Chlorinated benzenes cause concomitantly oxidative stress and induction of apoptotic markers in lung epithelial cells (A549) at nonacute toxic concentrations

Multiple Chemical Sensitivity: It's time to catch up to the science

Multiple chemical sensitivity (MCS) is a complex medical condition associated with low dose chemical exposures. MCS is characterized by diverse features and common comorbidities, including fibromyalgia, cough hypersensitivity, asthma, and migraine, and stress/anxiety, with which the syndrome shares numerous neurobiological processes and altered functioning within diverse brain regions. Predictive factors linked to MCS comprise genetic influences, gene-environment interactions, oxidative stress, systemic inflammation, cell dysfunction, and psychosocial influences. The development of MCS may be attributed to the sensitization of transient receptor potential (TRP) receptors, notably TRPV1 and TRPA1. Capsaicin inhalation challenge studies demonstrated that TRPV1 sensitization is manifested in MCS, and functional brain imaging studies revealed that TRPV1 and TRPA1 agonists promote brain-region specific neuronal variations. Unfortunately, MCS has often been inappropriately viewed as stemming exclusively from psychological disturbances, which has fostered patients being stigmatized and ostracized, and often being denied accommodation for their disability. Evidence-based education is essential to provide appropriate support and advocacy. Greater recognition of receptor-mediated biological mechanisms should be incorporated in laws, and regulation of environmental exposures.

Neurological susceptibility to environmental exposures: pathophysiological mechanisms in neurodegeneration and multiple chemical sensitivity

The World Health Organization lists air pollution as one of the top five risks for developing chronic non-communicable disease, joining tobacco use, harmful use of alcohol, unhealthy diets and physical inactivity. This review focuses on how host defense mechanisms against adverse airborne exposures relate to the probable interacting and overlapping pathophysiological features of neurodegeneration and multiple chemical sensitivity. Significant long-term airborne exposures can contribute to oxidative stress, systemic inflammation, transient receptor subfamily vanilloid 1 (TRPV1) and subfamily ankyrin 1 (TRPA1) upregulation and sensitization, with impacts on olfactory and trigeminal nerve function, and eventual loss of brain mass. The potential for neurologic dysfunction, including decreased cognition, chronic pain and central sensitization related to airborne contaminants, can be magnified by genetic polymorphisms that result in less effective detoxification. Onset of neurodegenerative disorders is subtle, with early loss of brain mass and loss of sense of smell. Onset of MCS may be gradual following long-term low dose airborne exposures, or acute following a recognizable exposure. Upregulation of chemosensitive TRPV1 and TRPA1 polymodal receptors has been observed in patients with neurodegeneration, and chemically sensitive individuals with asthma, migraine and MCS. In people with chemical sensitivity, these receptors are also sensitized, which is defined as a reduction in the threshold and an increase in the magnitude of a response to noxious stimulation. There is likely damage to the olfactory system in neurodegeneration and trigeminal nerve hypersensitivity in MCS, with different effects on olfactory processing. The associations of low vitamin D levels and protein kinase activity seen in neurodegeneration have not been studied in MCS. Table 2 presents a summary of neurodegeneration and MCS, comparing 16 distinctive genetic, pathophysiological and clinical features associated with air pollution exposures. There is significant overlap, suggesting potential comorbidity. Canadian Health Measures Survey data indicates an overlap between neurodegeneration and MCS (p < 0.05) that suggests comorbidity, but the extent of increased susceptibility to the other condition is not established. Nevertheless, the pathways to the development of these conditions likely involve TRPV1 and TRPA1 receptors, and so it is hypothesized that manifestation of neurodegeneration and/or MCS and possibly why there is divergence may be influenced by polymorphisms of these receptors, among other factors.

Design and Characterization of Atorvastatin Dry Powder Formulation as a potential Lung Cancer Treatment

Lung cancer is the leading cause of cancer death. Many studies have shown the beneficial effects of Atorvastatin in decreasing the mortality risk and improving survival among patients with lung cancer. This research paper focuses on improving AVT cytotoxic activity and cellular uptake by developing mannitol microcarriers as a promising drug delivery system for lung cancer treatment and, studying the impact of improving inhalation deposition on the delivery and Dry Powder formulations efficiency. The AVT loaded mannitol (AM) microparticles (AVT-AM) formulation was prepared by spray drying and characterized for its physicochemical properties and aerodynamic deposition. The results revealed that the AVT-AM formulation has good flow properties and aerosol deposition with a particle size of 3418 nm ± 26.86. The formulation was also assessed in vitro for cytotoxicity effects (proliferation, apoptosis, and cell cycle progression) on A549 human lung adenocarcinoma. Compared with free AVT, the AVT-AM formulation has significantly higher cellular uptake and anti-cancer properties by disrupting cell cycle progression via either apoptosis or cell cycle arrest in the G2/M phase. This study shows that AVT loaded mannitol microcarriers may provide a potentially effective and sustained pulmonary drug delivery for lung cancer treatment.

Accumulation of prohibitin is a common cellular response to different stressing stimuli and protects melanoma cells from ER stress and chemotherapy-induced cell death

Melanoma is responsible for most deaths among skin cancers and conventional and palliative care chemotherapy are limited due to the development of chemoresistance. We used proteomic analysis to identify cellular responses that lead to chemoresistance of human melanoma cell lines to cisplatin. A systems approach to the proteomic data indicated the participation of specific cellular processes such as oxidative phosphorylation, mitochondrial organization and homeostasis, as well as the unfolded protein response (UPR) to be required for the survival of cells treated with cisplatin. Prohibitin (PHB) was among the proteins consistently accumulated, interacting with the functional clusters associated with resistance to cisplatin. We showed PHB accumulated at different levels in melanoma cell lines under stressing stimuli, such as (i) treatment with temozolomide (TMZ), dacarbazine (DTIC) and cisplatin; (ii) serum deprivation; (iii) tunicamycin, an UPR inducer. Prohibitin accumulated in the mitochondria of melanoma cells after cisplatin and tunicamycin treatment and its de novo accumulation led to chemoresistance melanoma cell lines. In contrast, PHB knock-down sensitized melanoma cells to cisplatin and tunicamycin treatment. We conclude that PHB participates in the survival of cells exposed to different stress stimuli, and can therefore serve as a target for the sensitization of melanoma cells to chemotherapy.

Domestic exposure to volatile organic compounds in relation to asthma and allergy in children and adults

Over the past decades, the prevalence of asthma, allergic disease and atopy has increased significantly and in parallel with the increased use of products and materials emitting volatile organic compounds (VOCs) in the indoor environment. The purpose of this review is to examine the evidence of the relationship between quantitatively measured domestic exposure to VOCs and allergic diseases and allergy in children and adults. Sources, potential immune-inflammatory mechanisms and risks for development and severity of asthma and allergy have been addressed. Available evidence is based on studies that have mainly used observational designs of variable quality. Total, aromatic, aliphatic, microbial VOCs and aldehydes have been the most widely investigated VOC classes, with formaldehyde being the most commonly examined single compound. Overall, the evidence is inadequate to draw any firm conclusions. However, given indicative evidence from a few high-quality studies and significant potential for improvements in asthma outcomes in those with established disease, there is a need to consider undertaking further investigation of the relationship between domestic VOC exposure and asthma/allergy outcomes that should encompass both high-quality, robust observational studies and ultimately clinical trials assessing the impact of interventions that aim to reduce VOC exposure in children and adults with asthma.

Diaphragm muscle weakness in mice is early-onset post-myocardial infarction and associated with elevated protein oxidation

Heart failure induced by myocardial infarction (MI) causes diaphragm muscle weakness, with elevated oxidants implicated. We aimed to determine whether diaphragm muscle weakness is 1) early-onset post-MI (i.e., within the early left ventricular remodeling phase of 72 h); and 2) associated with elevated protein oxidation. Ligation of the left coronary artery to induce MI (n = 10) or sham operation (n = 10) was performed on C57BL6 mice. In vitro contractile function of diaphragm muscle fiber bundles was assessed 72 h later. Diaphragm mRNA and protein expression, enzyme activity, and individual carbonylated proteins (by two-dimensional differential in-gel electrophoresis and mass spectrometry) were subsequently assessed. Infarct size averaged 57 ± 1%. Maximal diaphragm function was reduced (P < 0.01) by 20% post-MI, with the force-frequency relationship depressed (P < 0.01) between 80 and 300 Hz. The mRNA expression of inflammation, atrophy, and regulatory Ca(2+) proteins remained unchanged post-MI, as did the protein expression of key contractile proteins. However, enzyme activity of the oxidative sources NADPH oxidase and xanthine oxidase was increased (P < 0.01) by 45 and 33%, respectively. Compared with sham, a 57 and 45% increase (P < 0.05) was observed in the carbonylation of sarcomeric actin and creatine kinase post-MI, respectively. In conclusion, diaphragm muscle weakness was rapidly induced in mice during the early left ventricular remodeling phase of 72 h post-MI, which was associated with increased oxidation of contractile and energetic proteins. Collectively, these findings suggest diaphragm muscle weakness may be early onset in heart failure, which is likely mediated in part by posttranslational oxidative modifications at the myofibrillar level.

Effects of subchronic exposure to low-dose volatile organic compounds on lung inflammation in mice

Inflammatory lung diseases are characterized by chronic inflammation and oxidant/antioxidant imbalance. Exposure to some kinds of volatile organic compounds (VOCs) leads to lung inflammation, oxidative stress, and immune modulation. However, it is suspected that sub-chronic exposure to low-dose VOCs mixture induces or aggravates lung inflammation. To clarify the effect of this exposure on lung inflammatory responses, 40 male Kunming mice were exposed in four similar static chambers, 0 (control) and three different doses of VOCs mixture (groups 1-3). The concentrations of VOCs mixture were as follows: formaldehyde, benzene, toluene, and xylene 0.10 + 0.11 + 0.20 + 0.20 mg/m(3) , 0.50 + 0.55 + 1.00 + 1.00 mg/m(3) , 1.00 + 1.10 + 2.00 + 2.00 mg/m(3) , respectively, which corresponded to 1, 5, and 10 times of indoor air quality standard in China. After 90 consecutive days of exposure (2 h/day), oxidative stress markers in lung, cellular infiltration and cytokines, chemokine, neurotrophin in bronchoalveolar lavage fluid (BALF), and immunoglobulin (Ig) in serum were examined. VOCs exposure could increase significantly reactive oxygen species (ROS) in lung, the levels of interleukin-8 (IL-8), IL-4, eotaxin, nerve growth factor (NGF), and various types of leukocytes in BALF, IgE concentration in serum. In contrast, GSH to GSSG ratio and interferon-gamma were significantly decreased following the VOCs exposure. These results indicate that the VOCs mixture-induced inflammatory response is at least partly caused by release of the ROS and mediators from the activated eosinophils, neutrophils, alveolar macrophages and epithelial cells.

Chlorobenzenes, lindane and dieldrin induce apoptotic alterations in human peripheral blood lymphocytes (in vitro study)

In this study, we have assessed apoptotic effect of 1,2,4-trichlorobenzene, hexachlorobenzene, lindane and dieldrin on human peripheral blood lymphocytes. We observed an increase in ROS formation and a decrease in mitochondrial transmembrane potential in the cells incubated with low concentrations of all compounds studied, in particular lindane and dieldrin. ROS formation and changes in mitochondrial transmembrane potential may have influenced caspase-3 activation, a crucial enzyme in the apoptotic process. Moreover, chlorobenzenes, and in particular lindane and dieldrin changed cells' membrane permeability and induced phosphatidylserine translocation, which confirmed that they are capable of inducing apoptosis in human lymphocytes. Apoptotic changes in human lymphocytes provoked by biologically relevant concentrations of these substances suggest that they may disturb function of immunological system especially among people occupationally exposed to their action.

Subtoxic and toxic concentrations of benzene and toluene induce Nrf2-mediated antioxidative stress response and affect the central carbon metabolism in lung epithelial cells A549

Since people in industrialized countries spend most of their time indoors, the effects of indoor contaminants such as volatile organic compounds become more and more relevant. Benzene and toluene are among the most abundant compounds in the highly heterogeneous group of indoor volatile organic compounds. In order to understand their effects on lung epithelial cells (A549) representing lung's first line of defense, we chose a global proteome and a targeted metabolome approach in order to detect adverse outcome pathways caused by exposure to benzene and toluene. Using a DIGE approach, 93 of 469 detected protein spots were found to be differentially expressed after exposure to benzene, and 79 of these spots were identified by MS. Pathway analysis revealed an enrichment of proteins involved in Nrf2-mediated and oxidative stress response glycolysis/gluconeogenesis. The occurrence of oxidative stress at nonacute toxic concentrations of benzene and toluene was confirmed by the upregulation of the stress related proteins NQO1 and SOD1. The changes in metabolism were validated by ion chromatography MS/MS analysis revealing significant changes of glucose-6-phosphate, fructose-6-phosphate, 3-phosphoglycerate, and NADPH. The molecular alterations identified as a result of benzene and toluene exposure demonstrate the detrimental effect of nonacute toxic concentrations on lung epithelial cells. The data provided here will allow for a targeted validation in in vivo models.

Essential nontranslational functions of tRNA synthetases

Nontranslational functions of vertebrate aminoacyl tRNA synthetases (aaRSs), which catalyze the production of aminoacyl-tRNAs for protein synthesis, have recently been discovered. Although these new functions were thought to be 'moonlighting activities', many are as critical for cellular homeostasis as their activity in translation. New roles have been associated with their cytoplasmic forms as well as with nuclear and secreted extracellular forms that affect pathways for cardiovascular development and the immune response and mTOR, IFN-γ and p53 signaling. The associations of aaRSs with autoimmune disorders, cancers and neurological disorders further highlight nontranslational functions of these proteins. New architecture elaborations of the aaRSs accompany their functional expansion in higher organisms and have been associated with the nontranslational functions for several aaRSs. Although a general understanding of how these functions developed is limited, the expropriation of aaRSs for essential nontranslational functions may have been initiated by co-opting the amino acid-binding site for another purpose.

Effect of cigarette smoke extract on insulin transport in alveolar epithelial cell line A549

BACKGROUND

The main purpose of this study was to evaluate the effect of cigarette smoke extract (CSE) on insulin transport in alveolar epithelial cells.

METHODS

We first examined the effect of CSE pretreatment on cell viability, mRNA expression, and lamellar body structures in A549 cells. Then the effect of CSE pretreatment on FITC-insulin transport was examined.

RESULTS

When A549 cells were treated with 30 μg/ml of CSE for 48 h, the expression of some mRNAs abundantly expressed in type II alveolar epithelial cells such as surfactant protein B was significantly increased. Lamellar bodylike structures became more evident with CSE treatment. FITC-insulin uptake from the apical side and subsequent efflux to the basal side was enhanced by CSE treatment in A549 cells. The enhancing effect of CSE on FITC-insulin uptake was concentration-dependent and reversible. A concentration-dependent enhancing effect of CSE on FITC-insulin uptake was also observed in normal, primary cultured alveolar type II epithelial cells isolated from rats.

CONCLUSIONS

Treatment of A549 cells by CSE may direct the cells to a more type II-like phenotype. In accordance with this observation, FITC-insulin uptake was enhanced by CSE treatment. These results may partly explain the higher insulin absorption from the lung in smokers than in nonsmokers.

Comparative expression profiling of distinct T cell subsets undergoing oxidative stress

The clinical outcome of adoptive T cell transfer-based immunotherapies is often limited due to different escape mechanisms established by tumors in order to evade the hosts' immune system. The establishment of an immunosuppressive micromilieu by tumor cells along with distinct subsets of tumor-infiltrating lymphocytes is often associated with oxidative stress that can affect antigen-specific memory/effector cytotoxic T cells thereby substantially reducing their frequency and functional activation. Therefore, protection of tumor-reactive cytotoxic T lymphocytes from oxidative stress may enhance the anti-tumor-directed immune response. In order to better define the key pathways/proteins involved in the response to oxidative stress a comparative 2-DE-based proteome analysis of naïve CD45RA⁺ and their memory/effector CD45RO⁺ T cell counterparts in the presence and absence of low dose hydrogen peroxide (H₂O₂) was performed in this pilot study. Based on the profiling data of these T cell subpopulations under the various conditions, a series of differentially expressed spots were defined, members thereof identified by mass spectrometry and subsequently classified according to their cellular function and localization. Representative targets responding to oxidative stress including proteins involved in signaling pathways, in regulating the cellular redox status as well as in shaping/maintaining the structural cell integrity were independently verified at the transcript and protein level under the same conditions in both T cell subsets. In conclusion the resulting profiling data describe complex, oxidative stress-induced, but not strictly concordant changes within the respective expression profiles of CD45RA⁺ and CD45RO⁺ T cells. Some of the differentially expressed genes/proteins might be further exploited as potential targets toward modulating the redox capacity of the distinct lymphocyte subsets thereby providing the basis for further studies aiming at rendering them more resistant to tumor micromilieu-induced oxidative stress.

Volatile organic compounds enhance allergic airway inflammation in an experimental mouse model

BACKGROUND

Epidemiological studies suggest an association between exposure to volatile organic compounds (VOCs) and adverse allergic and respiratory symptoms. However, whether VOCs exhibit a causal role as adjuvants in asthma development remains unclear.

METHODS

To investigate the effect of VOC exposure on the development of allergic airway inflammation Balb/c mice were exposed to VOCs emitted by new polyvinylchloride (PVC) flooring, sensitized with ovalbumin (OVA) and characterized in acute and chronic murine asthma models. Furthermore, prevalent evaporated VOCs were analyzed and mice were exposed to selected single VOCs.

RESULTS

Exposure of mice to PVC flooring increased eosinophilic lung inflammation and OVA-specific IgE serum levels compared to un-exposed control mice. The increased inflammation was associated with elevated levels of Th2-cytokines. Long-term exposure to PVC flooring exacerbated chronic airway inflammation. VOCs with the highest concentrations emitted by new PVC flooring were N-methyl-2-pyrrolidone (NMP) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB). Exposure to NMP or TXIB also increased the allergic immune response in OVA-sensitized mice. In vitro or in vivo exposure to NMP or TXIB reduced IL-12 production in maturing dendritic cells (DCs) and enhanced airway inflammation after adoptive DC transfer into Balb/c mice. At higher concentrations both VOCs induced oxidative stress demonstrated by increased isoprostane and glutathione-S-transferase-pi1 protein levels in the lung of non-sensitized mice. Treatment of PVC flooring-exposed mice with N-acetylcysteine prevented the VOC-induced increase of airway inflammation.

CONCLUSIONS

Our results demonstrate that exposure to VOCs may increase the allergic immune response by interfering with DC function and by inducing oxidative stress and has therefore to be considerate as risk factor for the development of allergic diseases.

Identification of protein targets of reactive metabolites of tienilic acid in human hepatocytes

Tienilic acid (TA) is a uricosuric diuretic that was withdrawn from the market only months after its introduction because of reports of serious incidents of drug-induced liver injury including some fatalities. Its hepatotoxicity is considered to be primarily immunoallergic in nature. Like other thiophene compounds, TA undergoes biotransformation to a S-oxide metabolite which then reacts covalently with cellular proteins. To identify protein targets of TA metabolites, we incubated [(14)C]-TA with human hepatocytes, separated cellular proteins by 2D gel electrophoresis, and analyzed proteins in 36 radioactive spots by tryptic digestion followed by LC-MS/MS. Thirty-one spots contained at least one identifiable protein. Sixteen spots contained only one of 14 nonredundant proteins which were thus considered to be targets of TA metabolites. Six of the 14 were also found in other radioactive spots that contained from 1 to 3 additional proteins. Eight of the 14 had not been reported to be targets for any reactive metabolite other than TA. The other 15 spots each contained from 2 to 4 identifiable proteins, many of which are known targets of other chemically reactive metabolites, but since adducted peptides were not observed, the identity of the adducted protein(s) in these spots is ambiguous. Interestingly, all the radioactive spots corresponded to proteins of low abundance, while many highly abundant proteins in the mixture showed no radioactivity. Furthermore, of approximately 16 previously reported protein targets of TA in rat liver ( Methogo, R., Dansette, P., and Klarskov, K. ( 2007 ) Int. J. Mass Spectrom. , 268 , 284 -295 ), only one (fumarylacetoacetase) is among the 14 targets identified in this work. One reason for this difference may be statistical, given that each study identified a small number of targets from among thousands present in hepatocytes. Another may be the species difference (i.e., rat vs human), and still another may be the method of detection of adducted proteins (i.e., Western blot vs C-14). Knowledge of human target proteins is very limited. Of more than 350 known protein targets of reactive metabolites, only 42 are known from humans, and only 21 of these are known to be targets for more than one chemical. Nevertheless, the demonstration that human target proteins can be identified using isolated hepatocytes in vitro should enable the question of species differences to be addressed more fully in the future.

DIGE proteome analysis reveals suitability of ischemic cardiac in vitro model for studying cellular response to acute ischemia and regeneration

Proteomic analysis of myocardial tissue from patient population is suited to yield insights into cellular and molecular mechanisms taking place in cardiovascular diseases. However, it has been limited by small sized biopsies and complicated by high variances between patients. Therefore, there is a high demand for suitable model systems with the capability to simulate ischemic and cardiotoxic effects in vitro, under defined conditions. In this context, we established an in vitro ischemia/reperfusion cardiac disease model based on the contractile HL-1 cell line. To identify pathways involved in the cellular alterations induced by ischemia and thereby defining disease-specific biomarkers and potential target structures for new drug candidates we used fluorescence 2D-difference gel electrophoresis. By comparing spot density changes in ischemic and reperfusion samples we detected several protein spots that were differentially abundant. Using MALDI-TOF/TOF-MS and ESI-MS the proteins were identified and subsequently grouped by functionality. Most prominent were changes in apoptosis signalling, cell structure and energy-metabolism. Alterations were confirmed by analysis of human biopsies from patients with ischemic cardiomyopathy.With the establishment of our in vitro disease model for ischemia injury target identification via proteomic research becomes independent from rare human material and will create new possibilities in cardiac research.

Endocytic uptake of FITC-albumin by human alveolar epithelial cell line A549

The uptake mechanism of FITC-labeled albumin (FITC-albumin) was examined in human alveolar epithelial cell line A549. FITC-albumin uptake by A549 cells was time- and temperature-dependent, and was markedly suppressed at 4°C compared with that at 37°C. The uptake was saturable, and was mediated by a high-affinity, low-capacity system and by a low-affinity, high-capacity system. In the following experiments, we focused on the low-affinity system. FITC-albumin uptake was markedly inhibited by metabolic inhibitors and by a vacuolar H⁺-ATPase, bafilomycin A₁. The uptake was inhibited by clathrin-mediated endocytosis inhibitors (phenylarsine oxide and chlorpromazine). Potassium depletion and hypertonicity that inhibit clathrin-mediated endocytosis also decreased FITC-albumin uptake. On the other hand, caveolae-mediated endocytosis inhibitors (indomethacin and nystatin) did not affect FITC-albumin uptake. In addition, FITC-albumin uptake was inhibited by macropinocytosis inhibitors such as 5-(N-ethyl-N-isopropyl) amiloride. These results suggest that the low-affinity system of FITC-albumin uptake is mediated by endocytosis in A549 cells, predominantly via a clathrin-mediated pathway. Macropinocytosis, but not caveolae-mediated endocytosis, may also be involved. Considering our previous findings, albumin may be transported by a similar mechanism and/or pathway in rat and human alveolar epithelial cells.

Combined proteomic and metabolomic profiling of serum reveals association of the complement system with obesity and identifies novel markers of body fat mass changes

Obesity is associated with multiple adverse health effects and a high risk of developing metabolic and cardiovascular diseases. Therefore, there is a great need to identify circulating parameters that link changes in body fat mass with obesity. This study combines proteomic and metabolomic approaches to identify circulating molecules that discriminate healthy lean from healthy obese individuals in an exploratory study design. To correct for variations in physical activity, study participants performed a one hour exercise bout to exhaustion. Subsequently, circulating factors differing between lean and obese individuals, independent of physical activity, were identified. The DIGE approach yielded 126 differentially abundant spots representing 39 unique proteins. Differential abundance of proteins was confirmed by ELISA for antithrombin-III, clusterin, complement C3 and complement C3b, pigment epithelium-derived factor (PEDF), retinol binding protein 4 (RBP4), serum amyloid P (SAP), and vitamin-D binding protein (VDBP). Targeted serum metabolomics of 163 metabolites identified 12 metabolites significantly related to obesity. Among those, glycine (GLY), glutamine (GLN), and glycero-phosphatidylcholine 42:0 (PCaa 42:0) serum concentrations were higher, whereas PCaa 32:0, PCaa 32:1, and PCaa 40:5 were decreased in obese compared to lean individuals. The integrated bioinformatic evaluation of proteome and metabolome data yielded an improved group separation score of 2.65 in contrast to 2.02 and 2.16 for the single-type use of proteomic or metabolomics data, respectively. The identified circulating parameters were further investigated in an extended set of 30 volunteers and in the context of two intervention studies. Those included 14 obese patients who had undergone sleeve gastrectomy and 12 patients on a hypocaloric diet. For determining the long-term adaptation process the samples were taken six months after the treatment. In multivariate regression analyses, SAP, CLU, RBP4, PEDF, GLN, and C18:2 showed the strongest correlation to changes in body fat mass. The combined serum proteomic and metabolomic profiling reveals a link between the complement system and obesity and identifies both novel (C3b, CLU, VDBP, and all metabolites) and confirms previously discovered markers (PEDF, RBP4, C3, ATIII, and SAP) of body fat mass changes.