GENDER DIFFERENCE IN GRANULOCYTE DYNAMICS AND APOPTOSIS AND THE ROLE OF IL-18 DURING ENDOTOXIN-INDUCED SYSTEMIC INFLAMMATION

Sex Differences of Neutrophil Extracellular Traps on Lipopolysaccharide-Stimulated Human Neutrophils

Objective: Sex differences exist in sepsis, but the commitment of neutrophils to these differences remains unclear. Neutrophil extracellular traps (NETs) function to remove pathogens, yet excessive NETs release can contribute to organ damage. This study explores effects of the gender hormones on endotoxin-induced NETs using neutrophils from both male and female sources. Methods: Blood samples were collected from healthy volunteers. Isolated neutrophils were seeded in collagen-coated cell culture plates, and NETs were induced by lipopolysaccharide (LPS) treatment. After 15 minutes of LPS treatment, 17β-estradiol (0.03-272.4 ng/mL), testosterone enanthate (0.01-10 ng/mL), dimethyl sulfoxide, or ethanol (vehicle control) was added to the plates. These were incubated for three hours at 37°C with 5% CO2. Neutrophil extracellular traps formation was assessed using immunofluorescence staining. Results: Lipopolysaccharide-induced NETs formation was significantly greater in females than in males. In male-derived neutrophils, 17β-estradiol at above the blood concentrations significantly suppressed LPS-induced NETs. No effect was seen while using testosterone enanthate to NETs at any concentration. In female-derived neutrophils, 17β-estradiol, which was near to the highest concentration of non-pregnant women's blood, tended to increase NETs. Testosterone enanthate, which was near to female blood concentration, significantly promoted NETs. Conclusions: Sex differences existed in LPS-induced NETs of human neutrophil. In males, high concentrations of 17β-estradiol administration may have a suppressive effect on excessive NETs during infection. In females, endogenous gender hormones may promote NETs during infection. Sex differences in neutrophils may need to be considered in organ damage owing to NETs excess such as sepsis.

Sex hormone influence on female-biased autoimmune diseases hints at puberty as an important factor in pathogenesis

The majority of autoimmune diseases affect more women than men, suggesting an important role for sex hormones in regulating immune response. Current research supports this idea, highlighting the importance of sex hormones in both immune and metabolic regulation. Puberty is characterized by drastic changes in sex hormone levels and metabolism. These pubertal changes may be what forms the gulf between men and women in sex bias towards autoimmunity. In this review, a current perspective on pubertal immunometabolic changes and their impact on the pathogenesis of a select group of autoimmune diseases is presented. SLE, RA, JIA, SS, and ATD were focused on in this review for their notable sex bias and prevalence. Due to both the scarcity of pubertal autoimmune data and the differences in mechanism or age-of-onset in juvenile analogues often beginning prior to pubertal changes, data on the connection between the specific adult autoimmune diseases and puberty often relies on sex hormone influence in pathogenesis and established sex differences in immunity that begin during puberty.

Age- and Gender-Related Serum Level of Interleukin 18 in Iranian Fars Ethnic Group with Metabolic Syndrome

Background: The purpose of the present study was to investigate the age- and gender-related serum level of interleukin 18 (IL18) in male and female Iranian Fars ethnic group with metabolic syndrome components. Methods: The study included 226 native Iranian Fars ethnic groups. One hundred sixteen females and 110 men were selected. There were 60 females and 50 males with metabolic syndrome and 56 females and 60 males without metabolic syndrome. The serum fasting blood glucose (FBS), lipid profiles, and IL18 were measured. The National Cholesterol Education Program Adult treatment Panel III criteria were used to determine metabolic syndrome components. Results: There were significant differences between the males and females [except high-density lipoprotein (HDL)] with and without metabolic syndrome for the mean body mass index, FBS, HDL-cholesterol, waist circumference (WC), triglyceride (TG), and IL18 levels in all age groups. Serum IL18 was the highest in males and females in age groups 61-70 and 41-50 years with metabolic syndrome, respectively. Serum IL18 levels significantly correlated with TG and waist WC in males (and also correlated with HDL) and females with the metabolic syndrome. There were significant correlations between IL18 and TG and WC in males (and also correlated with HDL) in ages 61-70 years and females in ages 41-50 years with the metabolic syndrome. Conclusions: The increased IL18 level in both gender and different ages may have an important role in the alteration of some metabolic syndrome components. These alterations may be made to happen in different related metabolic diseases. IL18 seems to be a useful biomarker for the management of metabolic syndrome components and the risk factors of cardiovascular disease.

Early-Life Maternal Deprivation Predicts Stronger Sickness Behaviour and Reduced Immune Responses to Acute Endotoxaemia in a Pig Model

Early-life adversity may have programming effects on neuroendocrine and immune adaptation mechanisms in humans and socially living animals. Using a pig model, we investigated the effect of daily 2-h maternal and littermate deprivation from postnatal days 2–15, either alone (DA) or in a group of littermates (DG) on the neuroendocrine, immunological and behavioural responses of piglets challenged with the bacterial endotoxin lipopolysaccharide (LPS) on day 42. LPS increased plasma concentrations of cortisol, tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-10 (IL-10) and induced typical signs of sickness in all piglets. DA+DG piglets showed stronger signs of sickness compared to control (C) piglets. Plasma TNF-α concentrations were significantly lower in DA+DG males. In addition, the TNF-α/IL-10 ratio was significantly lower in DA than in DG and C males. Gene expression analyses showed lower hypothalamic TNF-α mRNA expression and diminished mRNA expression of the mineralocorticoid receptor (MR) and IL-10 in the amygdala of DA+DG piglets in response to LPS. Interestingly, males showed a higher MR- and a lower IL-10 mRNA expression in the amygdala than females. The present data suggest that repeated maternal deprivation during early life may alter neuroendocrine and immune responses to acute endotoxaemia in a sex-specific manner.

Effect of Rosmarinic Acid and Sinapic Acid on Oxidative Stress Parameters in the Cardiac Tissue and Serum of Type 2 Diabetic Female Rats

Cardiovascular diseases are one of the most common complications of type 2 diabetes. They are considered the leading cause of death among diabetics. One of the mechanisms underlying diabetic cardiovascular complications is oxidative stress. Many phenolic acids are regarded as antioxidants. The aim of the study was to investigate the effect of rosmarinic acid (RA) and sinapic acid (SA) on oxidative stress parameters in the cardiac tissue and serum of type 2 diabetic female rats. Additionally, the effect of these compounds on glucose homeostasis and lipid profile in the serum was evaluated. Type 2 diabetes was induced with high-fat diet and streptozotocin. RA at the doses of 10 and 50 mg/kg and SA at the doses of 5 and 25 mg/kg were administrated orally for 28 days. Untreated diabetic rats exhibited unfavorable changes in glucose metabolism and lipid profile. Changes in the enzymatic and non-enzymatic markers indicated the onset of oxidative stress in these animals. The results showed that the higher doses of the tested phenolic acids-50 mg/kg of RA and 25 mg/kg of SA-revealed beneficial effects on oxidative stress in the cardiac tissue of diabetic rats.

Metabolic control and sex: A focus on inflammatory-linked mediators

Men and women have many differing biological and physiological characteristics. Thus, it is no surprise that the control of metabolic processes and the mechanisms underlying metabolic-related diseases have sex-specific components. There is a clear metabolic sexual dimorphism in that up until midlife, men have a far greater likelihood of acquiring cardio-metabolic disease than women. Following menopause, however, this difference is reduced, suggestive of a protective role of the female sex hormones. Inflammatory processes have been implicated in the pathogenesis of cardio-metabolic disease with human studies correlating metabolic disease acquisition or risk with levels of various inflammatory markers. Rodent studies employing genetic modifications or novel pharmacological approaches have provided mechanistic insight into the role of these inflammatory mediators. Sex differences impact inflammatory processes and the subsequent biological response. As a consequence, this may affect how inflammation alters metabolic processes between the sexes. Recently, some of our work in the field of inflammatory genes and metabolic control identified a sexual dimorphism in a preclinical model and caused us to question the frequency and scale of such findings in the literature. This review concentrates on inflammatory-related signalling in relation to obesity, insulin resistance, and type 2 diabetes and highlights the differences observed between males and females. Differences in the activation and signalling of various inflammatory genes and proteins present another reason why studying both male and female patients or animals is important in the context of understanding and finding therapeutics for metabolic-related disease. LINKED ARTICLES: This article is part of a themed section on The Importance of Sex Differences in Pharmacology Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.21/issuetoc.

Cytokine secretion responsiveness of lymphomonocytes following cortisol cell exposure: Sex differences

The stress hormone cortisol has been recognized as a coordinator of immune response. However, its different ability to modulate the release of inflammatory mediators in males and females has not been clarified yet. Indeed, the dissection of cortisol specific actions may be difficult due to the complex hormonal and physio-pathological individual status. Herein, the release of inflammatory mediators following increasing cortisol concentrations was investigated in an in vitro model of primary human male and female lymphomonocytes. The use of a defined cellular model to assess sex differences in inflammatory cytokine secretion could be useful to exclude the effects of divergent and fluctuating sex hormone levels occurring in vivo. Herein, the cells were challenged with cortisol concentrations resembling the plasma levels achieving in physiological and stressful conditions. The production of cytokines and other molecules involved in inflammatory process was determined. In basal conditions, male cells presented higher levels of some pro-inflammatory molecules (NF-kB and IDO-1 mRNAs, IL-6 and kynurenine) than female cells. Following cortisol exposure, the levels of the pro-inflammatory cytokines, IL-6 and IL-8, were increased in male cells. Conversely, in female cells IL-6 release was unchanged and IL-8 levels were decreased. Anti-inflammatory cytokines, IL-4 and IL-10, did not change in male cells and increased in female cells. Interestingly, kynurenine levels were higher in female cells than in male cells following cortisol stimulus. These results highlighted that cortisol differently affects male and female lymphomonocytes, shifting the cytokine release in favour of a pro-inflammatory pattern in male cells and an anti-inflammatory secretion profile in female cells, opening the way to study the influences of other stressful factors involved in the neurohumoral changes occurring in the response to stress conditions.

Deciphering sex differences in the immune system and depression

Certain mood disorders and autoimmune diseases are predominately female diseases but we do not know why. Here, we explore the relationship between depression and the immune system from a sex-based perspective. This review characterizes sex differences in the immune system in health and disease. We explore the contribution of gonadal and stress hormones to immune function at the cellular and molecular level in the brain and body. We propose hormonal and genetic sex specific immune mechanisms that may contribute to the etiology of mood disorders.

Interleukin-18 and testosterone levels in men with metabolic syndrome

OBJECTIVE

Interleukin 18 (IL-18) is an adipokine associated with obesity. Data about the relationship of IL-18 to the metabolic syndrome (MS) are still scarce. Low testosterone (T) levels are common in men with MS, but we did not find data about the levels of IL-18 in men with low T. The aim of this study was to determine the levels of IL-18 in men with MS with or without low T.

PATIENTS AND METHODS

A total of 251 men were included in the study. Of them 218 had MS (IDF 2005) and they were divided according to their morning total testosterone (TT) level (cutoff 10.4 nmol/l) into two groups: MS-low T (N = 84) and MS-normal T (N = 134). The control group consisted of 33 men without MS and low T. IL-18 was determined in serum using enzyme-linked immunosorbent assay. A small group of eight men with MS and low T levels received testosterone therapy for three months and physical and laboratory parameters were monitored at the end of that period.

RESULTS

MS men were at mean age (±SD) = 53.77 ± 9.59 years; body mass index (BMI) = 34.0 ± 6.3 kg/m²; and TT = 12.59 ± 5.66 nmol/l. The control group was at age = 52.12 ± 5.2 years (NS); BMI = 25.6 ± 2.4 kg/m² (p < .001); and TT = 17.8 ± 5.68 nmol/l (p < .001), respectively. The levels of IL-18 were higher in the MS group - 345 pg/ml compared to the control one - 264 pg/ml (p < .01). There was no significant difference between MS-low T (330.6 pg/ml) and MS-normal T (350.2 pg/ml) subgroups. The MS-normal T differed more significantly from the control group (p < .001). Significant correlation of testosterone with IL-18 levels was not found. IL-18 correlated with parameters of obesity, lipids, fasting blood sugar (p < .05) and the number of criteria for MS (p < .001). Three months on T treatment showed improvement in obesity parameters and only in one patient IL-18 had clear reduction while the rest showed no change.

CONCLUSIONS

In this study, higher IL-18 levels were found in the presence of MS compared to healthy men, but they did not differ between men having MS with or without LOH.

Female sex hormones are necessary for the metabolic effects mediated by loss of Interleukin 18 signaling

OBJECTIVE

Interleukin (IL)-18 plays a crucial role in maintaining metabolic homeostasis and levels of this cytokine are influenced by gender, age, and sex hormones. The role of gender on IL-18 signaling, however, is unclear. We hypothesized that the presence of female sex hormone could preserve the metabolic phenotype of the IL-18R^-/- animals.

METHODS

We studied female mice with a global deletion of the α isoform of the IL-18 receptor (IL-18R^-/-) and littermates control. Three studies were done: 1) animals fed a high fat diet (HFD) for 16 weeks; 2) animals fed chow diet for 72 weeks and 3) animals (3 weeks-old) randomized to either bilateral ovariectomy (OVX) or control surgery (SHAM) and followed for 16 weeks.

RESULTS

Female IL-18R^-/- mice gained less weight and maintained glucose homeostasis on a chow diet compared with HFD, but no differences between genotypes were observed. The maintenance of body weight and glucose homeostasis in IL-18R^-/- mice was lost with aging. By 72 weeks of age, IL-18R^-/- mice became heavier compared with WT mice due to an increase in both visceral and subcutaneous adiposity and displayed glucose intolerance. OVX did not affect body weight in IL-18R^-/- mice but exacerbated glucose intolerance and impaired liver insulin signaling when compared with SHAM mice.

CONCLUSIONS

Female mice harboring a global deletion of the IL-18R, only present the same phenotype as reported in male IL-18R^-/- mice if they are aged or have undergone OVX, in which circulating estrogen is likely to be blunted. The role of estrogen signaling in the protection against altered metabolic homeostasis in IL-18R^-/- mice appears to be mediated by liver insulin signaling. We therefore suggest that the metabolic effects mediated by loss of IL-18 signaling are only present in a female sex hormone free environment.

A cold-inducible RNA-binding protein (CIRP)-derived peptide attenuates inflammation and organ injury in septic mice

Cold-inducible RNA-binding protein (CIRP) is a novel sepsis inflammatory mediator and C23 is a putative CIRP competitive inhibitor. Therefore, we hypothesized that C23 can ameliorate sepsis-associated injury to the lungs and kidneys. First, we confirmed that C23 dose-dependently inhibited TNF-α release, IκBα degradation, and NF-κB nuclear translocation in macrophages stimulated with CIRP. Next, we observed that male C57BL/6 mice treated with C23 (8 mg/kg BW) at 2 h after cecal ligation and puncture (CLP) had lower serum levels of LDH, ALT, IL-6, TNF-α, and IL-1β (reduced by ≥39%) at 20 h after CLP compared with mice treated with vehicle. C23-treated mice also had improved lung histology, less TUNEL-positive cells, lower serum levels of creatinine (34%) and BUN (26%), and lower kidney expression of NGAL (50%) and KIM-1 (86%). C23-treated mice also had reduced lung and kidney levels of IL-6, TNF-α, and IL-1β. E-selectin and ICAM-1 mRNA was significantly lower in C23-treated mice. The 10-day survival after CLP of vehicle-treated mice was 55%, while that of C23-treated mice was 85%. In summary, C23 decreased systemic, lung, and kidney injury and inflammation, and improved the survival rate after CLP, suggesting that it may be developed as a new treatment for sepsis.

IL-18 Serum Levels and Variants of the Serotonin Transporter Gene Are Related to Awareness of Emotions in Healthy Subjects: A Preliminary Study

OBJECTIVE

Interaction between the nervous and immune systems may influence emotions, ultimately affecting human health. Cytokines may play a role in developing emotional dysregulation as in alexithymia, a personality construct characterized by the subclinical inability to identify and describe emotions, often associated with several psychiatric and psychosomatic disorders. The proinflammatory cytokine IL-18, with a recognized role in brain functions, may influence serotonin metabolism and appears to be associated with alexithymia. Healthy individuals carrying the long allele (L) of the serotonin transporter gene polymorphic region (5-HTTLPR), and thus having lower concentrations of serotonin in the synaptic cleft, show a greater tendency toward alexithymia, with some gender differences. To explore a potential physiological interaction between IL-18, serotonin neurotransmission, and alexithymia, we investigated whether IL-18 serum levels and 5-HTTLPR are linked to alexithymic traits in healthy subjects.

METHODS

We measured IL-18 serum levels in 115 Italian-Caucasian healthy subjects genotyped for 5-HTTLPR allele variants, divided by gender and assessed for alexithymia scores using the 20-item Toronto Alexithymia Scale.

RESULTS

IL-18 levels are significantly more elevated in individuals with the LL genotype (n = 25) than in carriers of the short allele (n = 90, p = 0.0073). Specifically, in LL males (n = 11), i.e., the group with the most relevant increase in IL-18, cytokine values positively correlated with difficulty identifying feelings, which is a component of alexithymia (r = 0.634, p = 0.036).

CONCLUSIONS

These results indicate a possible novel interaction between IL-18 and the serotoninergic system to mediate emotional unawareness, suggesting putative biological predictors of emotional dysregulation, which in turn can act as a risk factor for a variety of medical conditions in susceptible subjects.

Human cells involved in atherosclerosis have a sex

The influence of sex has been largely described in cardiovascular diseases. Atherosclerosis is a complex process that involves many cell types such as vessel cells, immune cells and endothelial progenitor cells; however, many, if not all, studies do not report the sex of the cells. This review focuses on sex differences in human cells involved in the atherosclerotic process, emphasizing the role of sex hormones. Furthermore, we report sex differences and issues related to the processes that determine the fate of the cells such as apoptotic and autophagic mechanisms. The analysis of the data reveals that there are still many gaps in our knowledge regarding sex influences in atherosclerosis, largely for the cell types that have not been well studied, stressing the urgent need for a clear definition of experimental conditions and the inclusion of both sexes in preclinical studies.

Antithrombin III improved neutrophil extracellular traps in lung after the onset of endotoxemia

BACKGROUND

Coagulation and inflammation are closely linked during acute inflammatory conditions, such as sepsis. Antithrombin (AT) is an anticoagulant that also has anti-inflammatory activities. The effects of therapeutically administering AT III after the onset of endotoxemia or sepsis were not clear. Here, we studied the effects of administering AT III after inducing lethal endotoxemia in mice.

METHODS

Mice were injected intraperitoneally with lipopolysaccharide (LPS) to induce endotoxemia. AT III was administered 3 h later. We assessed survival and the severity of endotoxemia and quantified plasma cytokine levels and biochemical markers of liver and kidney function. In the lungs, we examined neutrophil accumulation, neutrophil extracellular traps, alveolar wall thickness, and chemokine (C-X-C motif) ligand 1 (cxcl-1), cxcl-2, and high mobility group box 1 expression.

RESULTS

Administering AT III reduced the severity and mortality of LPS-induced endotoxemia as indicated by 24-h survival of 84% of the mice that received LPS + AT III and only 53% of mice given LPS alone (P < 0.05). AT III treatment attenuated several changes induced in the lungs by endotoxemia including cxcl-2 mRNA expression, high mobility group box 1 protein expression, neutrophil accumulation, alveolar septal thickening, and neutrophil extracellular trap formation. AT III did not decrease plasma cytokine levels or plasma urea nitrogen levels that were upregulated as a result of LPS-induced endotoxemia.

CONCLUSIONS

Administration of AT III after the onset of endotoxemia improved outcomes in a mouse model. The attenuation of lung inflammation may have a large impact on mortality and morbidity. Because lung inflammation increases the likelihood of mortality from sepsis, AT III could be a useful agent in septic patients.

Endogenous interleukin 18 regulates testicular germ cell apoptosis during endotoxemia

Orchitis (testicular swelling) often occurs during systemic inflammatory conditions, such as sepsis. Interleukin 18 (IL18) is a proinflammatory cytokine and is an apoptotic mediator during endotoxemia, but the role of IL18 in response to inflammation in the testes was unclear. WT and IL18 knockout (KO) mice were injected lipopolysaccharide (LPS) to induce endotoxemia and examined 12 and 48  h after LPS administration to model the acute and recovery phases of endotoxemia. Caspase activation was assessed using immunohistochemistry. Protein and mRNA expression were examined by western blot and quantitative real-time RT-PCR respectively. During the acute phase of endotoxemia, apoptosis (as indicated by caspase-3 cleavage) was increased in WT mice but not in IL18 KO mice. The death receptor-mediated and mitochondrial-mediated apoptotic pathways were both activated in the WT mice but not in the KO mice. During the recovery phase of endotoxemia, apoptosis was observed in the IL18 KO mice but not in the WT mice. Activation of the death-receptor mediated apoptotic pathway could be seen in the IL18 KO mice but not the WT mice. These results suggested that endogenous IL18 induces germ cell apoptosis via death receptor mediated- and mitochondrial-mediated pathways during the acute phase of endotoxemia and suppresses germ cell apoptosis via death-receptor mediated pathways during recovery from endotoxemia. Taken together, IL18 could be a new therapeutic target to prevent orchitis during endotoxemia.

Endogenous interleukin 18 suppresses hyperglycemia and hyperinsulinemia during the acute phase of endotoxemia in mice

BACKGROUND

Hyperglycemia associated with insulin resistance is common among critically ill patients. Interleukin (IL)-18 has been linked with hyperglycemia and insulin resistance in chronic disease, but the relation between IL-18 and insulin resistance during critical illness was unexplored. This study investigated whether IL-18 modulates hyperglycemia and insulin resistance during acute inflammation.

METHODS

We injected lipopolysaccharide (LPS) 40 mg/kg into wild-type (WT) and IL-18 knockout (KO) mice to induce endotoxemia and examined insulin resistance and insulin-dependent signaling pathways during the acute phase.

RESULTS

During the first hour after LPS treatment, IL-18 KO mice showed higher blood glucose and insulin and less insulin receptor substrate-1 and less phosphorylated Akt in the liver compared with WT mice. Interleukin-18 KO mice exhibited better survival after LPS treatment.

CONCLUSIONS

The findings suggest that endogenous IL-18 may attenuate hyperglycemia and modulate insulin signaling in liver. Accordingly, IL-18 may modulate glucose tolerance during acute inflammation.

Abandon the mouse research ship? Not just yet!

Many preclinical studies in critical care medicine and related disciplines rely on hypothesis-driven research in mice. The underlying premise posits that mice sufficiently emulate numerous pathophysiologic alterations produced by trauma/sepsis and can serve as an experimental platform for answering clinically relevant questions. Recently, the lay press severely criticized the translational relevance of mouse models in critical care medicine. A series of provocative editorials were elicited by a highly publicized research report in the Proceedings of the National Academy of Sciences (PNAS; February 2013), which identified an unrecognized gene expression profile mismatch between human and murine leukocytes following burn/trauma/endotoxemia. Based on their data, the authors concluded that mouse models of trauma/inflammation are unsuitable for studying corresponding human conditions. We believe this conclusion was not justified. In conjunction with resulting negative commentary in the popular press, it can seriously jeopardize future basic research in critical care medicine. We will address some limitations of that PNAS report to provide a framework for discussing its conclusions and attempt to present a balanced summary of strengths/weaknesses of use of mouse models. While many investigators agree that animal research is a central component for improved patient outcomes, it is important to acknowledge known limitations in clinical translation from mouse to man. The scientific community is responsible to discuss valid limitations without overinterpretation. Hopefully, a balanced view of the strengths/weaknesses of using animals for trauma/endotoxemia/critical care research will not result in hasty discount of the clear need for using animals to advance treatment of critically ill patients.

Effect of ozone exposure and infection on bronchoalveolar lavage: sex differences in response patterns

Female mice exhibit a better survival rate than males after infection, but if infection follows an ozone-induced oxidative stress, male survival exceeds that of females. Our goal was to study bronchoalveolar lavage factors that contribute to these sex differences in outcome. We studied parameters at 4, 24, and 48 h after ozone exposure and infection, including markers of inflammation, oxidative stress, and tissue damage, and surfactant phospholipids and surfactant protein A (SP-A). A multianalyte immunoassay at the 4h time point measured 59 different cytokines, chemokines, and other proteins. We found that: (1) Although some parameters studied revealed sex differences, no sex differences were observed in LDH, total protein, MIP-2, and SP-A. Males showed more intragroup significant differences in SP-A between filtered air- and ozone-exposed mice compared to females. (2) Oxidized dimeric SP-A was higher in FA-exposed female mice. (3) Surfactant phospholipids were typically higher in males. (4) The multianalyte data revealed differences in the exuberance of responses under different conditions - males in response to infection and females in response to oxidative stress. These more exuberant, and presumably less well-controlled responses associate with the poorer survival. We postulate that the collective effects of these sex differences in response patterns of lung immune cells may contribute to the clinical outcomes previously observed.

Whey Peptide-Based Formulas With ω-3 Fatty Acids Are Protective in Lipopolysaccharide-Mediated Sepsis

BACKGROUND

Sepsis and septic shock syndrome are among the leading causes of death in critically ill patients. Lipopolysaccharide (LPS) released by bacteria within the colon may translocate across a compromised epithelium, leading to oxidative stress, inflammation, sepsis, and eventually death.

METHODS

We examined the effects of a whey-based enteral formula high in cysteine (antioxidant precursor) and the addition of ω-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), against a mouse model of LPS-induced sepsis. Mice were fed either a whey-based diet with EPA-DHA (PAF), a whey-based diet without EPA-DHA (PSTD), or a casein-based control diet (CONT).

RESULTS

Mice fed PAF or PSTD were protected against LPS-induced weight loss. Whey-based diets suppressed inflammatory cytokine release and oxidative stress damage. Furthermore, PAF and PSTD were able to inhibit autophagy, a mechanism in which the cell recycles damaged organelles. These anti-inflammatory and antioxidative effects of PSTD and PAF resulted in decreased liver inflammation and intestinal damage and promoted protective microbiota within the intestines.

CONCLUSIONS

These data suggest a clinical role for whey peptide-based diets in promoting healing and recovery in critically ill patients.

Role of endogenous IL-18 in the lung during endotoxin-induced systemic inflammation

Background

Overactivated neutrophils are causes of acute lung injury, which is a major clinical problem with significant morbidity and mortality in sepsis. Serum interleukin (IL)-18 levels correspond to severity of systemic inflammation.

Aim

To elucidate the roles of endogenous IL-18 in lung injury during endotoxin-induced systemic inflammation.

Methods

Wild-type (WT) and IL-18 gene knockout (KO) mice were injected with lipopolysaccharide (40 mg/kg) intraperitoneally and killed. Lungs were collected at 0 and 12 h to assess mRNA for intercellular adhesion molecule (ICAM)-1, inducible nitric oxide synthase, myeloperoxidase, immunohistochemistry (cleaved caspase-3, 8-hydroxy-2-deoxyguanosine), and wet/dry ratio. Blood was collected at 0, 1, 12, 18, and 24 h to assess plasma cytokine levels.

Results

The survival rates at 24 h were approximately 43% and 76% in the WT and KO mice, respectively. Plasma IL-18 levels were induced time-dependently only in the WT mice. Plasma interferon-γ levels were significantly higher in the WT than in the KO mice at 12 h, but IL-6 and tumor necrosis factor-α levels did not differ between the WT and KO mice. At 12 h, the WT mice showed higher myeloperoxidase activity (P < 0.05), ICAM-1, and wet/dry ratios than KO mice. Cleaved caspase-3 positive neutrophils, which migrated in the lung interstitium, were lower in WT mice than in KO mice.

Conclusions

Endogenous IL-18 induced neutrophil accumulation, accompanied by induction of ICAM-1 expression, inhibition of neutrophil apoptosis, and increased inducible nitric oxide synthase-induced oxidative tissue injury in the lung, leading to lung edema and poor outcome during endotoxemia.

Intravenous immunoglobulin-induced neutrophil apoptosis in the lung during murine endotoxemia

BACKGROUND

The pathophysiologic features of acute respiratory distress syndrome (ARDS) are attributed to neutrophil accumulation and over-activation. Low blood immunoglobulin G concentrations in septic shock patients are associated with higher risk of developing ARDS. This study showed the effects of intravenous immunoglobulin (IVIg) on neutrophil apoptosis and accumulation in the lung during murine endotoxemia.

METHODS

Male C57BL/6J mice were injected with saline or 7 mg/kg of lipopolysaccharide (LPS), and 3 h later also were injected with saline, IVIg 300 mg/kg, or IVIg 1000 mg/kg intraperitoneally. At 12 h after LPS injection, mice were sacrificed and peripheral blood and lungs were collected. The lung messenger ribonucleic acid expression (tumor necrosis factor-α [TNF-α], inducible nitric oxide synthase [iNOS], and intercellular adhesion molecule-1 [ICAM-1]) was determined using quantitative realtime reverse transcriptase-polymerase chain reaction. Lungs were immersed in 4% paraformaldehyde and then embedded in paraffin. Tissue slices were prepared and stained with naphthol AS-D chloroacetate esterase to detect neutrophils. The numbers of neutrophils (characterized by the segment number of their nuclei) were counted. Peripheral neutrophil apoptosis was detected by annexin V using flow cytometry and lung neutrophil apoptosis was detected by cleaved caspase-3 using immunohistochemistry.

RESULTS

The survival rates of the saline group, LPS group, and IVIg group were all 100%. Apoptosis of peripheral blood neutrophils was inhibited by LPS. Neutrophil accumulation in the lung was decreased by both IVIg 300 mg/kg and 1000 mg/kg. Segmented neutrophils were reduced by IVIg during endotoxemia. However, IVIg 300 mg/kg and 1000 mg/kg had no influence on the lung messenger ribonucleic acid expression of TNF-α, iNOS, or ICAM-1. Cleaved-caspase-3-positive neutrophils were increased in the IVIg 300 mg/kg group during endotoxemia. The 1000 mg/kg IVIG dose reduced the number of segmented neutrophils, but did not induce cleaved-caspase 3-positive neutrophils.

CONCLUSION

A therapeutic IVIg dose can attenuate neutrophil accumulation and regulate neutrophil apoptosis in the lung during endotoxemia. It is possible that the pathways by which IVIG induces neutrophil apoptosis may differ depending on the IVIg concentration.

Sex and inflammation in respiratory diseases: a clinical viewpoint

This review discusses sex differences in the prognosis of acute or chronic inflammatory diseases. The consequences of severe inflammation vary in relation to sex, depending on illness duration. In the majority of acute diseases, males present higher mortality rates, whereas continuous chronic inflammation associated with tissue damage is more deleterious in females. The recruitment of cells, along with its clinical expression, is more significant in females, as reflected by higher inflammatory markers. Given that estrogens or androgens are known to modulate inflammation, their different levels in males and females cannot account for the sexual dimorphism observed in humans and animals from birth to death with regard to inflammation. Numerous studies evaluated receptors, cytokine production, and clinical outcomes in both animals and humans, revealing that estrogens clearly modulate the immune response, but the results are contradictory and difficult to link to hormone concentrations. Even in prepubescent children, the presentation of acute pneumonia or chronic diseases mimics the adult pattern. Several genes located on the X chromosome have been shown to encode molecules involved in inflammation. Moreover, 10% to 15% of the genes from silenced X chromosome may escape inhibition. Females are also a mosaic of cells with genes from either paternal or maternal X chromosome. Therefore, polymorphism of X-linked genes would result in the presence of two cell populations with distinct regulatory arsenals, providing females with greater diversity to fight against infectious challenges, in comparison with the uniform cell populations in hemizygous males. The similarities observed between males and Turner syndrome patients using an endotoxin stimulation model support the difference in gene expression between monosomy and disomy for the X chromosome. Considering the enhanced inflammation in females, cytokine production may be assumed to be higher in females than males. Even if all results are not clear-cut, nonetheless, many studies have reported higher cytokine levels in both male humans and animals than in females. High IL-6 levels in males correlated with poorer prognosis and shorter longevity. A sound understanding of the basic regulatory mechanisms responsible for these gender differences may lead to new therapeutic targets.

Circulating levels of IL-18 are significantly influenced by the IL-18 +183 A/G polymorphism in coronary artery disease patients with diabetes type 2 and the metabolic syndrome: an observational study

BACKGROUND

Increased IL-18 serum levels have been associated with diabetes type 2, metabolic syndrome and the severity of atherosclerosis. The present study investigated the presence and influence of IL-18 genetic variants on gene- and protein expression in stable coronary artery disease (CAD) patients.

METHODS

The +183 A/G (rs 5744292), -137 G/C (rs 187238) and -607 C/A (rs 1946518) polymorphisms were determined in 1001 patients with angiographically verified stable CAD, and in 204 healthy controls. IL-18 gene-expression was measured in circulating leukocytes in 240 randomly selected patients. Circulating IL-18 and IL-18 binding protein levels were measured immunologically in all patients.

RESULTS

The +183 G-allele associated significantly with lower serum levels of IL-18 (p = 0.002, adjusted for age, glucose, body mass index and gender) and a 1.13- fold higher IL-18 gene-expression (p = 0.010). No influence was observed for the -137 G/C and -607 C/A polymorphisms. The IL-18 binding protein levels were not influenced by IL-18 genotypes. IL-18 levels were significantly higher in men as compared to women, and in patients with diabetes type 2 and metabolic syndrome compared to those without (p ≤ 0.001, all). The reduction in IL-18 levels according to the +183 G-allele was 3-4 fold more pronounced in diabetes and metabolic syndrome as compared to unaffected patients.Finally, the +183 AA genotype was more frequent in patients with hypertension (p = 0.042, adjusted for age, body mass index and gender).

CONCLUSION

The reduction in serum IL-18 levels across increasing numbers of +183 G-alleles was especially apparent in patient with diabetes type 2 and metabolic syndrome, suggesting a beneficial GG genotype in relation to cardiovascular outcome in these patients.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT00222261.

Gender specific differences in the immune response to infection

There are many instances where males and females differ in the susceptibility to infections. The reason for these differences in susceptibility is multifactorial. The primary cause is thought to be due to differences induced by sex hormones and their effects on gene expression as well as the immune system, but may also be due to innate physiological differences between males and females. This review summarizes gender specific differences seen in infections caused by bacteria, fungi, parasites and viruses. Ultimately, gender specific differences appear to be dependent on the microbe causing the infection, as not every infection with a specific microbial type results in increased susceptibility of one gender over the other. This suggests that there is an interaction between gender specific immune differences and the specific immune response to individual microbes.

Gender differences and inflammation: an in vitro model of blood cells stimulation in prepubescent children

Background

Gender influences clinical presentations and markers in inflammatory diseases. In many chronic conditions, frequency of complications is greater in females, suggesting that continuous inflammatory reaction may induce greater damage in targeted organs and functions.

Methods

To investigate gender dimorphism at a cellular level, we evaluated the production of cytokines implicated in inflammatory processes (IL -1, IL- 6, PGE-2 and TNF alpha), in healthy prepubescent children of both sex and Turner's syndrome (TS) patients (genotype XO). We used stimulation by LPS (0.2 and 1 ng/ml) and Pokeweed Mitogen (PWM) on overnight cultures from whole blood samples, collected in 57 subjects: 22 girls/26 boys (5-96 months), and 9 TS patients (6-15 years). The primary outcome was to evaluate if gender influences the production of cytokines, with potential relation to X chromosome monosomy. Secondary endpoints were to relate different cytokines level productions and conditions.

Results

We confirm the male over female increased cytokine productions already observed in adults. This is contrasting with numerous observations obtained in vivo about increased production of inflammatory markers in females (CRP, ESR and neutrophil counts), as we recently reported in children. Relative variations of the dimorphism according to stimulus, its concentration and cytokine type are discussed, presenting IL6 with a modulating function that could be more potent in males. TS subjects follow mostly the male pattern of reactivity, sustaining the role of some gene expression differing with X chromosome monosomy and disomy.

Conclusions

Persistence of the latter dimorphism throughout life casts doubts on its direct relationship with individual hormonal status, as already documented by others in vitro, and supports the need for alternative hypothesis, such as the influence of X chromosome gene products escaping X inactivation in females and absent in subjects with X monosomy (males, TS).

Gender differences in inflammatory markers in children

No clear explanation exists to understand how sex hormones and/or chromosomes affect the immune system. In vitro studies of human lymphoid cells also show sex differences in immune function. To evaluate these differences in frequent pediatric emergencies, we analyze the expression of inflammatory markers (C-reactive protein, erythrocyte sedimentation rate, and neutrophil count) underlying inflammatory processes in children: 482 children (241 girls and 241 boys) hospitalized for pneumonia (n = 384), pyelonephritis (n = 39), or bronchiolitis (n = 59) matched for age and sex. All patients were younger than 10 years. A control population of 97 children (50 girls and 47 boys) admitted for day surgery (tonsillectomy, circumcision, or strabismus) was included. We observed highly significant differences between girls and boys: median C-reactive protein concentration of 5.45 mg/dL (range, 0.2-36.0 mg/dL) for girls and 2.6 mg/dL (range, 0.3-37.3 mg/dL) for boys (P < 0.0001), and median erythrocyte sedimentation rate of 39.5 mm/h (range, 2-104 mm/h) for girls and 24 mm/h (range, 4-140 mm/h) for boys (P < 0.005). Neutrophil counts were also significantly different: a median of 8,796 cells/microL (range, 328-27,645 cells/microL) for girls and 6,774 cells/microL (range, 600-38,668 cells/microL) for boys (P < 0.02). The duration of fever after initiating antibiotic therapy was longer in girls than in boys, but there was no difference (Fisher exact test, P < 0.06). The present study documents a relationship between sex and both the production of inflammatory markers and neutrophil recruitment. Sex difference also showed more direct clinical relevance with associations seen between sex and both duration of fever and duration of disease (bronchiolitis P < 0.0007).

The role of sex hormones in the development of Th2 immunity in a gender-biased model of Trichuris muris infection

Trichuris muris infection is an ideal model for defining T-cell-driven immunity, and also provides essential insights that may impact on potential helminth therapies currently in development. Conflicting host variables determine the efficiency of such treatments and we have identified host-derived sex steroid hormones as key factors in the development of immunity. The female-associated hormone 17-β estradiol (E2) significantly enhanced the generation of a Th2 response in vitro; however, this stimulatory effect was found to be dispensable for the generation of immunity to Trichuris in the gender-biased IL-4KO mouse model. In contrast, the male-associated hormone dihydrotestosterone significantly inhibited the T-cell stimulatory capacity of DC and directly suppressed the immune response of male IL-4KO mice, with worm expulsion restored following castration. This finding was associated with dramatically reduced IL-18 mRNA expression suggesting androgens may act via this cytokine to suppress Th2 immunity to Trichuris. This study has critical implications for the development and efficacy of potential helminth therapeutics and identifies host gender – specifically sex hormones – as important factors in the development of Th2 immunity in susceptible and immunocompromised mice.