Differential Changes in Inflammatory Mononuclear Phagocyte and T-Cell Profiles within Psoriatic Skin during Treatment with Guselkumab vs. Secukinumab.

Cellular sources of IL-23 and IL-17A driving skin inflammation in psoriasis remain unclear. Using high-dimensional unsupervised flow cytometry analysis, mononuclear phagocytes and T cells were examined in the same lesions of patients before and during guselkumab (IL-23p19 blocker) or secukinumab (IL-17A blocker) treatment. Among CD11c+HLA-DR+ mononuclear phagocytes, CD64brightCD163-CD14brightCD1c-CD1a‒ inflammatory monocyte‒like cells were the predominant IL-23-producing cells and, together with CD64-CD163-CD14-IL-23p19-TNF-α+ inflammatory dendritic cell‒like cells, were increased in lesional compared with those in nonlesional skin taken from the same patient. Within T cells, CD8+CD49a+ and/or CD103+ tissue-resident memory T cells, CD4+CD25+FoxP3+ regulatory T cells, and CD4+CD49a-CD103- T cells were increased. Moreover, CD4+CD49a-CD103- T cells and the relatively rare CD8+ memory T cells equally contributed to IL-17A production. Both treatments decreased the frequencies of inflammatory monocyte‒like, inflammatory dendritic cell‒like, and CD4+CD49a-CD103- T cells. In contrast, guselkumab reduced memory T cells while maintaining regulatory T cells and vice versa for secukinumab. Neither drug modified the frequencies of IL-17A+IL‒17F+/- CD4+ or CD8+ T cells. This study reveals the identity of the major IL-23+ mononuclear phagocyte and IL-17+ T-cell subsets in psoriatic skin lesions and paves the way for a better understanding of the mode of action of drugs targeting the IL-23/IL-17A pathway in psoriasis.

T Cell Subset and Stimulation Strength-Dependent Modulation of T Cell Activation by Kv1.3 Blockers.

Kv1.3 is a voltage-gated potassium channel expressed on T cells that plays an important role in T cell activation. Previous studies have shown that blocking Kv1.3 channels in human T cells during activation results in reduced calcium entry, cytokine production, and proliferation. The aim of the present study was to further explore the effects of Kv1.3 blockers on the response of different human T cell subsets under various stimulation conditions. Our studies show that, unlike the immune suppressor cyclosporine A, the inhibitory effect of Kv1.3 blockers was partial and stimulation strength dependent, with reduced inhibitory efficacy on T cells under strengthened anti-CD3/CD28 stimulations. T cell responses to allergens including house dust mites and ragweed were partially reduced by Kv1.3 blockers. The effect of Kv1.3 inhibition was dependent on T cell subsets, with stronger effects on CCR7- effector memory compared to CCR7+ central memory CD4 T cells. Calcium entry studies also revealed a population of CD4 T cells resistant to Kv1.3 blockade. Activation of CD4 T cells was accompanied with an increase in Kv1.3 currents but Kv1.3 transcripts were found to be reduced, suggesting a posttranscriptional mechanism in the regulation of Kv1.3 activities. In summary, Kv1.3 blockers inhibit T cell activation in a manner that is highly dependent on the T cell identity and stimulation strength, These findings suggest that Kv1.3 blockers inhibit T cells in a unique, conditional manner, further refining our understanding of the therapeutic potential of Kv1.3 blockers.

Efferocytosis as a regulator of macrophage chemokine receptor expression and polarization.

Efferocytosis has been suggested to promote macrophage resolution programs that are dependent on motility and emigration, however, few studies have addressed directed migration in resolving macrophages. In this report, we hypothesized that efferocytosis would induce differential chemokine receptor expression. Polarized macrophage populations, including macrophages actively engaged in efferocytosis, were characterized by PCR array and traditional transwell motility assays. We identified specific up-regulation of chemokine receptor CXCR4 on both mouse and human macrophages and characterized in vivo expression of CXCR4 in a resolving model of murine peritonitis. Using adoptive transfer and AMD3100 blocking, we confirmed a role for CXCR4 in macrophage egress to draining lymphatics. Collectively these data provide an important mechanistic link between efferocytosis and macrophage emigration.

Syndecan-1 modulates the motility and resolution responses of macrophages.

OBJECTIVE: Syndecan-1 (Sdc-1) is a member of a family of cell surface proteoglycans, which has been reported to participate in the regulation of events relevant to tissue repair and chronic injury responses, including cell-substrate interactions, matrix remodeling, and cell migration. In this study, we report the functional significance of Sdc-1 in polarized macrophage populations and its role in adhesion and motility events relevant to resolution of the inflammatory program. APPROACH AND RESULTS: Macrophage Sdc-1 expression is associated with differentiated M2 macrophages with high intrinsic motility, and Sdc-1 deficiency is characterized by impaired migration and enhanced adhesion. Leukocyte infiltration and emigration were examined in a thioglycollate-induced model of peritonitis in Sdc-1(+/+) and Sdc-1(-/-) mice. Although the infiltration of inflammatory cells was similar in both cohorts, a significant delay in the lymphatic clearance of Sdc-1(-/-) macrophages was observed. Moreover, we observed enhanced inflammation and greater burden of atherosclerotic plaques in ApoE(-/-)Sdc-1(-/-) mice maintained on a Western diet. CONCLUSIONS: These results demonstrate that defective motility in Sdc-1(-/-) macrophages promotes a persistent inflammatory state with relevance to the pathogenesis of atherosclerosis.

Syndecan-1 displays a protective role in aortic aneurysm formation by modulating T cell-mediated responses.

OBJECTIVE: Chronic inflammation drives progressive and pathological remodeling inherent to formation of abdominal aortic aneurysm (AAA). Syndecan-1 (Sdc-1) is a cell surface heparan sulfate proteoglycan that displays the capacity to modulate inflammatory processes within the vascular wall. In the current investigation, the role of Sdc-1 in AAA formation was examined using 2 models of experimental aneurysm induction, angiotensin II infusion and elastase perfusion. METHODS AND RESULTS: Sdc-1 deficiency exacerbated AAA formation in both experimental models and was associated with increased degradation of elastin, greater protease activity, and enhanced inflammatory cell recruitment into the aortic wall. Bone marrow transplantation studies indicated that deficiency of Sdc-1 in marrow-derived cells significantly contributed to AAA severity. Immunostaining revealed augmented Sdc-1 expression in a subset of AAA localized macrophages. We specifically characterized a higher percentage of CD4(+) T cells in Sdc-1-deficient AAA, and antibody depletion studies established the active role of T cells in aneurysmal dilatation. Finally, we confirmed the ability of Sdc-1 macrophage to modulate the inflammatory chemokine environment. CONCLUSIONS: These investigations identify cross-talk between Sdc-1-expressing macrophages and AAA-localized CD4(+) T cells, with Sdc-1 providing an important counterbalance to T-cell-driven inflammation in the vascular wall.

Liposomal formulations of thrombomodulin increase engraftment after intraportal islet transplantation.

Early destruction of donor islet grafts due to an instant blood-mediated inflammatory reaction (IBMIR) remains a major obstacle in islet transplantation. Thrombomodulin plays an important role in limiting coagulation and inflammatory events through a variety of effects. In this study, we investigated the ability of thrombomodulin (TM), when reconstituted as a liposomal formulation, to enhance early syngeneic islet engraftment by minimizing or abrogating the IBMIR. Administration of TM significantly improved early engraftment of syngeneic islets after intraportal transplantation in diabetic mice. In the absence of treatment, conversion to euglycemia was observed among 46.6% (7/15) of recipients. In contrast, administration of TM led to euglycemia in 93.3% (14/15) of recipients (p = 0.0142). Recipients that received TM exhibited a lower incidence of primary nonfunction and better glucose control over a 30-day period after transplantation. Fibrin deposition (p < 0.05), neutrophil infiltration (p < 0.05), expression of TNF-α and IL-ß mRNA (p < 0.05), as well as NF-κB activity (p < 0.05) were significantly reduced in the liver of islet recipients having been treated with liposomal TM. These data demonstrate that TM significantly improves early syngeneic islet engraftment through effects that target both coagulation and inflammatory pathways.