Mohammad Abolhassani

Is inflammation a consequence of extracellular hyperosmolarity

BackgroundThere are several reports suggesting that hyperosmolarity induces inflammation. We recently showed that Dextran Sodium Sulfate causes inflammatory bowel disease due to hyperosmolarity. The aim of this study was to confirm the link between hyperosmolarity and inflammation by assessing osmolarity values in vivo during inflammation, compare the inflammatory potential of different osmotic agents and finally study the long-term consequences of hyperosmolarity on cell fate.MethodsOsmotic pressures were measured in inflammatory liquids withdrawn from mice subjected to inflammation caused either by subcutaneous injection of Bacille Calmette-Guérin (BCG) or Freund adjuvant. Three epithelial cell lines (HT29, T24 and A549) were exposed up to 48 hours to increasing osmolarities (300, 600, 900 mOsm) of chemically inert molecules such as Mannitol, Propylene Glycol, and Glycerol and inflammatory response was assessed by Enzyme Linked ImmunoSorbent Assay (ELISA) and RNA Protection Assay (RPA). Finally, normal mouse macrophages were exposed to hyperosmotic conditions for long-term culture.ResultsThe inflammation caused either by BCG or Freund adjuvant is correlated to hyperosmolarity in inflammatory liquids. The exposure of cells to the different compounds, whatever their molecular weight, has no effect on the secretion of cytokines as long as the osmolarity is below a threshold of 300 mOsm. Higher osmolarities result in the secretion of proinflammatory cytokines (Interleukin-8, Interleukin-6, Interleukin-1β and Tumor Necrosis factor-α). Long-term hyperosmotic culture extends normal macrophage half-life, from 44 days to 102 days, and alters the expression of p53, Bcl-2 and Bax.ConclusionThe present study further suggests inflammation and hyperosmolarity are closely related phenomena if not synonymous.

Hyperosmotic stress contributes to mouse colonic inflammation through the methylation of protein phosphatase 2A

There are several reports suggesting hyperosmotic contents in the feces of patients suffering from inflammatory bowel disease (IBD). Previous works have documented that hyperosmolarity can cause inflammation attributable to methylation of the catalytic subunit of protein phosphatase 2A (PP2A) and subsequent NF-kappaB activation resulting in cytokine secretion. In this study, we demonstrate that dextran sulfate sodium (DSS) induces colitis due to hyperosmolarity and subsequent PP2A activation. Mice were randomized and fed with increased concentrations of DSS (0 mOsm, 175 mOsm, 300 mOsm, and 627 mOsm) for a duration of 3 wk or with hyperosmotic concentrations of DSS (627 mOsm) or mannitol (450 mOsm) for a duration of 12 wk. Long-term oral administration of hyposmotic DSS or mannitol had no demonstrable effect. Hyperosmotic DSS or mannitol produced a significant increase in colonic inflammation, as well as an increase in the weight of sacral lymph nodes and in serum amyloid A protein levels. Similar results were obtained through the ingestion of comparable osmolarities of mannitol. Hyperosmolarity induces the methylation of PP2A, nuclear p65 NF-kappaB activation. and cytokine secretion. The rectal instillation of okadaic acid, a well-known PP2A inhibitor, reverses the IBD. Short inhibiting RNAs (siRNAs) targeted toward PP2Ac reverse the effect of hyperosmotic DSS. The present study strongly suggests that DSS-induced chronic colitis is a consequence of the methylation of PP2Ac induced by hyperosmolarity.

Hyperosmolarity causes inflammation through the methylation of protein phosphatase 2A.

Abstract.Objective and Design:We evaluated the role of the osmolarity in the pro-inflammatory responses of epithelial cells.Material:Twenty-five female Wistar rats and colorectal (HT-29) and bladder (T24) cell lines were used.Treatments:Rats and cells were exposed for 48 hours to hyperosmotic solutions.Methods:Interleukin-8 (IL-8) production was measured by Enzyme Linked ImmunoSorbent Assay, mRNA transcription of pro-inflammatory cytokines by microarrays or RNase Protection Assay. Nuclear factor-kappa B (NF-κB) pathway and Protein Phosphatase 2A (PP2A) activations were measured. Myeloperoxydase (MPO) activation and Macrophage-Inflammatory Protein-2 (MIP-2) transcription were monitored.Results:The exposure to hyperosmotic solutions enhanced the production of IL-8 and induced pro-inflammatory cytokines transcription. In vivo, MPO enhanced activity accompanied by an increased MIP-2 transcription was observed. In vitro, NF-κB activation is accompanied by an inhibitor of kappa B-alpha degradation and inhibitor of kappa B kinase (IKKγ) activation. We demonstrated the induction of IKKγ after methylation and activation of PP2A. Cytokine induction was inhibited by okadaic acid and calyculin A and stimulated by xylitol.Conclusion:Hyperosmolarity can induce pro-inflammatory cytokine responses in colorectal and bladder epithelial cells. Inflammation appears to be the simple consequence of a shift of methylation of PP2A which in turn activates NF-κB.

Screening of well-established drugs targeting cancer metabolism: reproducibility of the efficacy of a highly effective drug combination in mice.

SummaryAlterations in metabolic pathways are known to characterize cancer. In order to suppress cancer growth, however, multiple proteins involved in these pathways have to be targeted simultaneously. We have developed a screening method to assess the best drug combination for cancer treatment based on targeting several factors implicated in tumor specific metabolism. Following a review of the literature, we identified those enzymes known to be deregulated in cancer and established a list of sixty-two drugs targeting them. These molecules are used routinely in clinical settings for diseases other than cancer. We screened a first library in vitro against four cell lines and then evaluated the most promising binary combinations in vivo against three murine syngeneic cancer models, (LL/2, Lewis lung carcinoma; B16-F10, melanoma; and MBT-2, bladder cancer). The optimum result was obtained using a combination of α-lipoic acid and hydroxycitrate (METABLOCTM). In this study, a third agent was added by in vivo evaluation of a large number of combinations. The addition of octreotide strongly reduced tumor development (T/C% value of 30.2 to 34.5%; P < 0.001) in the same models and prolonged animal survival (P < 0.001) as compared to cisplatin. These results were confirmed in a different laboratory setting using a human xenograft model (NCI-H69, small cell lung cancer). None of these three molecules are known to target DNA. The effectiveness of this combination in several animal models, as well as the low toxicity of these inexpensive drugs, emphasizes the necessity of rapidly setting up a clinical trial.

Tumor regression with a combination of drugs interfering with the tumor metabolism: efficacy of hydroxycitrate, lipoic acid and capsaicin

SummaryCellular metabolic alterations are now well described as implicated in cancer and some strategies are currently developed to target these different pathways. In previous papers, we demonstrated that a combination of molecules (namely alpha-lipoic acid and hydroxycitrate, i.e. Metabloc™) targeting the cancer metabolism markedly decreased tumor cell growth in mice. In this work, we demonstrate that the addition of capsaicin further delays tumor growth in mice in a dose dependant manner. This is true for the three animal model tested: lung (LLC) cancer, bladder cancer (MBT-2) and melanoma B16F10. There was no apparent side effect of this ternary combination. The addition of a fourth drug (octreotide) is even more effective resulting in tumor regression in mice bearing LLC cancer. These four compounds are all known to target the cellular metabolism not its DNA. The efficacy, the apparent lack of toxicity, the long clinical track records of these medications in human medicine, all points toward the need for a clinical trial. The dramatic efficacy of treatment suggests that cancer may simply be a disease of dysregulated cellular metabolism.

Carbon dioxide is largely responsible for the acute inflammatory effects of tobacco smoke

Tobacco smoking is responsible for a vast array of diseases, particularly chronic bronchitis and lung cancer. It is still unclear which constituent(s) of the smoke is responsible for its toxicity. The authors decided to focus on carbon dioxide, since its level of concentration in mainstream cigarette smoke is about 200 times higher than in the atmosphere. The authors previously demonstrated that inhalation of carbon dioxide concentrations above 5% has a deleterious effect on lungs. In this study, the authors assessed the inflammatory potential of carbon dioxide contained in cigarette smoke. Mice were exposed to cigarette smoke containing a high or reduced CO2 level by filtration through a potassium hydroxyde solution. The inflammatory response was evaluated by histological analysis, protein phosphatase 2 A (PP2A) and nuclear factor (NF)-κB activation, and proinflammatory cytokine secretion measurements. The data show that the toxicity of cigarette smoke may be largely due to its high level of CO2. Pulmonary injuries consequent to tobacco smoke inhalation observed by histology were greatly diminished when CO2 was removed. Cigarette smoke exposure causes an inflammatory response characterized by PP2A and NF-κB activation followed by proinflammatory cytokine secretion. This inflammatory response was reduced when the cigarette smoke was filtered through a potassium hydroxide column, and reestablished when CO2 was injected downstream from the filtration column.Given that there is an extensive literature linking a chronic inflammatory response to the major smoking-related diseases, these data suggest that carbon dioxide may play a key role in the causation of these diseases by tobacco smoking.

The Redox Status of Cancer Cells Supports Mechanisms behind the Warburg Effect

To better understand the energetic status of proliferating cells, we have measured the intracellular pH (pHi) and concentrations of key metabolites, such as adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD), and nicotinamide adenine dinucleotide phosphate (NADP) in normal and cancer cells, extracted from fresh human colon tissues. Cells were sorted by elutriation and segregated in different phases of the cell cycle (G0/G1/S/G2/M) in order to study their redox (NAD, NADP) and bioenergetic (ATP, pHi) status. Our results show that the average ATP concentration over the cell cycle is higher and the pHi is globally more acidic in normal proliferating cells. The NAD+/NADH and NADP+/NADPH redox ratios are, respectively, five times and ten times higher in cancer cells compared to the normal cell population. These energetic differences in normal and cancer cells may explain the well-described mechanisms behind the Warburg effect. Oscillations in ATP concentration, pHi, NAD+/NADH, and NADP+/NADPH ratios over one cell cycle are reported and the hypothesis addressed. We also investigated the mitochondrial membrane potential (MMP) of human and mice normal and cancer cell lines. A drastic decrease of the MMP is reported in cancer cell lines compared to their normal counterparts. Altogether, these results strongly support the high throughput aerobic glycolysis, or Warburg effect, observed in cancer cells.

Mechanical stress increases brain amyloid β, tau, and α-synuclein concentrations in wild-type mice

Exposure to traumatic brain injury is a core risk factor that predisposes an individual to sporadic neurodegenerative diseases. We provide evidence that mechanical stress increases brain levels of hallmark proteins associated with neurodegeneration.