Przemysław Lewkowicz

Neutrophil--CD4+CD25+ T regulatory cell interactions: a possible new mechanism of infectious tolerance.

This study tested the hypothesis that CD4(+)CD25(+)CD127(low) regulatory T (Treg) cells might induce immunosuppressive properties in apoptotic neutrophils. Treg cells are recognized as a major subset of immune cells possessing potent suppressive properties directed at T effector cells. However, Treg cells have recently been found to inhibit neutrophil function and promote their apoptosis. One of the mechanisms of action of Treg cells is the induction of other suppressor cell populations according to an infectious tolerance model. We showed that LPS-activated Treg cells promote generation of IL-10 and TGF-β1, inhibit IL-6 production by PMNs and induce the expression of heme oxygenase-1 (HO-1) and the suppressor of cytokine signaling 3 molecule (SOCS3). However, CD3/CD28-activated Treg cells were seen to promote TGF-β1 production, as well as IDO and HO-1 expression by PMNs. These findings suggest that Treg cells might play an important role in the direct control of innate immune responses through the induction of neutrophils with immunosuppressive properties that generate IL-10, TGF-β1, IDO and HO-1.

Expression of Th1/Th2/Th3/Th17-Related Genes in Recurrent Aphthous Ulcers

The pathogenesis of recurrent aphthous ulceration (RAU) is unknown, although an abnormal immune reaction appears to be involved. RAU may result from oral epithelium damage caused by T cell-mediated immune response. To improve understanding of the role of T cells in RAU, the present study analyzed. the expression of T cell-related genes in oral ulcers from patients with RAU, as well as in healthy non-keratinized oral mucosa from aphthae-free volunteers. Biopsies from RAU patients and healthy individuals were analyzed using Human Th1-Th2-Th3 RT2 Profiler PCR Array and qRT-PCR that allowed to quantify the transcript levels of 86 genes related to T cell activation. We found that cells present in aphthous ulcers express a characteristic Th1-like gene profile. The majority of genes up-regulated in aphthous lesions such as IFN-γ, TNF, IL-15, IRF1, STAT-1 and STAT-4 were Th1-associated. Th2-realated genes were not overexpressed in RAU tissues, with the exception for CCR3. Th3- and Th17-related gene expression patterns were not demonstrated in RAU. These findings clearly reveal that aphthous ulcer formation is predominantly dependent on the activation of the Th1-type immune response.

Dysregulated RNA-Induced Silencing Complex (RISC) Assembly within CNS Corresponds with Abnormal miRNA Expression during Autoimmune Demyelination

MicroRNAs (miRNAs) associate with Argonaute (Ago), GW182, and FXR1 proteins to form RNA-induced silencing complexes (RISCs). RISCs represent a critical checkpoint in the regulation and bioavailability of miRNAs. Recent studies have revealed dysregulation of miRNAs in multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE); however, the function of RISCs in EAE and MS is largely unknown. Here, we examined the expression of Ago, GW182, and FXR1 in CNS tissue, oligodendrocytes (OLs), brain-infiltrating T lymphocytes, and CD3+splenocytes (SCs) of EAE mic, and found that global RISC protein levels were significantly dysregulated. Specifically, Ago2 and FXR1 levels were decreased in OLs and brain-infiltrating T cells in EAE mice. Accordingly, assembly of Ago2/GW182/FXR1 complexes in EAE brain tissues was disrupted, as confirmed by immunoprecipitation experiments. In parallel with alterations in RISC complex content in OLs, we found downregulation of miRNAs essential for differentiation and survival of OLs and myelin synthesis. In brain-infiltrating T lymphocytes, aberrant RISC formation contributed to miRNA-dependent proinflammatory helper T-cell polarization. In CD3+ SCs, we found increased expression of both Ago2 and FXR1 in EAE compared with nonimmunized mice. Therefore, our results demonstrate a gradient in expression of miRNA between primary activated T cells in the periphery and polarized CNS-infiltrating T cells. These results suggest that, in polarized autoreactive effector T cells, miRNA synthesis is inhibited in response to dysregulated RISC assembly, allowing these cells to maintain a highly specific proinflammatory program. Therefore, our findings may provide a mechanism that leads to miRNA dysregulation in EAE/MS.

Heat shock protein 70 (Hsp70) interacts with the Notch1 intracellular domain and contributes to the activity of Notch signaling in myelin-reactive CD4 T cells.

Notch receptors (Notch1-4) are involved in the differentiation of CD4 T cells and the development of autoimmunity. Mechanisms regulating Notch signaling in CD4 T cells are not fully elucidated. In this study we investigated potential crosstalk between Notch pathway molecules and heat shock protein 70 (Hsp70), the major intracellular chaperone involved in the protein transport during immune responses and other stress conditions. Using Hsp70(-/-) mice we found that Hsp70 is critical for up-regulation of NICD1 and induction of Notch target genes in Jagged1- and Delta-like1-stimulated CD4 T cells. Co-immunoprecipitation analysis of wild-type CD4 T cells stimulated with either Jagged1 or Delta-like1 showed a direct interaction between NICD1 and Hsp70. Both molecules co-localized within the nucleus of CD4 T cells stimulated with Notch ligands. Molecular interaction and nuclear colocalization of NICD1 and Hsp70 were also detected in CD4 T cells reactive against myelin oligodendrocyte glycoprotein (MOG)35-55, which showed Hsp70-dependent up-regulation of both NICD1 and Notch target genes. In conclusion, we demonstrate for the first time that Hsp70 interacts with NICD1 and contributes to the activity of Notch signaling in CD4 T cells. Interaction between Hsp70 and NICD1 may represent a novel mechanism regulating Notch signaling in activated CD4 T cells.

Plasmocytoid dendritic cell deficit of early response to toll-like receptor 7 agonist stimulation in multiple sclerosis patients

Plasmacytoid dendritic cells (pDCs), an important immunoregulatory population, are characterized by vigorous secretion of type I interferons (IFNs) in response to toll-like receptor (TLR) 7 and 9 stimulation. We studied the function of pDCs in multiple sclerosis (MS) patients by analysis of TLR7 responses. We assessed a pDC secretion pattern of cytokines in the short term PBMC cultures stimulated with TLR7 agonist. pDCs sorted from PBMCs of both MS patients and controls were used to assess TLR7 expression profile. TLR7 induced signaling in pDCs has been analyzed with intracellular flow cytometry. We have identified a clinically correlated significant decrease of the TLR7-induced IFN-alfa (IFNa) secretion by pDCs from MS patients. This deficit has been accompanied by insufficient intracellular phosphorylation of protein kinase Akt and a decrease of the TLR7 gene expression in MS pDCs. Our results demonstrated a selective pDC deficit in MS supporting a relationship between pDCs and mechanisms of MS.

Sub-optimal primary surgery leads to unfavorable immunological changes in ovarian cancer patients

Primary cytoreduction, followed by chemotherapy, is a standard treatment of patients with epithelial ovarian cancer (EOC). However, the effectiveness of this treatment depend on various elements e.g. type of operation. It is accepted that optimal surgery correlates with longer survival of patients. The other element, an efficiency of immune system after surgical intervention although important is less elucidated. The aim of this study was to establish the impact of optimal and sub-optimal operation on immunological status of EOC patients regarding also their overall survival (OS). On the day of primary cytoreduction and 7days after, the selected serum immunological parameters were determined in 49 patients with confirmed EOC. We found that, the level of immunosuppressive (interleukin 10; transforming growth factor-β - TGF-β1) and pro-inflammatory (interleukin-6 and 8) cytokines was significantly higher in the group of patients with advanced stage of disease, compared to early stage. However, the number of circulating CD3+, CD4+ or CD8+ cells, CD19+ and NK cells was similar in both group of EOC patients. The overall survival of patients who underwent optimal cytoreduction was significantly higher than that in whom only sub-optimal surgery was performed. Sub-optimal cytoreduction only partially weakened the serum level of TGF-β1 and IL-8 and what is more enhanced the number of circulating CD4+CD25+high cells in patients with advanced stage of disease. Sub-optimal surgery and high post-operative level of TGF-β1 increased the hazard ratio for patients. Besides, we noticed that the high pre-operative concentration of TGF-β1 could distinguish all EOC patients (independently of FIGO classification) for whom optimal or sub-optimal surgery would be applied. Sub-optimal debulking resulted in higher immunosuppression and lower OS of EOC patients.

C5a-Preactivated Neutrophils Are Critical for Autoimmune-Induced Astrocyte Dysregulation in Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune neuroinflammatory disease. In contrast to multiple sclerosis, autoantibodies against aquaporin-4 (AQP4) expressed on astrocytic end-feet have been exclusively detected in sera of NMOSD patients. Several lines of evidence suggested that anti-AQP4 autoantibodies are pathogenic, but the mechanism triggering inflammation, impairment of astrocyte function, and the role of neutrophils presented in NMOSD cerebrospinal fluid remains unknown. In this study, we tested how human neutrophils affect astrocytes in the presence of anti-AQP4 Ab-positive serum derived from NMOSD patients. An in vitro model of inflammation consisted of human astrocyte line, NMOSD serum, and allogenic peripheral blood neutrophils from healthy individuals. We showed evidence of pathogenicity of NMOSD serum, which by consecutive action of anti-AQP4 Abs, complement system, and neutrophils affected astrocyte function. Anti-AQP4 Ab binding astrocytes initiated two parallel complementary reactions. The first one was dependent on the complement cytotoxicity via C5b-9 complex formation, and the second one on the reverse of astrocyte glutamate pump into extracellular space by C5a-preactivated neutrophils. As a consequence, astrocytes were partially destroyed; however, a major population of astrocytes polarized into proinflammatory cells which were characterized by pathological glutamate removal from extracellular space.