Short-chain fatty acids induced lung tumor cell death and increased peripheral blood CD4+ T cells in NSCLC and control patients ex vivo

Background

Despite therapy advances, one of the leading causes of cancer deaths still remains lung cancer. To improve current treatments or prevent non-small cell lung cancer (NSCLC), the role of the nutrition in cancer onset and progression needs to be understood in more detail. While in colorectal cancer, the influence of local microbiota derived SCFAs have been well investigated, the influence of SCFA on lung cancer cells via peripheral blood immune system should be investigated more deeply. In this respect, nutrients absorbed via the gut might affect the tumor microenvironment (TME) and thus play an important role in tumor cell growth.

Objective

This study focuses on the impact of the short-chain fatty acid (SCFA) Sodium Butyrate (SB), on lung cancer cell survival. We previously described a pro-tumoral role of glucose on A549 lung adenocarcinoma cell line. In this study, we wanted to know if SB would counteract the effect of glucose and thus cultured A549 and H520 in vitro with and without SB in the presence or absence of glucose and investigated how the treatment with SB affects the survival of lung cancer cells and its influence on immune cells fighting against lung cancer.

Methods

In this study, we performed cell culture experiments with A549, H520 and NSCLC-patient-derived epithelial cells under different SB levels. To investigate the influence on the immune system, we performed in vitro culture of peripheral mononuclear blood cells (PBMC) from control, smoker and lung cancer patients with increasing SB concentrations.

Results

To investigate the effect of SB on lung tumor cells, we first analyzed the effect of 6 different concentrations of SB on A549 cells at 48 and 72 hours cell culture. Here we found that, SB treatment reduced lung cancer cell survival in a concentration dependent manner. We next focused our deeper analysis on the two concentrations, which caused the maximal reduction in cell survival. Here, we observed that SB led to cell cycle arrest and induced early apoptosis in A549 lung cancer cells. The expression of cell cycle regulatory proteins and A549 lung cancer stem cell markers (CD90) was induced. Additionally, this study explored the role of interferon-gamma (IFN-γ) and its receptor (IFN-γ-R1) in combination with SB treatment, revealing that, although IFN-γ-R1 expression was increased, IFN-γ did not affect the efficacy of SB in reducing tumor cell viability. Furthermore, we examined the effects of SB on immune cells, specifically CD8+ T cells and natural killer (NK) cells from healthy individuals, smokers, and NSCLC patients. SB treatment resulted in a decreased production of IFN-γ and granzyme B in CD8+ T cells and NK cells. Moreover, SB induced IFN-γ-R1 in NK cells and CD4+ T cells in the absence of glucose both in PBMCs from controls and NSCLC subjects.

Conclusion

Overall, this study highlights the potential of SB in inhibiting lung cancer cell growth, triggering apoptosis, inducing cell cycle arrest, and modulating immune responses by activating peripheral blood CD4+ T cells while selectively inducing IFN-γ-R1 in NK cells in peripheral blood and inhibiting peripheral blood CD8+ T cells and NK cells. Thus, understanding the mechanisms of action of SB in the TME and its influence on the immune system provide valuable insights of potentially considering SB as a candidate for adjunctive therapies in NSCLC.

Contribution of serum lipids and cholesterol cellular metabolism in lung cancer development and progression

Neoplasms of the lungs are the leading cause of cancer incidence and mortality worldwide. Although immunotherapy has increased the overall survival of patients with lung cancer, there is the need to improve this treatment. At this regard, blood lipid levels are thought to be linked to cancer risk and thus a preventive intervention through regulation of the nutrition of patients with lung cancer is gaining much attention. In this study, we therefore asked about the contribution of serum lipids and cholesterol cellular metabolism in lung cancer development and progression. We measured different serum lipids and analyzed cholesterol synthesis enzymes 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) and acetyl-coenzyme A cholesterol acetyltransferase 1 (ACAT1) as well as the cholesterol cellular export protein ATP-binding cassette (ABC) A-1 mRNA by quantitative PCR (qPCR) in the control and tumoral regions of post-surgery lung tissues to analyze the accumulation of cholesterol in cancer cells in a cohort of patients with lung adenocarcinoma (LUAD). We found that triglycerides in serum directly correlated with the body mass index (BMI) in patients with LUAD. By contrast, we found that high-density lipoprotein (HDL) cholesterol inversely correlated with the BMI, C-reactive protein (CRP) and overall survival and total cholesterol inversely correlated with the tumor diameter, serum CRP and overall survival in these LUAD patients. Functionally, the role of cholesterol is indispensable for the growth and development of normal animal cells where it is tightly regulated. Excess of cellular cholesterol regulated by HMGCR is converted to cholesteryl esters by the enzyme ACAT1 and exported extracellularly by the cholesterol transporter ABCA1. Here we found HMGCR and ACAT1 upregulated and ABCA1 downregulated in the lung's tumoral region of our LUAD cohort, indicating cholesterol dysregulated cellular export in lung tumor cells.

Glucose-Restricted Diet Regulates the Tumor Immune Microenvironment and Prevents Tumor Growth in Lung Adenocarcinoma

Background

Lung cancer is the second common cancer type in western countries and has a high mortality. During the development and progression of the tumor, the nutrients in its environment play a central role. The tumor cells depend crucially on glucose metabolism and uptake. Tumor cell metabolism is dominated by the Warburg effect, where tumor cells produce large amounts of lactate from pyruvate under aerobic conditions. We thus reasoned that, reducing carbohydrates in the diet might support anti-tumoral effects of current immunotherapy and additionally target tumor immune escape.

Objectives

The link between reducing carbohydrates to improve current immunotherapy is not clear. We thus aimed at analyzing the effects of different glucose levels on the tumor development, progression and the anti-tumoral immune response.

Methods

We correlated the clinical parameters of our LUAD cohort with different metabolic markers. Additionally, we performed cell culture experiments with A549 tumor cell line under different glucose levels. Lastly, we investigated the effect of low and high carbohydrate diet in an experimental murine model of lung cancer on the tumor progression and different immune subsets.

Results

Here we found a positive correlation between the body mass index (BMI), blood glucose levels, reduced overall survival (OS) and the expression of Insulin-like growth factor-1 receptor (IGF1R) in the lung tumoral region of patients with lung adenocarcinoma (LUAD). Furthermore, increasing extracellular glucose induced IGF1R expression in A549 LUAD cells. Functional studies in a murine model of LUAD demonstrated that, glucose restricted diet resulted in decreased tumor load in vivo. This finding was associated with increased presence of lung infiltrating cytotoxic CD8+ T effector memory (TEM), tissue resident memory T (TRM) and natural killer cells as well as reduced IGFR mRNA expression, suggesting that glucose restriction regulates lung immunity in the tumor microenvironment.

Conclusions

These results indicate that, glucose restricted diet improves lung immune responses of the host and suppresses tumor growth in experimental lung adenocarcinoma. As glucose levels in LUAD patients were negatively correlated to postoperative survival rates, glucose-restricted diet emerges as therapeutic avenue for patients with LUAD.

IL-9 Producing Tumor-Infiltrating Lymphocytes and Treg Subsets Drive Immune Escape of Tumor Cells in Non-Small Cell Lung Cancer

Although lung cancer is the leading cause of cancer deaths worldwide, the mechanisms how lung cancer cells evade the immune system remain incompletely understood. Here, we discovered IL-9-dependent signaling mechanisms that drive immune evasion in non-small cell lung cancer (NSCLC). We found increased IL-9 and IL-21 production by T cells in the tumoral region of the lung of patients with NSCLC, suggesting the presence of Th9 cells in the lung tumor microenvironment. Moreover, we noted IL-9 producing Tregs in NSCLC. IL-9 target cells in NSCLC consisted of IL-9R+ tumor cells and tumor-infiltrating lymphocytes. In two murine experimental models of NSCLC, and in vitro, IL-9 prevented cell death and controlled growth of lung adenocarcinoma cells. Targeted deletion of IL-9 resulted in successful lung tumor rejection in vivo associated with an induction of IL-21 and reduction of Treg cells. Finally, anti-IL-9 antibody immunotherapy resulted in suppression of tumor development even in established experimental NSCLC and was associated with reduced IL-10 production in the lung. In conclusion, our findings indicate that IL-9 drives immune escape of lung tumor cells via effects on tumor cell survival and tumor infiltrating T cells. Thus, strategies blocking IL-9 emerge as a new approach for clinical therapy of lung cancer.

Tumour immune evasion mechanism in non-small cell lung cancer by inducing Blimp-1 in CD4+CD25+Foxp-3+ T regulatory cells

Immunotherapy improves the life expectancy of patients with lung cancer by targeting the immune inhibitory T cell surface markers resulting in the activation of anti-tumor T cell survival and suppression of tumor cell growth.

The transcription factor repressor Positive Regulatory Domain Containing Protein 1 (encoded in humans by the Prdm1 gene) also known as B lymphocytes-induced maturation protein-1 (Blimp-1) affects the homeostasis and function of CD4+ and CD8+ T cells as well as T regulatory cells (T regs).

We recently reported that Blimp-1 is induced in the lung tumoral region of patients with lung ADC. To further investigate whether Blimp-1 could be a candidate gene involved in the regulation of the anti-tumor immune-response in lung cancer, we started to investigate peripheral blood mononuclear cells (PBMCs) isolated from healthy control subjects and NSCLC patients for Blimp-1 expression in immunosuppressive CD4+CD25+Foxp3+ T regs. The PBMCs were cultured with and without antiCD3/CD28 antibodies, without and with TGF-beta, to mimic the tumor microenvironment, for 4 days and subsequently analyzed by flow cytometry using antibodies against Blimp-1, Foxp3, CD4 and CD25(IL-2R alpha chain).

Here we found, by trend, induced CD4+Blimp1+CD25+Foxp3+ Tregs in unstimulated PBMCs from patients with lung cancer. Moreover, TGF-beta further induced these Blimp1+CD4+CD25+Foxp3+ Tregs in PBMCs obtained both from healthy controls and from NSCLC patients.

Taken together these data indicate that the tumor microenvironment induces Blimp-1 in immunosuppressive CD4+CD25+Foxp3+ Tregs via TGF-beta.

Thus, current immunotherapy should be combined to TGF-beta inhibitors to target CD4+CD25+Blimp1+Foxp-3+ T regulatory cells.

Lung tumor immune evasion mechanism in Non-small cell lung cancer (NSCLC) targets pSTAT5 in CD4+CD25+FoxP3− T effector cells

The mechanisms of lung cancer evading the immune system are still not fully understood. As regulatory T cells (Tregs) exhibit a pro-tumoral function they are in focus of immunotherapies. Peripheral Treg differentiation is driven by TCR and its co-stimulation. A further crucial signal displays the binding of IL-2 to the high affinity receptor CD25 with downstream involvement of Signal Transducer and Activator of Transcription 5 (STAT5). STAT5 activation as well as TGF-beta stimulation in the periphery leads to expression of the Treg key factor FoxP3.

In this study, we wanted to investigate the role of STAT5 and its activated status via phosphorylation (pSTAT5) within lung cancer. We thus isolated peripheral blood mononuclear cells (PBMC) from NSCLC patients and healthy donors. PBMCs were cultured under different stimulation conditions for 4 days and analyzed by FACS.

Here we found CD4+ T cells with high induction of pSTAT5A and CD25 upon aCD3 and aCD28 antibody treatment. Moreover, CD4+CD25+FoxP3+ Tregs were detected under T cell activating conditions, and were found to be increased by TGFβ in smokers and NSCLC patients. The Treg population was further inducible by adding low doses of IL-2 while CD4+CD25+FoxP3− effector T cells decreased in the presence of TGFβ. Our findings point to an immunosuppressive microenvironment induced by the tumor with increased TGFβ and reduced IL-2 forcing effector T cells into a Treg state. These preliminary data suggest that current immunotherapy by aCD3/aCD28 antibody treatment could be improved by an additional blockade of TGFβ and induction of IL-2 levels. This treatment would result in an increase of CD4+CD25+pSTAT5+FoxP3− effector cells and a reduction of CD4+CD25+FoxP3+STAT5+ Tregs.

Effects of glucose concentration in the tumor microenvironment on Non Small Lung Cancer (NSCLC) Progression

Lung cancer is one of the most common cancer types in the western world, with a high lethality and increasing incidence. One major factor, supporting tumor growth is a high sugar diet. Thus, reducing the sugar intake by different diets might be a way to improve current cancer treatment. These metabolic changes are accompanied by regulation of systemic levels of Insulin and insulin like growth factors. As oppose to normal cells, tumor cells metabolism mainly depends on glycolysis. Thus, reducing diet carbohydrate intake might be a way to improve current immunotherapy by inducing immunological changes caused by the extracellular glucose concentration in tumor microenvironment.

Therefore, we cultured the human lung adenocarcinoma (ADC) cell line A549 with different extracellular glucose concentrations to analyze effects by flow cytometry and qPCR. Moreover, lung tissue samples from patients with non small cell lung cancer (NSCLC), were analyzed by qPCR. In a murine model of lung ADC, tumor cells were injected intravenously and mice were fed with different diets. Lung cells were isolated and analyzed by flow cytometry.

Here we show that, IGF1R expression is upregulated in A549 cells line, depending on increasing extracellular glucose concentration. Moreover, in studies on human cohorts of patients with NSCLC, we found a direct correlation between BMI and IGF1R expression and its downstream signaling. Finally, in a murine model of disease, diet glucose restriction decreased significantly tumor load associated with increased lung infiltrating CD8+ T-cells and tissue-resident memory T-cells.

Thus, this study supports the need to introduce glucose restrictions in the diet of patients with NSCLC in association with current immunotherapy.

[The carotid sinus pressure test--a screening method for the demonstration of latent bradycardial arrhythmias]

100 patients with peripheral arteriosclerotic obstructive disease were examined for latent bradycardic disturbances of the rhythm by means of the pressure experiment on the carotid sinus under screening conditions. 57% of the arteriosclerotics had sinus-auricular or atrioventricular blockings, 67% of them an asystole over 3 s. In 84% of the cases this asystole was conditioned by a sinus-auricular block. In a comparative group of the same age only a retardation of the sinus rhythm was found. An asystole over 3 s in a pressure experiment on the carotid sinus refers to an endangering by Morgagni-Adams-Stokes-attacks, since the substitution pacemaker in form of the secondary stimulation formation system insufficiency compensatorily steps into the breach. Particularly endangered seem to be patients with additionally bradycardizing medicaments (glycosides, antihypertensive drugs, beta-receptor blockers, antiarrhythmic drugs) which frequently and combined are prescribed in arteriosclerotics with hypertensive cardiac disease. In synopsis with anamnesis, findings of the examinations and the ECG-analysis with and without pressure experiment on the carotid sinus can be decided on the actual therapy up to the pacemaker implantation. The method proved to be suitable as screening and preliminary examination before the prescription of the medicaments mentioned above when performed correctly and the contraindication was taken into consideration. It is to be discussed whether before recommendation of the broad application of the pressure on the carotid sinus without possibility of reanimation a phase of another testing should precede.

[Carotid sinus pressure as an aid for the detection of latent asystole]

For the detection of intermitting blockings the pressure of the carotid sinus was used. In 21 patients with ascertained intermitting block the pressure of the carotid sinus caused an asystolia during 3 seconds. In control persons such a duration of asystolia could not be observed. Despite spontaneous blockings not in every case a pathological pressure of the carotid sinus was present. Diagnostic and therapeutic aspects as well as influences on the result of the reflex are discussed.