Biomaterial contact triggers dendritic cell (DC) maturation, to an extent depending on the biomaterial, ultimately enhancing an immune response toward associated antigens, implying a role for biomaterials as adjuvants. Self-assembled monolayers (SAM) of alkanethiols on titanium/gold-coated surfaces presenting different chemistries were used to study effects of biomaterial surface chemistry on DC maturation. Although DCs treated with OH, COOH, or NH(2) SAMs showed modest maturation, those treated with CH(3) SAMs were least mature, all based on cytospins, allostimulatory capacity, or maturation marker expression. Surprisingly, DCs treated with CH(3) SAMs secreted highest levels of proinflammatory tumor necrosis factor-alpha (TNF-alpha) or interleukin-6 (IL-6) but were least mature. Secretion of anti-inflammatory mediators by DCs treated with CH(3) SAMs was not responsible for mitigating DC maturation under these conditions. Interestingly, elevated levels of apoptotic markers were measured associated with DCs and T cells upon CH(3) SAMs contact. Since phagocytosis of apoptotic DCs has strong immunosuppressive effects on DCs, more apoptotic DCs on CH(3) SAMs may account for lower DC maturation. Finally, higher expression of cytotoxic T lymphocyte associated antigen receptor-4 (CTLA-4) on T cells may imply a mechanism of T cell inhibition on CH(3) SAMs.

The Regulators of G protein signaling (RGS) protein superfamily negatively controls G-protein-coupled receptor (GPCR) signal transduction pathways. RGS16 is enriched in activated/effector T lymphocytes. Here, we show that RGS16 constrains pulmonary inflammation by regulating chemokine-induced T-cell trafficking in response to challenge with Schistosoma mansoni. Naïve Rgs16–/– mice were “primed” for inflammation by accumulation of CCR10+ T cells in the lung. Upon pathogen exposure, these mice developed more robust granulomatous lung fibrosis than wild-type (WT) counterparts. Distinct TH2 or putative TH17 subsets expressing CCR4 or CCR10 accumulated more rapidly in Rgs16–/– lungs following challenge and produced pro-inflammatory cytokines IL-13 and IL-17B. CCR4+ Rgs16–/– TH2 cells migrated excessively to CCL17 and localized aberrantly in challenged lungs. T lymphocytes were partially excluded from lung granulomas in Rgs16–/– mice, instead forming peribronchial/perivascular aggregates. Thus, RGS16-mediated confinement of T cells to Schistosome granulomas mitigates widespread cytokine-mediated pulmonary inflammation.

CTLA-4 is an inhibitory protein that contributes to immune homeostasis and tolerance, a role that has led to its exploitation as a therapeutic in several clinical settings including cancer and autoimmune disease. Development of CTLA-4 therapies focused largely on the full-length receptor isoform but other CTLA-4 isoforms are also expressed, including a secretable form of CTLA-4 (soluble CTLA-4 [sCTLA-4]). The contribution of sCTLA-4 to immune regulation has been less well studied, primarily because it was identified some years after the original description of CTLA-4. Here, we examine how sCTLA-4 might contribute to immune regulation and ask whether it might be a biomarker to inform current CTLA-4 therapies or represent a novel CTLA-4 target for future therapeutics.

Activated T cells are known to promote fibrosis, a major complication limiting the range of polymeric hydrogels as artificial corneal implants. As T cells are activated by dendritic cells (DC), minimally activating hydrogels would be optimal. In this study, we evaluated the ability of a series of engineered (manufactured/fabricated) and natural collagen matrices to either activate DC or conversely induce DC apoptosis in vitro. Bone marrow DC were cultured on a series of singly and doubly crosslinked hydrogels (made from recombinant human collagen III [RHCIII] or collagen mimetic peptide [CMP]) or on natural collagen‐containing matrices, MatrigelTM and de‐cellularised mouse corneal stroma. DC surface expression of major histocompatibility complex Class II and CD86 as well as apoptosis markers were examined. Natural matrices induced low levels of DC activation and maintained a “tolerogenic” phenotype. The same applied to singly crosslinked CMP‐PEG gels. RHCIII gels singly crosslinked using either N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide with the coinitiator N‐hydroxy succinimide (EDC‐NHS) or N‐cyclohexyl‐N‐(2‐morpholinoethyl)carbodiimide metho‐p‐toulenesulfonate with NHS (CMC‐NHS) induced varying levels of DC activation. In contrast, however, RHCIII hydrogels incorporating an additional polymeric network of 2‐methacryloyloxyethyl phosphorylcholine did not activate DC but instead induced DC apoptosis, a phenomenon observed in natural matrices. This correlated with increased DC expression of leukocyte‐associated immunoglobulin‐like receptor‐1. Despite low immunogenic potential, viable tolerogenic DC migrated into and through both natural and manufactured RHCIII gels. These data show that the immunogenic potential of RHCIII gels varies with the nature and composition of the gel. Preclinical evaluation of hydrogel immunogenic/fibrogenic potential is recommended.