-DR, CD40, CD80 and CD86, which synergistically induced Th17 expansion. In the above process, anaphylatoxins enhanced the interactions between monocytes and PMCs by increasing the level of the cytokines IL-1β, IL-6, IL-23 and upregulating the phenotype of CD40 and CD80 in CD16+ monocytes. In summary, these data highlighted the importance of anaphylatoxins and the innate immune system in eliciting pathogenic T cell responses in TPE and suggested that monocytes, especially the CD16⁺ subset, might be an efficient target for controlling inflammation.

Digital Gene Expression Analysis of Epithelioid and Sarcomatoid Mesothelioma Reveals Differences in Immunogenicity

Malignant pleural mesothelioma (MPM) is an aggressive malignancy associated with asbestos exposure. Median survival ranges from 14 to 20 months after initial diagnosis. As of November 2020, the FDA approved a combination of immune checkpoint inhibitors after promising intermediate results. Nonetheless, responses remain unsatisfying. Adequate patient stratification to improve response rates is still lacking. This retrospective study analyzed formalin fixed paraffin embedded specimens from a cohort of 22 MPM. Twelve of those samples showed sarcomatoid, ten epithelioid differentiation. Complete follow-up, including radiological assessment of response by modRECIST and time to death, was available with reported deaths of all patients. RNA of all samples was isolated and subjected to digital gene expression pattern analysis. Our study revealed a notable difference between epithelioid and sarcomatoid mesothelioma, showing differential gene expression for 304/698 expressed genes. Whereas antigen processing and presentation to resident cytotoxic T cells as well as phagocytosis is highly affected in sarcomatoid mesothelioma, cell-cell interaction via cytokines seems to be of greater importance in epithelioid cases. Our work reveals the specific role of the immune system within the different histologic subtypes of MPM, providing a more detailed background of their immunogenic potential. This is of great interest regarding therapeutic strategies including immunotherapy in mesothelioma.

VEGF/Src signaling mediated pleural barrier damage and increased permeability contributes to subpleural pulmonary fibrosis

The distribution of fibrosis in idiopathic pulmonary fibrosis (IPF) is subpleural with basal predominance. Alveolar epithelial cell was considered as the key cell in the initial phase of IPF. However, the idea of activation and damage of alveolar epithelial cells is very difficult to explain why fibrosis distributes in the subpleural area. In this study, human pleural mesothelial cell (PMC) line and primary rat PMC was used as in vitro model. Intraperitoneal injection of bleomycin was used for making a pulmonary fibrosis model. The integrity of cultured monolayer PMCs was determined by transepithelial electric resistance (TEER). Pleural permeability was estimated by measuring paracellular transport of fluorescein isothiocyanate (FITC)-conjugated dextran. Changes in lung tissue of patients with IPF were analyzed by Masson's and immunofluorescence staining. We found bleomycin induced PMCs damage and increased PMCs permeability; increased PMCs permeability aggravated bleomycin-induced subpleural inflammation and pulmonary fibrosis. Moreover, bleomycin was found to activate VEGF/Src signaling which increased PMCs permeability. In vivo, inhibition of VEGF/Src signaling prevented bleomycin-induced subpleural pulmonary fibrosis. At last, activation of VEGF/Src signaling was confirmed in subpleural area in patients with IPF. Taken together, our findings indicate that VEGF/Src signaling mediated pleural barrier damage and increased permeability which contributes to subpleural pulmonary fibrosis.

Tracheal deviation with phrenic nerve palsy after brachial plexus block

We present a case of a woman who received a left single-injection supraclavicular brachial plexus block for analgesia to facilitate upper extremity orthopaedic surgery. Before tracheal extubation she desaturated, was noted to have a low tidal volume and reduced left-sided air entry on auscultation of the chest. A chest x-ray taken 1 h following tracheal extubation revealed elevation of the left hemidiaphragm and a rightward shift of the trachea and mediastinal structures, with no evidence of pneumothorax. Findings were in-keeping with phrenic nerve palsy complicating the brachial plexus block performed. The patient was asymptomatic and discharged home the next day following repeat chest x-rays. We believe this is the first report of tracheal deviation contralateral to the side of an elevated hemidiaphragm secondary to phrenic nerve palsy from a brachial plexus block.

Evaluation of cellular alterations and inflammatory profile of mesothelial cells and/or neoplastic cells exposed to talc used for pleurodesis

Introdution: To determine the role of Pleural Mesothelial Cells (PMC) and/or Neoplasic Cells (NC) in the initiation and regulation of acute inflammatory response after exposure to talc for evaluating inflammatory mediators and cellular alterations.

Materials and Methods: PMC cultures, human lung (A549) and breast (MCF7) adenocarcinoma cells were divided in 5 groups: 100% PMC, 100% NC, 25% PMC + 75% NC, 50% of each type and 75% PMC + 25% NC. All groups were exposed to talc and measured IL-6, IL-1β, IL-10, TNF-α, TNFRI, pH, LDH, apoptosis and necrosis. Statistical Analysis: One-way Anova.

Results: High IL-6, IL-1β and TNFRI levels were found in PMC and NC exposed to talc. IL-6 was higher at the points of more confluence of PMC. The highest levels of IL-1β and TNFRI were found in mixed cultures. In pure cultures TNFRI was higher in A549 followed by PMC and MCF7. LDH was higher in A549 than PMC. The lowest pH was found in 100% NC. All cell line exposed to talc reduced viability and increased necrosis. Apoptotic cells exposed to talc were higher in pure cultures of NC than in PMC. Mixed cultures of PMC and A549 showed lower levels of apoptosis in cultures with more NC.

Conclusions: PMC after talc exposure participates in the inflammatory process contributing to production of molecular mediators, necessary for effective pleurodesis. Talc acted in NC causing higher rates of apoptosis, contributing in a modest way to tumoral decrease. Different types of tumor cells may respond differently to exposure to talc.

Nitrodi thermal water downregulates protein S‑nitrosylation in RKO cells

Balneotherapy and spa therapy have been used in the treatment of ailments since time immemorial. Moreover, there is evidence to suggest that the beneficial effects of thermal water continue for months following the completion of treatment. The mechanisms through which thermal water exerts its healing effects remain unknown. Both balneological and hydroponic therapy at 'the oldest spa in the world', namely, the Nitrodi spring on the Island of Ischia (Southern Italy) are effective in a number of diseases and conditions. The aim of the present study was to investigate the molecular basis underlying the therapeutic effects of Nitrodi spring water in low-grade inflammation and stress-related conditions. For this purpose, an in vitro model was devised in which RKO colorectal adenocarcinoma cells were treated with phosphate-buffered saline or phosphate-buffered saline prepared with Nitrodi water for 4 h daily, 5 days a week for 6 weeks. The RKO cells were then subjected to the following assays: 3-(4,5- Dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay, Transwell migration assay, western blot analysis, the fluorimetric detection of protein S-nitrosothiols and S-nitrosylation western blot analysis. The results revealed that Nitrodi spring water promoted cell migration and cell viability, and downregulated protein S-nitrosylation, probably also the nitrosylated active form of the cyclooxygenase (COX)-2 protein. These results concur with all the previously reported therapeutic properties of Nitrodi spring water, and thus rein-force the concept that this natural resource is an important complementary therapy to traditional medicine.

Influence of the progression of pleural neoplasia on the outcome of pleurodesis in mice

Purpose: Experimental study aimed at evaluating whether pleural neoplastic disease is associated with the degree of pleural fibrosis over time caused by talc pleurodesis. The study describes changes in levels of inflammatory mediators and determines whether the course of time involved in progression of neoplastic pleural disease is the factor that influences safety of talc pleurodesis usage in mice.

Materials and Methods: Animals were randomized into two groups: Cancer group (CG) that received intrapleural injection of Lewis cells or Saline group (SG) that received saline injection. After, the animals were subdivided into Early (pleurodesis 3 days after pleural injection) and Late (pleurodesis 7 days after pleural injection) groups. Half of the animals in each group were euthanized 24 hours after pleurodesis (to obtain the inflammatory data); the remaining animals were killed after 8 days (to obtain the scores of pleural fibrosis).

Results: CGs had lower fibrosis scores than SGs comparing early phases to late phases. Inflammation scores were lower in CGs, particularly in Late group. In SGs the inflammation was intense in 100% of the animals.

In Late CG group pleural adhesions had the lowest scores; we found intense fibrosis only in SGs. VEGF and LDH levels had increased in animals with cancer, particularly in Late group. Systemic distribution of talc occurred only in Late CG.

Conclusions: The time for pleural neoplasia to evolve is inversely proportional to the degree of pleural fibrosis. Earlier pleurodesis yielded the best results related to fibrosis, with less systemic inflammation and is safer in mice.

Anaphylatoxins Enhance Recruitment of Nonclassical Monocytes via Chemokines Produced by Pleural Mesothelial Cells in Tuberculous Pleural Effusion

In the present study, we sought to elucidate the mechanisms by which monocytes migrate into the pleural space in the presence of anaphylatoxins in tuberculous pleural effusion (TPE). Monocytes in both pleural effusion and blood were counted, and their phenotypic characteristics were analyzed. Activation of the complement system was detected in TPE. The effects of Mpt64 and anaphylatoxins on the production of chemokines in pleural mesothelial cells (PMCs) were measured. The chemoattractant activity of chemokines produced by PMCs for monocytes was observed. Levels of CD14⁺CD16⁺ monocytes were significantly higher in TPE than in blood. Three pathways of the complement system were activated in TPE. C3a-C3aR1, C5a-C5aR1, CCL2-CCR2, CCL7-CCR2, and CX3CL1-CX3CR1 were coexpressed in PMCs and monocytes isolated from TPE. Moreover, we initially found that Mpt64 stimulated the expression of C3a and C5a in PMCs. C3a and C5a not only induced CCL2, CCL7, and CX3CL1 expression in PMCs but also stimulated production of IL-1β, IL-17, and IL-27 in monocytes. C3a and C5a stimulated PMCs to secrete CCL2, CCL7, and CX3CL1, which recruited CD14⁺CD16⁺ monocytes to the pleural cavity. As a result, the infiltration of CD14⁺CD16⁺ monocytes engaged in the pathogenesis of TPE by excessive production of inflammatory cytokines.

Treatment of Pleural Effusions with Nonintubated Video-Assisted Thoracoscopic Surgery

Video-assisted thoracic surgery has considerably improved the care of the thoracic surgical patient. Patients are able to leave the hospital sooner and experience less pain with equal oncologic outcomes when compared with open surgery. Nonintubated thoracic surgery has more recently been applied in the management of both benign and malignant pleural effusions. This article provides the general thoracic surgeon a detailed description on how to manage pleural effusions using video-assisted thoracoscopic surgery in a nonintubated patient. Surgical techniques and pearls are also presented.

Dual RNA-seq in Streptococcus pneumoniae Infection Reveals Compartmentalized Neutrophil Responses in Lung and Pleural Space

The factors that regulate the passage of bacteria between different anatomical compartments are unclear. We have used an experimental model of infection with Streptococcus pneumoniae to examine the host and bacterial factors involved in the passage of bacteria from the lung to the pleural space. The transcriptional profile of host and bacterial cells within the pleural space and lung was analyzed using deep sequencing of the entire transcriptome using the technique of dual RNA-seq. We found significant differences in the host and bacterial RNA profiles in infection, which shed light on the key factors that allow passage of this bacterium into the pleural space.

Streptococcus pneumoniae is the dominant cause of community-acquired pneumonia worldwide. Invasion of the pleural space is common and results in increased mortality. We set out to determine the bacterial and host factors that influence invasion of the pleural space. In a murine model of pneumococcal infection, we isolated neutrophil-dominated samples of bronchoalveolar and pleural fluid containing bacteria 48 hours after infection. Using dual RNA sequencing (RNA-seq), we characterized bacterial and host transcripts that were differentially regulated between these compartments and bacteria in broth and resting neutrophils, respectively. Pleural and lung samples showed upregulation of genes involved in the positive regulation of neutrophil extravasation but downregulation of genes mediating bacterial killing. Compared to the lung samples, cells within the pleural space showed marked upregulation of many genes induced by type I interferons, which are cytokines implicated in preventing bacterial transmigration across epithelial barriers. Differences in the bacterial transcripts between the infected samples and bacteria grown in broth showed the upregulation of genes in the bacteriocin locus, the pneumococcal surface adhesin PsaA, and the glycopeptide resistance gene vanZ; the gene encoding the ClpP protease was downregulated in infection. One hundred sixty-nine intergenic putative small bacterial RNAs were also identified, of which 43 (25.4%) small RNAs had been previously described. Forty-two of the small RNAs were upregulated in pleura compared to broth, including many previously identified as being important in virulence. Our results have identified key host and bacterial responses to invasion of the pleural space that can be potentially exploited to develop alternative antimicrobial strategies for the prevention and treatment of pneumococcal pleural disease.

IMPORTANCE The factors that regulate the passage of bacteria between different anatomical compartments are unclear. We have used an experimental model of infection with Streptococcus pneumoniae to examine the host and bacterial factors involved in the passage of bacteria from the lung to the pleural space. The transcriptional profile of host and bacterial cells within the pleural space and lung was analyzed using deep sequencing of the entire transcriptome using the technique of dual RNA-seq. We found significant differences in the host and bacterial RNA profiles in infection, which shed light on the key factors that allow passage of this bacterium into the pleural space.

Contralateral Traumatic Hemopneumothorax

Pneumothorax is the entry of air into the virtual space between the visceral and the parietal pleurae, which can occur spontaneously or to a greater extent in a traumatic way. In daily clinical practice it is frequent to find injuries that generate traumatic pneumothorax that is ipsilateral to the lesion. However, there are case reports of contralateral pneumothorax that occurred in procedures such as insertion of pacemakers, or in cases of pneumonectomy. The following is the case report of a 37-year-old man who was admitted with a sharp wound to the right paravertebral region who developed a left haemopneumothorax due to a tangential course of the injuring agent. Adequate clinical judgment was followed, and several imaging studies were carried out, leading to the diagnosis of traumatic pneumothorax that was contralateral to the described injury.

Anti-inflammatory, antiproliferative and cytoprotective potential of the Attalea phalerata Mart. ex Spreng. pulp oil

The anti-inflammatory, antiproliferative and cytoprotective activity of the Attalea phalerata Mart. ex Spreng pulp oil was evaluated by in vitro and in vivo methods. As for the chemical profile, the antioxidant activity was performed by spectrophotometry, and the profile of carotenoids and amino acids by chromatography. Our data demonstrated that A. phalerata oil has high carotenoid content, antioxidant activity and the presence of 5 essential amino acids. In the in vitro models of inflammation, the oil demonstrated the capacity to inhibit COX1 and COX2 enzymes, the production of nitric oxide and also induces macrophages to spreading. In the in vivo models of inflammation, the oil inhibited edema and leukocyte migration in the Wistar rats. In the in vitro model of antiproliferative and cytoprotective activity, the oil was shown inactive against the kidney carcinoma and prostate carcinoma lineage cells and with cytoprotective capacity in murine fibroblast cells, inhibiting the cytotoxic action of doxorubicin. Therefore, it is concluded that A. phalerata pulp oil has anti-inflammatory effects with nutraceutical properties potential due to the rich composition. Moreover, the oil also has cytoprotective activity probably because of its ability to inhibit the action of free radicals.

Circulating complement component 4d (C4d) correlates with tumor volume, chemotherapeutic response and survival in patients with malignant pleural mesothelioma

Only limited information is available on the role of complement activation in malignant pleural mesothelioma (MPM). Thus, we investigated the circulating and tissue levels of the complement component 4d (C4d) in MPM. Plasma samples from 55 MPM patients, 21 healthy volunteers (HV) and 14 patients with non-malignant pleural diseases (NMPD) were measured by ELISA for C4d levels. Tissue specimens from 32 patients were analyzed by C4d immunohistochemistry. Tumor volumetry was measured in 20 patients. We found no C4d labeling on tumor cells, but on ectopic lymphoid structures within the tumor stroma. Plasma C4d levels did not significantly differ between MPM, HV or NMPD. Late-stage MPM patients had higher plasma C4d levels compared to early-stage (p = 0.079). High circulating C4d was associated with a higher tumor volume (p = 0.047). Plasma C4d levels following induction chemotherapy were significantly higher in patients with stable/progressive disease compared to those with partial/major response (p = 0.005). Strikingly, patients with low C4d levels at diagnosis had a significantly better overall survival, confirmed in a multivariate cox regression model (hazard ratio 0.263, p = 0.01). Our findings suggest that circulating plasma C4d is a promising new prognostic biomarker in patients with MPM and, moreover, helps to select patients for surgery following induction chemotherapy.

Mesothelial cells and peritoneal homeostasis

The mesothelium was traditionally thought to be a simple tissue with the sole function of providing a slippery, nonadhesive, and protective surface to allow easy movement of organs within their body cavities. However, our knowledge of mesothelial cell physiology is rapidly expanding, and the mesothelium is now recognized as a dynamic cellular membrane with many other important functions. When injured, mesothelial cells initiate a cascade of processes leading either to complete regeneration of the mesothelium or the development of pathologies such as adhesions. Normal mesothelial healing is unique in that, unlike with other epithelial-like surfaces, healing appears diffusely across the denuded surface, whereas for epithelium healing occurs solely at the wound edges. This is because of a free-floating population of mesothelial cells which attach to the injured serosa. Taking advantage of this phenomenon, intraperitoneal injections of mesothelial cells have been assessed for their ability to prevent adhesion formation. This review discusses some of the functions of mesothelial cells regarding maintenance of serosal integrity and outlines the mechanisms involved in mesothelial healing. In addition, the pathogenesis of adhesion formation is discussed with particular attention to the potential role of mesothelial cells in both preventing and inducing their development.

A clinical study of efficacy of polyglycolic acid sleeve after video-assisted thoracoscopic bullectomy for primary spontaneous pneumothorax

BACKGROUND

Primary spontaneous pneumothorax (PSP) is a common disease in thoracic surgery, and a prolonged postoperative air leakage is the most frequent and troublesome early complication after video-assisted thoracoscopic (VATS) bullectomy. This study aimed to explore the efficacy of polyglycolic acid (PGA) sleeve in preventing postoperative air leakage after a VATS bullectomy for PSP.

METHODS

This study was a prospectively randomised clinical study. The patients who underwent a VATS bullectomy were continuously enrolled from January 2015 to June 2016 in the Beijing Chaoyang Hospital and were randomly assigned to the experimental and control groups. The experimental group applied a PGA sleeve combined with an automatic stapler in the bullectomy, while in the control group, the bullae were resected using an automatic stapler alone during the operation. In addition, the staple lines in both groups were covered with an absorbable polyglycolic acid sheet and both groups performed pleural abrasion after the resection. Useful clinical data were recorded, including the number of cases there was no air leakage immediately after the operation and air leakage lasted more than 3 days, the average postoperative air leakage, the drainage tube removal time, the postoperative hospital stay, the postoperative complications, and the postoperative recurrence.

RESULTS

A total of 134 patients were enrolled in this study. The experimental group consisted of 60 subjects, and there were 74 in the control group. No operative related mortality was observed in either group. In the experimental group, 44 of the 60 patients did not have an air leakage immediately after the operation, which was significantly higher than the control group (73.33% vs. 54.05%, P=0.031). Compared with the control group, the average postoperative air leakage (0.57±1.11 days), the chest tube removal time (3.03±0.92 days), and the postoperative hospital stay (3.98±0.92 days) were all significantly shorter in the experimental group (P=0.048, P=0.012, and P=0.010, respectively). Moreover, the rate of postoperative complications in the experimental group was lower than the control group (3.33% vs. 16.22%, P=0.021). No postoperative recurrence was observed in either group during the follow-up period that ranged from 8 to 25 months.

CONCLUSIONS

The use of PGA sleeve during surgery for PSP might effectively prevent early postoperative air leakage, as well as reduce the postoperative drainage tube removal time and the postoperative hospital stay.

Trends in Pleural Effusion Research

Background:

Research in pleural diseases has traditionally been neglected but is now growing.

Objectives:

This study aimed to analyze scientific research trends on pleural effusions over the last decades.

Method:

We conducted a bibliometric analysis of the Scopus database from its inception to March 2016, searching for original articles and reviews on “pleural effusion” (key word). Journal, year of publication, number of citations, authors and their affiliations, and the Hirsch (H)-index for some of these variables were recorded and analyzed.

Results:

A total of 15 982 documents were retrieved, of which half have been published in the last 18 years and a quarter during the last 8 years. Chest ranked first regarding the number of documents on pleural effusions (both absolute number and yearly rate) and their scientific relevance (H-index of 76). The United States had contributed the most to pleural research productivity (23%). American pulmonologists Dr Richard Light and Dr Steven Sahn exhibited the highest number of papers (206 and 156, respectively) and author H-indexes (44 and 38, respectively).

Conclusion:

There is growing research activity in the field of pleural effusions, which has gained relevance and visibility in clinical respiratory journals. The United States is the leader in quantity and quality of research productivity in pleural medicine.

The Potential Protective Effects of Polyphenols in Asbestos-Mediated Inflammation and Carcinogenesis of Mesothelium

Malignant Mesothelioma (MM) is a tumor of the serous membranes linked to exposure to asbestos. A chronic inflammatory response orchestrated by mesothelial cells contributes to the development and progression of MM. The evidence that: (a) multiple signaling pathways are aberrantly activated in MM cells; (b) asbestos mediated-chronic inflammation has a key role in MM carcinogenesis; (c) the deregulation of the immune system might favor the development of MM; and (d) a drug might have a better efficacy when injected into a serous cavity thus bypassing biotransformation and reaching an effective dose has prompted investigations to evaluate the effects of polyphenols for the therapy and prevention of MM. Dietary polyphenols are able to inhibit cancer cell growth by targeting multiple signaling pathways, reducing inflammation, and modulating immune response. The ability of polyphenols to modulate the production of pro-inflammatory molecules by targeting signaling pathways or ROS might represent a key mechanism to prevent and/or to contrast the development of MM. In this review, we will report the current knowledge on the ability of polyphenols to modulate the immune system and production of mediators of inflammation, thus revealing an important tool in preventing and/or counteracting the growth of MM.

Innate response activator B cells: origins and functions

Innate response activator (IRA) B cells are a subset of B-1a derived B cells that produce the growth factors granulocyte macrophage colony stimulating factor and IL-3. In mouse models of sepsis and pneumonia, B-1a B cells residing in serosal sites recognize bacteria, migrate to the spleen or lung, and differentiate to IRA B cells that then contribute to the host response by amplifying inflammation and producing polyreactive IgM. In atherosclerosis, IRA B cells accumulate in the spleen, where they promote extramedullary hematopoiesis and activate classical dendritic cells. In this review, we focus on the ontogeny and function of IRA B cells in acute and chronic inflammation.

A modified experimental model of malignant pleural disease induced by lung Lewis carcinoma (LLC) cells

Background

Malignant pleural effusion resulting mainly from pleural metastases of lung adenocarcinoma has clinical relevance, being a sign of poor prognosis and low life expectancy. Experimental models can mimic the human condition, contributing to advances in current understanding of the mechanisms patients’ pleural fluid accumulation and possible therapeutic strategies. The objective of this study is to evaluate the role of different concentrations of Lewis lung carcinoma cells (LLC cells) at the time of induction of experimental MPE and the main effects on survival of animals.

Methods

C57BL/6 mice received intrapleural injection of 0.1, 0.5 or 1.5 × 10⁵ LLC cells and survival curve, biochemical and pathological analyses of pleural fluid and tissue were analyzed.

Results

Evaluation of weight loss, mobility and survival showed that animals that received 0.5 × 10⁵ cells maintained more stable condition up to day 14 and a gain of 6 days survival over mice that received the highest concentration.

Conclusion

This study may allow a better understanding the mechanisms involved in the development of malignant pleural effusion and it may be promising in evaluating therapy to avoid recurrence, as the best time to indicate pleurodesis or target therapies.

Pleural Fluid Analysis in Chronic Hemothorax: A Mimicker of Infection

OBJECTIVES

Timing to video-assisted thoracoscopic surgery (VATS) in hemothorax is based on preventing acute and long-term complications of retained blood products in the pleural space, including pleural space infection. We propose that the persistence of blood in the pleural space induces a proinflammatory state, independent of active infection.

METHODS

We identified six patients with a hemothorax by clinical history, radiographic imaging, and pleural fluid analysis from a database of 1133 patients undergoing thoracentesis from 2002 to 2010 at the Medical University of South Carolina.

RESULTS

In four of the six patients identified, the time from injury to thoracentesis was one, four, four, and five days, respectively. The fluid pH range was 7.32–7.41. The lactate dehydrogenase (LDH) range was 210–884 IU/L (mean 547 IU/L), and the absolute neutrophil count (ANC) range was 1196–3631 cells/µL. In two patients, the time from injury to thoracentesis was 7 and 60 days. In these two patients, the pH was 7.18 and 6.91, LDH was 1679 and 961 IU/L, and the ANC was 8134 and 5943 cells/µL. Microbiology and pathology were negative in all patients.

CONCLUSIONS

The persistence of blood outside the vascular compartment, and within the pleural space, biochemically mirrors infection. We will explore the multiple mechanisms that account for development of pleural fluid acidosis, inflammation, and neutrophil recruitment.

Pleural mesothelial cells in pleural and lung diseases

During development, the mesoderm maintains a complex relationship with the developing endoderm giving rise to the mature lung. Pleural mesothelial cells (PMCs) derived from the mesoderm play a key role during the development of the lung. The pleural mesothelium differentiates to give rise to the endothelium and smooth muscle cells via epithelial-to-mesenchymal transition (EMT). An aberrant recapitulation of such developmental pathways can play an important role in the pathogenesis of disease processes such as idiopathic pulmonary fibrosis (IPF). The PMC is the central component of the immune responses of the pleura. When exposed to noxious stimuli, it demonstrates innate immune responses such as Toll-like receptor (TLR) recognition of pathogen associated molecular patterns as well as causes the release of several cytokines to activate adaptive immune responses. Development of pleural effusions occurs due to an imbalance in the dynamic interaction between junctional proteins, n-cadherin and β-catenin, and phosphorylation of adherens junctions between PMCs, which is caused in part by vascular endothelial growth factor (VEGF) released by PMCs. PMCs play an important role in defense mechanisms against bacterial and mycobacterial pleural infections, and in pathogenesis of malignant pleural effusion, asbestos related pleural disease and malignant pleural mesothelioma. PMCs also play a key role in the resolution of inflammation, which can occur with or without fibrosis. Fibrosis occurs as a result of disordered fibrin turnover and due to the effects of cytokines such as transforming growth factor-β, platelet-derived growth factor (PDGF), and basic fibroblast growth factor; which are released by PMCs. Recent studies have demonstrated a role for PMCs in the pathogenesis of IPF suggesting their potential as a cellular biomarker of disease activity and as a possible therapeutic target. Pleural-based therapies targeting PMCs for treatment of IPF and other lung diseases need further exploration.

Mesothelial cells in tissue repair and fibrosis

Mesothelial cells are fundamental to the maintenance of serosal integrity and homeostasis and play a critical role in normal serosal repair following injury. However, when normal repair mechanisms breakdown, mesothelial cells take on a profibrotic role, secreting inflammatory, and profibrotic mediators, differentiating and migrating into the injured tissues where they contribute to fibrogenesis. The development of new molecular and cell tracking techniques has made it possible to examine the origin of fibrotic cells within damaged tissues and to elucidate the roles they play in inflammation and fibrosis. In addition to secreting proinflammatory mediators and contributing to both coagulation and fibrinolysis, mesothelial cells undergo mesothelial-to-mesenchymal transition, a process analogous to epithelial-to-mesenchymal transition, and become fibrogenic cells. Fibrogenic mesothelial cells have now been identified in tissues where they have not previously been thought to occur, such as within the parenchyma of the fibrotic lung. These findings show a direct role for mesothelial cells in fibrogenesis and open therapeutic strategies to prevent or reverse the fibrotic process.

Pleural puncture that excludes the ablation zone decreases the risk of pneumothorax after percutaneous microwave ablation in porcine lung

PURPOSE

To test the hypothesis that the geometry of probe placement with respect to the pleural puncture site affects the risk of pneumothorax after microwave (MW) ablation in the lung.

MATERIALS AND METHODS

Computed tomography-guided MW ablation of the lung was performed in 8 swine under general anesthesia and mechanical ventilation. The orientation of the 17-gauge probe was either perpendicular (90°) or parallel (< 30°) with respect to the pleural puncture site, and the ablation power was 30 W or 65 W for 5 minutes. After MW ablation, swine were euthanized, and histopathologic changes were assessed. Frequency and factors affecting pneumothorax were evaluated by multivariate analysis.

RESULTS

Among 62 lung MW ablations, 13 (21%) pneumothoraces occurred. No statistically significant difference was noted in the rate of pneumothorax between the perpendicular and the parallel orientations of the probe (31% vs 14%; odds ratio [OR], 2.8; P = .11). The pneumothorax rate was equal for 65-W and 30-W ablation powers (21% and 21%; OR, 1.0; P = .94). Under multivariate analysis, 2 factors were independent positive predictors of pneumothorax: ablation zone inclusive of pleural insertion point (OR, 7.7; P = .02) and time since intubation (hours) (OR, 2.7; P = .02).

CONCLUSIONS

Geometries where the pleural puncture site excluded the ablation zone decreased pneumothorax in swine undergoing MW ablation in the lung. Treatment planning to ensure that the pleural puncture site excludes the subsequent ablation zone may reduce the rate of pneumothorax in patients undergoing MW ablation in the lung.

The role for medical thoracoscopy in pneumothorax

Pneumothorax is a life threatening situation that requires fast treatment. There are two major classifications: Primary and Secondary. Staging of pneumothorax is also very important for treatment. Treatment of pneumont can be performed either from thoracic surgeons, or pulmonary physicians. In our current work we provide up-to-date information regarding pneumothorax classification, staging and treatment from the point of view of expert pulmonary physicians.

Pneumothorax and asthma

This review is focused on the relationship between asthma, pneumothorax and pneumomediastinum while presenting a number of case reports that include these conditions. The association between pneumothorax and asthma is not widely known. While asthma includes a common disorder and is prevalent worldwide, its morbidity and mortality is high when is associated with pneumothorax. Furthermore, the delayed diagnosis of pneumothorax while focusing on asthma includes the higher risk of coincidental pneumothorax in asthmatic patients. In addition, pneumomediastinum is considered benign and self-limiting condition that responds to conservative therapy. Although it is rare, the concurrence of pneumomediastinum with pneumothorax may prove fatal during a serious asthma attack. In conclusion, the symptoms of chest pain, dyspnea or focal chest findings when presented in asthmatic patients, must always create suspicion of pneumothorax or pneumomediastinum to the physician.

Expression of fibroblast specific protein-1 in pleural tuberculosis and its clinical biological significance

Background

Fibroblast specific protein-1 (S100A4) is related with many fibrotic diseases, but its role in the pathogenesis of pleural fibrosis has not been fully elucidated. Then we aim to investigate the expression and effect of fibroblast specific protein-1 (S100A4) in pleural tuberculosis and, subsequently, pleural fibrosis.

Methods

The expression of S100A4 in pleura was examined in 30 patients with pleural tuberculosis and 5 control (disease-free) patients by immunohistochemistry using the streptavidin-peroxidase (S-P) conjugated method.

Results

The expression of S100A4 in pleura was mainly distributed in the nucleus and cytoplasm of fibroblasts and vascular endothelial cells, and the positive rate was 90.0% (27 out of 30 patients with pleural tuberculosis). There were no expressions of S100A4 in the control group. In the pleura of all 30 patients with pleural tuberculosis, S100A4 had a higher expression in the two- to eight-week duration of the disease.

Conclusions

S100A4 plays an important role in the phenotypic transformation of pleural mesothelial cells and the development of pleural fibrosis.

Malignant pleural effusion

Malignant pleural effusion (MPE) refers to the presence of neoplastic cells in the pleural fluid. Approximately 40 000 people per year in the UK are affected by MPE and it is associated with significant morbidity and an overall poor prognosis. Management should be prompt and care plans should be individualized and involve a multidisciplinary team of healthcare professionals. This article reviews the pathophysiology of MPE along with available investigations and management strategies for these patients.

Evaluation of pleural effusion sCD26 and DPP-IV as diagnostic biomarkers in lung disease

In this study, we measured ADA and DPP-IV enzymatic activity and sCD26 concentration in 150 pleural effusion (PE) samples and tested for correlations between these and other cellular and biochemical measures. We found that DPP-IV in particular might improve the specificity (but not the sensitivity) of the ADA test for diagnosis of pulmonary tuberculosis, since half of the false ADA positive results in non-tuberculous PE were also DPP-IV positive. A percentage of patients with malignant PE were sCD26 or DPP-IV positive; however, some patients with benign PE also tested positive. As a pattern associated with DPP-IV (but not the CD26 protein) was observed in PE, we searched for a finding that might increase the value of these biomarkers for diagnosis of malignancy. The observed pattern was related to the presence of leukocytes, as indicated by correlations with the cell count, and to a band of 180 kDa, detected by immunoblotting.

Down-regulation of Aquaporin1 (AQP1) by peptidoglycan via p38 MAPK pathways in primary rat pleural mesothelial cells

BACKGROUND AND OBJECTIVE

This study was designed to investigate the p38 mitogen-activated protein kinase (MAPK) signaling pathway involved in Aquaporin1 (AQP1) expression caused by staphylococcal peptidoglycan (PGN) in cultured rat pleural mesothelial cells (rPMCs) in vitro.

METHODS

RT-PCR and immunoblot analysis were used to determine the relative mRNA and protein levels of AQP1 by PGN in rPMCs. P38 kinase inhibitor SB203580, JNK inhibitor SP600125, and ERK1/2 inhibitor PD98059 were used to determine the effects of PGN-induced AQP1 expression by immunoblot. Activation of p38 by PGN was reflected by detecting the phosphorylation constituent of p38, using immunoblot. The shift of localization after activation of p38 by PGN was investigated by immunofluorescence assay.

RESULTS

AQP1 transcription and protein expression were decreased by PGN in dose-dependent and time-dependent manners in rPMCs. Down-regulation of AQP1 by PGN was blocked only by SB203580, neither by SP600125 nor by PD98059. Furthermore, rPMCs exposed to PGN showed activation of p38 MAPK. Phospho-p38 protein production was increased by PGN stimulation in rPMCs. The localization of phospho-p38 was both in the cytosol and nuclei after PGN treatment, while its normal distribution is mainly in the cytosol in rPMCs.

CONCLUSION

AQP1 expression was decreased by PGN in both dose-dependent and time-dependent manners in rPMCs. This down-regulation by PGN-induced AQP1 in rPMCs may be mediated by the activation of p38 MARK pathway.

PD-1/PD-Ls pathways between CD4(+) T cells and pleural mesothelial cells in human tuberculous pleurisy

Programmed death 1 (PD-1), PD-ligand 1 (PD-L1), and PD-L2 have been demonstrated to be involved in tuberculosis immunity, however, the expression and regulation of PD-1/PD-Ls pathways in pleural mesothelial cells (PMCs) and CD4(+) T cells in tuberculous pleural effusion (TPE) have not been investigated. Expression of PD-1 on CD4(+) T cells and expressions of PD-L1 and PD-L2 on PMCs in TPE were determined. The impacts of PD-1/PD-Ls pathways on proliferation, apoptosis, adhesion, and migration of CD4(+) T cells were explored. Concentrations of soluble PD-l, but not of soluble PD-Ls, were much higher in TPE than in serum. Expressions of PD-1 on CD4(+) T cells in TPE were significantly higher than those in blood. Expressions of PD-Ls were much higher on PMCs from TPE when compared with those from transudative effusion. Interferon-γ not only upregulated the expression of PD-1 on CD4(+) T cells, but also upregulated the expressions of PD-Ls on PMCs. Blockage PD-1/PD-Ls pathways abolished the inhibitory effects on proliferation and adhesion activity of CD4(+) T cells induced by PMCs. PD-1/PD-Ls pathways on PMCs inhibited proliferation and adhesion activity of CD4(+) T cells, suggesting that Mycobacterium tuberculosis might exploit PD-1/PD-Ls pathways to evade host cell immune response in human.

Regulation of CD4(+) T cells by pleural mesothelial cells via adhesion molecule-dependent mechanisms in tuberculous pleurisy

Background

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) have been demonstrated to be expressed on pleural mesothelial cells (PMCs), and to mediate leukocyte adhesion and migration; however, little is known about whether adhesion molecule-dependent mechanisms are involved in the regulation of CD4⁺ T cells by PMCs in tuberculous pleural effusion (TPE).

Methods

Expressions of ICAM-1 and VCAM-1 on PMCs, as well as expressions of CD11a and CD29, the counter-receptors for ICAM-1 and VCAM-1, respectively, expressed on CD4⁺ T cells in TPE were determined using flow cytometry. The immune regulations on adhesion, proliferation, activation, selective expansion of CD4⁺ helper T cell subgroups exerted by PMCs via adhesion molecule-dependent mechanisms were explored.

Results

Percentages of ICAM-1-positive and VCAM-1‒positive PMCs in TPE were increased compared with PMC line. Interferon-γ enhanced fluorescence intensity of ICAM-1, while IL-4 promoted VCAM-1 expression on PMCs. Percentages of CD11a^highCD4⁺ and CD29^highCD4⁺ T cells in TPE significantly increased as compared with peripheral blood. Prestimulation of PMCs with anti‒ICAM-1 or ‒VCAM-1 mAb significantly inhibited adhesion, activation, as well as effector regulatory T cell expansion induced by PMCs.

Conclusions

Our current data showed that adhesion molecule pathways on PMCs regulated adhesion and activation of CD4⁺ T cells, and selectively promoted the expansion of effector regulatory T cells.

Spontaneous mesotheliomas in F344/N rats are characterized by dysregulation of cellular growth and immune function pathways

Aged male Fischer 344/N rats are prone to developing spontaneous peritoneal mesotheliomas that arise predominantly from the tunica vaginalis of the testes. A definitive cause for the predominance of this neoplasm in F344/N rats is unknown. Investigation of the molecular alterations that occur in spontaneous rat mesotheliomas may provide insight into their pathogenesis as well enable a better understanding regarding the mechanisms underlying chemically induced mesothelioma in rodents. Mesothelial cell function represents a complex interplay of pathways related to host defense mechanisms and maintenance of cellular homeostasis. Global gene expression profiles of spontaneous mesotheliomas from vehicle control male F344/N rats from 2-year National Toxicology Program carcinogenicity bioassays were analyzed to determine the molecular features of these tumors and elucidate tumor-specific gene expression profiles. The resulting gene expression pattern showed that spontaneous mesotheliomas are associated with upregulation of various growth factors, oncogenes, cytokines, pattern recognition response receptors, and pathogen-associated molecular patterns receptors, and the production of reactive oxygen and nitrogen species, as well as downregulation of apoptosis pathways. Alterations in these pathways in turn trigger molecular responses that stimulate cell proliferation and promote tumor survival and progression.

[Pleural lymphatics and effusions]

The pleural lymphatic system has a great absorption capacity. Its most known function is fluid resorption. The pleura which cover the lungs (visceral pleura), the mediastinum, diaphragm and thoracic wall (parietal pleura) are formed by a mesothelial cell layer (mesothelium). This permeable layer is in direct contact with the vascular endothelium. The mesothelium is based over a connective tissue (interstitium) containing the blood and lymphatic vessels. The primary lymphatic vessels drain interstitium but are also in direct contact with pleural space by the stoma or openings, situated in the lower parts of parietal pleura, i.e: diaphragm, over lower ribs and mediastinum but not existing in the adjacent visceral pleura. In addition, a part of interstitial pulmonary fluid entered in the pleural cavity by passing the visceral pleura would be absorbed by these openings. The resorption process is active and directly related to the function of smooth muscles of lymphatic vessels. Besides resorption, we must emphasize that this "pumping" activity is permanent and the origin of negative pressure (the pleural void) in pleural cavity, a unique property. The other resorbed elements are molecules, bacterial and cellular debris, cells, red blood and cancer cells.

The evaluation and clinical application of pleural physiology

Pleural disease is commonly encountered by the chest physician. Evaluation of pleural disease typically begins with thoracentesis and pleural fluid analysis. With improvements in minimally invasive procedures, imaging, and the use of pleural manometry, a more complete understanding of lung, pleural, and chest wall physiology is possible. The improved knowledge of pleural physiology can help the clinician in clinical decision making, as well as the diagnosis and treatment of pleural disease. This article reviews pleural physiology and summarizes the relevant data supporting the use of ultrasound and manometry in the evaluation and treatment of pleural disease.

Immunotoxicological impact of engineered nanomaterial exposure: mechanisms of immune cell modulation

Abstract Engineered nanomaterials (ENMs) are increasingly being utilized in many consumer products and various medical applications, thereby leading to the potentiality of increased human exposures. Assessment of the adverse effects on the immune system is an important component for evaluating the overall health and safety of ENM. Tasked with eliminating pathogens and removing cancerous cells, the immune system is constantly functioning to maintain homeostasis. Small modifications to the immune system, which may occur following ENM exposure, could lead to impaired protection or an inappropriate immune response resulting in autoimmunity and damage to the host. This review seeks to survey and evaluate the current literature to better understand the impact of ENM exposure on cells critical to the innate and adaptive immune systems.

Pleural mesothelial cells promote expansion of IL-17-producing CD8+ T cells in tuberculous pleural effusion

IL-17-producing CD8(+) T lymphocytes (Tc17 cells) have recently been detected in many cancers and autoimmune diseases. However, the possible implication of Tc17 cells in tuberculous pleural effusion remains unclarified. In this study, distribution and phenotypic features of Tc17 cells in both tuberculous pleural effusion (TPE) and peripheral blood from patients with tuberculosis were determined. The effects of proinflammatory cytokines and local accessory cells (pleural mesothelial cells) on Tc17 cell expansion were also explored. We found that TPE contained more Tc17 cells than the blood. Compared with IFN-γ-producing CD8(+) T cells, Tc17 cells displayed higher expression of chemokine receptors (CCRs) and lower expression of cytotoxic molecules. In particularly, Tc17 cells in TPE exhibited high expression levels of CCR6, which could migrate in response to CCL20. Furthermore, IL-1β, IL-6, IL-23, or their various combinations could promote Tc17 cell expansion from CD8(+) T cells, whereas the proliferative response of Tc17 cells to above cytokines was lower than that of Th17 cells. Pleural mesothelial cells (PMCs) were able to stimulate Tc17 cell expansion via cell contact in an IL-1β/IL-6/IL-23 independent fashion. Thus this study demonstrates that Tc17 cells marks a subset of non-cytotoxic, CCR6(+) CD8(+) T lymphocytes with low proliferative capacity. The overrepresentation of Tc17 cells in TPE may be due to Tc17 cell expansion stimulated by pleural proinflammatory cytokines and to recruitment of Tc17 cells from peripheral blood. Additionally, PMCs may promote the production of IL-17 by CD8(+) T cells at sites of TPE via cell-cell interactions.