Five-year follow-up of a phase I trial of donor-derived modified immune cell infusion in kidney transplantation

Background

The administration of modified immune cells (MIC) before kidney transplantation led to specific immunosuppression against the allogeneic donor and a significant increase in regulatory B lymphocytes. We wondered how this approach affected the continued clinical course of these patients.

Methods

Ten patients from a phase I clinical trial who had received MIC infusions prior to kidney transplantation were retrospectively compared to 15 matched standard-risk recipients. Follow-up was until year five after surgery.

Results

The 10 MIC patients had an excellent clinical course with stable kidney graft function, no donor-specific human leukocyte antigen antibodies (DSA) or acute rejections, and no opportunistic infections. In comparison, a retrospectively matched control group receiving standard immunosuppressive therapy had a higher frequency of DSA (log rank P = 0.046) and more opportunistic infections (log rank P = 0.033). Importantly, MIC patients, and in particular the four patients who had received the highest cell number 7 days before surgery and received low immunosuppression during follow-up, continued to show a lack of anti-donor T lymphocyte reactivity in vitro and high CD19⁺CD24^hiCD38^hi transitional and CD19⁺CD24^hiCD27⁺ memory B lymphocytes until year five after surgery.

Conclusions

MIC infusions together with reduced conventional immunosuppression were associated with good graft function during five years of follow-up, no de novo DSA development and no opportunistic infections. In the future, MIC infusions might contribute to graft protection while reducing the side effects of immunosuppressive therapy. However, this approach needs further validation in direct comparison with prospective controls.

Trial registration

https://clinicaltrials.gov/, identifier NCT02560220 (for the TOL-1 Study). EudraCT Number: 2014-002086-30.

Induction of Long-Lasting Regulatory B Lymphocytes by Modified Immune Cells in Kidney Transplant Recipients

BACKGROUND

We recently demonstrated that donor-derived modified immune cells (MICs)-PBMCs that acquire immunosuppressive properties after a brief treatment-induced specific immunosuppression against the allogeneic donor when administered before kidney transplantation. We found up to a 68-fold increase in CD19 + CD24 hi CD38 hi transitional B lymphocytes compared with transplanted controls.

METHODS

Ten patients from a phase 1 clinical trial who had received MIC infusions before kidney transplantation were followed to post-transplant day 1080.

RESULTS

Patients treated with MICs had a favorable clinical course, showing no donor-specific human leukocyte antigen antibodies or acute rejections. The four patients who had received the highest dose of MICs 7 days before surgery and were on reduced immunosuppressive therapy showed an absence of in vitro lymphocyte reactivity against stimulatory donor blood cells, whereas reactivity against third party cells was preserved. In these patients, numbers of transitional B lymphocytes were 75-fold and seven-fold higher than in 12 long-term survivors on minimal immunosuppression and four operationally tolerant patients, respectively ( P <0.001 for both). In addition, we found significantly higher numbers of other regulatory B lymphocyte subsets and a gene expression signature suggestive of operational tolerance in three of four patients. In MIC-treated patients, in vitro lymphocyte reactivity against donor blood cells was restored after B lymphocyte depletion, suggesting a direct pathophysiologic role of regulatory B lymphocytes in donor-specific unresponsiveness.

CONCLUSIONS

These results indicate that donor-specific immunosuppression after MIC infusion is long-lasting and associated with a striking increase in regulatory B lymphocytes. Donor-derived MICs appear to be an immunoregulatory cell population that when administered to recipients before transplantation, may exert a beneficial effect on kidney transplants.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

MIC Cell Therapy for Individualized Immunosuppression in Living Donor Kidney Transplant Recipients (TOL-1), NCT02560220.

Dimethyl Fumarate Reduces Inflammation in Chronic Active Multiple Sclerosis Lesions

Background and Objectives

To determine the effects of dimethyl fumarate (DMF) and glatiramer acetate on iron content in chronic active lesions in patients with multiple sclerosis (MS) and in human microglia in vitro.

Methods

This was a retrospective observational study of 34 patients with relapsing-remitting MS and clinically isolated syndrome treated with DMF or glatiramer acetate. Patients had lesions with hyperintense rims on quantitative susceptibility mapping, were treated with DMF or glatiramer acetate (GA), and had a minimum of 2 on-treatment scans. Changes in susceptibility in rim lesions were compared among treatment groups in a linear mixed effects model. In a separate in vitro study, induced pluripotent stem cell–derived human microglia were treated with DMF or GA, and treatment-induced changes in iron content and activation state of microglia were compared.

Results

Rim lesions in patients treated with DMF had on average a 2.77-unit reduction in susceptibility per year over rim lesions in patients treated with GA (bootstrapped 95% CI −5.87 to −0.01), holding all other variables constant. Moreover, DMF but not GA reduced inflammatory activation and concomitantly iron content in human microglia in vitro.

Discussion

Together, our data indicate that DMF-induced reduction of susceptibility in MS lesions is associated with a decreased activation state in microglial cells. We have demonstrated that a specific disease modifying therapy, DMF, decreases glial activity in chronic active lesions. Susceptibility changes in rim lesions provide an in vivo biomarker for the effect of DMF on microglial activity.

Classification of Evidence

This study provided Class III evidence that DMF is superior to GA in the presence of iron as a marker of inflammation as measured by MRI quantitative susceptibility mapping.

Neutralization of SARS-CoV-2 Variants of Concern in Kidney Transplant Recipients after Standard COVID-19 Vaccination

BACKGROUND AND OBJECTIVES

Antibody response after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is impaired in kidney transplant recipients. Emerging variants, such as B.1.617.2 (δ), are of particular concern because of their higher transmissibility and partial immune escape. Little is known about protection against these variants in immunocompromised patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this prospective two-center study, antispike 1 IgG and surrogate neutralizing antibodies were measured in 173 kidney transplant recipients and 166 healthy controls with different vaccination schedules. In addition, different SARS-CoV-2 epitope antibodies from 135 vaccinated kidney transplant recipients were compared with antibodies in 25 matched healthy controls after second vaccination. In 36 kidney transplant recipients with seroconversion, neutralization against B.1.1.7 (α), B.1.351 (β), and B.1.617.2 (δ) was determined on VeroE6 cells and compared with neutralization in 25 healthy controls.

RESULTS

Kidney transplant recipients had significantly lower seroconversion rates compared with healthy controls. After the second vaccination, antispike 1, antireceptor-binding domain, and surrogate neutralizing antibodies were detectable in 30%, 27%, and 24% of kidney transplant recipients, respectively. This compares with 100%, 96%, and 100% in healthy controls, respectively (P<0.001). Neutralization against B.1.1.7 was detectable in all kidney transplant recipients with seroconversion, with a median serum dilution that reduces infection of cells by 50% of 80 (interquartile range, 80-320). In contrast, only 23 of 36 (64%) and 24 of 36 (67%) kidney transplant recipients showed neutralization against B.1.351 and B.1.617.2, respectively, with median serum dilutions that reduce infection of cells by 50% of 20 (interquartile range, 0-40) and 20 (interquartile range, 0-40), respectively. Neutralization against different variants was significantly higher in healthy controls (P<0.001), with all patients showing neutralization against all tested variants.

CONCLUSIONS

Seroconverted kidney transplant recipients show impaired neutralization against emerging variants of concern after standard two-dose vaccination.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Observational study to assess the SARS-CoV-2 specific immune response in kidney transplant recipients (COVID-19 related immune response), DRKS00024668.

Tet2 Controls the Responses of β cells to Inflammation in Autoimmune Diabetes

β cells may participate and contribute to their own demise during Type 1 diabetes (T1D). Here we report a role of their expression of Tet2 in regulating immune killing. Tet2 is induced in murine and human β cells with inflammation but its expression is reduced in surviving β cells. Tet2-KO mice that receive WT bone marrow transplants develop insulitis but not diabetes and islet infiltrates do not eliminate β cells even though immune cells from the mice can transfer diabetes to NOD/scid recipients. Tet2-KO recipients are protected from transfer of disease by diabetogenic immune cells.Tet2-KO β cells show reduced expression of IFNγ-induced inflammatory genes that are needed to activate diabetogenic T cells. Here we show that Tet2 regulates pathologic interactions between β cells and immune cells and controls damaging inflammatory pathways. Our data suggests that eliminating TET2 in β cells may reduce activating pathologic immune cells and killing of β cells.

Humoral Responses to Single-Dose BNT162b2 mRNA Vaccination in Dialysis Patients Previously Infected With SARS-CoV-2

Seroconversion rates following infection and vaccination are lower in dialysis patients compared to healthy controls. There is an urgent need for the characterization of humoral responses and success of a single-dose SARS-CoV-2 vaccination in previously infected dialysis patients. We performed a dual-center cohort study comparing three different groups: 25 unvaccinated hemodialysis patients after PCR-confirmed COVID-19 (Group 1), 43 hemodialysis patients after two-time BNT162b2 vaccination without prior SARS-CoV-2 infection (Group 2), and 13 single-dose vaccinated hemodialysis patients with prior SARS-CoV-2 infection (Group 3). Group 3 consists of seven patients from Group 1 and 6 additional patients with sera only available after single-dose vaccination. Anti-S1 IgG, neutralizing antibodies, and antibodies against various SARS-CoV-2 protein epitopes were measured 3 weeks after the first and 3 weeks after the second vaccination in patients without prior SARS-CoV-2 infection, 6 weeks after the onset of COVID-19 in unvaccinated patients, and 3 weeks after single-dose vaccination in patients with prior SARS-CoV-2 infection, respectively. Unvaccinated patients after COVID-19 showed a significantly higher neutralizing antibody capacity than two-time vaccinated patients without prior COVID-19 [median (IQR) percent inhibition 88.0 (71.5-95.5) vs. 50.7 (26.4-81.0); P = 0.018]. After one single vaccine dose, previously infected individuals generated 15- to 34-fold higher levels of anti-S1 IgG than age- and dialysis vintage-matched unvaccinated patients after infection or two-time vaccinated patients without prior SARS-CoV-2 infection with a median (IQR) index of 274 (151-791) compared to 18 (8-41) and 8 (1-21) (for both P < 0.001). With a median (IQR) percent inhibition of 97.6 (97.2-98.9), the neutralizing capacity of SARS-CoV-2 antibodies was significantly higher in single-dose vaccinated patients with prior SARS-CoV-2 infection compared to other groups (for both P < 0.01). Bead-based analysis showed high antibody reactivity against various SARS-CoV-2 spike protein epitopes after single-dose vaccination in previously infected patients. In conclusion, single-dose vaccination in previously infected dialysis patients induced a strong and broad antibody reactivity against various SARS-CoV-2 spike protein epitopes with high neutralizing capacity.

Heterologous ChAdOx1 nCoV-19/BNT162b2 Prime-Boost Vaccination Induces Strong Humoral Responses among Health Care Workers

Despite limited data on safety and immunogenicity, heterologous prime-boost vaccination is currently recommended for individuals with ChAdOx1 nCoV-19 prime immunization in certain age groups. In this prospective, single-center study we included 166 health care workers from Heidelberg University Hospital who received either heterologous ChAdOx1 nCoV-19/BNT162b2, homologous BNT162b2 or homologous ChAdOx1 nCoV-19 vaccination between December 2020 and May 2021. We measured anti-S1 IgG, SARS-CoV-2 specific neutralizing antibodies, and antibodies against different SARS-CoV-2 fragments 0-3 days before and 19-21 days after boost vaccination. Before boost, 55/70 (79%) ChAdOx1 nCoV-19-primed compared with 44/45 (98%) BNT162b2-primed individuals showed positive anti-S1 IgG with a median (IQR) anti-S1 IgG index of 1.95 (1.05-2.99) compared to 9.38 (6.26-17.12). SARS-CoV-2 neutralizing antibodies exceeded the threshold in 24/70 (34%) of ChAdOx1 nCoV-19-primed and 43/45 (96%) of BNT162b2-primed individuals. After boosting dose, median (IQR) anti-S1 IgG index in heterologous ChAdOx1 nCoV-19/BNT162b2 vaccinees was 116.2 (61.84-170), compared to 13.09 (7.03-29.02) in homologous ChAdOx1 nCoV-19 and 145.5 (100-291.1) in homologous BNT162b2 vaccinees. All boosted vaccinees exceeded the threshold for neutralization, irrespective of their vaccination scheme. Vaccination was well-tolerated overall. We show that heterologous ChAdOx1 nCoV-19/BNT162b2 vaccination is safe and induces a strong and broad humoral response in healthy individuals.

Early Humoral Responses of Hemodialysis Patients after COVID-19 Vaccination with BNT162b2

BACKGROUND AND OBJECTIVES

Patients receiving hemodialysis are at high risk for both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe coronavirus disease 2019. A lifesaving vaccine is available, but sensitivity to vaccines is generally lower in patients on dialysis. Little is yet known about antibody responses after coronavirus disease 2019 (COVID-19) vaccination in this vulnerable group.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

In this prospective single-center study, we included 22 patients on dialysis and 46 healthy controls from Heidelberg University Hospital between December 2020 and February 2021. We measured anti-S1 IgG with a threshold index for detection greater than one, neutralizing antibodies with a threshold for viral neutralization of ≥30%, and antibodies against different SARS-CoV2 fragments 17-22 days after the first dose and 18-22 days after the second dose of the mRNA vaccine BNT162b2.

RESULTS

After the first vaccine dose, four of 22 (18%) patients on dialysis compared with 43 of 46 (93%) healthy controls developed positive anti-S1 IgG, with a median anti-S1 IgG index of 0.2 (interquartile range, 0.1-0.7) compared with nine (interquartile range, 4-16), respectively. SARS-CoV2 neutralizing antibodies exceeded the threshold for neutralization in four of 22 (18%) patients on dialysis compared with 43 of 46 (93%) healthy controls, with a median percent inhibition of 11 (interquartile range, 3-24) compared with 65 (interquartile range, 49-75), respectively. After the second dose, 14 of 17 (82%) patients on dialysis developed neutralizing antibodies exceeding the threshold for viral neutralization and antibodies against the receptor binding S1 domain of the spike protein, compared with 46 of 46 (100%) healthy controls, respectively. The median percent inhibition was 51 (interquartile range, 32-86) compared with 98 (interquartile range, 97-98) in healthy controls.

CONCLUSIONS

Patients receiving long-term hemodialysis show a reduced antibody response to the first and second doses of the mRNA vaccine BNT162b2. The majority (82%) develop neutralizing antibodies after the second dose but at lower levels than healthy controls.

QSM is an imaging biomarker for chronic glial activation in multiple sclerosis lesions

BACKGROUND

Inflammation in chronic active lesions occurs behind a closed blood-brain barrier and cannot be detected with MRI. Activated microglia are highly enriched for iron and can be visualized with quantitative susceptibility mapping (QSM), an MRI technique used to delineate iron.

OBJECTIVE

To characterize the histopathological correlates of different QSM hyperintensity patterns in MS lesions.

METHODS

MS brain slabs were imaged with MRI and QSM, and processed for histology. Immunolabeled cells were quantified in the lesion rim, center, and adjacent normal-appearing white matter (NAWM). Iron⁺ myeloid cell densities at the rims were correlated with susceptibilities. Human-induced pluripotent stem cell (iPSC)-derived microglia were used to determine the effect of iron on the production of reactive oxygen species (ROS) and pro-inflammatory cytokines.

RESULTS

QSM hyperintensity at the lesion perimeter correlated with activated iron⁺ myeloid cells in the rim and NAWM. Lesions with high punctate or homogenous QSM signal contained no or minimally activated iron^- myeloid cells. In vitro, iron accumulation was highest in M1-polarized human iPSC-derived microglia, but it did not enhance ROS or cytokine production.

CONCLUSION

A high QSM signal outlining the lesion rim but not punctate signal in the center is a biomarker for chronic inflammation in white matter lesions.

Differential expression of the T-cell inhibitor TIGIT in glioblastoma and MS

OBJECTIVE

To identify coinhibitory immune pathways important in the brain, we hypothesized that comparison of T cells in lesions from patients with MS with tumor-infiltrating T cells (TILs) from patients with glioblastoma multiforme may reveal novel targets for immunotherapy.

METHODS

We collected fresh surgical resections and matched blood from patients with glioblastoma, blood and unmatched postmortem CNS tissue from patients with MS, and blood from healthy donors. The expression of TIGIT, CD226, and their shared ligand CD155 as well as PD-1 and PDL1 was assessed by both immunohistochemistry and flow cytometry.

RESULTS

We found that TIGIT was highly expressed on glioblastoma-infiltrating T cells, but was near-absent from MS lesions. Conversely, lymphocytic expression of PD-1/PD-L1 was comparable between the 2 diseases. Moreover, TIGIT was significantly upregulated in circulating lymphocytes of patients with glioblastoma compared with healthy controls, suggesting recirculation of TILs. Expression of CD226 was also increased in glioblastoma, but this costimulatory receptor was expressed alongside TIGIT in the majority of tumor-infiltrating T cells, suggesting functional counteraction.

CONCLUSIONS

The opposite patterns of TIGIT expression in the CNS between MS and glioblastoma reflects the divergent features of the immune response in these 2 CNS diseases. These data raise the possibility that anti-TIGIT therapy may be beneficial for patients with glioblastoma.

The landscape of myeloid and astrocyte phenotypes in acute multiple sclerosis lesions

Activated myeloid cells and astrocytes are the predominant cell types in active multiple sclerosis (MS) lesions. Both cell types can adopt diverse functional states that play critical roles in lesion formation and resolution. In order to identify phenotypic subsets of myeloid cells and astrocytes, we profiled two active MS lesions with thirteen glial activation markers using imaging mass cytometry (IMC), a method for multiplexed labeling of histological sections. In the acutely demyelinating lesion, we found multiple distinct myeloid and astrocyte phenotypes that populated separate lesion zones. In the post-demyelinating lesion, phenotypes were less distinct and more uniformly distributed. In both lesions cell-to-cell interactions were not random, but occurred between specific glial subpopulations and lymphocytes. Finally, we demonstrated that myeloid, but not astrocyte phenotypes were activated along a lesion rim-to-center gradient, and that marker expression in glial cells at the lesion rim was driven more by cell-extrinsic factors than in cells at the center. This proof-of-concept study demonstrates that highly multiplexed tissue imaging, combined with the appropriate computational tools, is a powerful approach to study heterogeneity, spatial distribution and cellular interactions in the context of MS lesions. Identifying glial phenotypes and their interactions at different lesion stages may provide novel therapeutic targets for inhibiting acute demyelination and low-grade, chronic inflammation.

Enhanced astrocyte responses are driven by a genetic risk allele associated with multiple sclerosis

Epigenetic annotation studies of genetic risk variants for multiple sclerosis (MS) implicate dysfunctional lymphocytes in MS susceptibility; however, the role of central nervous system (CNS) cells remains unclear. We investigated the effect of the risk variant, rs7665090^G, located near NFKB1, on astrocytes. We demonstrated that chromatin is accessible at the risk locus, a prerequisite for its impact on astroglial function. The risk variant was associated with increased NF-κB signaling and target gene expression, driving lymphocyte recruitment, in cultured human astrocytes and astrocytes within MS lesions, and with increased lesional lymphocytic infiltrates and lesion sizes. Thus, our study establishes a link between genetic risk for MS (rs7665090^G) and dysfunctional astrocyte responses associated with increased CNS access for peripheral immune cells. MS may therefore result from variant-driven dysregulation of the peripheral immune system and of the CNS, where perturbed CNS cell function aids in establishing local autoimmune inflammation.

It is unclear if multiple sclerosis (MS) genetic susceptibility can be mediated through perturbations of CNS-intrinsic pathways. Authors show that the rs7665090 risk variant is associated with astrocyte responses that enhance lymphocyte recruitment, and with increased lymphocyte infiltration and lesion sizes in MS lesions.

The Role of Astrocytes in Multiple Sclerosis

The role traditionally assigned to astrocytes in the pathogenesis of multiple sclerosis (MS) lesions has been the formation of the glial scar once inflammation has subsided. Astrocytes are now recognized to be early and highly active players during lesion formation and key for providing peripheral immune cells access to the central nervous system. Here, we review the role of astrocytes in the formation and evolution of MS lesions, including the recently described functional polarization of astrocytes, discuss prototypical pathways for astrocyte activation, and summarize mechanisms by which MS treatments affect astrocyte function.

Myeloid cell plasticity in the evolution of central nervous system autoimmunity

OBJECTIVE

Myeloid cells, including macrophages and dendritic cells, are a prominent component of central nervous system (CNS) infiltrates during multiple sclerosis (MS) and the animal model experimental autoimmune encephalomyelitis (EAE). Although myeloid cells are generally thought to be proinflammatory, alternatively polarized subsets can serve noninflammatory and/or reparative functions. Here we investigate the heterogeneity and biological properties of myeloid cells during central nervous system autoimmunity.

METHODS

Myeloid cell phenotypes in chronic active MS lesions were analyzed by immunohistochemistry. In addition, immune cells were isolated from the CNS during exacerbations and remissions of EAE and characterized by flow cytometric, genetic, and functional assays.

RESULTS

Myeloid cells expressing inducible nitric oxide synthase (iNOS), indicative of a proinflammatory phenotype, were detected in the actively demyelinating rim of chronic active MS lesions, whereas macrophages expressing mannose receptor (CD206), a marker of alternatively polarized human myeloid cells, were enriched in the quiescent lesion core. During EAE, CNS-infiltrating myeloid cells, as well as microglia, shifted from expression of proinflammatory markers to expression of noninflammatory markers immediately prior to clinical remissions. Murine CNS myeloid cells expressing the alternative lineage marker arginase-1 (Arg1) were partially derived from iNOS⁺ precursors and were deficient in activating encephalitogenic T cells compared with their Arg1^- counterparts.

INTERPRETATION

These observations demonstrate the heterogeneity of CNS myeloid cells, their evolution during the course of autoimmune demyelinating disease, and their plasticity on the single cell level. Future therapeutic strategies for disease modification in individuals with MS may be focused on accelerating the transition of CNS myeloid cells from a proinflammatory to a noninflammatory phenotype. Ann Neurol 2018;83:131-141.

Myelin phagocytosis by astrocytes after myelin damage promotes lesion pathology

Astrocytes are key players in the pathology of multiple sclerosis and can assume beneficial and detrimental roles during lesion development. The triggers and timing of the different astroglial responses in acute lesions remain unclear. Astrocytes in acute multiple sclerosis lesions have been shown previously to contain myelin debris, although its significance has not been examined. We hypothesized that myelin phagocytosis by astrocytes is an early event during lesion formation and leads to astroglial immune responses. We examined multiple sclerosis lesions and other central nervous system pathologies with prominent myelin injury, namely, progressive multifocal leukoencephalopathy, metachromatic leukodystrophy and subacute infarct. In all conditions, we found that myelin debris was present in most astrocytes at sites of acute myelin breakdown, indicating that astroglial myelin phagocytosis is an early and prominent feature. Functionally, myelin debris was taken up by astrocytes through receptor-mediated endocytosis and resulted in astroglial NF-κB activation and secretion of chemokines. These in vitro results in rats were validated in human disease where myelin-positive hypertrophic astrocytes showed increased nuclear localization of NF-κB and elevated chemokine expression compared to myelin-negative, reactive astrocytes. Thus, our data suggest that myelin uptake is an early response of astrocytes in diseases with prominent myelin injury that results in recruitment of immune cells. This first line response of astrocytes to myelin injury may exert beneficial or detrimental effects on the lesion pathology, depending on the inflammatory context. Modulating this response might be of therapeutic relevance in multiple sclerosis and other demyelinating conditions.

Serum S100B Protein is Specifically Related to White Matter Changes in Schizophrenia

Background: Schizophrenia can be conceptualized as a form of dysconnectivity between brain regions.To investigate the neurobiological foundation of dysconnectivity, one approach is to analyze white matter structures, such as the pathology of fiber tracks. S100B is considered a marker protein for glial cells, in particular oligodendrocytes and astroglia, that passes the blood brain barrier and is detectable in peripheral blood. Earlier Studies have consistently reported increased S100B levels in schizophrenia. In this study, we aim to investigate associations between S100B and structural white matter abnormalities.

Methods: We analyzed data of 17 unmedicated schizophrenic patients (first and recurrent episode) and 22 controls. We used voxel based morphometry (VBM) to detect group differences of white matter structures as obtained from T1-weighted MR-images and considered S100B serum levels as a regressor in an age-corrected interaction analysis.

Results: S100B was increased in both patient subgroups. Using VBM, we found clusters indicating significant differences of the association between S100B concentration and white matter. Involved anatomical structures are the posterior cingulate bundle and temporal white matter structures assigned to the superior longitudinal fasciculus.

Conclusions: S100B-associated alterations of white matter are shown to be existent already at time of first manifestation of psychosis and are distinct from findings in recurrent episode patients. This suggests involvement of S100B in an ongoing and dynamic process associated with structural brain changes in schizophrenia. However, it remains elusive whether increased S100B serum concentrations in psychotic patients represent a protective response to a continuous pathogenic process or if elevated S100B levels are actively involved in promoting structural brain damage.

A highly conserved cytoplasmic cysteine residue in the α4 nicotinic acetylcholine receptor is palmitoylated and regulates protein expression

Nicotinic acetylcholine receptor (nAChR) cell surface expression levels are modulated during nicotine dependence and multiple disorders of the nervous system, but the mechanisms underlying nAChR trafficking remain unclear. To determine the role of cysteine residues, including their palmitoylation, on neuronal α4 nAChR subunit maturation and cell surface trafficking, the cysteines in the two intracellular regions of the receptor were replaced with serines using site-directed mutagenesis. Palmitoylation is a post-translational modification that regulates membrane receptor trafficking and function. Metabolic labeling with [(3)H]palmitate determined that the cysteine in the cytoplasmic loop between transmembrane domains 1 and 2 (M1-M2) is palmitoylated. When this cysteine is mutated to a serine, producing a depalmitoylated α4 nAChR, total protein expression decreases, but surface expression increases compared with wild-type α4 levels, as determined by Western blotting and enzyme-linked immunoassays, respectively. The cysteines in the M3-M4 cytoplasmic loop do not appear to be palmitoylated, but replacing all of the cysteines in the loop with serines increases total and cell surface expression. When all of the intracellular cysteines in both loops are mutated to serines, there is no change in total expression, but there is an increase in surface expression. Calcium accumulation assays and high affinity binding for [(3)H]epibatidine determined that all mutants retain functional activity. Thus, our results identify a novel palmitoylation site on cysteine 273 in the M1-M2 loop of the α4 nAChR and determine that cysteines in both intracellular loops are regulatory factors in total and cell surface protein expression of the α4β2 nAChR.

Risk variants in the S100B gene predict elevated S100B serum concentrations in healthy individuals

Several lines of evidence suggest an important role of the S100B protein and its coding gene in different neuropathological and psychiatric disorders like dementia, bipolar affective disorders and schizophrenia. To clarify whether a direct link exists between gene and gene product, that is, whether S100B variants directly modulate S100B serum concentration, 196 healthy individuals were assessed for S100B serum concentrations and genotyped for five potentially functional S100B SNPs. Functional variants of the serotonergic genes 5-HT1A and 5-HTT possibly modulating S100B serum levels were also studied. Further, publicly available human postmortem gene expression data were re-analyzed to elucidate the impact of S100B, 5-HT1A and 5-HTT SNPs on frontal cortex S100B mRNA expression. Several S100B SNPs, particularly rs9722, and the S100B haplotype T-G-G-A (including rs2186358-rs11542311-rs2300403-rs9722) were associated with elevated S100B serum concentrations (Bonferroni corrected P < 0.05). Of these, rs11542311 was also associated with S100B mRNA expression directly (Bonferroni corrected P = 0.05) and within haplotype G-A-T-C (rs11542311-rs2839356-rs9984765-rs881827; P = 0.004), again with the G-allele increasing S100B expression. Our results suggest an important role of S100B SNPs on S100B serum concentrations and S100B mRNA expression. It hereby links recent evidence for both, the impact of S100B gene variation on various neurological or psychiatric disorders like dementia, bipolar affective disorders and schizophrenia and the strong relation between S100B serum levels and these disorders.

Association between cytokines and cerebral MRI changes in the aging brain

The association between cytokines (IL-1 beta, sIL-4R, IL-6, IL-8, IL-10, IL-12, TNF-alpha) and subcortical white matter lesions, cortical atrophy and lacunar infarctions of the aging brain was investigated among 268 elderly community participants. Single pro- and anti-inflammatory cytokines were neither associated with WML nor with atrophy and lacunar infarction. An association between atrophy and the chemokine-cytokine factor (containing sIL-4R, IL-6, IL-8) remained significant after adjustment for age, gender, education, depressive symptoms, diabetes mellitus, cardiovascular diseases (stroke, TIA, myocardial infarction, myocardial insufficiency, arrhythmic heart), hypertension, body-mass index, smoking status and aggregation inhibitors as opposed to single cytokines. Atrophy of the parietal, temporal and occipital lobes was associated with the same cytokine-chemokine factor for both the whole sample or restricted to those without history of stroke/TIA. The results indicate that a combination of chemokine-cytokines rather than single cytokines may contribute to inflammatory processes associated with cortical atrophy in the aging brain.

Memory impairment correlates with increased S100B serum concentrations in patients with chronic schizophrenia

Astrocyte activation indicated by increased S100B is considered a potential pathogenic factor for schizophrenia. To investigate the relationship between astrocyte activation and cognitive performance, S100B serum concentration, memory performance, and psychopathology were assessed in 40 first-episode and 35 chronic schizophrenia patients upon admission and after four weeks of treatment. Chronic schizophrenia patients with high S100B were impaired concerning verbal memory performance (AVLT, Auditory Verbal Learning Test) compared to chronic and first-episode patients with low S100B levels. The findings support the hypothesis that astrocyte activation might contribute to the development of cognitive dysfunction in schizophrenia.

Association between IL-8 cytokine and cognitive performance in an elderly general population—The MEMO-Study

OBJECTIVES

To investigate the associations between circulating cytokines and specific neuropsychological domains of cognitive functioning (memory, processing speed and motor function) and general cognitive function (MMSE) in healthy elderly individuals.

METHODS

In a cross-sectional study of 369 community dwelling elderly subjects, we examined the relationship between serum IL-1beta, sIL-4R, IL-6, IL-8, IL-10, IL-12 and TNF-alpha concentrations and cognitive performance using an extensive standardized and validated cognitive test battery assessing memory, word fluency, perceptual/cognitive speed, attention and executive functioning, and motor speed.

RESULTS

Multivariate analysis adjusted for various confounders and Bonferroni correction for multiple comparisons demonstrated that increased serum concentrations of IL-8 were associated with poor performance in the memory and speed domains and in motor function. No significant associations were found between the remaining cytokines and domains of cognitive functioning. Global cognitive functioning, as measured with MMSE, was not associated with any cytokine.

CONCLUSIONS

This study suggests an association between circulating IL-8 concentrations and cognitive dysfunction in the elderly. An interaction between this cytokine and glial cells may help explain the pathophysiological mechanisms leading to cognitive impairment in our study group.

Association between genetic variants of IL-1beta, IL-6 and TNF-alpha cytokines and cognitive performance in the elderly general population of the MEMO-study

This study is to investigate the associations between specific polymorphisms in three cytokine genes and domains of cognitive functioning in a population based study in the elderly. In a cross-sectional study of 369 community dwelling elderly subjects we examined the relationships between the polymorphisms IL-1beta-1418C-->T, IL-6-572G-->C and TNF-alpha-308G-->A and the cognitive function domains memory, processing speed and motor function using an extensive neuropsychological test battery. Linear regression models were used in the analysis and results adjusted for multiple comparisons. A significant association between the IL-1beta-1418C-->T polymorphism and memory performance was found with carriers of the T allele (dominant model) having worse memory performance than those with the C allele. In addition, a significant association between the TNF-alpha-308G-->A polymorphism and processing speed was observed, indicating better performance for heterozygous or homozygous carriers of the A allele. These results remained significant after adjustment for known confounders of cognitive function and additional Bonferroni correction for multiple comparisons. Our study provides first results on detrimental effects of the IL-1beta-1418C-->T polymorphism on memory performance and neuroprotective effects of the TNF-alpha-308G-->A polymorphism on processing speed in elderly individuals. Further research is needed to prospectively examine changes in cognitive performance in relation to cytokine genotypes.

Glial cell activation in a subgroup of patients with schizophrenia indicated by increased S100B serum concentrations and elevated myo-inositol

Post-mortem and in-vivo studies support the hypothesis that astrocytes might be involved in the pathogenesis of schizophrenia. To further substantiate this hypothesis two markers of astroglial activation (myo-inositol, S100B) acquired with independent methods ((1)H-MRS, quantitative immunoassay) were concomitantly measured in schizophrenic patients. Patients with increased S100B levels showed elevated myo-inositol concentrations. This pilot study demonstrates a concomitant elevation of two markers indicating astrocyte activation in a subgroup of schizophrenic patients.

Autocrine S100B effects on astrocytes are mediated via RAGE

To find out if the astrocytic protein S100B involves its autocrine effects via RAGE we investigated the capacity of astrocytes to upregulate IL-6 and TNF-alpha expression by stimulation with S100B. The subcellular localization of RAGE expression at the cell surface membrane of cultured astrocytes was demonstrated by immunofluorescence microscopy, flow cytometry and Western blotting. S100B was able to stimulate IL-6 and TNF-alpha secretion in cultured astrocytes in a concentration- and time-dependent manner as shown by ELISA. S100B induced IL-6 and TNF-alpha secretion was blocked by the use of RAGE siRNA specific for knocking down RAGE expression.

Different activation patterns of proinflammatory cytokines in melancholic and non-melancholic major depression are associated with HPA axis activity

BACKGROUND

Recent studies showed an activation of the cytokine system and the HPA axis in major depression, although with inconsistent results. While the non-melancholic subtype displayed a proinflammatory cytokine pattern, the melancholic subtype showed signs of impaired cytokine production. In order to understand the potential pathogenic significance of these systems further, the interplay between the cytokine system and the HPA axis in depressive subtypes as well as potential changes of these systems during the course of disease were investigated.

METHODS

N=37 initially unmedicated patients with acute major depression were sub-classified (melancholic vs. non-melancholic) and compared with N=37 matched healthy controls. Upon admission and after complete clinical remission, basal plasma ACTH and serum cortisol levels as well as cytokine productions (IL-1beta, IL-1 receptor antagonist (IL-1RA)) upon mitogen stimulation (PHA) were measured in a whole blood assay.

RESULTS

ACTH and cortisol concentrations were significantly elevated on admission in the melancholic but not the non-melancholic subgroup. Non-melancholic patients produced significantly more IL-1beta and IL-1RA upon admission than controls or melancholic patients. The IL-1 RA/IL-1beta ratio was significantly lower in the non-melancholic compared to the melancholic subgroup and increased significantly upon remission.

LIMITATIONS

Patient treatment was not standardized. No Dex/CRH test was performed.

CONCLUSIONS

Melancholic patients demonstrated an activation of the HPA axis in acute stage with partial normalization upon remission but no signs of inflammation. Non-melancholic patients showed signs of inflammation in acute depression with normalization upon remission while the function of the HPA axis was normal.

The astroglial protein S100B and visually evoked event-related potentials before and after antidepressant treatment

RATIONALE

S100B is an astrocytic, calcium-binding protein which in nanomolar concentrations has neuroprotective and regenerating effects on neurons and glial cells. Increased levels have been shown to be positively correlated with therapeutic response in major depression. Event-related potentials (ERP) have been reported to be impaired in depressed patients.

OBJECTIVES

The aim of our study was to assess the relationship between S100B and visually evoked ERP in depression.

METHODS

ERP and S100B serum concentration were studied in 18 patients with major depression, before and after 4 weeks of antidepressant treatment.

RESULTS

The S100B concentration in patients was increased at intake and after 4 weeks of treatment compared to healthy controls. Initially increased P3-latency normalized and P2-latency significantly decreased after 4 weeks of treatment, although only in patients with clearly elevated initial S100B levels (mean plus 2 SD of the healthy controls).

CONCLUSION

The neuroregenerative activity of moderately increased S100B levels in major depression might be a factor contributing to a decrease of prolonged ERP parameters in major depression during antidepressant treatment.

S100B serum levels and long-term improvement of negative symptoms in patients with schizophrenia

S100B, a calcium-binding protein produced by astroglial cells, mediates paracrine and autocrine effects on neurons and glial cells. It regulates the balance between proliferation and differentiation in neurons and glial cells by affecting protective and apoptotic mechanisms. Post-mortem studies have demonstrated a deficit in synapses and dendrites in brains of schizophrenics. Recent studies have shown increased S100B levels in medicated acutely psychotic schizophrenic patients as well as unmedicated or drug naive schizophrenics. One study reported a positive correlation between negative symptoms and S100B. S100B serum levels (quantitative immunoassay) and psychopathology (Positive and Negative Syndrome Scale, PANSS) were examined upon study admission and after 12 and 24 weeks of standardized treatment in 98 chronic schizophrenic patients with primarily negative symptoms. Compared to age- and sex-matched healthy controls, the schizophrenic patients showed significantly increased S100B concentrations upon admission and after 12 and 24 weeks of treatment. High PANSS negative scores were correlated with high S100B levels. Regression analysis comparing psychopathology subscales and S100B identified negative symptomatology as the predicting factor for S100B. S100B is not just elevated during acute stages of disease since it remains elevated for at least 6 months following an acute exacerbation. With regard to psychopathology, negative symptomatology appears to be the predicting factor for the absolute S100B concentration. This might indicate that S100B in schizophrenic patients either promotes apoptotic mechanisms by itself or is released from astrocytes as part of an attempt to repair a degenerative or destructive process.

S100B in Schizophrenic Psychosis

Recent findings have strengthened the hypothesis that a dysfunction of neuronal synapses and dendrites is relevant for the pathogenesis of schizophrenia. It might be present during neurodevelopment as well as in degenerative and regenerative processes of the mature brain. S1OOB, a small, Ca2+-binding, astrocytic protein, plays an important role in modulating the proliferation and differentiation of neurons and glia cells. It is involved in the regulation of cellular energy metabolism and interacts with many immunological functions of the brain. This review addresses findings from cell cultural and animal experiments potentially pertinent for the pathogenesis of schizophrenic psychoses. Morphological and functional data are analyzed and clinical studies reporting alterations of S1OOB concentrations in schizophrenic patients are reviewed. Evidence and limitations of the available studies are pointed out and promising future research strategies are outlined.