CCL20 neutralization by a monoclonal antibody in healthy subjects selectively inhibits recruitment of CCR6+ cells in an experimental suction blister.

AIMS: GSK3050002, a humanized IgG1κ antibody with high binding affinity to human CCL20, was administered in a first-in-human study to evaluate safety, pharmacokinetics (PK) and pharmacodynamics (PD). An experimental skin suction blister model was employed to assess target engagement and the ability of the compound to inhibit recruitment of inflammatory CCR6 expressing cells. METHODS: This study was a randomized, double-blind (sponsor open), placebo-controlled, single-centre, single ascending intravenous dose escalation trial in 48 healthy male volunteers. RESULTS: GSK3050002 (0.1-20 mg kg-1 ) was well tolerated and no safety concerns were identified. The PK was linear over the dose range, with a half-life of approximately 2 weeks. Complex of GSK3050002/CCL20 increased in serum and blister fluid with increasing doses of GSK3050002. There were dose-dependent decreases in CCR6+ cell recruitment to skin blisters with maximal effects at doses of 5 mg kg-1 and higher, doses at which GSK3050002/CCL20 complex in serum and blister fluid also appeared to reach maximum levels. CONCLUSIONS: These results indicate a relationship between PK, target engagement and PD, suggesting a selective inhibition of recruitment of CCR6+ cells by GSK3050002 and support further development of GSK3050002 in autoimmune and inflammatory diseases.

Biochemistry: role of PQQ as a mammalian enzyme cofactor?

The announcement by Kasahara and Kato of a new redox-cofactor vitamin for mammals, pyrroloquinoline quinone (PQQ), was based on their claim that an enzyme, predicted to be involved in mouse lysine metabolism, is a PQQ-dependent dehydrogenase. However, this claim was dependent on a sequence analysis using databases that inappropriately label beta-propeller sequences as PQQ-binding motifs. What the evidence actually suggests is that the enzyme is an interesting novel protein that has a seven-bladed beta-propeller structure, but there is nothing to indicate that it is a PQQ-dependent dehydrogenase.

Immune-to-brain signalling: the role of cerebral CD163-positive macrophages.

Systemic inflammation induces cytokine synthesis within the central nervous system. This results in sickness behaviour and may exacerbate ongoing neuroinflammatory disease. The precise mechanisms underlying the relay of signal from the periphery to the central nervous system are not entirely understood. CD163-positive macrophages occupy a unique position at the blood-brain barrier and upregulate prostaglandin-synthesizing enzymes in response to systemic inflammation. This finding suggests that they might play a role in signalling inflammation to the central nervous system. However, here we demonstrate that de novo brain cytokine transcription during systemic endotoxaemia may be prostaglandin-independent. We therefore set out to interrogate more directly the role of CD163-positive macrophages in immune-to-brain signalling. Intracerebroventricular injections of clodronate liposomes were used to selectively deplete CD163-positive macrophages. We show that de novo brain cytokine synthesis during systemic endotoxaemia persists in the absence of CD163-positive macrophages. Cerebral endothelial cells outnumber CD163-positive macrophages and are arguably better situated to signal circulating inflammatory stimuli to the brain.

Optimization of Novel Indazoles as Highly Potent and Selective Inhibitors of Phosphoinositide 3-Kinase δ for the Treatment of Respiratory Disease.

Optimization of lead compound 1, through extensive use of structure-based design and a focus on PI3Kδ potency, isoform selectivity, and inhaled PK properties, led to the discovery of clinical candidates 2 (GSK2269557) and 3 (GSK2292767) for the treatment of respiratory indications via inhalation. Compounds 2 and 3 are both highly selective for PI3Kδ over the closely related isoforms and are active in a disease relevant brown Norway rat acute OVA model of Th2-driven lung inflammation.

Characterisation of a K390R ITK kinase dead transgenic mouse--implications for ITK as a therapeutic target.

Interleukin-2 inducible tyrosine kinase (ITK) is expressed in T cells and plays a critical role in signalling through the T cell receptor. Evidence, mainly from knockout mice, has suggested that ITK plays a particularly important function in Th2 cells and this has prompted significant efforts to discover ITK inhibitors for the treatment of allergic disease. However, ITK is known to have functions outside of its kinase domain and in general kinase knockouts are often not good models for the behaviour of small molecule inhibitors. Consequently we have developed a transgenic mouse where the wild type Itk allele has been replaced by a kinase dead Itk allele containing an inactivating K390R point mutation (Itk-KD mice). We have characterised the immune phenotype of these naive mice and their responses to airway inflammation. Unlike Itk knockout (Itk-/-) mice, T-cells from Itk-KD mice can polymerise actin in response to CD3 activation. The lymph nodes from Itk-KD mice showed more prominent germinal centres than wild type mice and serum antibody levels were significantly abnormal. Unlike the Itk-/-, γδ T cells in the spleens of the Itk-KD mice had an impaired ability to secrete Th2 cytokines in response to anti-CD3 stimulation whilst the expression of ICOS was not significantly different to wild type. However ICOS expression is markedly increased on αßCD3+ cells from the spleens of naïve Itk-KD compared to WT mice. The Itk-KD mice were largely protected from inflammatory symptoms in an Ovalbumin model of airway inflammation. Consequently, our studies have revealed many similarities but some differences between Itk-/-and Itk-KD transgenic mice. The abnormal antibody response and enhanced ICOS expression on CD3+ cells has implications for the consideration of ITK as a therapeutic target.

The sickness behaviour and CNS inflammatory mediator profile induced by systemic challenge of mice with synthetic double-stranded RNA (poly I:C).

Poly inosinic:poly cytidylic acid (poly I:C) is a synthetic double-stranded RNA and is a ligand for the Toll like receptor-3. This receptor is involved in the innate immune response to viral infection and poly I:C has been used to mimic the acute phase of a viral infection. The effects of TLR3 activation on brain function have not been widely studied. In the current study we investigate the spectrum of sickness behavioural changes induced by poly I:C in C57BL/6 mice and the CNS expression of inflammatory mediators that may underlie this. Poly I:C, at doses of 2, 6 and 12 mg/kg, induced a dose-responsive sickness behaviour, decreasing locomotor activity, burrowing and body weight, and caused a mild hyperthermia at 6h. The 12 mg/kg dose caused significant hypothermia at later times. The Remo400 remote Telemetry system proved a sensitive measure of this biphasic temperature response. The behavioural responses to poly I:C were not significantly blunted upon a second poly I:C challenge either 1 or 3 weeks later. Plasma concentrations of IL-6, TNF-alpha and IFN-beta were markedly elevated and IL-1 beta was also detectable. Cytokine synthesis within the CNS, as determined by quantitative PCR, was dominated by IL-6, with lesser inductions of IL-1 beta, TNF-alpha and IFN-beta and there was a clear activation of cyclooxygenase-2 at the brain endothelium. These findings demonstrate clear CNS effects of peripheral TLR3 stimulation and will be useful in studying aspects of the effects of systemic viral infection on brain function in both normal and pathological situations.