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During human pregnancy, regulatory T cell (T reg ) function is enhanced and immune activation is repressed allowing the growth and development of the feto-placental unit. Here, we have investigated whether human labour is associated with a reversal of the pregnancy-induced changes in the maternal immune system. We tested the hypothesis that human labour is associated with a decline in T reg function, specifically their ability to modulate Toll-like receptor (TLR)-induced immune responses. We studied the changes in cell number, activation status and functional behaviour of peripheral blood, myometrial (myoMC) and cord blood mononuclear cells (CBMC) with the onset of labour. We found that T reg function declines and that T reg cellular targets change with labour onset. The changes in T reg function were associated with increased activation of myoMC, assessed by their expression of major histocompatibility complex (MHC) class II molecules and CBMC inflammatory cells. The innate immune system showed increased activation, as shown by altered monocyte and neutrophil cell phenotypes, possibly to be ready to respond to microbial invasion after birth or to contribute to tissue remodelling. Our results highlight changes in the function of the adaptive and innate immune systems that may have important roles in the onset of human labour., (© 2019 British Society for Immunology.)

Systemic sclerosis (SSc) is an idiopathic systemic autoimmune disease. It is characterized by a triad of hallmarks: immune dysfunction, fibrosis and vasculopathy. Immune dysfunction in SSc is characterized by the activation and recruitment of immune cells and the production of autoantibodies and cytokines. How immune abnormalities link the fibrosis and vasculopathy in SSc is poorly understood. A plethora of immune cell types are implicated in the immunopathogenesis of SSc, including T cells, B cells, dendritic cells, mast cells and macrophages. How these different cell types interact to contribute to SSc is complicated, and can involve cell-to-cell interactions and communication via cytokines, including transforming growth factor (TGF)-β, interleukin (IL)-6 and IL-4. We will attempt to review significant and recent research demonstrating the importance of immune cell regulation in the immunopathogenesis of SSc with a particular focus on fibrosis., (© 2018 British Society for Immunology.)

Sjögren's syndrome (SS) is a common autoimmune disease targeting salivary and lacrimal glands. It is strongly female-dominant, characterized by low oestrogen levels combined with a local intracrine dihydrotestosterone defect. We hypothesized that these hormonal deficits lead to increased apoptosis of the epithelial cells and plasmacytoid dendritic cell (pDC)-mediated proinflammatory host responses. Expression of Toll-like receptors (TLRs)-7 and -9 and cytokine profiles was studied in pDCs treated with apoptotic particles collected in consecutive centrifugation steps of media from apoptotic cells. Expression and localization of SS autoantigens in these particles was also analysed. Furthermore, the effects of sex steroids were studied in pDCs cultured with several concentrations of dihydrotestosterone and 17-β-oestradiol, and in saliva of patient treated with dehydroepiandrosterone. Apoptosis of the epithelial cells led to cleavage and translocation of SS-autoantigens, α-fodrin and SS-A, into apoptotic particles. The apoptosis-induced apoptotic particles also contained another SS-autoantigen, hy1-RNA. These particles were internalized by pDCs in a size-dependent manner and affected TLR-7 and -9 expression and the production of proinflammatory cytokines. The analysed androgens protected cells from apoptosis, influenced redistribution of autoantigens and diminished the apoptotic particle-stimulated increase of the TLRs in pDCs. Our findings suggest that the formation of apoptotic particles may play a role in loss of immune tolerance, manifested by production of autoantibodies and the onset of autoinflammation in SS., (© 2017 British Society for Immunology.)

Toll-like receptor (TLR) genetic polymorphisms may modify their expression causing inflammatory disorders and influencing both susceptibility and severity of lupus erythematosus. We aim to determine whether TLR-5 and TLR-9 gene polymorphisms are implicated in the susceptibility to systemic lupus erythematosus (SLE) and lupus nephritis (LN) and to evaluate their expressions and distributions in renal LN patients' biopsies. The frequencies of two SNP in the TLR-9 gene and one in the TLR-5 gene was examined in 106 SLE patients (among them 37 LN patients) and in 200 matched controls by polymerase chain reaction-restriction fragment-length polymorphisms (PCR-RFLP) analysis. TLR-9 and TLR-5 expressions were assessed by reverse transcription (RT)-PCR and immunohistochemistry carried on LN renal biopsies compared to healthy renal tissue. A significant genotypic and allelic association was revealed between TLR-9-rs352140 and both SLE and LN (P < 0·05). The TLR-9 transcript level was significantly higher in LN biopsies compared to control (P < 0·05). This increase was observed histochemically in the tubulointerstitial compartment. TLR-9 was detectable in LN glomeruli patients but not in normal control glomeruli. No allelic nor genotype association was found with TLR-5-rs5744168 in SLE. but the T allele and the TT genotype were raised significantly in the LN group (P < 0·05). A significant increase in TLR-5 gene expression in LN biopsies, which contrasted with normal kidneys (P < 0·05), was confirmed by an intense and diffuse staining for TLR-5 only in LN tubules (P < 0·05). Our data show that TLR-5 and TLR-9 are susceptible genes to LN and that their expression is dysregulated in LN patients' kidneys, supporting a role of these mediators in the pathogenesis of LN., (© 2017 British Society for Immunology.)

Toll-like receptors (TLRs) are germline-encoded, non-clonal innate immune receptors, which are often the first receptors to recognize the molecular patterns on pathogens. Therefore, the immune response initiated by TLRs has far-reaching consequences on the outcome of an infection. As soon as the cell surface TLRs and other receptors recognize a pathogen, the pathogen is phagocytosed. Inclusion of TLRs in the phagosome results in quicker phagosomal maturation and stronger adaptive immune response, as TLRs influence co-stimulatory molecule expression and determinant selection by major histocompatibility complex (MHC) class II and MHC class I for cross-presentation. The signals delivered by the TCR-peptide-MHC complex and co-stimulatory molecules are indispensable for optimal T cell activation. In addition, the cytokines induced by TLRs can skew the differentiation of activated T cells to different effector T cell subsets. However, the potential of TLRs to influence adaptive immune response into different patterns is severely restricted by multiple factors: gross specificity for the molecular patterns, lack of receptor rearrangements, sharing of limited number of adaptors that assemble signalling complexes and redundancy in ligand recognition. These features of apparent redundancy and regulation in the functioning of TLRs characterize them as important and probable contributory factors in the resistance or susceptibility to an infection., (© 2017 British Society for Immunology.)

The assessment of Toll-like receptor (TLR) agonists as candidate adjuvants for induction of effective T helper type 1 (Th1) immunity continues to rely on the use of mice. However, the genetic variation among inbred mice may influence the efficacy of adjuvants and bias a study's conclusions. Here, we evaluated the differences in cellular and humoral responses of genetically non-identical mouse strains immunized with ovalbumin (OVA) plus alum, TLR-3, TLR-4, TLR-7/8 or TLR-9 agonists. We found that all the tested TLR agonists recruited dendritic cells (DCs) and natural killer (NK) cells significantly into the lymph nodes, promoted DC-NK cross-talk and enhanced the cellular responses in B6 strain. In contrast, TLR-3 and TLR-7/8 were the only two agonists that showed the cellular adjuvanticity in the BALB/c strain. Compared with other TLR agonists, TLR-3 and TLR-7/8 were demonstrated to be the most effective adjuvants to generate interferon (IFN)-γ-producing effector NK, CD4, and CD8 T cells in B6 and BALB/c strains, respectively. We also found that compared with alum, all adjuvants induced the recruitment of B cells and production of OVA-specific immunoglobulin (Ig)G2a more effectively in both strains. In addition, the B6 strain recruited more B cells, but surprisingly produced significantly lower amounts of OVA-specific IgG2a in response to all adjuvants. However, consistent with the frequency of IFN-γ-producing effector cells observed in individual strains following immunizations, we detected more OVA-specific IgG2a in serum of B6 and BALB/c strains in response to TLR-3 and TLR-7/8, respectively. Our data suggest that genetic background should be taken into consideration when evaluating the activities of TLR agonists for the development of prophylactic and therapeutic vaccines., (© 2016 British Society for Immunology.)

Macaques provide important animal models in biomedical research into infectious and chronic inflammatory disease. Therefore, a proper understanding of the similarities and differences in immune function between macaques and humans is needed for adequate interpretation of the data and translation to the human situation. Dendritic cells are important as key regulators of innate and adaptive immune responses. Using a new whole blood assay we investigated functional characteristics of blood plasmacytoid dendritic cells (pDC), myeloid dendritic cells (mDC) and monocytes in rhesus macaques by studying induction of activation markers and cytokine expression upon Toll-like receptor (TLR) stimulation. In a head-to-head comparison we observed that rhesus macaque venous blood contained relatively lower numbers of pDC than human venous blood, while mDC and monocytes were present at similar percentages. In contrast to humans, pDC in rhesus macaques expressed the interleukin (IL)-12p40 subunit in response to TLR-7/8 as well as TLR-9 stimulation. Expression of IL-12p40 was confirmed by using different monoclonal antibodies and by reverse transcription-polymerase chain reaction (RT-PCR). Both in humans and rhesus macaques, TLR-4 stimulation induced IL-12p40 expression in mDC and monocytes, but not in pDC. The data show that, in contrast to humans, pDC in macaques are able to express IL-12p40, which could have consequences for evaluation of human vaccine candidates and viral infection., (© 2013 British Society for Immunology.)