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Abstract. Because its secretion is changed in cerebrospinal fluid and peripheral blood, the neuronal polypeptide VGF (nonacronymic) has been discussed as a biomarker for neuropsychiatric disorders. We have shown an enhanced VGF expression by T-cells from Alzheimer’s disease (AD) patients. In this study, we investigated the VGF expression by peripheral monocytes in 38 AD patients, 5 patients with vascular dementia (VD), and 20 neuropsychiatrically healthy individuals using flow cytometry. We determined an enhanced number of VGF-expressing monocytes in VD patients compared to AD patients. VGF+CD14+ monocytes were not correlated with age, body mass index, Mini-Mental State Examination (MMSE), or Q albumin. These preliminary data support findings indicating that VGF might play a role as a peripheral biomarker in VD.

Objectives S100B belongs to the family of danger signaling proteins. It is mainly expressed by glial-specific cells in the brain. However, S100B was also detected in other cell likewise immune cells. This molecule was suggested as biomarker for inflammation and fetal brain damage in spontaneous preterm birth (sPTB), preeclampsia (PE) and HELLP (hemolysis, elevated liver enzymes, and low platelet count). Methods The aim of our study was to determine the concentration of S100B in maternal and cord blood (CB) plasma and placenta supernatant as well as the expression of S100B in maternal and CB CD4+ T cells and CD19+ B cells in sPTB and patients delivering following PE/HELLP diagnosis compared to women delivering at term (TD). The S100B expression was further related to the birth weight in our study cohort. Results S100B concentration was enhanced in maternal and CB plasma of sPTB and PE/HELLP patients and positively correlated with interleukin-6 (IL-6) levels. Increased S100B was also confirmed in CB of small-for-gestational-age (SGA) infants. S100B expression in maternal blood was elevated in CD4+ T cells of PE/HELLP patients and patients who gave birth to SGA newborns as well as in CD19+ B cells of sPTB and PE/HELLP patients and patients with SGA babies. In CB, the expression of S100B was increased in CD19+ B cells of sPTB, PE/HELLP and SGA babies. Conclusions Our results support the hypothesis that S100B expression is enhanced in inflammatory events associated with preterm birth and that S100B expression in immune cells is a relevant marker for inflammation during pregnancy complications.

Although the expression of co-stimulatory molecules plays an important role in the immune system, only little is known about their regulation in dementias. Therefore, we determined the expression of CD28, ICOS (CD278) and CTLA-4 (CD152) by CD4 + and CD8 + T cells in the peripheral blood of patients with mild cognitive impairment (MCI; N = 19), Alzheimer’s disease (AD; N = 51), vascular dementia (VD; N = 21) and frontotemporal dementia (FTD; N = 6) at the point in time of diagnosis compared to 19 non-demented elderly persons. The expression of CD28 and ICOS by CD4 + and CD8 + T cells was not changed in AD, FTD or VD patients. The expression of the negative regulator CTLA-4 was increased by CD4 + T cells from AD and FTD patients and by CD8 + T cells from VD patients. The classification of the AD patients according to the severity of the disorder showed stage-dependent alterations of CD28, ICOS and CTLA-4 expression. In AD patients, the correlation analysis showed an association between the decline in CD28 + T cells and the increase in CTLA-4 + T cells with cognitive decline, measured by the mini-mental state examination (MMSE), tau proteins and Amyloid-β, important AD biomarkers in cerebrospinal fluid (CSF). In FTD patients, a positive association between Q Albumin, a marker for blood-CSF-barrier function, and CD28 and a negative correlation between Q Albumin and ICOS expression were determined. Our data suggest a dysregulated balance between the expression of negative and positive co-stimulatory molecules by T cells in AD patients, which might contribute to chronic inflammation observed in dementia.

Background: Although it is known that the nutritional status among elderly persons and, in particular, patients with dementia, is compromised, malnutrition that results in insufficient uptake of several vitamins is often not diagnosed. Objective: An elevated homocysteine level is a known strong risk factor for vascular dementia (VaD) and Alzheimer’s disease (AD). Several B vitamins are involved in the metabolism of homocysteine. Therefore, we investigated the serum levels of vitamin B1, vitamin B6, folate, and vitamin B12 in 97 patients with mild cognitive impairment (MCI) or different forms of dementia and 54 elderly control persons without dementia. Results: Compared to aged non-demented people, vitamins B1, B6, B12, and folate were decreased in serum of patients with AD, and patients with Lewy body dementia had reduced vitamin B12 level. Vitamin B6 was diminished in VaD. Patients with frontotemporal dementia showed no alterations in vitamin levels. Age was identified as an important factor contributing to the concentrations of vitamin B1 and B6 in serum, but not vitamin B12 and folate. Increased levels of total homocysteine were detected especially in MCI and AD. Homocysteine correlated negatively with levels of vitamins B6, B12, and folate and positively with Q Albumin. Conclusion: Our data suggest that despite increased homocysteine already present in MCI, vitamin levels are decreased only in dementia. We propose to determine the vitamin levels in patients with cognitive decline, but also elderly people in general, and recommend supplementing these nutrients if needed.

The enormous challenge in unraveling the etiology of preterm birth (PTB) is to understand the complex interactions between gestational hormones, the immune system and reproductive tissues. PTB can be divided into spontaneous PTB (sPTB) and medically-indicated PTB, e.g. due to preeclampsia (PE) or HELLP syndrome. Progesterone (P4), important for establishment and maintenance of pregnancy, exerts anti-inflammatory effects. The impact of P4 on B cells and its support of maintaining maternal-fetal tolerance is widely unexplored. Therefore, we aimed to determine whether B cells express the progesterone receptor (PR) and to dissect a possible role of PR+ B cells in PTB. We found enhanced IL-6, IL-21 and TNF-α concentrations in maternal plasma in patients with sPTB and PE/HELLP compared to term delivery (TD), accompanied by enhanced PR-A expression by CD19+ B cells. In a second phase of the study, we recruited patients with imminent PTB (iPTB) and controls. Samples were collected at hospital admission and to a later time point, then divided into iPTB patients who delivered preterm and patients whose PTB was prevented. Within the group of iPTB patients, we observed very clear differences: enhanced levels of pro-inflammatory cytokines and increased percentages of PR-A+CD19+ B cells were found in iPTB patients that delivered preterm compared to patients who did not deliver preterm. We conclude that PTB is associated with the activation of an inflammatory pathway leading to the induction of PR-A by B cells. This might further trigger inflammation, result in the break of maternal-fetal tolerance and induce delivery.

IL-17 is associated with different phenotypes of asthma, however, it is not fully elucidated how it influences induction and maintenance of asthma and allergy. In order to determine the role of IL-17 in development of allergic asthma, we used IL-17A/F double KO (IL-17A/F KO) and WT mice with or without neutralization of IL-17 in an experimental allergic asthma model and analyzed airway hyperresponsiveness, lung inflammation, T helper cell polarization, and DCs influx and activation. We report that the absence of IL-17 reduced influx of DCs into lungs and lung draining LNs. Compared to WT mice, IL-17A/F KO mice or WT mice after neutralization of IL-17A showed reduced airway hyperresponsiveness, eosinophilia, mucus hypersecretion, and IgE levels. DCs from draining LNs of allergen-challenged IL-17A/F KO mice showed a reduction in expression of migratory and costimulatory molecules CCR7, CCR2, MHC-II, and CD40 compared to WT DCs. Moreover, in vivo stimulation of adoptively transferred antigen-specific cells was attenuated in lung-draining LNs in the absence of IL-17. Thus, we report that IL-17 enhances airway DC activation, migration, and function. Consequently, lack of IL-17 leads to reduced antigen-specific T cell priming and impaired development of experimental allergic asthma.

B cell participation in early embryo/fetal development and the underlying molecular pathways have not been explored. To understand whether maternal B cell absence or impaired signaling interferes with placental and fetal growth, we paired CD19-deficient (CD19−/−) mice, females with B cell-specific MyD88 (BMyD88−/−) or IL10 (BIL10−/−) deficiency as well as wild-type and MyD88−/− controls on C57Bl/6 background with BALB/c males. Pregnancies were followed by ultrasound and Doppler measurements. Implantation number was reduced in BMyD88−/− and MyD88−/− mice. Loss of MyD88 or B cell-specific deletion of MyD88 or IL10 resulted in decreased implantation areas at gestational day (gd) 5, gd8 and gd10, accompanied by reduced placental thickness, diameter and areas at gd10. Uterine artery resistance was enhanced in BIL10−/− dams at gd10. Challenge with 0.4 mg lipopolysaccharide/kg bodyweight at gd16 revealed that BMyD88−/−, BIL10−/− and CD19−/− mothers delivered preterm, whereas controls maintained their pregnancy. B cell-specific MyD88 and IL10 expression is essential for appropriate in utero development. IL10+B cells are involved in uterine blood flow regulation during pregnancy. Finally, B cell-specific CD19, MyD88 and IL10 expression influences susceptibility towards preterm birth.

Immunological networks balance tolerance towards paternal alloantigens during pregnancy with normal immune response to pathogens. Subclinical infections can impact this balance and lead to preterm birth or even intrauterine fetal death (IUFD). We recently showed that loss of maternal B cells renders murine fetuses susceptible to IUFD after LPS exposure. Since the signaling pathway involved in this B-cell mediated response remains unclear, we aimed to understand the participation of MyD88 in this response using B-cell-specific MyD88-deficient (BMyD88-/-) mice. B cells isolated from wild-type (WT), BMyD88-/-, CD19-/- and MyD88-/- dams on gestational day (gd) 10 responded differently to LPS concerning cytokine secretion. In vivo LPS challenge on gd 10 provoked IUFD in CD19-/- mothers with functional MyD88, while fetuses from BMyD88-/- and MyD88-/- mice were protected. These outcomes were associated with altered cytokine levels in the maternal serum and changes in CD4+ T-cell responses. Overall, the loss of MyD88 signaling in maternal B cells prevents the activation of cytokine release that leads to IUFD. Thus, while MyD88 signaling in maternal B cells protects the mother from infection, it ultimately kills the fetus. Understanding the cellular mechanisms underlying infection-driven pregnancy complications is the first step to designing powerful therapeutic strategies in the future.

Inflammation and alterations in essential protein structures in the brain might also change the cellular distribution in the cerebrospinal fluid (CSF). Using flow cytometry, we analyzed cell populations of the innate and adaptive immune system associated with the most frequent forms of dementias. We included patients with mild cognitive impairment (MCI; N ​= ​33), Alzheimer’s disease (AD; N ​= ​90), vascular dementia (VD; N ​= ​35) and frontotemporal dementia (FTD; N ​= ​17) at the time of diagnosis, before onset of treatment and 11 elderly non-demented individuals. Dependent on the form of dementia, an increased frequency of CD14+ monocytes, NK cells and NKT cells was measured. Within the T cell population, a dementia-associated shift from central memory towards (late-stage) effector cells was detected. T cells and NKT cells were correlated with MMSE, NK and NKT cells were correlated with ptau, CD14+ monocytes and NK cells were correlated with Amyloid-β 1–40. Our data suggest that each investigated immune cell type is involved in dementia-associated alterations within the CSF, possibly having distinct functions in their pathogenesis.

A complex interplay between immune cells, the molecules they secrete, the cells they interact with, and hormones is crucial for pregnancy establishment and maintenance. Small perturbances of this finely modulated and timely defined balance can have serious consequences for both mother and fetus. In this chapter, we revise data regarding B cells and their importance for gestation. The study of this particular cell type during pregnancy has long been neglected. B cells represent an extremely complex cell population as they can present antigen, interact with other immune cells, secrete cytokines, and antibodies. Most recent data show their plasticity and the pivotal role they play in sustaining pregnancy and as regulators of the balance between tolerance and immunity.

Preterm birth (PTB) is defined as birth before 37 completed weeks of gestation. The causes of PTB are multiple and complex, the underlying pathophysiology being largely unknown. Interferences in the fine-tuned balance of the maternal immune system have been pointed to as one possible cause of PTB. Regulatory B cells (Breg) are part of the adaptive immune response, and recent data suggest that they may contribute to a healthy pregnancy by their regulatory/suppressive function. We investigated the frequency of Breg cells in peripheral blood of women undergoing PTB and control women immediately before giving birth via cesarean section. We detected an enhanced number of B cells, but a reduced number of Breg cells in women delivering preterm. In addition, the percentage of IL-10-producing B cells was decreased in PTB following stimulation with TLR agonists CpG or LPS, alone or combined with CD40L. This was associated with increased levels of pro-inflammatory cytokines in maternal serum. Moreover, isolated maternal B cells before delivering premature babies secreted higher level of the pro-inflammatory cytokine IL-6. No alterations in the frequency of regulatory T cells were found. Our data indicate that alterations in the number and function of Breg cells in peripheral maternal blood contribute to the immunological changes observed in preterm delivery and suggest these cells as important regulators of maternal immune responses.

Background Asthma is a widespread, multifactorial chronic airway disease. The influence of regulatory B cells on airway hyperreactivity (AHR) and remodeling in asthma is poorly understood. Objective Our aim was to analyze the role of B cells in a house dust mite (HDM)-based murine asthma model. Methods The influence of B cells on lung function, tissue remodeling, and the immune response were analyzed by using wild-type and B-cell–deficient (μMT) mice and transfer of IL-10–proficient and IL-10–deficient B cells to μMT mice. Results After HDM-sensitization, both wild-type and μMT mice developed AHR, but the AHR was significantly stronger in μMT mice, as confirmed by 2 independent techniques: invasive lung function measurement in vivo and examination of precision-cut lung slices ex vivo. Moreover, airway remodeling was significantly increased in allergic μMT mice, as shown by enhanced collagen deposition in the airways, whereas the numbers of FoxP3+ and FoxP3– IL-10–secreting regulatory T cells were reduced. Adoptive transfer of IL-10–proficient but not IL-10–deficient B cells into μMT mice before HDM-sensitization attenuated AHR and lung remodeling. In contrast, FoxP3+ regulatory T cells were equally upregulated by transfer of IL-10–proficient and IL-10–deficient B cells. Conclusion Our data in a murine asthma model illustrate a central role of regulatory B cells in the control of lung function and airway remodeling and may support future concepts for B-cell–targeted prevention and treatment strategies for allergic asthma.

Preterm birth (PTB) is one of the most frequent pregnancy complications. It affects millions of babies each year worldwide and is associated with increased morbidity and mortality. PTB-associated alterations in the maternal immune response may have a direct effect on the developing fetal immune system. Having recently shown that B regulatory (Breg) cells are decreased in number and functionally impaired in maternal blood from women delivering preterm, we now addressed the question whether the adaptive immune system is also altered in cord blood (CB) after the onset of PTB. PTB was associated with increased concentrations of IL-6, TNF-α and IL-21 in CB and enhanced IL-6, but decreased IFN-γ and IL-4 in amniotic fluid (AF) samples compared to term delivery (TD). We found no differences in the frequency of CD19 + B cells, CD4 + T cells or CD4+Foxp3+CD25+ T regulatory (Treg) cells in CB cells in PTB vs TD. The frequency of CD86 + B cells was increased, while the percentage of CD24hiCD38hiCD19 + Breg and CD1dhiCD5+ Breg cells and the ability of B cells to convert into Breg cells was diminished in PTB compared to TD. CB B cells from PTB secreted more IL-6, TNF-α, IL-9 and IL-2 compared to B cells obtained from term samples. We conclude that, after PTB onset, a shift from immunoregulation towards inflammation takes place in CB cells that are reportedly representative of the fetal compartment. B cells have a substantial contribution herein. This phenomenon might account for the observed enhanced mortality and morbidity in prematurely born infants. Further studies will clarify how to employ this easy-to-obtain information for closely monitoring newborns at risk.

Alterations in the immune response that result in inflammation might play a role in the pathology of dementias. In order to analyze changes of the peripheral immune system associated with different types of dementias, we determined several innate and adaptive cell populations in whole blood using flow cytometry. We included patients with Alzheimer's disease (AD; n = 60), vascular dementia (VaD; n = 20), and frontotemporal dementia (FTD; n = 12) at the time point of diagnosis and 24 age-matched neuropsychiatric healthy persons. Monocytes and NK cells were diminished in VaD, but not in AD and FTD. B cell and T cell numbers were decreased in all investigated forms of dementia. Changes in the contribution of naïve/memory T cells were only present in AD. Correlation and regression analyses revealed associations between altered immune cell populations and Q Albumin as marker for the integrity of the blood-cerebrospinal fluid-barrier, Mini-Mental State Examination values, and age. The peripheral immune system is altered in AD, VaD, and FTD. However, each disorder presents unique changes in the investigated cell types indicating different mechanisms underlying the pathology.

N-Methyl-D-aspartate glutamate receptor (NMDA-R) antibodies (Abs) could play a role in neurodegenerative disorders. Since, in these diseases, NMDA-R Abs were detected in serum, but only sporadic in cerebrospinal fluid (CSF), the origin and impact of the Abs are still unresolved. We examined the presence of NMDA-R Abs in serum and CSF using a cell-based immunofluorescence assay as well as the function of the blood-CSF-barrier (B-CSF-B) by determination of Q albumin (ratio of albumin in CSF and serum) in patients with mild cognitive impairment (MCI; N = 59) and different types of dementia, Alzheimer's disease (AD; N = 156), subcortical ischemic vascular dementia (SIVD; N = 61), and frontotemporal dementia (FTD; N = 34). Serum IgA/IgM NMDA-R Abs and/or a disturbed B-CSF-B were sporadically present in all investigated patients' groups. In AD, these Abs often developed during the disease course. Patients with either no hippocampal atrophy and/or no AD-related characteristic changes in CSF, referred to "non-classical" AD, were characterized by seropositivity at diagnosis and loss of function of the B-CSF-B showed a progressive decline in cognitive functions and a poor prognosis. Our data indicate that NMDA-R Abs are present in different types of dementia and elderly healthy individuals. In combination with disturbed B-CSF-B integrity, they seem to promote their pathological potential on cognitive decline, and thus, a subgroup of dementia patients with these unique characteristics might inform clinicians.

The high susceptibility of newborn infants to sepsis is ascribed to an immaturity of the neonatal immune system, but the molecular mechanisms remain unclear. Newborn monocytes massively release the alarmins S100A8/S100A9. In adults, these are major regulators of immunosuppressive myeloid-derived suppressor cells (MDSCs). We investigated whether S100A8/S100A9 cause an expansion of monocytic MDSCs (Mo-MDSCs) in neonates, thereby contributing to an immunocompromised state. Mo-MDSCs have been assigned to CD14+/human leukocyte antigen (HLA)-DR-/low/CD33+ monocytes in humans and to CD11b+/Gr-1int/Ly6G-/Ly6Chi cells in mice. We found monocytes with these phenotypes significantly expanded in their respective newborns. Functionally, however, they did not prove immunosuppressive but rather responded inflammatorily to microbial stimulation. Their expansion did not correlate with high S100A8/S100A9 levels in cord blood. Murine studies revealed an excessive expansion of CD11b+/Gr-1int/Ly6G-/Ly6Chi monocytes in S100A9-/- neonates compared to wild-type neonates. This strong baseline expansion was associated with hyperinflammatory responses during endotoxemia and fatal septic courses. Treating S100A9-/- neonates directly after birth with S100A8/S100A9 alarmins prevented excessive expansion of this inflammatory monocyte population and death from septic shock. Our data suggest that a specific population of inflammatory monocytes promotes fatal courses of sepsis in neonates if its expansion is not regulated by S100A8/S100A9 alarmins.-Heinemann, A. S., Pirr, S., Fehlhaber, B., Mellinger, L., Burgmann, J., Busse, M., Ginzel, M., Friesenhagen, J., von Kockritz-Blickwede, M., Ulas, T., von Kaisenberg, C. S., Roth, J., Vogl, T., Viemann, D. In neonates S100A8/S100A9 alarmins prevent the expansion of a specific inflammatory monocyte population promoting septic shock.

Different models of experimental allergic asthma have shown that the TLR7/8 agonist resiquimod (R848) is a potential inhibitor of type 2 helper cell–driven inflammatory responses. However, the mechanisms mediating its therapeutic effects are not fully understood. Using a model of experimental allergic asthma, we show that induction of IL-27 by R848 is critical for the observed ameliorative effects. R848 significantly inhibited all hallmarks of experimental allergic asthma, including airway hyperreactivity, eosinophilic airway inflammation, mucus hypersecretion, and Ag-specific Ig production. Whereas R848 significantly reduced IL-5, IL-13, and IL-17, it induced IFN-γ and IL-27. Neutralization of IL-27 completely reversed the therapeutic effect of R848 in the experimental asthma model, demonstrating dependence of R848-mediated suppression on IL-27. In vitro, R848 induced production of IL-27 by murine alveolar macrophages and dendritic cells and enhanced expression of programmed death–ligand 1, whose expression on monocytes and dendritic cells has been shown to regulate peripheral tolerance in both murine and human studies. Moreover, in vitro IL-27 enhanced secretion of IFN-γ whereas it inhibited IL-5 and IL-13, demonstrating its direct effect on attenuating Th2 responses. Taken together, our study proves that R848-mediated suppression of experimental asthma is dependent on IL-27. These data provide evidence of a central role of IL-27 for the control of Th2-mediated allergic diseases.

Asthma is a widespread chronic multifactorial disease of the airways which is often triggered by the perennial allergen house dust mite (HDM). Next to regulatory T cells (Tregs), IL10 producing regulatory B cells are crucial to substantially counteract inflammatory responses. However, their regulatory impact in asthma is inadequately known so far. To better understand the regulatory influence of B cells in allergic asthma, we employed a HDM-based experimental asthma model using wildtype (WT) and B cell deficient (µMT) mice. Compared to WT counterparts, HDM-sensitized µMT mice developed a significantly increased airway hyperreactivity (AHR), a cardinal feature of asthma, measured by invasive lung function. This observation was confirmed by independent precision cut lung slices (PCLS) technique, demonstrating stronger bronchoconstriction of explanted lung tissue slices of allergic µMT mice after methacholine provocation. Furthermore, allergic µMT mice displayed diminished levels of Tregs and Th2 cytokines, especially IL10, as determined by flow cytometry and immunoassays. Adoptive transfer of naive WT B cells followed by HDM-sensitization substantially attenuated AHR in µMT mice and boosted IL10 production and Treg expansion. To test the impact of IL10, B cells from IL10 deficient (IL10-/-) mice were transferred, but failed to improve lung function of allergic µMT mice. Furthermore, transfer of WT and IL10-/- B cells provoked comparable amounts of IL10 and Tregs. Taken together, our data indicate that B cells are critical in HDM-induced AHR, and that IL10 competent B cells may be central in regulating AHR in allergic airway inflammation.

Understanding the mechanisms leading to fetal death following maternal subclinical infections is crucial to develop new therapeutic strategies. Here we addressed the relevance of IL-10 secreting B cells (B10) in the maintenance of the immune balance during gestation. µMT females lacking mature B cells presented normal pregnancies, although their fetuses were smaller and their Treg pool did not expand as in B cell sufficient controls. Pregnant µMT females were more susceptible to LPS despite having less Treg; their fetuses died at doses compatible with pregnancy in WT animals. Adoptive transfer of IL-10 negative B effector cells or B cells from IL-10 deficient mice did not modify this outcome. The transfer of B10 cells or application of recombinant murine IL-10 reduced the fetal loss, associated with a normalization of Treg numbers and cytokine modulation at the feto-maternal interface. B cell-derived IL-10 suppressed the production of IL-17A and IL-6 by T cells and promoted the conversion of naïve cells into Treg. B10 cells are required to restore the immune balance at the feto-maternal interface when perturbed by inflammatory signals. Our data position B cells in a central role in the maintenance of the balance between immunity and tolerance during pregnancy.

Although monocytes and macrophages could serve as new therapeutic targets for treatment of Alzheimer's disease (AD) and aging of the human innate immune system, its role in the pathogenesis of neurodegenerative disorders such as AD are only poorly understood. We have addressed this here by determining the number of CD14+ monocytes and the frequency of HLA-DR-, CD80-, and CD86-expression in peripheral blood from healthy volunteers aged 20-79 years, and in AD patients at diagnosis and after 12, 30, and 52 weeks of rivastigmine treatment. While the number of CD14+ monocytes remained constant, the expression of HLA-DR, CD80, and CD86 by monocytes increased with age. However, no differences were identified by comparing AD patients with age-matched healthy controls or following treatment of AD patients with rivastigmine. These results indicate that changes in the expression of HLA-DR, CD80, and CD86 are caused by immunosenescence rather than by AD pathology or treatment of AD patients with rivastigmine.

Secretion of VGF is increased in cerebrospinal fluid and blood in neurodegenerative disorders like Alzheimer's disease (AD) and VGF is a potential biomarker for these disorders. We have shown that VGF is expressed in peripheral T cells and is correlated with T cell survival and cytokine secretion. The frequency of VGF+CD3+ T cells increases with normal aging. We found an increased number of VGF-expressing T cells in patients with AD compared to aged healthy controls, which was associated with enhanced HbA1c levels in blood. Upon treatment with rivastigmine, T cell proliferation and VGF expression in AD patients decreased to the level found in controls. Moreover, rapamycin treatment in vitro reduced the number of VGF+CD3+ cells in AD patients to control levels.

Neonates rely on their innate immune system. Resident tissue macrophages are considered to be initiators and regulators of the innate immune response and thus, appear to be especially important to neonates. We hypothesized that the phenotype and function of neonatal tissue macrophages differ from their adult counterparts. Peritoneal macrophages from neonatal (

Patients suffering from cognitive decline such as mild cognitive impairment or neurodegenerative disorders including Alzheimer's dementia, vascular dementia, frontotemporal dementia, and Lewy body dementia are often accompanied by symptoms like psychosis, depression, agitation, and apathy. Aging increases not only the prevalence of dementia but also the development of kidney disorders, which had emerged as possible risk factor of cognitive impairment and dementia. However, a contribution of renal dysfunction to psychosis associated with cognitive decline remains to be investigated. We addressed the question whether patients diagnosed with mild cognitive impairment or dementia and co-symptoms show alterations in serum parameters. Analyzing 309 patients in total, we detected a positive correlation between the occurrence of psychotic symptoms and increased retention parameters in serum, including creatinine and urea levels and the estimated glomerular filtration rates. This was in particular detected in female patients. In male patients, psychotic symptoms were associated with an increased number of leukocytes in blood. We propose that clinicians should be aware of psychotic symptoms in patients with reduced cognitive functions that could be associated with changes in the retention parameters.

The N-methyl-d-aspartate glutamate receptor (NMDA-R) plays a central role in learning and memory and has therefore a potential role in the pathophysiology of neuropsychiatric disorders. Recently, we detected NMDA-R autoantibodies in aged healthy volunteers without neuropsychiatric disorders. Since studies showing the involvement of NMDA-R antibodies in mild cognitive impairment and different forms of dementia are rare, we examined NMDA-R antibodies (Abs) in serum of 46 patients with Alzheimer's disease (AD), 26 patients with subcortical ischemic vascular dementia (SIVD), 18 patients with frontotemporal dementia (FTD), 11 patients with Lewy body disease (LBD) and 33 patients with mild cognitive impairment (MCI) and in 21 healthy aged, gender-matched volunteers. While IgM and/or IgA NMDA-R Abs were present in all groups, IgG was only detected in one AD sample. Seropositivity could be correlated with the presence of co-symptoms: MCI and AD patients suffering from depression and AD and SIVD patients with a psychosis were almost all NMDA-R Ab positive. We conclude that the presence of NMDA-R Abs in dementia could influence the incidence of comorbid depressive and/or psychotic states.

VGF is a protein expressed by neurons and processed into several peptides. It plays a role in energy homeostasis and promotes growth and survival. Recently, VGF mRNA was detected in peripheral leukocytes. Since it is known that aging is associated with a decrease in the development and function of neuronal as well as immune cells, we addressed the question whether a peripheral expression of VGF by CD3+ T cells and CD56+ NK cells is correlated with age. Therefore, the frequency of VGF+CD3+ and VGF+CD56+ cells was determined in mentally healthy volunteers aged between 22 and 88. We found an age-dependent increase in the number of VGF+CD3+ T cells that correlated with HbA1c and the body mass index (BMI). VGF-expression by NK cells was age-independent. Blockade of VGF reduced proliferation and secretion of cytokines such as IL-2, IL-17A, IL-1β, IL-10 and TNF by CD3+ T cells and PBMCs. Rapamycin-mediated T cell blockade significantly reduced the frequency of VGF-expressing T cells. We conclude that VGF contributes to survival and function of peripheral T cells. The age-dependent increase in VGF-expression could serve as mechanism that counterregulates the decrease in functionality of T lymphocytes.

Cellular therapy with chimeric antigen receptor (CAR)-redirected cytotoxic T cells has shown impressive efficacy in the treatment of hematologic malignancies. We explored a regulatory T cell (Treg)-based therapy in the treatment of allergic airway inflammation, a model for asthma, which is characterized by an airway hyper-reactivity (AHR) and a chronic, T helper-2 (Th2) cell-dominated immune response to allergen. To restore the immune balance in the lung, we redirected Tregs by a CAR toward lung epithelia in mice upon experimentally induced allergic asthma, closely mimicking the clinical situation. Adoptively transferred CAR Tregs accumulated in the lung and in tracheobronchial lymph nodes, reduced AHR and diminished eosinophilic airway inflammation, indicated by lower cell numbers in the bronchoalveolar lavage fluid and decreased cell infiltrates in the lung. CAR Treg cells furthermore prevented excessive pulmonary mucus production as well as increase in allergen-specific IgE and Th2 cytokine levels in exposed animals. CAR Tregs were more efficient in controlling asthma than non-modified Tregs, indicating the pivotal role of specific Treg cell activation in the affected organ. Data demonstrate that lung targeting CAR Treg cells ameliorate key features of experimental airway inflammation, paving the way for cell therapy of severe allergic asthma.

The role of monocytes and macrophages in the pathogenesis of neurodegenerative disorders such as Alzheimer’s disease (AD) is poorly understood. Recently, we have shown that the number of CD14+ monocytes remained constant during healthy aging and in AD patients. Although only little is known about the function of activated macrophages and microglia in AD, one important mechanism involves the expression of quinolinic acid (QUIN), an endogenous N-methyl-d-aspartate glutamate receptor (NMDA-R) agonist which mediates excitotoxicity especially in the hippocampus. We used immunofluorescence stainings of PBMCs to determine the expression of quinolinic acid (QUIN) and the MHC class II molecule HLA-DR in peripheral monocytic cells in 51 healthy volunteers aged 22–87 years and 43 patients with AD at diagnosis (0 weeks) and during the course of rivastigmine treatment at 0.25 year (12 weeks), 0.5 year (30 weeks), 1 year, and 1.5 years. The number of QUIN+ HLA-DR+ cells rises in healthy persons aged 30–40 years compared to persons aged 60–70 years, indicating that this cell population increases with aging. AD patients at diagnosis had an increased frequency of QUIN+, QUIN+ HLA-DR+, and QUIN+ HLA-DR+/HLA-DR+ cells compared to aged-matched controls. These cell populations remained increased in AD for up to one year after initiation of treatment with rivastigmine; no alterations were detected in aged healthy persons. We conclude that the expression of the neurotoxic agent QUIN is increased in peripheral monocytes from AD patients. These cells could enter the brain and contribute to excitotoxicity.

// Theresa Lowinus 1 , Tanima Bose 2, 6 , Stefan Busse 3 , Mandy Busse 4 , Dirk Reinhold 1 , Burkhart Schraven 1, 5 , Ursula H.H. Bommhardt 1 1 Institute of Molecular and Clinical Immunology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany 2 Molecular Physiology, Leibniz Institute for Neurobiology, Magdeburg, Germany 3 Department of Psychiatry, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany 4 Department of Pediatric Pulmonology & Allergology, Medical University of Hannover, Hannover, Germany 5 Department of Immune Control, Helmholtz Centre for Infection Research, Braunschweig, Germany 6 Current address: Lee Kong Chian School of Medicine, Singapore Correspondence to: Ursula H.H. Bommhardt, email: Ursula.Bommhardt@med.ovgu.de Keywords: human T cells, memantine, K v 1.3 potassium channel, NMDA receptor antagonist, Alzheimer´s disease Received: February 04, 2016 Accepted: July 09, 2016 Published: July 22, 2016 ABSTRACT Memantine is approved for the treatment of advanced Alzheimer´s disease (AD) and reduces glutamate-mediated neuronal excitotoxicity by antagonism of N-methyl-D-aspartate receptors. In the pathophysiology of AD immune responses deviate and infectious side effects are observed during memantine therapy. However, the particular effects of memantine on human T lymphocytes are unresolved. Here, we provide evidence that memantine blocks K v 1.3 potassium channels, inhibits CD3-antibody- and alloantigen-induced proliferation and suppresses chemokine-induced migration of peripheral blood T cells of healthy donors. Concurrent with the in vitro data, CD4 + T cells from AD patients receiving therapeutic doses of memantine show a transient decline of K v 1.3 channel activity and a long-lasting reduced proliferative response to alloantigens in mixed lymphocyte reactions. Furthermore, memantine treatment provokes a profound depletion of peripheral blood memory CD45RO + CD4 + T cells. Thus, standard doses of memantine profoundly reduce T cell responses in treated patients through blockade of K v 1.3 channels. This may normalize deviant immunopathology in AD and contribute to the beneficial effects of memantine, but may also account for the enhanced infection rate.

Protein expression of VGF (nonacronymic) is induced by nerve/brain-derived growth factor, neurotrophin 3, and insulin. VGF is synthesized by neurons in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. After enzymatic processing, smaller VGF-derived peptides are secreted into the cerebrospinal fluid (CSF) or blood. These peptides play important roles by improving synaptic plasticity, neurogenesis, and energy homeostasis, which are impaired in schizophrenia. Based on previous observations of neuroendocrine and hypothalamic deficits in schizophrenia and to determine whether increased levels of the VGF fragment 23-62 in CSF, which have been described in a recent study, were related to changes in hypothalamic VGF expression, an immunohistochemical study was performed in 20 patients with schizophrenia and 19 matched control subjects. N- (D-20) and C-terminal (R-15) VGF antibodies yielded similar results and immunolabeled a vast majority of PVN and SON neurons. Additionally, D20-VGF immunohistochemistry revealed immunostained fibers in the pituitary stalk and neurohypophysis that ended at vessel walls, suggesting axonal transport and VGF secretion. The cell density of D20-VGF-immunoreactive neurons was reduced in the left PVN (P = 0.002) and SON (P = 0.008) of patients with schizophrenia. This study provides the first evidence for diminished hypothalamic VGF levels in schizophrenia, which might suggest increased protein secretion. Our finding was particularly significant in subjects without metabolic syndrome (patients with a body mass index ≤28.7 kg/m(2)). In conclusion, apart from beneficial effects on synaptic plasticity and neurogenesis, VGF may be linked to schizophrenia-related alterations in energy homeostasis.

Background: Abdominal sepsis due to intestinal leakage of endogenous gut bacteria is a life-threatening condition. In healthy individuals, T lymphocytes have essential functions in balancing the immune response to the commensal gut flora. Aim: To determine how T lymphocytes shape the process of diffuse faecal peritonitis. Methods: In colon ascendens stent peritonitis (CASP), a clinically relevant mouse model of diffuse peritonitis, the kinetics of systemic T cell activation were investigated by assessment of activation markers. CD4 + T cells were then depleted with monoclonal antibodies, and survival, bacterial dissemination and cytokine concentrations were measured. T cell receptor signalling was blocked with tacrolimus. Results: In diffuse peritonitis, CD4 + T cells, both Foxp3 − and Foxp3 + , became systemically involved within hours and upregulated CTLA-4 and other activation markers. Depletion of the CD4 + T cells enhanced local bacterial clearance from the peritoneal cavity, reduced bacterial dissemination and improved survival. This was accompanied by increased immigration of granulocytes and macrophages into the peritoneum, indicating that CD4 + T cells inhibit the local innate immune response. Blockade of T cell receptor (TCR) signalling by tacrolimus did not influence the survival in this peritonitis model, showing that the inhibitory effects of the CD4 + T lymphocytes were independent of TCR-mediated antigen recognition. Conclusion: In diffuse peritonitis caused by commensal gut bacteria the CD4 + T lymphocytes exert a net negative effect on the local anti-bacterial defence, and thereby contribute to bacterial dissemination and poor outcome.

Background: Several studies suggest an involvement of Th17 cells and related cytokines in the pathology of allergic asthma. However, cellular mechanisms involved in induction, maintenance and pathophysiology of asthma are multifaceted. IL-17 isoforms have been shown to be involved in the modulation of asthma both in humans and in murine models of allergic asthma, but the exact IL-17A and F dependent mechanisms in asthma still remain to be elucidated. Objective: Our aim was to decipher the cellular mechanisms involved in IL-17A and F dependent modulation of allergic asthma. Methods: WT, IL-17 AF -/- and IL-17F -/- mice were tested in an ovalbumin based murine asthma model. Furthermore, blocking experiments employing systemic application of anti-IL-17A specific neutralizing monoclonalantibody was performed. In all mice, airway inflammation and airway hyperresponsiveness (AHR), and antigen-specific serum IgG/IgE levels, and cytokine production was compared. Results: Using single or double knockout mice and neutralizing antibodies, we show that IL-17A is crucial for development of experimental asthma and AHR. By contrast, absence of IL-17F does not influence induction of AHR in our model. Interestingly, neutralization of IL-17A using specific monoclonal antibody prevented establishment of allergic asthma, an observation that was co-related with diminished recruitment of innate lymphoid cell (ILC2) population specifically into the lung. Conclusions: Our data show that IL-17A and F play non-redundant roles in development and maintenance of experimental allergic asthma and, point towards a crucial role of IL-17A in recruitment of ILC2 cells to the lung.

Background: Counter balancing Th2-cytokine production through enhanced skewing of CD4+ T helper cells into Th1 cells is currently one of the central immunomodulatory approaches for treatment of allergic diseases. Methods: We systemically sensitized mice followed by intranasal challenge with the model allergen. Resiquimod was administered intranasally before the challenge period. Airway inflammation, antigen-specific immunoglobulins and, cytokines production were assessed to determine the degree of air way hyper responsiveness between animals pre-treated with Resiquimod and those which were untreated. Results: We show that, pre-treatment with Resiquimod before challenge with the allergen alleviates AHR in murine model. Through blocking experiments, we reveal that, the suppressive effect is dependent on induction of IL-27 and is associated with enhanced expression of immunomodulatory molecule B7-H1 (PD-L1) on pulmonary antigen presenting cells. In addition, Resiquimod application leads to inhibition of IL-17 which is reversed on blocking IL-27. Conclusions: Resiquimod driven alleviation AHR in murine models is dependent on IL-27 production and associated downstream mechanims such as induction of immunomodulatory molecules PD-L1 on antigen presenting cells. Concomitant Th2 to Th1 switching and, inhibition of Th17 through abolishment of IL-17 on Resiquimod application, leads to reduction in inflammatory responses usually associated with allergic airway hyper-responsiveness in this models. Thus, we believe targeting IL-27 dependent pathways in modulation of Th2 driven pathologies such as allergic asthma is a feasibly promising approach.

Disturbances of glutamatergic neurotransmission and mononuclear phagocyte system activation have been described uni- and bipolar depression (UD/BD). Linking the glutamate and immune hypotheses of depression, quinolinic acid (QUIN) is synthesized by activated microglia and acts as an endogenous N-methyl-D-aspartate glutamate receptor (NMDA-R) agonist with neurotoxic properties. Recently, we observed an increased microglial QUIN expression in the subgenual and supracallosal, but not in the pregenual part of the anterior cingulate cortex in postmortem brains of suicide cases with severe depression. Since several hints point to a role of the hippocampus in depression, we extended our study and addressed the question whether microglial QUIN is also changed in subregions of the hippocampus (CA1 and CA2/3 areas) in these patients. Postmortem brains of 12 acutely depressed patients (UD, n = 6; BD, n = 6) and 10 neuropsychiatric healthy age- and gender-matched control subjects were analyzed using QUIN-immunohistochemistry. Hippocampal volumes were determined in order to assess possible neurotoxic or neurodegenerative aspects. Microglial QUIN expression in the whole group of depressed patients was either comparable (left CA1, right CA2/3) or decreased (right CA1: p = 0.004, left CA2/3: p = 0.044) relative to controls. Post hoc tests showed that QUIN was reduced both in UD and BD in the right CA1 field (UD, p = 0.048; BD, p = 0.031). No loss of hippocampal volume was detected. Our data indicate that UD and BD are associated with a local reduction in QUIN-immunoreactive microglia in the hippocampus and underline the importance of the NMDA-R signaling in depressive disorders.

Neonates rely on their innate immune system. Resident tissue macrophages are considered to be initiators and regulators of the innate immune response and thus, appear to be especially important to neonates. We hypothesized that the phenotype and function of neonatal tissue macrophages differ from their adult counterparts. Peritoneal macrophages from neonatal (24 h) and adult (6 weeks old) C57BL/6J mice were isolated and analyzed by high-content chipcytometry. After stimulation for 6 h with LPS (0, 1, 10, 100 ng/mL), macrophage transcriptome was analyzed by microarray and cytokine release was measured using multiparametric bead assays. Antigen presenting capacity was compared by T-cell stimulation assays. We observed that neonatal murine peritoneal macrophages are characterized by selective lack of expression of F4/80, MHC class II, and costimulatory molecules (CD80, CD86). Furthermore, we found differences in the transcriptome between neonatal and adult macrophages, unstimulated and after LPS stimulation. Although neonatal macrophages showed a significantly increased secretion of proinflammatory cytokines upon LPS stimulation, their potential to induce T-cell proliferation was significantly reduced. In conclusion, we observed a distinct phenotype of the neonatal macrophage population. The specific functions of this macrophage population could help to understand the excessive inflammatory reactions observed in the very young.

N-methyl-D-aspartate glutamate receptors (NMDA-R) play a key role in learning and memory. Therefore, they may be involved in the pathophysiology of dementia. NMDA-R autoantibodies directed against the NR1a subunit of the NMDA-R, which were first identified as a specific marker for a severe form of encephalitis, cause a decrease in NMDA-Rs, resulting in cognitive impairment and psychosis. We examined the prevalence of NR1a NMDA-R autoantibodies in the serum and cerebrospinal fluid (CSF) of 24 patients with Alzheimer's disease (AD), 20 patients with subcortical ischemic vascular dementia (SIVD), and 274 volunteers without neuropsychiatric disorder. The latter cases showed an association of seropositivity with age. Notably, the overall seroprevalence was not statistically different between dementia patients and matched controls. Further analysis of the patient samples showed that four patients with AD and three patients with SIVD had positive NMDA-R IgM, IgG, and/or IgA autoantibody titers in serum. These patients suffered from psychosis (with the exception of one case). CSF samples were negative for NMDA-R autoantibodies. We conclude that the seroprevalence of NMDA-R-directed autoantibodies is age-related. It has to be clarified by larger studies whether NMDA-R autoantibodies in peripheral blood may predispose patients with AD and SIVD to susceptibility for psychotic episodes if disturbances of blood-brain-barrier integrity occur.

Costimulatory molecules like ICOS are crucial in mediating T cell differentiation and function after allergen contact and thereby strongly affect the immunologic decision between tolerance or allergy development. In this study, we show in two independent approaches that interruption of the ICOS signaling pathway by application of a blocking anti-ICOSL mAb in wild-type (WT) mice and in ICOS−/− mice inhibited respiratory tolerance development leading to eosinophilic airway inflammation, mucus hypersecretion, and Th2 cytokine production in response to OVA sensitization. Respiratory Ag application almost doubled the number of CD4+Foxp3+ regulatory T cells (Tregs) in the lung of WT mice with 77% of lung-derived Tregs expressing ICOS. In contrast, in ICOS−/− mice the number of CD4+CD25+Foxp3+ Tregs did not increase after respiratory Ag application, and ICOS−/− Tregs produced significantly lower amounts of IL-10 than those of WT Tregs. Most importantly, in contrast to WT Tregs, ICOS−/− Tregs did not convey protection when transferred to “asthmatic” recipients demonstrating a strongly impaired Treg function in the absence of ICOS signaling. Our findings demonstrate a crucial role of ICOS for the generation and suppressive function of Tregs conveying respiratory tolerance and support the importance of ICOS as a target for primary prevention strategies.

Certain cytokines have been identified in the peripheral blood as trait markers of schizophrenia, while others are considered relapse-related state markers. Furthermore, data from peripheral blood, cerebrospinal fluid (CSF) and nuclear imaging studies suggest that (1) blood-brain barrier (BBB) dysfunction (e.g., immigration of lymphocytes into brain tissue and intrathecal antibody production) correlates with the development of negative symptoms, while (2) the brain's mononuclear phagocyte system (microglial cells) is activated during acute psychosis. Based on these neuroinflammatory hypotheses, we have quantified the numerical density of immunostained CD3+ T-lymphocytes, CD20+ B-lymphocytes, and HLA-DR+ microglial cells in the posterior hippocampus of 17 schizophrenia patients and 11 matched controls. Disease course-related immune alterations were considered by a separate analysis of residual (prevailing negative symptoms, n=7) and paranoid (prominent positive symptoms, n=10) schizophrenia cases. Higher densities of CD3+ and CD20+ lymphocytes were observed in residual versus paranoid schizophrenia (CD 3: left: P=0.047, right: P=0.038; CD20: left: P=0.020, right: P=0.010) and controls (CD3: left: P=0.057, right: P=0.069; CD20: left: P=0.008, right: P=0.006). In contrast, HLA-DR+ microglia were increased in paranoid schizophrenia versus residual schizophrenia (left: P=0.030, right: P=0.012). A similar trend emerged when this group was compared to controls (left: P=0.090, right: P=0.090). BBB impairment and infiltration of T cells and B cells may contribute to the pathophysiology of residual schizophrenia, while microglial activation seems to play a role in paranoid schizophrenia. The identification of diverse immune endophenotypes may facilitate the development of distinct anti-inflammatory schizophrenia therapies to normalize BBB function, (auto)antibody production or microglial activity.

T cells orchestrate the adaptive immune response, making them targets for immunotherapy. Although immunosuppressive therapies prevent disease progression, they also leave patients susceptible to opportunistic infections. To identify novel drug targets, we established a logical model describing T-cell receptor (TCR) signaling. However, to have a model that is able to predict new therapeutic approaches, the current drug targets must be included. Therefore, as a next step we generated the interleukin-2 receptor (IL-2R) signaling network and developed a tool to merge logical models. For IL-2R signaling, we show that STAT activation is independent of both Src- and PI3-kinases, while ERK activation depends upon both kinases and additionally requires novel PKCs. In addition, our merged model correctly predicted TCR-induced STAT activation. The combined network also allows information transfer from one receptor to add detail to another, thereby predicting that LAT mediates JNK activation in IL-2R signaling. In summary, the merged model not only enables us to unravel potential cross-talk, but it also suggests new experimental designs and provides a critical step towards designing strategies to reprogram T cells., Author Summary The cells of the mammalian immune system do not exist in isolation, but rather form an integrated network that is constantly scanning the body for signs of ‘foreign’ invasion. Working together, these cells possess the ability to repel invaders and thereby establish protective immunity. One central population in this network are T lymphocytes; whose role it is to coordinate the activity of the adaptive arm of defense. However, T cells constantly receive multiple inputs and therefore it is not clear how they are able to reach a decision. Traditionally, these inputs are studied in isolation using a top-down or stimulus-response approach. Confounding this issue is that our knowledge of these input pathways is not cell-type-specific, but rather represents the sum of all knowledge related to a given stimulus. Therefore, we have undertaken to validate signaling pathways in primary human T cells. We are particularly interested to study the cross-talk between pathways to see how common elements are utilized to make specific decisions that determine cell fate. In doing so, we have identified new components in what were considered to be well-characterized receptor pathways.