PI3Kγδ inhibition suppresses key disease features in a rat model of asthma.

BACKGROUND: Two isoforms of Phosphoinositide 3-kinase (PI3K), p110γ and p110δ, are predominantly expressed in leukocytes and represent attractive therapeutic targets for the treatment of allergic asthma. The study aim was to assess the impact of administration of an inhaled PI3Kγδ inhibitor (AZD8154) in a rat model of asthma. METHODS: Firstly, we checked that the tool compound, AZD8154, inhibited rat PI3K γ & δ kinases using rat cell-based assays. Subsequently, a time-course study was conducted in a rat model of asthma to assess PI3K activity in the lung and how it is temporally associated with other key transcription pathways and asthma like features of the model. Finally, the impact on lung dosed AZD8154 on target engagement, pathway specificity, airway inflammation and lung function changes was assessed. RESULTS: Data showed that AZD8154 could inhibit rat PI3K γ & δ isoforms and, in a rat model of allergic asthma the PI3K pathway was activated in the lung. Intratracheal administration of AZD8154 caused a dose related suppression PI3K pathway activation (reduction in pAkt) and unlike after budesonide treatment, STAT and NF-κB pathways were not affected by AZD8154. The suppression of the PI3K pathway led to a marked inhibition of airway inflammation and reduction in changes in lung function. CONCLUSION: These data show that a dual PI3Kγδ inhibitor suppress key features of disease in a rat model of asthma to a similar degree as budesonide and indicate that dual PI3Kγδ inhibition may be an effective treatment for people suffering from allergic asthma.

Selective Janus kinase 1 inhibition resolves inflammation and restores hair growth offering a viable treatment option for alopecia areata.

Background: Janus Kinase (JAK) inhibition has recently demonstrated therapeutic efficacy in both restoring hair growth and resolving inflammation in Alopecia Areata (AA). These effects are dose dependent and mainly efficacious at ranges close to a questionable risk profile. Objectives: We explored the possibility to separate the beneficial and adverse effects of JAK inhibition by selectively inhibiting JAK1 and thereby avoiding side effects associated with JAK2 blockade. Methods: The C3H/HeJ mouse model of AA was used to demonstrate therapeutic efficacy in vivo with different regimens of a selection of JAK inhibitors in regards to systemic versus local drug exposure. Human peripheral blood lymphocytes were stimulated in vitro to demonstrate translation to the human situation. Results: We demonstrate that selective inhibition of JAK1 produces fast resolution of inflammation and complete restoration of hair growth in the C3H/HeJ mouse model of AA. Furthermore, we show that topical treatment does not restore hair growth and that treatment needs to be extended well beyond that of restored hair growth in order to reach treatment-free remission. For translatability to human disease, we show that cytokines involved in AA pathogenesis are similarly inhibited by selective JAK1 and pan-JAK inhibition in stimulated human peripheral lymphocytes and specifically in CD8+ T cells. Conclusion: This study demonstrates that systemic exposure is required for efficacy in AA and we propose that a selective JAK1 inhibitor will offer a treatment option with a superior safety profile to pan-JAK inhibitors for these patients.

Evaluation of FOXO1 Target Engagement Using a Single-Cell Microfluidic Platform.

The cellular thermal shift assay (CETSA) has been used extensively since its introduction to study drug-target engagement within both live cells and cellular lysate. This has proven to be a useful tool in early stage drug discovery and is used to study a wide range of protein classes. We describe the application of a single-cell CETSA workflow within a microfluidic affinity capture (MAC) chip. This has enabled us to quantitatively determine the active FOXO1 single-molecule count and observe FOXO1 stabilization and destabilization in the presence of three small molecule inhibitors, including demonstrating the determination of EC50. The successful use of the MAC chip for single-cell CETSA paves the way for the study of precious clinical samples owing to the low number of cells needed by the chip. It also provides a useful tool for studying any underlying population heterogeneity that exists within a cellular system, a feature that is usually masked when conducting ensemble measurements.

Multi-omics links IL-6 trans-signalling with neutrophil extracellular trap formation and Haemophilus infection in COPD.

BACKGROUND: Interleukin (IL)-6 trans-signalling (IL-6TS) is emerging as a pathogenic mechanism in chronic respiratory diseases; however, the drivers of IL-6TS in the airways and the phenotypic characteristic of patients with increased IL-6TS pathway activation remain poorly understood. OBJECTIVE: Our aim was to identify and characterise COPD patients with increased airway IL-6TS and to elucidate the biological drivers of IL-6TS pathway activation. METHODS: We used an IL-6TS-specific sputum biomarker profile (soluble IL-6 receptor (sIL-6R), IL-6, IL-1ß, IL-8, macrophage inflammatory protein-1ß) to stratify sputum data from patients with COPD (n=74; Biomarkers to Target Antibiotic and Systemic Corticosteroid Therapy in COPD Exacerbation (BEAT-COPD)) by hierarchical clustering. The IL-6TS signature was related to clinical characteristics and sputum microbiome profiles. The induction of neutrophil extracellular trap formation (NETosis) and IL-6TS by Haemophilus influenzae were studied in human neutrophils. RESULTS: Hierarchical clustering revealed an IL-6TS-high subset (n=24) of COPD patients, who shared phenotypic traits with an IL-6TS-high subset previously identified in asthma. The subset was characterised by increased sputum cell counts (p=0.0001), persistent sputum neutrophilia (p=0.0004), reduced quality of life (Chronic Respiratory Questionnaire total score; p=0.008), and increased levels of pro-inflammatory mediators and matrix metalloproteinases in sputum. IL-6TS-high COPD patients showed an increase in Proteobacteria, with Haemophilus as the dominating genus. NETosis induced by H. influenzae was identified as a potential mechanism for increased sIL-6R levels. This was supported by a significant positive correlation between sIL-6R and NETosis markers in bronchoalveolar lavage fluid from COPD patients. CONCLUSION: IL-6TS pathway activation due to chronic colonisation with Haemophilus may be an important disease driver in a subset of COPD patients.

A MALT1 inhibitor suppresses human myeloid DC, effector T-cell and B-cell responses and retains Th1/regulatory T-cell homeostasis.

The paracaspase mucosa-associated lymphoid tissue lymphoma translocation protein-1 (MALT1) regulates nuclear-factor-kappa-B (NF-κB) activation downstream of surface receptors with immunoreceptor tyrosine-based activation motifs (ITAMs), such as the B-cell or T-cell receptor and has thus emerged as a therapeutic target for autoimmune diseases. However, recent reports demonstrate the development of lethal autoimmune inflammation due to the excessive production of interferon gamma (IFN-É£) and defective differentiation of regulatory T-cells in genetically modified mice deficient in MALT1 paracaspase activity. To address this issue, we explored the effects of pharmacological MALT1 inhibition on the balance between T-effector and regulatory T-cells. Here we demonstrate that allosteric inhibition of MALT1 suppressed Th1, Th17 and Th1/Th17 effector responses, and inhibited T-cell dependent B-cell proliferation and antibody production. Allosteric MALT1 inhibition did not interfere with the suppressive function of human T-regulatory cells, although it impaired de novo differentiation of regulatory T-cells from naïve T-cells. Treatment with an allosteric MALT1 inhibitor alleviated the cytokine storm, including IFN-É£, in a mouse model of acute T-cell activation, and long-term treatment did not lead to an increase in IFN-É£ producing CD4 cells or tissue inflammation. Together, our data demonstrate that the effects of allosteric inhibition of MALT1 differ from those seen in mice with proteolytically inactive MALT1, and thus we believe that MALT1 is a viable target for B and T-cell driven autoimmune diseases.

Genetic variations in A20 DUB domain provide a genetic link to citrullination and neutrophil extracellular traps in systemic lupus erythematosus.

OBJECTIVES: Genetic variations in TNFAIP3 (A20) de-ubiquitinase (DUB) domain increase the risk of systemic lupus erythematosus (SLE) and rheumatoid arthritis. A20 is a negative regulator of NF-κB but the role of its DUB domain and related genetic variants remain unclear. We aimed to study the functional effects of A20 DUB-domain alterations in immune cells and understand its link to SLE pathogenesis. METHODS: CRISPR/Cas9 was used to generate human U937 monocytes with A20 DUB-inactivating C103A knock-in (KI) mutation. Whole genome RNA-sequencing was used to identify differentially expressed genes between WT and C103A KI cells. Functional studies were performed in A20 C103A U937 cells and in immune cells from A20 C103A mice and genotyped healthy individuals with A20 DUB polymorphism rs2230926. Neutrophil extracellular trap (NET) formation was addressed ex vivo in neutrophils from A20 C103A mice and SLE-patients with rs2230926. RESULTS: Genetic disruption of A20 DUB domain in human and murine myeloid cells did not give rise to enhanced NF-κB signalling. Instead, cells with C103A mutation or rs2230926 polymorphism presented an upregulated expression of PADI4, an enzyme regulating protein citrullination and NET formation, two key mechanisms in autoimmune pathology. A20 C103A cells exhibited enhanced protein citrullination and extracellular trap formation, which could be suppressed by selective PAD4 inhibition. Moreover, SLE-patients with rs2230926 showed increased NETs and increased frequency of autoantibodies to citrullinated epitopes. CONCLUSIONS: We propose that genetic alterations disrupting the A20 DUB domain mediate increased susceptibility to SLE through the upregulation of PADI4 with resultant protein citrullination and extracellular trap formation.

Bleomycin hydrolase regulates the release of chemokines important for inflammation and wound healing by keratinocytes.

Bleomycin hydrolase (BLMH) is a well-conserved cysteine protease widely expressed in several mammalian tissues. In skin, which contains high levels of BLMH, this protease is involved in the degradation of citrullinated filaggrin monomers into free amino acids important for skin hydration. Interestingly, the expression and activity of BLMH is reduced in patients with atopic dermatitis (AD) and psoriasis, and BLMH knockout mice acquire tail dermatitis. Apart from its already known function, we have discovered a novel role of BLMH in the regulation of inflammatory chemokines and wound healing. We show that lowered BLMH levels in keratinocytes result in increased release of the pro-inflammatory chemokines CXCL8 and GROα, which are upregulated in skin from AD patients compared to healthy individuals. Conditioned media from keratinocytes expressing low levels of BLMH increased chemotaxis by neutrophils and caused a delayed wound healing in the presence of low-level TNFα. This defective wound healing was improved by blocking the shared receptor of CXCL8 and GROα, namely CXCR2, using a specific receptor antagonist. Collectively, our results present a novel function of BLMH in regulating the secretion of chemokines involved in inflammation and wound healing in human keratinocytes.

Polymorphisms in the multidrug-resistance 1 gene related to glucocorticoid response in rheumatoid arthritis treatment.

A substantial proportion of rheumatoid arthritis (RA)-patients experience an insufficient response to glucocorticoids, an important therapeutic agent in RA. The multidrug-resistance 1 (MDR1) gene product P-glycoprotein (P-gp) is an efflux pump that actively transports substrates, such as glucocorticoids, out of the cell. We investigated if the variation in response might be explained by single-nucleotide polymorphisms (SNPs) in the MDR1 gene. RA-patients treated with intravenous methylprednisolone pulses (n = 18) or oral prednisone/prednisolone (n = 22) were included in a prospective cohort, and clinical response was measured after 5 and 30 days, respectively. The C1236T, G2677A/T, and C3435T SNPs were determined, and the functionality of P-gp was assessed by flow cytometry (Rhodamine efflux assay). Carriage of the G2677A/T SNP was significantly associated with response (OR = 6.18, p = 0.035), the other SNPs showed trends. Stratified for received treatment, the effect was only present in methylprednisolone treated patients. Mutant allele carriage significantly decreased functionality of P-gp in B cells, though had a smaller impact in other PBMC subtypes. Carriage of a MDR1 SNP was related to a response to methylprednisolone in this study, which his suggests that RA-patients carrying wild-type alleles might benefit from P-gp inhibition or administration of glucocorticoid analogues that are non-P-gp substrates.

Induction of mucosal immune responses against Helicobacter pylori infection after sublingual and intragastric route of immunization.

There is a current lack of effective mucosal vaccines against major gastroenteric pathogens and particularly against Helicobacter pylori, which causes a chronic infection that can lead to peptic ulcers and gastric cancer in a subpopulation of infected individuals. Mucosal CD4+ T-cell responses have been shown to be essential for vaccine-induced protection against H. pylori infection. The current study addresses the influence of the adjuvant and site of mucosal immunization on early CD4+ T-cell priming to H. pylori antigens. The vaccine formulation consisted of H. pylori lysate antigens and mucosal adjuvants, cholera toxin (CT) or a detoxified double-mutant heat-labile enterotoxin from Escherichia coli (dmLT), which were administered by either the sublingual or intragastric route. We report that in vitro, adjuvants CT and dmLT induce up-regulation of pro-inflammatory gene expression in purified dendritic cells and enhance the H. pylori-specific CD4+ T-cell response including interleukin-17A (IL-17A), interferon-γ (IFN-γ) and tumour necrosis factor-α (TNF-α) secretion. In vivo, sublingual immunization led to an increased frequency of IL-17A+ , IFN-γ+ and TNF-α+ secreting CD4+ T cells in the cervical lymph nodes compared with in the mesenteric lymph nodes after intragastric immunization. Subsequently, IL-17A+ cells were visualized in the stomach of sublingually immunized and challenged mice. In summary, our results suggest that addition of an adjuvant to the vaccine clearly activated dendritic cells, which in turn, enhanced CD4+ T-cell cytokines IL-17A, IFN-γ and TNF-α responses, particularly in the cervical lymph nodes after sublingual vaccination.

CD47-deficient mice have decreased production of intestinal IgA following oral immunization but a maintained capacity to induce oral tolerance.

Signal regulatory protein α (SIRPα/CD172a), expressed by myeloid cells including CD11b(+) dendritic cells, interacts with ubiquitously expressed CD47 to mediate cell-cell signalling and therefore, may be pivotal in the development of tolerance or immunity. We show that in mice deficient in CD47 (CD47(-/-) ) the cellularity in gut-associated lymphoid tissues is reduced by 50%. In addition, the frequency of CD11b(+) CD172a(+) dendritic cells is significantly reduced in the gut and mesenteric lymph nodes, but not in Peyer's patches. Activation of ovalbumin (OVA)-specific CD4(+) T cells in the mesenteric lymph nodes after feeding OVA is reduced in CD47(-/-) mice compared with wild-type however, induction of oral tolerance is maintained. The addition of cholera toxin generated normal serum anti-OVA IgG and IgA titres but resulted in reduced intestinal anti-OVA IgA in CD47(-/-) mice. Replacing the haematopoietic compartment in CD47(-/-) mice with wild-type cells restored neither the cellularity in gut-associated lymphoid tissues nor the capacity to produce intestinal anti-OVA IgA following immunization. This study demonstrates that CD47 signalling is dispensable for oral tolerance induction, whereas the expression of CD47 by non-haematopoietic cells is required for intestinal IgA B-cell responses. This suggests that differential CD4 T cell functions control tolerance and enterotoxin-induced IgA immunity in the gut.

ADP-ribosylation controls the outcome of tolerance or enhanced priming following mucosal immunization.

Accumulating evidence suggests that the dichotomy between tolerance and active IgA immunity in mucosal immune responses is regulated at the APC level. Therefore, immunomodulation of the APC could be an effective mechanism to control the two response patterns. In this study, we demonstrate that ADP-ribosylation controls the outcome of tolerance or active effector T cell immunity to an internal peptide p323-339 from OVA inserted into the cholera toxin (CT)-derived CTA1-OVA-DD adjuvant. We found that a single point mutation, CTA1R7K-OVA-DD, resulting in lack of enzymatic activity, promoted peptide-specific tolerance in TCR transgenic CD4(+) T cells following a single intranasal (i.n.) treatment. The CTA1R7K-OVA-DD-induced tolerance was strong, long-lasting, and impaired the ability of adoptively transferred naive peptide-specific CD4(+) T cells to respond to Ag-challenge, irrespective if this was given i.p or i.n. The tolerance correlated with induction of regulatory T cells of the regulatory T type 1 characterized by CD25(-)Foxp3(-)CD4(+) T cells producing IL-10. In contrast, in IL-10-deficient mice, no peptide-specific tolerance was observed, and these mice exhibited unimpaired CD4(+) T cell responsiveness to recall Ag irrespective of if they were untreated (PBS) or treated i.n. with CTA1R7K-OVA-DD. Thus, for the first time, we can provide unequivocal proof that ADP-ribosylation can control the outcome of mucosal Ag exposure from tolerance to an enhanced effector CD4(+) T cell response. The exploitation of this system for clinical treatment of autoimmune diseases is discussed.

CD11c(high )dendritic cells are essential for activation of CD4+ T cells and generation of specific antibodies following mucosal immunization.

To generate vaccines that protect mucosal surfaces, a better understanding of the cells required in vivo for activation of the adaptive immune response following mucosal immunization is required. CD11c(high) conventional dendritic cells (cDCs) have been shown to be necessary for activation of naive CD8(+) T cells in vivo, but the role of cDCs in CD4(+) T cell activation is still unclear, especially at mucosal surfaces. The activation of naive Ag-specific CD4(+) T cells and the generation of Abs following mucosal administration of Ag with or without the potent mucosal adjuvant cholera toxin were therefore analyzed in mice depleted of CD11c(high) cDCs. Our results show that cDCs are absolutely required for activation of CD4(+) T cells after oral and nasal immunization. Ag-specific IgG titers in serum, as well as Ag-specific intestinal IgA, were completely abrogated after feeding mice OVA and cholera toxin. However, giving a very high dose of Ag, 30-fold more than required to detect T cell proliferation, to cDC-ablated mice resulted in proliferation of Ag-specific CD4(+) T cells. This proliferation was not inhibited by additional depletion of plasmacytoid DCs or in cDC-depleted mice whose B cells were MHC-II deficient. This study therefore demonstrates that cDCs are required for successful mucosal immunization, unless a very high dose of Ag is administered.