IFNAR signaling in fibroblastic reticular cells can modulate CD8+ memory fate decision.

CD8+ memory T cells (TM ) are crucial for long-term protection from infections and cancer. Multiple cell types and cytokines are involved in the regulation of CD8+ T cell responses and subsequent TM formation. Besides their direct antiviral effects, type I interferons (IFN-I) modulate CD8+ T cell immunity via their action on several immune cell subsets. However, it is largely unclear how nonimmune cells are involved in this multicellular network modulating CD8+ TM formation. Fibroblastic reticular cells (FRCs) form the 3D scaffold of secondary lymphoid organs, express the IFN-I receptor (IFNAR), and modulate adaptive immune responses. However, it is unclear whether and how early IFNAR signals in lymph node (LN) FRCs affect CD8+ TM differentiation. Using peptide vaccination and viral infection, we studied CD8+ TM differentiation in mice with an FRC-specific IFNAR deletion (FRCΔIFNAR ). We show here that the differentiation of CD8+ TCR-transgenic T cells into central memory cells (TCM ) is enhanced in peptide-vaccinated FRCΔIFNAR mice. Conversely, vesicular stomatitis virus infection of FRCΔIFNAR mice is associated with impaired TCM formation and the accumulation of vesicular stomatitis virus specific double-positive CD127hi KLRG-1hi effector memory T cells. In summary, we provide evidence for a context-dependent contribution of FRC-specific IFNAR signaling to CD8+ TM differentiation.

IL-7 derived from lymph node fibroblastic reticular cells is dispensable for naive T cell homeostasis but crucial for central memory T cell survival.

The survival of peripheral T cells is dependent on their access to peripheral LNs (pLNs) and stimulation by IL-7. In pLNs fibroblastic reticular cells (FRCs) and lymphatic endothelial cells (LECs) produce IL-7 suggesting their contribution to the IL-7-dependent survival of T cells. However, IL-7 production is detectable in multiple organs and is not restricted to pLNs. This raises the question whether pLN-derived IL-7 is required for the maintenance of peripheral T cell homeostasis. Here, we show that numbers of naive T cells (TN ) remain unaffected in pLNs and spleen of mice lacking Il7 gene activity in pLN FRCs, LECs, or both. In contrast, frequencies of central memory T cells (TCM ) are reduced in FRC-specific IL-7 KO mice. Thus, steady state IL-7 production by pLN FRCs is critical for the maintenance of TCM , but not TN , indicating that both T cell subsets colonize different ecological niches in vivo.

Analysis of Phosphorylation-dependent Protein Interactions of Adhesion and Degranulation Promoting Adaptor Protein (ADAP) Reveals Novel Interaction Partners Required for Chemokine-directed T cell Migration.

Stimulation of T cells leads to distinct changes of their adhesive and migratory properties. Signal propagation from activated receptors to integrins depends on scaffolding proteins such as the adhesion and degranulation promoting adaptor protein (ADAP)(1). Here we have comprehensively investigated the phosphotyrosine interactome of ADAP in T cells and define known and novel interaction partners of functional relevance. While most phosphosites reside in unstructured regions of the protein, thereby defining classical SH2 domain interaction sites for master regulators of T cell signaling such as SLP76, Fyn-kinase, and NCK, other binding events depend on structural context. Interaction proteomics using different ADAP constructs comprising most of the known phosphotyrosine motifs as well as the structured domains confirm that a distinct set of proteins is attracted by pY571 of ADAP, including the ζ-chain-associated protein kinase of 70 kDa (ZAP70). The interaction of ADAP and ZAP70 is inducible upon stimulation either of the T cell receptor (TCR) or by chemokine. NMR spectroscopy reveals that the N-terminal SH2 domains within a ZAP70-tandem-SH2 construct is the major site of interaction with phosphorylated ADAP-hSH3(N) and microscale thermophoresis (MST) indicates an intermediate binding affinity (Kd = 2.3 µm). Interestingly, although T cell receptor dependent events such as T cell/antigen presenting cell (APC) conjugate formation and adhesion are not affected by mutation of Y571, migration of T cells along a chemokine gradient is compromised. Thus, although most phospho-sites in ADAP are linked to T cell receptor related functions we have identified a unique phosphotyrosine that is solely required for chemokine induced T cell behavior.

S. aureus haemolysin A-induced IL-8 and IL-6 release from human airway epithelial cells is mediated by activation of p38- and Erk-MAP kinases and additional, cell type-specific signalling mechanisms.

Soluble virulence-associated factors of Staphylococcus aureus like haemolysin A (Hla) induce secretion of chemo/cytokines from airway epithelial cells. To elucidate the potential roles of specific signalling pathways in this response, we treated 16HBE14o-, S9 or A549 cells with recombinant Hla (rHla). In a dose-dependent manner, rHla induced secretion of IL-8 in all three cell types, but IL-6 release only in 16HBE14o- and S9 cells. rHla-mediated secretion of IL-8 and IL-6 was suppressed by pre-incubation of cells with inhibitors of Erk type or p38 MAP kinases, indicating that activation of these signalling pathways is essential for IL-8 release in all three cell types and for IL-6 release in 16HBE14o- and S9 cells. The rHla-mediated phosphorylation and activation of p38 MAP kinase seem to depend on elevations in [Ca(2+)]i, an early response in rHla-treated cells. Inhibitors of calmodulin or calcium/calmodulin-dependent kinase II attenuated rHla-mediated release of IL-8 in 16HBE14o- and A549 cells and of IL-6 in 16HBE14o- cells. This indicates that rHla may mediate simultaneous activation of calmodulin-dependent processes as additional prerequisites for chemo/cytokine secretion.However, the inhibitors of calmodulin-dependent signalling did not affect rHla-induced p38 MAP kinase phosphorylation, indicating that this pathway works in parallel with p38 MAP kinase.

Prednisolone Versus Colchicine for Acute Gout in Primary Care: statistical analysis plan for the pragmatic, multicenter, randomized, and double-blinded COPAGO non-inferiority trial.

BACKGROUND: To date, colchicine and prednisolone are two effective therapies for the treatment of acute gout but have never been compared directly in a randomized clinical trial. In addition, in previous trials of treating acute gout patients with concomitant comorbidities were often excluded due to contraindications to naproxen. STUDY DESIGN: This pragmatic, prospective, double-blind, double-dummy, parallel-group, randomized, non-inferiority trial compares prednisolone with colchicine in terms of non-inferiority in patients with acute gout. Patients presenting to their general practitioner with acute gout can be included if the gout attack has occurred within the last 2 days. A total of 60 practices in the vicinity of three university medical centers (Greifswald, Göttingen, and Würzburg) participate in the study. The intervention group receives 30 mg prednisolone for 5 days, while the group of standard care receives low-dose colchicine (day 1: 1.5 mg; days 2-5: 1 mg). The first dose of treatment is provided at day 0 when patients present to the general practitioner due to an acute gout attack. From day 0 to day 6, patients will be asked to complete a study diary on daily basis regarding pain quantification. For safety reasons, potential side effects and the course of systolic blood pressure are also assessed. STATISTICAL ANALYSIS PLAN: N = 314 patients have to be recruited to compensate for 10% of dropout and to allow for showing non-inferiority of prednisolone compared to colchicine with a power of 90%. We use permuted block randomization with block sizes of 2, 4, and 6 to avoid imbalanced treatment arms in this multi-center study; patients are randomized in a 1:1 ratio. The absolute level of pain on day 3 (in the last 24 h) is the primary outcome and measured on a numerical rating scale (NRS: 0-10). Using a multiple linear regression model adjusted for age, sex, and pain at baseline, prednisolone is considered non-inferior if the effect estimate including the confidence intervals is lower than a margin of 1 unit on the NRS. Average response to treatment, joint swelling and tenderness, physical function of the joint, and patients' global assessment of treatment success are secondary outcomes. DISCUSSION: The trial will provide evidence from a direct comparison of colchicine and prednisolone regarding their efficacy of pain reduction in acute gout patients of primary care and to indicate possible safety signals. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05698680 first posted on January 26, 2023 (retrospectively registered).

Prednisolone Versus Colchicine for Acute Gout in Primary Care (COPAGO): protocol for a two-arm multicentre, pragmatic, prospective, randomized, double-blind, controlled clinical trial of prednisolone and colchicine for non-inferiority with a parallel group design.

BACKGROUND: Gout is the most common form of rheumatic disease in which monosodium urate crystals are deposited in the joints followed by acute inflammatory reactions. There are various approved drugs that can be prescribed for pain relief during an acute gout attack. However, to date, no direct comparison of efficacy of colchicine and prednisolone for the treatment of acute gout attacks has been investigated. Furthermore, the majority of previous research studies were not only conducted in tertiary centres but also excluded patients with common comorbidities due to contraindications to naproxen. METHODS: This pragmatic, prospective, double-blind, double-dummy, parallel-group, randomized, non-inferiority trial investigates whether prednisolone (intervention) is non-inferior to treatment with colchicine (active control) in patients with acute gout. Adult patients presenting with acute gout to their general practitioners in 60 practices across 3 university sites (Greifswald, Göttingen, and Würzburg) are eligible to participate in the study. Participants in the intervention group receive 30 mg prednisolone for 5 days. Those in the control group receive low-dose colchicine (day 1: 1.5 mg; days 2-5: 1 mg). The primary outcome is the absolute level of the most severe pain on day 3 (in the last 24 h) measured with an 11-item numerical rating scale. Day 0 is the day patients take their study medication for the first time. They are then asked to fill out a study diary the same time each day for pain quantification. Pain scores are used for comparison between the two medications. Secondary outcomes are average response to treatment, swelling, tenderness and physical function of the joint, patients' global assessment of treatment success, use of additional pain medication and non-pharmacological pain therapies. For safety reasons, potential side effects and course of systolic blood pressure are assessed. DISCUSSION: This trial will provide evidence on the effectiveness of pain reduction and side effects of colchicine and prednisolone in acute gout in primary care. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05698680 first posted on January 26, 2023 (retrospectively registered). URL of trial registry record: https://clinicaltrials.gov/study/NCT05698680.

The Multiple Roles of the Cytosolic Adapter Proteins ADAP, SKAP1 and SKAP2 for TCR/CD3 -Mediated Signaling Events.

T cells are the key players of the adaptive immune response. They coordinate the activation of other immune cells and kill malignant and virus-infected cells. For full activation T cells require at least two signals. Signal 1 is induced after recognition of MHC/peptide complexes presented on antigen presenting cells (APCs) by the clonotypic TCR (T-cell receptor)/CD3 complex whereas Signal 2 is mediated via the co-stimulatory receptor CD28, which binds to CD80/CD86 molecules that are present on APCs. These signaling events control the activation, proliferation and differentiation of T cells. In addition, triggering of the TCR/CD3 complex induces the activation of the integrin LFA-1 (leukocyte function associated antigen 1) leading to increased ligand binding (affinity regulation) and LFA-1 clustering (avidity regulation). This process is termed "inside-out signaling". Subsequently, ligand bound LFA-1 transmits a signal into the T cells ("outside-in signaling") which enhances T-cell interaction with APCs (adhesion), T-cell activation and T-cell proliferation. After triggering of signal transducing receptors, adapter proteins organize the proper processing of membrane proximal and intracellular signals as well as the activation of downstream effector molecules. Adapter proteins are molecules that lack enzymatic or transcriptional activity and are composed of protein-protein and protein-lipid interacting domains/motifs. They organize and assemble macromolecular complexes (signalosomes) in space and time. Here, we review recent findings regarding three cytosolic adapter proteins, ADAP (Adhesion and Degranulation-promoting Adapter Protein), SKAP1 and SKAP2 (Src Kinase Associated Protein 1 and 2) with respect to their role in TCR/CD3-mediated activation, proliferation and integrin regulation.

c-FLIP is crucial for IL-7/IL-15-dependent NKp46+ ILC development and protection from intestinal inflammation in mice.

NKp46+ innate lymphoid cells (ILC) modulate tissue homeostasis and anti-microbial immune responses. ILC development and function are regulated by cytokines such as Interleukin (IL)-7 and IL-15. However, the ILC-intrinsic pathways translating cytokine signals into developmental programs are largely unknown. Here we show that the anti-apoptotic molecule cellular FLICE-like inhibitory protein (c-FLIP) is crucial for the generation of IL-7/IL-15-dependent NKp46+ ILC1, including conventional natural killer (cNK) cells, and ILC3. Cytokine-induced phosphorylation of signal transducer and activator of transcription 5 (STAT5) precedes up-regulation of c-FLIP, which protects developing NKp46+ ILC from TNF-induced apoptosis. NKp46+ ILC-specific inactivation of c-FLIP leads to the loss of all IL-7/IL-15-dependent NKp46+ ILC, thereby inducing early-onset chronic colitis and subsequently microbial dysbiosis; meanwhile, the depletion of cNK, but not NKp46+ ILC1/3, aggravates experimental colitis. In summary, our data demonstrate a non-redundant function of c-FLIP for the generation of NKp46+ ILC, which protect T/B lymphocyte-sufficient mice from intestinal inflammation.

D120 and K152 within the PH Domain of T Cell Adapter SKAP55 Regulate Plasma Membrane Targeting of SKAP55 and LFA-1 Affinity Modulation in Human T Lymphocytes.

The ß2-integrin lymphocyte function-associated antigen 1 (LFA-1) is needed for the T cell receptor (TCR)-induced activation of LFA-1 to promote T cell adhesion and interaction with antigen-presenting cells (APCs). LFA-1-mediated cell-cell interactions are critical for proper T cell differentiation and proliferation. The Src kinase-associated phosphoprotein of 55 kDa (SKAP55) is a key regulator of TCR-mediated LFA-1 signaling (inside-out/outside-in signaling). To gain an understanding of how SKAP55 controls TCR-mediated LFA-1 activation, we assessed the functional role of its pleckstrin homology (PH) domain. We identified two critical amino acid residues within the PH domain of SKAP55, aspartic acid 120 (D120) and lysine 152 (K152). D120 facilitates the retention of SKAP55 in the cytoplasm of nonstimulated T cells, while K152 promotes SKAP55 membrane recruitment via actin binding upon TCR triggering. Importantly, the K152-dependent interaction of the PH domain with actin promotes the binding of talin to LFA-1, thus facilitating LFA-1 activation. These data suggest that K152 and D120 within the PH domain of SKAP55 regulate plasma membrane targeting and TCR-mediated activation of LFA-1.