Impact of nutritional status on vaccine-induced immunity in children living in South Africa: Investigating the B-cell repertoire and metabolic hormones.

OBJECTIVES: We explored the role of metabolic hormones and the B-cell repertoire in the association between nutritional status and vaccine responses. METHODS: In this prospective cohort study, nested within a larger randomized open-label trial, 211 South African children received two doses of measles vaccine and two or three doses of pneumococcal conjugate vaccine (PCV). Metabolic markers (leptin, ghrelin and adiponectin) and distribution of B-cell subsets (n = 106) were assessed at 18 months of age. RESULTS: Children with a weight-for-height z-score (WHZ) ≤ -1 standard deviation (SD) at booster vaccination had a decreased mean serotype-specific PCV IgG response compared with those with WHZ > -1 and <+1 SD or WHZ ≥ +1 SD at 9 months post-booster (18 months of age). (Naive) pre-germinal center B-cells were associated with pneumococcal antibody decay between one to nine months post-booster. Predictive performance of elastic net models for the combined effect of B-cell subsets, metabolic hormones and nutritional status (in addition to age, sex, and randomization group) on measles and PCV vaccine response had an average area under the receiver operating curve of 0.9 and 0.7, respectively. CONCLUSIONS: The combined effect of B-cell subsets, metabolic hormones and nutritional status correlated well with the vaccination response for measles and most PCV serotypes. CLINICALTRIALS: gov registration of parent studies: NCT02943902 and NCT03330171.

Current Aspects of the Role of Autoantibodies Directed Against Appetite-Regulating Hormones and the Gut Microbiome in Eating Disorders.

The equilibrium and reciprocal actions among appetite-stimulating (orexigenic) and appetite-suppressing (anorexigenic) signals synthesized in the gut, brain, microbiome and adipose tissue (AT), seems to play a pivotal role in the regulation of food intake and feeding behavior, anxiety, and depression. A dysregulation of mechanisms controlling the energy balance may result in eating disorders such as anorexia nervosa (AN) and bulimia nervosa (BN). AN is a psychiatric disease defined by chronic self-induced extreme dietary restriction leading to an extremely low body weight and adiposity. BN is defined as out-of-control binge eating, which is compensated by self-induced vomiting, fasting, or excessive exercise. Certain gut microbiota-related compounds, like bacterial chaperone protein Escherichia coli caseinolytic protease B (ClpB) and food-derived antigens were recently described to trigger the production of autoantibodies cross-reacting with appetite-regulating hormones and neurotransmitters. Gut microbiome may be a potential manipulator for AT and energy homeostasis. Thus, the regulation of appetite, emotion, mood, and nutritional status is also under the control of neuroimmunoendocrine mechanisms by secretion of autoantibodies directed against neuropeptides, neuroactive metabolites, and peptides. In AN and BN, altered cholinergic, dopaminergic, adrenergic, and serotonergic relays may lead to abnormal AT, gut, and brain hormone secretion. The present review summarizes updated knowledge regarding the gut dysbiosis, gut-barrier permeability, short-chain fatty acids (SCFA), fecal microbial transplantation (FMT), blood-brain barrier permeability, and autoantibodies within the ghrelin and melanocortin systems in eating disorders. We expect that the new knowledge may be used for the development of a novel preventive and therapeutic approach for treatment of AN and BN.

Thyrotropin-Releasing Hormone (TRH) and Somatostatin (SST), but not Growth Hormone-Releasing Hormone (GHRH) nor Ghrelin (GHRL), Regulate Expression and Release of Immune Growth Hormone (GH) from Chicken Bursal B-Lymphocyte Cultures.

It is known that growth hormone (GH) is expressed in immune cells, where it exerts immunomodulatory effects. However, the mechanisms of expression and release of GH in the immune system remain unclear. We analyzed the effect of growth hormone-releasing hormone (GHRH), thyrotropin-releasing hormone (TRH), ghrelin (GHRL), and somatostatin (SST) upon GH mRNA expression, intracellular and released GH, Ser133-phosphorylation of CREB (pCREBS133), intracellular Ca2+ levels, as well as B-cell activating factor (BAFF) mRNA expression in bursal B-lymphocytes (BBLs) cell cultures since several GH secretagogues, as well as their corresponding receptors (-R), are expressed in B-lymphocytes of several species. The expression of TRH/TRH-R, ghrelin/GHS-R1a, and SST/SST-Rs (Subtypes 1 to 5) was observed in BBLs by RT-PCR and immunocytochemistry (ICC), whereas GHRH/GHRH-R were absent in these cells. We found that TRH treatment significantly increased local GH mRNA expression and CREB phosphorylation. Conversely, SST decreased GH mRNA expression. Additionally, when added together, SST prevented TRH-induced GH mRNA expression, but no changes were observed in pCREBS133 levels. Furthermore, TRH stimulated GH release to the culture media, while SST increased the intracellular content of this hormone. Interestingly, SST inhibited TRH-induced GH release in a dose-dependent manner. The coaddition of TRH and SST decreased the intracellular content of GH. After 10 min. of incubation with either TRH or SST, the intracellular calcium levels significantly decreased, but they were increased at 60 min. However, the combined treatment with both peptides maintained the Ca2+ levels reduced up to 60-min. of incubation. On the other hand, BAFF cytokine mRNA expression was significantly increased by TRH administration. Altogether, our results suggest that TRH and SST are implicated in the regulation of GH expression and release in BBL cultures, which also involve changes in pCREBS133 and intracellular Ca2+ concentration. It is likely that TRH, SST, and GH exert autocrine/paracrine immunomodulatory actions and participate in the maturation of chicken BBLs.

Potential role of adipose tissue and its hormones in burns and critically III patients.

Obesity has become a world-wide pandemic and is considered a major risk factor for various diseases. Despite this, recent intriguing clinical observations have been made suggesting that being overweight has some advantages. Overweight and some obese patients were reported to have significantly lower all-cause mortality, described as the 'obesity paradox'. This phenomenon resulted in increased research aimed at investigating the influence of adipose tissue on outcomes of various clinical states including critical illness. In this review, we summarise research findings on the effect burn injury and trauma-related critical illness have on adipose tissue and discuss potential mechanisms by which adipose tissue influences outcomes in burn and other critically ill patients. Burn injury and critical illness influence adipose tissue functionally and morphologically, with circulating levels of fat derived hormones, adipokines, altered in patients following injury and/or critical illness. As adipokines regulate a variety of processes including inflammation and metabolism, this disruption in the adipokine axis may explain the obesity paradox phenomenon observed in critically ill patients. We conclude that further research on the influence of individual adipokines on prognosis in burn and critically ill patients and the mechanisms involved is required to increase understanding of their therapeutic potential.

Peptide mimetic of N-terminal ghrelin enhances ghrelin-induced growth hormone secretion and c-Fos expression in mice.

Orexigenic peptide ghrelin and its receptor have been extensively investigated as potential therapeutic targets, primarily because of their role in feeding initiation and growth hormone (GH) release. However, no specific ghrelin targeting anti-obesity or cachexia therapeutics are available for clinical use thus far and further efforts in this direction are warranted. The present study aimed to find new peptide drug leads modulating ghrelin signal transduction. By targeting neutralising antibodies against ghrelin with phage display libraries, we aimed to identify peptides binding to the cognate receptor. Four synthetic peptides were selected and tested using calcium screening assays. The most effective competitive antagonist FSFLPPE was further tested in vivo. Administration of the peptide produced no significant effect on either food intake or GH release. Surprisingly, when co-administered with ghrelin, the peptide significantly enhanced GH secretion and c-Fos expression. The evidence obtained in the present study indicates that FSFLPPE might act as an ago-allosteric modulator.

Effect of HTST and Holder Pasteurization on the Concentration of Immunoglobulins, Growth Factors, and Hormones in Donor Human Milk.

Donor human milk (DHM) is submitted to Holder pasteurization (HoP) to ensure its microbiological safety in human milk banks but this treatment affects some of its bioactive compounds. The objective of this work was to compare the effects of HoP and high temperature short time (HTST) treatments on some bioactive compounds found in DHM. A total of 24 DHM batches were processed in a continuous HTST system (70, 72, and 75°C for 5-25 s) and by HoP (62.5°C for 30 min). The concentrations of immunoglobulins (Igs) A, G, and M, transforming growth factor-beta 2 (TGF-ß2), adiponectine, ghrelin, and leptin were measured using a multiplex system, whereas the concentration of epidermal growth factor (EGF) was determined by ELISA. In relation to Igs, IgG showed the highest preservation rates (87-101%) after HTST treatments, followed by IgA (54-88%) and IgM (25-73%). Ig retention after any of the HTST treatments was higher than after HoP (p < 0.001). Treatment times required to reduce the concentration of IgM by 90% (D-value) were 130, 88, and 49 s at 70, 72, and 75°C, while the number of degrees Celsius required to change the D-value by one factor of 10 (z-value) was 11.79°C. None of the heat treatments had a significant effect on the concentrations of TGF-ß2, EGF, adiponectin, and ghrelin. In contrast, leptin was detected only in 4 of the samples submitted to HoP, whereas it was present in all samples after the different HTST treatments, with retention rates ranging between 34 and 68%. Globally, the concentration of IgA, IgG, IgM, and leptin in DHM was significantly higher after HTST pasteurization performed in a continuous system designed to be used in human milk banks than after the HoP procedure that is routinely applied at present.

The Impact of Ghrelin in Metabolic Diseases: An Immune Perspective.

Obesity and insulin resistance have reached epidemic proportions. Obesogenic conditions are associated with increased risk for the development of other comorbidities and obesity-related diseases. In metabolic disorders, there is chronic low-grade inflammation induced by the activation of immune cells, especially in metabolic relevant organs such as white adipose tissue (WAT). These immune cells are regulated by environmental and systemic cues. Ghrelin is a peptide secreted mainly by X/A-like gastric cells and acts through the growth hormone secretagogue receptor (GHS-R). This receptor is broadly expressed in the central nervous system (CNS) and in several cell types, including immune cells. Studies show that ghrelin induces an orexigenic state, and there is increasing evidence implicating an immunoregulatory role for ghrelin. Ghrelin mainly acts on the innate and adaptive immune systems to suppress inflammation and induce an anti-inflammatory profile. In this review, we discuss the immunoregulatory roles of ghrelin, the mechanisms by which ghrelin acts and potential pharmacological applications for ghrelin in the treatment of obesity-associated inflammatory diseases, such as type 2 diabetes (T2D).

Beta-glucans and cancer: The influence of inflammation and gut peptide.

Dietary ß-glucans are soluble fibers with potentially health-promoting effects. Gut peptides are important signals in the regulation of energy and glucose homeostasis. This article reviews the effects of different enriched ß-glucan food consumption on immune responses, inflammation, gut hormone and cancer. Gut hormones are influenced by enriched ß-glucan food consumption and levels of such peptide as YY, ghrelin, glucagon-like peptide 1 and 2 in humans influence serum glucose concentration as well as innate and adaptive immunity. Cancer cell development is also regulated by obesity and glucose dishomeostasy that are influenced by ß-glucan food consumption that in turn regulated gut hormones.

Growth hormone releasing peptide-6 enhanced antibody titers against subunit antigens in mice (BALB/c), tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus).

Modern subunit vaccines have excellent safety profiles and improved tolerability, but do not elicit strong immune responses without the addition of adjuvants. Developing a safe and affective adjuvant remains a challenge for peptide-based vaccine design. Growth Hormone Releasing Peptide-6 (GHRP-6) is one of the earliest-developed, synthetic, peptidyl growth hormone secretagogue receptor agonists. These compounds mimic the effect of the endogenous ligand, ghrelin. In the present study, we evaluated the ability of GHRP-6 to enhance the humoral immune response against co-injected antigens in mice, tilapia and African catfish. This peptide was able to increase the antigen-specific antibody response using heterologous proteins and peptides as antigens, which were also formulated in "water in oil" emulsions (Freund and Montanide). As long as we know there is no previous report describing any ghrelin analogous as molecular immunomodulator stimulating a humoral immune response. Further studies will be conducted to evaluate the functionality of this humoral immune response in challenge trials.

Gastrointestinal neuroendocrine peptides/amines in inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a chronic recurrent condition whose etiology is unknown, and it includes ulcerative colitis, Crohn's disease, and microscopic colitis. These three diseases differ in clinical manifestations, courses, and prognoses. IBD reduces the patients' quality of life and is an economic burden to both the patients and society. Interactions between the gastrointestinal (GI) neuroendocrine peptides/amines (NEPA) and the immune system are believed to play an important role in the pathophysiology of IBD. Moreover, the interaction between GI NEPA and intestinal microbiota appears to play also a pivotal role in the pathophysiology of IBD. This review summarizes the available data on GI NEPA in IBD, and speculates on their possible role in the pathophysiology and the potential use of this information when developing treatments. GI NEPA serotonin, the neuropeptide Y family, and substance P are proinflammatory, while the chromogranin/secretogranin family, vasoactive intestinal peptide, somatostatin, and ghrelin are anti-inflammatory. Several innate and adaptive immune cells express these NEPA and/or have receptors to them. The GI NEPA are affected in patients with IBD and in animal models of human IBD. The GI NEPA are potentially useful for the diagnosis and follow-up of the activity of IBD, and are candidate targets for treatments of this disease.

Nanogel-based nasal ghrelin vaccine prevents obesity.

Obesity is associated with multiple comorbidities such as cardiovascular diseases and has a huge economic impact on the health-care system. However, the treatment of obesity remains insufficient in terms of efficacy, tolerability, and safety. Here we created a nasal vaccine against obesity for the first time. To avoid the injectable administration-caused pain and skin-related adverse event, we focused on the intranasal route of antigen delivery. We developed a vaccine antigen (ghrelin-PspA (pneumococcal surface protein A)), which is a recombinant fusion protein incorporating ghrelin, a hormone that stimulates food intake and decreases energy expenditure, and PspA, a candidate of pneumococcal vaccine as a carrier protein. Ghrelin-PspA antigen was mixed with cyclic di-GMP adjuvant to enhance the immunogenicity and incorporated within a nanometer-sized hydrogel for the effective antigen delivery. Intranasal immunization with ghrelin-PspA vaccine elicited serum immunoglobulin G antibodies against ghrelin and attenuated body weight gain in diet-induced obesity mice. This obesity-attenuating effect was caused by a decrease in fat accumulation and an increase in energy expenditure that was partially due to an increase in the expression of mitochondrial uncoupling protein 1 in brown adipose tissue. The development of this nasal vaccine provides a new strategy for the prevention and treatment of obesity.

Therapeutic effect of human ghrelin and growth hormone: Attenuation of immunosuppression in septic aged rats.

Sepsis is a leading cause of mortality in intensive care units, and is more common in the geriatric population. The control of hyperinflammation has been suggested as a therapeutic approach in sepsis, but to date clinical trials utilizing this strategy have not lead to an effective treatment. In addition to hyperinflammation, patients with sepsis often experience a state of immunosuppression, which serves as an important determinant for increased morbidity and mortality. We previously used aged animals to demonstrate the effectiveness of combined treatment with human ghrelin (Ghr) and human growth hormone (GH) in improving organ injury and survival in septic animals. Here, we hypothesized that combined treatment with Ghr and GH could improve immune function in septic aged animals. Male 24-month-old rats were subjected to cecal ligation and puncture (CLP) for sepsis induction. Human Ghr (80nmol/kg BW) plus GH (50µg/kg BW) or vehicle (normal saline) was administrated subcutaneously at 5h after CLP. The ex vivo production of TNF-α, IL-6 and IL-10 to LPS-stimulation, as well as TNF-α, IL-6, IL-10 and IFN-γ production to anti-CD3/anti-CD28 antibody-stimulation, in splenocytes isolated 20h after CLP, was significantly decreased compared to production of these cytokines in splenocytes from sham animals. The production of cytokines from splenocytes isolated from septic animals that received the combined treatment, however, was significantly higher than from those isolated from vehicle-treated septic animals. Combined treatment prevented the loss of splenic CD4+ and CD8+ T cells in septic aged rats, and reduced lymphocyte apoptosis. Combined treatment also inhibited an increase in the regulatory T cell (Treg) population and expression of the immune co-inhibitory molecule PD-1 in the spleens of septic aged rats. In contrast, expression of HLA-DR was increased after combined treatment with Ghr and GH. Based on these findings, we conclude that co-administration of Ghr and GH is a promising therapeutic tool for reversing immunosuppression caused by sepsis in the geriatric population. This article is part of a Special Issue entitled: Immune and Metabolic Alterations in Trauma and Sepsis edited by Dr. Raghavan Raju.

Ghrelin-immunoreactive cells in the gastrointestinal tract of hypertensive rats.

INTRODUCTION: Ghrelin, an appetite-stimulating hormone secreted by the endocrine cells of the gastrointestinal (GI) tract, has recently been shown to affect the function of the cardiovascular system. This study aimed to assess the number and morphology of ghrelin-immunopositive (GhrIP) cells in the gastrointestinal tract of rats at different developmental phases of experimentally evoked renovascular hypertension. MATERIAL AND METHODS: The study involved 40 rats divided into two groups: control (C; n = 20) and rats with experimentally induced hypertension (EH; n = 20). The Goldblatt model of two-kidneys, one clip (2K1C) was used to induce hypertension. Renovascular hypertension was maintained for either 3 (EH1 group; n = 10) or 42 (EH2 group; n = 10) days. Paraffin sections from the cardia, corpus and pylorus of the stomach, as well as from the duodenum, jejunum, ileum and colon were processed for peroxidase immunohistochemistry. RESULTS: The number of GhrIP cells was significantly higher in the cardia and corpus of the stomach as well as the duodenum and jejunum of hypertensive rats compared to that found in the control animals. CONCLUSIONS: The increased number of GhrIP cells in the rat gastrointestinal tract after partial unilateral ligation of the renal artery suggests that renovascular hypertension may affect ghrelin secretion, which can contribute to the development of cardiovascular complications.

Roles of leptin and ghrelin in the regulation of the phenotype and cytokine production by NK cells from peripheral blood.

Both leptin and ghrelin used separately at the concentrations corresponding to trimesters II-III of pregnancy increase the number of CD56bright NK cells in mononuclear cell suspension; their combination also enhances the L-selectin expression on the surface of these cells in the culture. These hormones do not affect the production of TGF-ß1, IL-17А, or IFN-γ by NK cells, and they inhibit the production of IL-10. Leptin decreses the IL-4 production by NKp46+ cells, but the presence of ghrelin abrogates this effect.

Prevalence of autoantibodies against some selected growth and appetite-regulating neuropeptides in serum of short children exposed to Candida albicans colonization and/or Helicobacter pylori infection: the molecular mimicry phenomenon.

OBJECTIVES: Many of peptides synthesized in gastrointestinal tract (GI) and adipose tissues, regulate growth and food intake. The GI microflora is an antigenic source. Based on the molecular mimicry hypothesis, intestinal microbe-derived antigens may trigger the production of autoantibodies cross-reacting with some neuropeptides. DESIGN: The aim of the study was to assess whether in idiopathic short stature (ISS) children with Candida albicans (C.albicans) colonisation and/or Helicobacter pylori (H.pylori) infection the autoantibodies (in positive levels) against selected neuropeptides [anti-NP Abs(+)]: ghrelin, leptin, orexin A, αMSH are more prevalent than in Controls. SETTING: The study group comprised 64 children with ISS and 36 children with normal height (Controls). In each child, IgG antibodies against H.pylori, ghrelin, leptin, orexin A and αMSH were assessed in serum, while presence of C.albicans - in stool samples. RESULTS: The higher prevalence of anti-NP Abs(+) in ISS children with C.albicans and/or H.pylori than in normal height children with the colonization in question (34.4% vs 21.1%, p<0.01) was found. The prevalence of anti-NP Abs(+) in groups of children without C.albicans and H.pylori were low, anti-NP Abs(+) were detected in 9.4% of ISS children only, while in Controls they were not found. CONCLUSIONS: In short children with C.albicans and/or H.pylori the incidence of autoantibodies against selected neuropeptides is high. It probably is connected with molecular mimicry between antigens of these microbiota and the mentioned peptides. It is tempting to speculate that presence of cross-reacting autoantibodies against regulatory neuropeptides may results in worse growth velocity. However, further studies are necessary to elucidate this issue.

Immunomodulatory effect of ghrelin in the intestinal mucosa.

The gastrointestinal tract is the largest endocrine organ in the body and it produces a wide array of hormones and neuropeptides. Ghrelin, a 28-amino acid hormone produced mainly by the X/A-like endocrine cells in the gastric mucosa, has widespread tissue distribution and diverse physiological functions such as hormonal, orexigenic, metabolic, cardiovascular, neurological and immunological activities. Recent research has implicated ghrelin in gastrointestinal pathological conditions and immune system regulation, but its contribution is controversial. Although ghrelin levels are elevated in clinical active inflammatory bowel diseases, confirmation of its exact role using experimental models remains unclear. This review discusses the conflicting effects of ghrelin on intestinal inflammation, through the different possible immune and intracellular mechanisms and highlights new findings.

Diversity and plasticity of microglial cells in psychiatric and neurological disorders.

Recent advanced immunological analyses have revealed that the diversity and plasticity of macrophages lead to the identification of functional polarization states (classically activated M1 type and alternatively activated M2 type) which are dependent on the extracellular environment. M1 and M2 polarization states of macrophages play an important role in controlling the balance between pro-inflammatory and anti-inflammatory conditions. Microglial cells are resident mononuclear phagocytes in the central nervous system (CNS), express several macrophage-associated markers, and appear to display functional polarization states similar to macrophages. Like M1 macrophages, M1 polarized microglia can produce pro-inflammatory cytokines and mediators such as interleukin (IL) 1ß, IL-6, tumor necrosis factor-α, CC-chemokine ligand 2, nitric oxide, and reactive oxygen species, suggesting that these molecules contribute to dysfunction of neural network in the CNS. On the other hand, M2 polarized microglia can produce anti-inflammatory cytokine, IL-10 and express several receptors that are implicated in inhibiting inflammation and restoring homeostasis. In this review, we summarize the diversity, plasticity, and immunoregulatory functions of M1 and M2 microglia in psychiatric and neurological disorders. Based on these aspects, we propose a contribution of imbalance between M1 and M2 polarization of microglia in bipolar disorder, obesity, amyotrophic lateral sclerosis, and Rett syndrome. Consequently, molecules that normalize the imbalance between M1 and M2 microglial polarization states may provide a beneficial therapeutic target for the treatment of these disorders.

One-day high-fat diet induces inflammation in the nodose ganglion and hypothalamus of mice.

A high-fat diet (HFD) induces inflammation in systemic organs including the hypothalamus, resulting in obesity and diabetes. The vagus nerve connects the visceral organs and central nervous system, and the gastric-derived orexigenic peptide ghrelin transmits its starvation signals to the hypothalamus via the vagal afferent nerve. Here we investigated the inflammatory response in vagal afferent neurons and the hypothalamus in mice following one day of HFD feeding. This treatment increased the number of macrophages/microglia in the nodose ganglion and hypothalamus. Furthermore, one-day HFD induced expression of Toll-like receptor 4 in the goblet cells of the colon and upregulated mRNA expressions of the proinflammatory biomarkers Emr1, Iba1, Il6, and Tnfα in the nodose ganglion and hypothalamus. Both subcutaneous administration of ghrelin and celiac vagotomy reduced HFD-induced inflammation in these tissues. HFD intake triggered inflammatory responses in the gut, nodose ganglion, and subsequently in the hypothalamus within 24 h. These findings suggest that the vagal afferent nerve may transfer gut-derived inflammatory signals to the hypothalamus via the nodose ganglion, and that ghrelin may protect against HFD-induced inflammation.