Modeling the Effects of Multiple Myeloma on Kidney Function

Multiple myeloma (MM), a plasma cell cancer, is associated with many health challenges, including damage to the kidney by tubulointerstitial fibrosis. We develop a mathematical model which captures the qualitative behavior of the cell and protein populations involved. Specifically, we model the interaction between cells in the proximal tubule of the kidney, free light chains, renal fibroblasts, and myeloma cells. We analyze the model for steady-state solutions to find a mathematically and biologically relevant stable steady-state solution. This foundational model provides a representation of dynamics between key populations in tubulointerstitial fibrosis that demonstrates how these populations interact to affect patient prognosis in patients with MM and renal impairment.Comment: Included version of model without tumor with steady-state analysis, corrected equations for free light chains and renal fibroblasts in model with tumor to reflect steady-state analysis, updated abstract, updated and added reference

Case Report: Apremilast for Therapy-Resistant Pemphigus Vulgaris

Background: In pemphigus, elucidating the disease-causing immune mechanism and developing new therapeutic strategies are needed. In this context, the second messenger 3',5'-cyclic adenosine monophosphate (cAMP) is gaining attention. cAMP is important in hematological and auto-inflammatory disorders. A class of enzymes called phosphodiesterases (PDEs) control intracellular cAMP levels. In pemphigus, cAMP levels increase following IgG binding to Dsg3. This appears to be a mechanism to preserve epithelial integrity. Objectives: To determine whether apremilast, an inhibitor of the PDE4 normally used in psoriasis, may be of benefit in the blistering skin disorder pemphigus. Methods: Here we report of a 62 years old patient with chronic debilitating and recalcitrant pemphigus not responding to several previous treatments, who received treatment with apremilast over a period of 32 weeks. Desmoglein autoantibody levels were assessed by Enzyme-linked Immunosorbent Assay (ELISA), whereas disease severity and quality of life were assessed by the Autoimmune Bullous Skin Disorder Intensity Score (ABSIS). In an attempt to explain the effects of apremilast in pemphigus, peripheral blood mononuclear cells (PBMCs) were analyzed for the duration of treatment by flow cytometry for the distribution of specialized T cell subsets. The frequencies of circulating T helper (Th) 1, Th2, Th17, Th17.1 and T follicular helper (Tfh) 1, Tfh2, Tfh17, and Tfh17.1 were analyzed by CCR6, CXCR3, and CXCR5 expression of CD4(+) T cells. Further, based on the different expressions of CXCR5, CD127, and CD25, we analyzed the T regulatory (Treg) and T follicular regulatory (Tfreg) compartment. Results: In response to apremilast treatment, Dsg-specific autoantibody titers decreased, blistering ceased and lesions healed, showing a long-lasting effect. While the frequencies of most of the Th and Tfh cell subsets remained unchanged, we observed a continuous increase in Treg and Tfreg cell levels. Conclusion: Our findings are encouraging and warrant extension of the beneficial effect of PDE4 inhibition on a larger cohort of pemphigus patients

Case Report: Apremilast for Therapy-Resistant Pemphigus Vulgaris

Background: In pemphigus, elucidating the disease-causing immune mechanism and developing new therapeutic strategies are needed. In this context, the second messenger 3′,5′-cyclic adenosine monophosphate (cAMP) is gaining attention. cAMP is important in hematological and auto-inflammatory disorders. A class of enzymes called phosphodiesterases (PDEs) control intracellular cAMP levels. In pemphigus, cAMP levels increase following IgG binding to Dsg3. This appears to be a mechanism to preserve epithelial integrity. Objectives: To determine whether apremilast, an inhibitor of the PDE4 normally used in psoriasis, may be of benefit in the blistering skin disorder pemphigus. Methods: Here we report of a 62 years old patient with chronic debilitating and recalcitrant pemphigus not responding to several previous treatments, who received treatment with apremilast over a period of 32 weeks. Desmoglein autoantibody levels were assessed by Enzyme-linked Immunosorbent Assay (ELISA), whereas disease severity and quality of life were assessed by the Autoimmune Bullous Skin Disorder Intensity Score (ABSIS). In an attempt to explain the effects of apremilast in pemphigus, peripheral blood mononuclear cells (PBMCs) were analyzed for the duration of treatment by flow cytometry for the distribution of specialized T cell subsets. The frequencies of circulating T helper (Th) 1, Th2, Th17, Th17.1 and T follicular helper (Tfh) 1, Tfh2, Tfh17, and Tfh17.1 were analyzed by CCR6, CXCR3, and CXCR5 expression of CD4+ T cells. Further, based on the different expressions of CXCR5, CD127, and CD25, we analyzed the T regulatory (Treg) and T follicular regulatory (Tfreg) compartment. Results: In response to apremilast treatment, Dsg-specific autoantibody titers decreased, blistering ceased and lesions healed, showing a long-lasting effect. While the frequencies of most of the Th and Tfh cell subsets remained unchanged, we observed a continuous increase in Treg and Tfreg cell levels. Conclusion: Our findings are encouraging and warrant extension of the beneficial effect of PDE4 inhibition on a larger cohort of pemphigus patients

Arginase 1+ IL-10+ polymorphonuclear myeloid-derived suppressor cells are elevated in patients with active pemphigus and correlate with an increased Th2/Th1 response

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells, which are characterized by their capability to suppress T-cell responses. While MDSCs have been traditionally associated with cancer diseases, their role as regulators of autoimmune diseases is emerging. Pemphigus is a chronic autoimmune blistering skin disease characterized by dysregulated T-cell responses and autoantibody production. The role of MDSCs in pemphigus disease has not been defined yet. The aim of this study was to characterize MDSCs in pemphigus patients and to dissect their relationship with CD4(+) T-cell subsets and clinical disease assessments. For this purpose, we performed a cross-sectional analysis of 20 patients with pemphigus. Our results indicate that a population of CD66b(+)CD11b(+) polymorphonuclear-like MDSCs (PMN-MDSCs) is expanded in the peripheral blood mononuclear cell fraction of pemphigus patients compared to age-matched healthy donors. These PMN-MDSCs have the capability of suppressing allogeneic T-cell proliferation in vitro and show increased expression of characteristic effector molecules such as arginase I and interleukin-10. We further demonstrate that PMN-MDSCs are especially expanded in patients with active pemphigus, but not in patients in remission. Moreover, MDSC frequencies correlate with an increased Th2/Th1 cell ratio. In conclusion, the identification of a functional PMN-MDSC population suggests a possible role of these cells as regulators of Th cell responses in pemphigus

Prevalence of Candida species in Psoriasis

Background: Psoriasis patients are more frequently colonised with Candida species. The correlation between fungal colonisation and clinical severity is unclear, but may exacerbate psoriasis and the impact of antipsoriatic therapies on the prevalence of Candida is unknown. Objectives: To examine the prevalence of C species in psoriasis patients compared to an age- and sex-matched control population, we investigated the influence of Candida colonisation on disease severity, immune cell activation and the interplay on psoriatic treatments. Methods: The prevalence of C species was examined in 265 psoriasis patients and 200 control subjects by swabs and stool samples for fungal cultures. Peripheral mononuclear blood cells (PBMCs) were collected from 20 fungal colonised and 24 uncolonised patients and stimulated. The expression of interferon (IFN)-γ, IL-17A, IL-22 and tumour necrosis factor (TNF)-α from stimulated PBMCs was measured by quantitative real-time polymerase chain reaction (qPCR). Results: A significantly higher prevalence for Candida was detected in psoriatic patients (p ≤ .001) compared to the control subjects; most abundant in stool samples, showing Candida albicans. Older participants (≥51 years) were more frequent colonised, and no correlation with gender, disease severity or systemic treatments like IL-17 inhibitors was found. Conclusions: Although Candida colonisation is significantly more common in patients with psoriasis, it does not influence the psoriatic disease or cytokine response. Our study showed that Candida colonisation is particularly more frequent in patients with psoriasis ≥51 years of age. Therefore, especially this group should be screened for symptoms of candidiasis during treatment with IL-17 inhibitors

The inflammation in cutaneous lichen planus is dominated by IFN‐ϒ and IL‐21—A basis for therapeutic JAK1 inhibition

Cutaneous lichen planus (CLP) and psoriasis (PSO) are both common chronic inflammatory skin diseases for which development of new treatments requires the identification of key targets. While PSO is a typical Th17/IL-17-disorder, there is some evidence that Th1/IFN-ɣ dominate the inflammatory process in CLP. Nonetheless, the immunopathogenesis of CLP is not fully explained and key immunological factors still have to be recognized. In this study, we compared the immune signature of CLP lesions with the well-characterized inflammation present in PSO skin. First, we analysed the histological and immunohistological characteristics of CLP and PSO. Second, we assessed the cytokine expression (IL1A, IL1B, IL4, IL6, IL8, IL10, IL17A, IL19, IL21, IL22, IL23A, IL13, IFNG, TNF, IL12A, IL12B and IL36G) of lesional skin of CLP with PSO by qPCR. Histology revealed a similar epidermal thickness in CLP and PSO. Immunohistochemically, both diseases presented with an inflammatory infiltrate mainly composed by CD3+CD4+ T cells rather than CD3+CD8+. Importantly, mRNA analysis showed a distinct cytokine signature: while levels of IL12B, IL1A, IL6 and IL23 were similar between the two groups, the characteristic PSO-associated cytokines IL8, IL17A, IL22, IL19 and IL36G were expressed at very low levels in CLP. In contrast, CLP lesional skin was dominated by the expression of IFNG, IL21, IL4, IL12A and TNF. Immunohistochemistry confirmed the dominance of IL-21, IFN-ɣ and also pSTAT1 in the dermal infiltrate of CLP, while IL-17A was more present in PSO. Collectively, this study improves our understanding of the immunological factors dominating CLP. The dominating cytokines and signalling proteins identified suggest that anti-cytokine therapeutics like JAK inhibitors may be beneficial in CLP

Molecular dissection of Wnt3a-Frizzled8 interaction reveals essential and modulatory determinants of Wnt signaling activity

Background: Wnt proteins are a family of secreted signaling molecules that regulate key developmental processes in metazoans. The molecular basis of Wnt binding to Frizzled and LRP5/6 co-receptors has long been unknown due to the lack of structural data on Wnt ligands. Only recently, the crystal structure of the Wnt8-Frizzled8-cysteine-rich-domain (CRD) complex was solved, but the significance of interaction sites that influence Wnt signaling has not been assessed. Results: Here, we present an extensive structure-function analysis of mouse Wnt3a in vitro and in vivo. We provide evidence for the essential role of serine 209, glycine 210 (site 1) and tryptophan 333 (site 2) in Fz binding. Importantly, we discovered that valine 337 in the site 2 binding loop is critical for signaling without contributing to binding. Mutations in the presumptive second CRD binding site (site 3) partly abolished Wnt binding. Intriguingly, most site 3 mutations increased Wnt signaling, probably by inhibiting Wnt-CRD oligomerization. In accordance, increasing amounts of soluble Frizzled8-CRD protein modulated Wnt3a signaling in a biphasic manner. Conclusions: We propose a concentration-dependent switch in Wnt-CRD complex formation from an inactive aggregation state to an activated high mobility state as a possible modulatory mechanism in Wnt signaling gradients

Immune signature in pemphigus and its potential for therapeutic JAK inhibition

Pemphigus vulgaris and pemphigus foliaceus are rare bullous autoimmune diseases of the skin and mucous membranes mediated by autoreactive antibodies directed against the desmosomal cadherins desmoglein (Dsg)1 and Dsg3. Binding of these antibodies leads to acantholysis, the loss of cell-cell adhesion between keratinocytes and thus manifests in blisters and erosions of the skin and mucosa in patients suffering from pemphigus. Previous data indicate that T helper type 2 (Th2) cells and related cytokines play a major role in disease initiation and manifestation, yet the contribution of other T cell subsets remains unclear and evidence is emerging for the involvement of Th17 cell subsets and associated cytokines in pemphigus pathogenesis. To address this issue, the cytokine signature in lesional skin of pemphigus patients was determined by whole transcriptome sequencing and quantitative real-time PCR (qPCR). Further, the distribution of Th and follicular T helper (Tfh) cells in peripheral blood from pemphigus patients with different disease activity stages was analyzed by flow cytometry. Transcriptome analysis identified a broad spectrum of cytokines and chemokines, including interleukins (IL), as well as other immune mediators differentially expressed in lesional pemphigus skin compared to healthy skin samples. Most importantly, an IL-17A-dominated immune signature and an upregulation of the IL-17A signaling pathway were revealed in the skin of pemphigus patients. The dominance of IL-17A and associated cytokines was further validated by qPCR. Moreover, flow cytometry analyses demonstrated elevated levels of IL 17A-producing Th17, Th17.1, Tfh17 and Tfh17.1 cells in the blood of patients with active pemphigus disease. Of note, levels of Th17, Tfh17 and Tfh17.1 cell subsets positively correlated with the levels of circulating Dsg3 reactive memory B cells in active patients. Follow-up experiments by the collaborating partners in Marburg identified Tfh17 cells as the primary inducers of Dsg-specific antibody production by B cells. These findings demonstrate that Tfh17 cells are substantially implicated in pemphigus pathogenesis and offer novel therapeutic approaches, for instance with small molecules targeting cytokine signal transduction of cells involved in disease initiation and manifestation. In the next step, such small compounds aiming to block Janus kinase (JAK)/signal transducer and activator of transcription (STAT)-mediated signal transduction were investigated for their ability to interfere with various signaling cascades initiated by cytokines in CD4+ Th cells. In particular, compounds targeting JAK3 were assessed and compared with the clinically established pan-JAK inhibitor Tofacitinib. In this setting, four of the five inhibitors tested were able to selectively block JAK3-mediated signal transduction without affecting other JAKs. Furthermore, the compounds abrogated the signaling cascade activated by IL-21, a cytokine crucial for Tfh cell differentiation and autoantibody formation. Immunohistochemical staining revealed STAT1 and STAT3 activation in epidermal keratinocytes of perilesional pemphigus skin. Blockade of JAK1 as well as JAK3 in primary human epidermal cells resulted in a protective effect towards cell sheet fragmentation of keratinocyte monolayers in dispase-based dissociation assays. Taken together, these findings indicate a potentially beneficial effect of JAK inhibition in patients suffering from pemphigus and provide the basis for further investigations regarding the therapeutic application of JAK inhibitors in clinical practice.Dissertation ist gesperrt bis zum 30.06.2023 !