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To explore the role of clonal hematopoiesis (CH) in chimeric antigen receptor (CAR) T-cell therapy outcomes, we performed targeted deep sequencing on buffy coats collected during the 21 days before lymphodepleting chemotherapy from 114 large B-cell lymphoma patients treated with anti-CD19 CAR T cells. We detected CH in 42 (36.8%) pretreatment samples, most frequently in PPM1D (19/114) and TP53 (13/114) genes. Grade ≥3 immune effector cell-associated neurotoxicity syndrome (ICANS) incidence was higher in CH-positive patients than CH-negative patients (45.2% vs. 25.0%, P = 0.038). Higher toxicities with CH were primarily associated with DNMT3A, TET2, and ASXL1 genes (DTA mutations). Grade ≥3 ICANS (58.9% vs. 25%, P = 0.02) and ≥3 cytokine release syndrome (17.7% vs. 4.2%, P = 0.08) incidences were higher in DTA-positive than in CH-negative patients. The estimated 24-month cumulative incidence of therapy-related myeloid neoplasms after CAR T-cell therapy was higher in CH-positive than CH-negative patients [19% (95% CI, 5.5–38.7) vs. 4.2% (95% CI, 0.3–18.4), P = 0.028].Significance:Our study reveals that CH mutations, especially those associated with inflammation (DNMT3A, TET2, and ASXL1), are associated with severe-grade neurotoxicities in lymphoma patients receiving anti-CD19 CAR T-cell therapy. Further studies to investigate the mechanisms and interventions to improve toxicities in the context of CH are warranted.See related content by Uslu and June, p. 382.This article is highlighted in the In This Issue feature, p. 369

Supplementary Figure from Clonal Hematopoiesis Is Associated with Increased Risk of Severe Neurotoxicity in Axicabtagene Ciloleucel Therapy of Large B-Cell Lymphoma

To explore the role of clonal hematopoiesis (CH) in chimeric antigen receptor (CAR) T-cell therapy outcomes, we performed targeted deep sequencing on buffy coats collected during the 21 days before lymphodepleting chemotherapy from 114 large B-cell lymphoma patients treated with anti-CD19 CAR T cells. We detected CH in 42 (36.8%) pretreatment samples, most frequently in PPM1D (19/114) and TP53 (13/114) genes. Grade ≥3 immune effector cell-associated neurotoxicity syndrome (ICANS) incidence was higher in CH-positive patients than CH-negative patients (45.2% vs. 25.0%, P = 0.038). Higher toxicities with CH were primarily associated with DNMT3A, TET2, and ASXL1 genes (DTA mutations). Grade ≥3 ICANS (58.9% vs. 25%, P = 0.02) and ≥3 cytokine release syndrome (17.7% vs. 4.2%, P = 0.08) incidences were higher in DTA-positive than in CH-negative patients. The estimated 24-month cumulative incidence of therapy-related myeloid neoplasms after CAR T-cell therapy was higher in CH-positive than CH-negative patients [19% (95% CI, 5.5–38.7) vs. 4.2% (95% CI, 0.3–18.4), P = 0.028]. Significance: Our study reveals that CH mutations, especially those associated with inflammation (DNMT3A, TET2, and ASXL1), are associated with severe-grade neurotoxicities in lymphoma patients receiving anti-CD19 CAR T-cell therapy. Further studies to investigate the mechanisms and interventions to improve toxicities in the context of CH are warranted. See related content by Uslu and June, p. 382. This article is highlighted in the In This Issue feature, p. 369

Adeno-associated viral (AAV) vectors are a leading candidate for the delivery of CRISPR-Cas9 for therapeutic genome editing in vivo. However, AAV-based delivery involves persistent expression of the Cas9 nuclease, a bacterial protein. Recent studies indicate a high prevalence of neutralizing antibodies and T cells specific to the commonly used Cas9 orthologs from Streptococcus pyogenes (SpCas9) and Staphylococcus aureus (SaCas9) in humans. We tested in a mouse model whether pre-existing immunity to SaCas9 would pose a barrier to liver genome editing with AAV packaging CRISPR-Cas9. Although efficient genome editing occurred in mouse liver with pre-existing SaCas9 immunity, this was accompanied by an increased proportion of CD8+ T cells in the liver. This cytotoxic T cell response was characterized by hepatocyte apoptosis, loss of recombinant AAV genomes, and complete elimination of genome-edited cells, and was followed by compensatory liver regeneration. Our results raise important efficacy and safety concerns for CRISPR-Cas9-based in vivo genome editing in the liver., Graphical Abstract, Li and colleagues demonstrated that pre-existing immunity to Cas9 poses a significant barrier to liver-directed genome editing with AAV-CRISPR. They found that AAV expression of Cas9 elicited a robust CD8+ T cell response, resulting in elimination of edited hepatocytes. This raises important safety and efficacy concerns for in vivo editing with CRISPR-Cas9.

Bortezomib, lenalidomide, and dexamethasone (VRD) induction is standard prior to autologous hematopoietic cell transplantation (auto-HCT) in newly diagnosed, high-risk multiple myeloma (ND-HRMM). Carfilzomib (K) is another proteasome inhibitor approved for MM. In this single-center, retrospective analysis, we compared outcomes in ND-HRMM with pre-transplant KRD or VRD induction. High-risk was defined by t(4:14), t(14:16), 1q21 gain/amplification, or del(17p). Primary endpoints were progression-free (PFS) and overall survival (OS). Of 121 ND-HRMM patients, 63 received KRD, and 58 received VRD. Post-induction, complete (CR), very good partial (VGPR), partial response (PR), and overall response (ORR) rates were 23.8%/49.2%/25.4%/98.4% with KRD, and 19%/46.6%/27.6%/93.1% with VRD. At day 100 post-auto-HCT, these were 38.1%/42.9%/19%/100% with KRD, versus 35.1%/49.1%/12.3%/94.8% with VRD. Pre-auto-HCT, 11 (18.3%) KRD and 7 (12.5%) VRD patients had minimal residual disease (MRD)-negative CR (p = 0.45). Post-auto-HCT, 14 (41.2%) and 13 (43.3%) patients had MRD-negative CR (p = 1.000). Median PFS was 38.2 (95%CI 28.7-NA) and 45.9 months (95%CI 43.2-NA) for KRD and VRD, respectively (p = 0.25). Respective 3-year PFS and OS were 53.5% (95%CI 41.1-69.6) and 95.2% (95%CI 90-100) for KRD and 64% (95%CI 51.6-79.5) and 84.2% (95%CI 73.5-96.3, p = 0.30) for VRD. Overall, KRD induction pre-auto-HCT does not improve outcomes. Prospective, randomized studies are needed to confirm these findings.

To explore the role of clonal hematopoiesis (CH) on chimeric antigen receptor (CAR) T-cell therapy outcomes, we performed targeted deep-sequencing on 114 large B-cell lymphoma patients treated with anti-CD19 CAR T-cells. We detected CH in 42 (36.8%) pre-treatment patient samples, most frequently in PPM1D (19/114) and TP53 (13/114) genes. The incidence of grade ≥3 immune-effector cell-associated neurotoxicity syndrome (ICANS) was higher in CH-positive patients compared to CH-negative patients (45.2% vs. 25.0%, p=0.038). Higher toxicities with CH were primarily driven by three CH genes, DNMT3A, TET2 and ASXL1 (DTA mutations). The incidence of grade ≥3 ICANS [58.9% vs. 25%, p=0.02] and grade ≥3 cytokine release syndrome [17.7% vs. 4.2%, p=0.08] were higher in patients with DTA mutations than those without CH. The estimated 24-month cumulative incidence of therapy-related myeloid neoplasms after CAR-T therapy was higher in patients with CH than those without CH (19% [95%CI: 5.5-38.7] vs. 4.2% [95%CI: 0.3-18.4], p=0.028).Statement of SignificanceOur study reveals that clonal hematopoiesis mutations, especially those associated with inflammation (DNMT3A, TET2, ASXL1), are associated with severe grade toxicities in lymphoma patients receiving anti-CD19 chimeric antigen receptor therapy. Further studies to investigate the mechanisms and interventions to improve toxicities in the context of CH are warranted.

Maintenance therapy with single-agent lenalidomide (Len) after autologous hematopoietic stem cell transplantation (autoHCT) for multiple myeloma (MM) is associated with improved progression-free survival (PFS). However, MM patients with high-risk chromosomal abnormalities (HRMMs) may need a more intense regimen. We hypothesized that adding another antimyeloma drug to Len maintenance would lead to improved outcomes. We conducted this retrospective single-center chart review analysis of adult HRMM patients who underwent autoHCT between 2008 and 2018, followed by Len-based maintenance therapy. High-risk cytogenetics were defined as del(17p), t(4;14), t(14;16), 1q21 gain or amplification by fluorescence in situ hybridization. We divided patients into those who received either single-agent Len maintenance (Len-only) or Len-based combinations (Len-combo). We compared nonrelapse mortality, day 100 and best post-transplantation responses, minimal residual disease status, PFS, and overall survival (OS) between the 2 groups. We also performed sensitivity analyses using inverse probability weights to correct for potential bias owing to nonrandomization of the 2 groups. A total of 231 patients with HRMM were included in our analysis, with a median age of 62.4 years (range, 33.5 to 79.9 years), and 55% were male. There were 153 patients in the Len-only group and 78 in the Len-combo group. Len-combo regimens were either doublets (Len with dexamethasone [dex] [n = 10], elotuzumab [n = 28], or ixazomib [n = 14]) or triplets (Len with bortezomib/dex [n = 10], ixazomib/dex [n = 10], or carfilzomib/dex [n = 6]). More patients in the Len-combo group had ≥2 high-risk cytogenetic abnormalities compared with the Len-only group (32% versus 12%: P.001). The median duration of follow-up was 40.7 months in the Len-only group and 37.0 months in the Len-combo group. For all patients, the median PFS was 25.5 months, and the median OS was 82.6 months. There was no significant between-group difference in PFS (hazard ratio [HR] 1.01; 95% confidence interval [CI], .71-1.44; P = .94) or OS (HR, .84; 95% CI, .49 to 1.43; P = .52). However, for patients with high-risk cytogenetic abnormalities other than 1q+, there was a trend toward better PFS in the Len-combo group (HR, .59; 95% CI, .32 to 1.09; P = .09), but no difference in OS (HR, .79; 95% CI, .37 to 1.65; P = .53). In this single-center retrospective analysis, the use of Len-based combinations for post-transplantation maintenance was not associated with improved outcomes in HRMM patients; however, there was a trend toward improved PFS in patients with high-risk abnormalities other than 1q+.

Background Fibroblast-like synoviocytes (FLS) and CCR7− effector memory T (TEM) cells are two of the major cell types implicated in the progression of rheumatoid arthritis (RA). In particular, FLS become highly invasive, whereas TEM cells proliferate and secrete proinflammatory cytokines, during RA. FLS and T cells may also interact and influence each other’s phenotypes. Inhibition of the pathogenic phenotypes of both FLS and TEM cells can be accomplished by selectively blocking the predominant potassium channels that they upregulate during RA: KCa1.1 (BK, Slo1, MaxiK, KCNMA1) upregulated by FLS and Kv1.3 (KCNA3) upregulated by activated TEM cells. In this study, we investigated the roles of KCa1.1 and Kv1.3 in regulating the interactions between FLS and TEM cells and determined if combination therapies of KCa1.1- and Kv1.3-selective blockers are more efficacious than monotherapies in ameliorating disease in rat models of RA. Methods We used in vitro functional assays to assess the effects of selective KCa1.1 and Kv1.3 channel inhibitors on the interactions of FLS isolated from rats with collagen-induced arthritis (CIA) with syngeneic TEM cells. We also used flow cytometric analyses to determine the effects of KCa1.1 blockers on the expression of proteins used for antigen presentation on CIA-FLS. Finally, we used the CIA and pristane-induced arthritis models to determine the efficacy of combinatorial therapies of KCa1.1 and Kv1.3 blockers in reducing disease severity compared with monotherapies. Results We show that the interactions of FLS from rats with CIA and of rat TEM cells are regulated by KCa1.1 and Kv1.3. Inhibiting KCa1.1 on FLS reduces the ability of FLS to stimulate TEM cell proliferation and migration, and inhibiting Kv1.3 on TEM cells reduces TEM cells’ ability to enhance FLS expression of KCa1.1 and major histocompatibility complex class II protein, as well as stimulates their invasion. Furthermore, we show that combination therapies of selective KCa1.1 and Kv1.3 blockers are more efficacious than monotherapies at reducing signs of disease in two rat models of RA. Conclusions Our results demonstrate the importance of KCa1.1 and Kv1.3 in regulating FLS and TEM cells during RA, as well as the value of combined therapies targeting both of these cell types to treat RA. Electronic supplementary material The online version of this article (10.1186/s13075-018-1783-9) contains supplementary material, which is available to authorized users.

Reactive oxygen species have been involved in the pathogenesis of rheumatoid arthritis (RA). Our goal was to determine the effects of selectively scavenging superoxide (O2&bull, &minus, ) and hydroxyl radicals with antioxidant nanoparticles, called poly(ethylene glycol)-functionalized hydrophilic carbon clusters (PEG-HCCs), on the pathogenic functions of fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) and on the progression of an animal model of RA. We used human FLS from patients with RA to determine PEG-HCC internalization and effects on FLS cytotoxicity, invasiveness, proliferation, and production of proteases. We used the pristane-induced arthritis (PIA) rat model of RA to assess the benefits of PEG-HCCs on reducing disease severity. PEG-HCCs were internalized by RA-FLS, reduced their intracellular O2&bull, and reduced multiple measures of their pathogenicity in vitro, including proliferation and invasion. In PIA, PEG-HCCs caused a 65% reduction in disease severity, as measured by a standardized scoring system of paw inflammation and caused a significant reduction in bone and tissue damage, and circulating rheumatoid factor. PEG-HCCs did not induce lymphopenia during PIA. Our study demonstrated a role for O2&bull, and hydroxyl radicals in the pathogenesis of a rat model of RA and showed efficacy of PEG-HCCs in treating a rat model of RA.

[Image: see text] We describe a cysteine-rich, membrane-penetrating, joint-targeting, and remarkably stable peptide, EgK5, that modulates voltage-gated K(V)1.3 potassium channels in T lymphocytes by a distinctive mechanism. EgK5 enters plasma membranes and binds to K(V)1.3, causing current run-down by a phosphatidylinositol 4,5-bisphosphate-dependent mechanism. EgK5 exhibits selectivity for K(V)1.3 over other channels, receptors, transporters, and enzymes. EgK5 suppresses antigen-triggered proliferation of effector memory T cells, a subset enriched among pathogenic autoreactive T cells in autoimmune disease. PET-CT imaging with (18)F-labeled EgK5 shows accumulation of the peptide in large and small joints of rodents. In keeping with its arthrotropism, EgK5 treats disease in a rat model of rheumatoid arthritis. It was also effective in treating disease in a rat model of atopic dermatitis. No signs of toxicity are observed at 10–100 times the in vivo dose. EgK5 shows promise for clinical development as a therapeutic for autoimmune diseases.

Fibroblast-like synoviocytes (FLSs) are a key cell type involved in rheumatoid arthritis (RA) progression. We previously identified the KCa1.1 potassium channel (Maxi-K, BK, Slo 1, KCNMA1) as a regulator of FLSs and found that KCa1.1 inhibition reduces disease severity in RA animal models. However, systemic KCa1.1 block causes multiple side effects. In this study, we aimed to determine whether the KCa1.1 β1-3–specific venom peptide blocker iberiotoxin (IbTX) reduces disease severity in animal models of RA without inducing major side effects. We used immunohistochemistry to identify IbTX-sensitive KCa1.1 subunits in joints of rats with a model of RA. Patch-clamp and functional assays were used to determine whether IbTX can regulate FLSs through targeting KCa1.1. We then tested the efficacy of IbTX in ameliorating disease in two rat models of RA. Finally, we determined whether IbTX causes side effects including incontinence or tremors in rats, compared with those treated with the small-molecule KCa1.1 blocker paxilline. IbTX-sensitive subunits of KCa1.1 were expressed by FLSs in joints of rats with experimental arthritis. IbTX inhibited KCa1.1 channels expressed by FLSs from patients with RA and by FLSs from rat models of RA and reduced FLS invasiveness. IbTX significantly reduced disease severity in two rat models of RA. Unlike paxilline, IbTX did not induce tremors or incontinence in rats. Overall, IbTX inhibited KCa1.1 channels on FLSs and treated rat models of RA without inducing side effects associated with nonspecific KCa1.1 blockade and could become the basis for the development of a new treatment of RA.

Ion channels play crucial roles in regulating a broad range of physiological processes. They form a very large family of transmembrane proteins. Their diversity results from not only a large number of different genes encoding for ion channel subunits but also the ability of subunits to assemble into homo- or heteromultimers, the existence of splice variants, and the expression of different regulatory subunits. These characteristics and the existence of very selective modulators make ion channels very attractive targets for therapy in a wide variety of pathologies. Some ion channels are already being targeted in the clinic while many more are being evaluated as novel drug targets in both clinical and preclinical studies. Advancing ion channel modulators from the bench to the clinic requires their assessment for safety and efficacy in animal models. While extrapolating results from one species to another is tempting, doing such without careful evaluation of the ion channels in different species presents a risk as the translation is not always straightforward. Here, we discuss differences between species in terms of ion channels expressed in selected tissues, differing roles of ion channels in some cell types, variable response to pharmacological agents, and human channelopathies that cannot fully be replicated in animal models.

Author(s): Ong, Seow Theng; Liu, Sanling; Bajaj, Saumya; Zhao, Yue; Tanner, Mark R; Chang, Shih Chieh; Zhang, Yong; Krishnarjuna, Bankala; Ng, Xuan Rui; Morales, Rodrigo AV; Ming, Wei Chen; Luo, Dahai; Patel, Dharmeshkumar; Yasmin, Sabina; Ng, Jeremy Jun Heng; Nguyen, Hai M; Abbas, El Sahili; Lescar, Julien; Patil, Rahul; Charman, Susan A; Robins, Edward; Goggi, Julian; Peng, Wen Tan; Sadasivam, Pragalath; Ramasamy, Boominathan; SV, Hartimath; Dhawan, Vikas; Bednenko, Janna; Colussi, Paul; Wulff, Heike; Zhang, Longhua; Pennington, Michael; Kuyucak, Serdar; Norton, Raymond S; Beeton, Christine; Tian, Changlin; Chandy, George

Little is known about the regulation of arthritis severity and joint damage in rheumatoid arthritis (RA). Fibroblast-like synoviocytes (FLS) have a central role in joint damage and express increased levels of the cation channel Trpv2. We aimed at determining the role of Trpv2 in arthritis. Treatment with Trpv2-specific agonists decreased the in vitro invasiveness of FLS from RA patients and arthritic rats and mice. Trpv2 stimulation suppressed IL-1β-induced expression of MMP-2 and MMP-3. Trpv2 agonists, including the new and more potent LER13, significantly reduced disease severity in KRN serum- and collagen-induced arthritis, and reduced histologic joint damage, synovial inflammation, and synovial blood vessel numbers suggesting anti-angiogenic activity. In this first in vivo use of Trpv2 agonists we discovered a new central role for Trpv2 in arthritis. These new compounds have the potential to become new therapies for RA and other diseases associated with inflammation, invasion, and angiogenesis.

Rotavirus (RV) nonstructural protein 4 (NSP4) is a virulence factor that disrupts cellular Ca 2+ homeostasis and plays multiple roles regulating RV replication and the pathophysiology of RV-induced diarrhea. Although its native oligomeric state is unclear, crystallographic studies of the coiled-coil domain (CCD) of NSP4 from two different strains suggest that it functions as a tetramer or a pentamer. While the CCD of simian strain SA11 NSP4 forms a tetramer that binds Ca 2+ at its core, the CCD of human strain ST3 forms a pentamer lacking the bound Ca 2+ despite the residues (E120 and Q123) that coordinate Ca 2+ binding being conserved. In these previous studies, while the tetramer crystallized at neutral pH, the pentamer crystallized at low pH, suggesting that preference for a particular oligomeric state is pH dependent and that pH could influence Ca 2+ binding. Here, we sought to examine if the CCD of NSP4 from a single RV strain can exist in two oligomeric states regulated by Ca 2+ or pH. Biochemical, biophysical, and crystallographic studies show that while the CCD of SA11 NSP4 exhibits high-affinity binding to Ca 2+ at neutral pH and forms a tetramer, it does not bind Ca 2+ at low pH and forms a pentamer, and the transition from tetramer to pentamer is reversible with pH. Mutational analysis shows that Ca 2+ binding is necessary for the tetramer formation, as an E120A mutant forms a pentamer. We propose that the structural plasticity of NSP4 regulated by pH and Ca 2+ may form a basis for its pleiotropic functions during RV replication. IMPORTANCE The nonstructural protein NSP4 of rotavirus is a multifunctional protein that plays an important role in virus replication, morphogenesis, and pathogenesis. Previous crystallography studies of the coiled-coil domain (CCD) of NSP4 from two different rotavirus strains showed two distinct oligomeric states, a Ca 2+ -bound tetrameric state and a Ca 2+ -free pentameric state. Whether NSP4 CCD from the same strain can exist in different oligomeric states and what factors might regulate its oligomeric preferences are not known. This study used a combination of biochemical, biophysical, and crystallography techniques and found that the NSP4 CCD can undergo a reversible transition from a Ca 2+ -bound tetramer to a Ca 2+ -free pentamer in response to changes in pH. From these studies, we hypothesize that this remarkable structural adaptability of the CCD forms a basis for the pleiotropic functional properties of NSP4.

Large-conductance calcium-activated potassium channel (KCa1.1; BK, Slo1, MaxiK, KCNMA1) is the predominant potassium channel expressed at the plasma membrane of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) isolated from the synovium of patients with RA. It is a critical regulator of RA-FLS migration and invasion and therefore represents an attractive target for the therapy of RA. However, the molecular mechanisms by which KCa1.1 regulates RA-FLS invasiveness have remained largely unknown. Here, we demonstrate that KCa1.1 regulates RA-FLS adhesion through controlling the plasma membrane expression and activation of β1 integrins, but not α4, α5, or α6 integrins. Blocking KCa1.1 disturbs calcium homeostasis, leading to the sustained phosphorylation of Akt and the recruitment of talin to β1 integrins. Interestingly, the pore-forming α subunit of KCa1.1 coimmunoprecipitates with β1 integrins, suggesting that this physical association underlies the functional interaction between these molecules. Together, these data outline a new signaling mechanism by which KCa1.1 regulates β1-integrin function and therefore invasiveness of RA-FLSs.-Tanner, M. R., Pennington, M. W., Laragione, T., Gulko, P. S., Beeton, C. KCa1.1 channels regulate β1-integrin function and cell adhesion in rheumatoid arthritis fibroblast-like synoviocytes.

Effector memory T lymphocytes (TEM cells) that lack expression of CCR7 are major drivers of inflammation in a number of autoimmune diseases, including multiple sclerosis and rheumatoid arthritis. The Kv1.3 potassium channel is a key regulator of CCR7- TEM cell activation. Blocking Kv1.3 inhibits TEM cell activation and attenuates inflammation in autoimmunity, and as such, Kv1.3 has emerged as a promising target for the treatment of TEM cell-mediated autoimmune diseases. The scorpion venom-derived peptide HsTX1 and its analog HsTX1[R14A] are potent Kv1.3 blockers and HsTX1[R14A] is selective for Kv1.3 over closely-related Kv1 channels. PEGylation of HsTX1[R14A] to create a Kv1.3 blocker with a long circulating half-life reduced its affinity but not its selectivity for Kv1.3, dramatically reduced its adsorption to inert surfaces, and enhanced its circulating half-life in rats. PEG-HsTX1[R14A] is equipotent to HsTX1[R14A] in preferential inhibition of human and rat CCR7- TEM cell proliferation, leaving CCR7+ naive and central memory T cells able to proliferate. It reduced inflammation in an active delayed-type hypersensitivity model and in the pristane-induced arthritis (PIA) model of rheumatoid arthritis (RA). Importantly, a single subcutaneous dose of PEG-HsTX1[R14A] reduced inflammation in PIA for a longer period of time than the non-PEGylated HsTX1[R14A]. Together, these data indicate that HsTX1[R14A] and PEG-HsTX1[R14A] are effective in a model of RA and are therefore potential therapeutics for TEM cell-mediated autoimmune diseases. PEG-HsTX1[R14A] has the additional advantages of reduced non-specific adsorption to inert surfaces and enhanced circulating half-life.

© FASEB. The voltage-gated potassium (Kv) 1.3 channel is widely regarded as a therapeutic target for immunomodulation in autoimmune diseases. ShK-186, a selective inhibitor of Kv1.3 channels, ameliorates autoimmune diseases in rodent models, and human phase 1 trials of this agent in healthy volunteers have been completed. In this study, we identified and characterized a large family of Stichodactyla helianthus toxin (ShK)-related peptides in parasitic worms. Based on phylogenetic analysis, 2 worm peptides were selected for study: AcK1, a 51-residue peptide expressed in the anterior secretory glands of the dog-infecting hookworm Ancylostoma caninum and the human-infecting hookworm Ancylostoma ceylanicum, and BmK1, the C-terminal domain of a metalloprotease from the filarial worm Brugia malayi. These peptides in solution adopt helical structures closely resembling that of ShK. At doses in the nanomolar-micromolar range, they block native Kv1.3 in human T cells and cloned Kv1.3 stably expressed in L929 mouse fibroblasts. They preferentially suppress the proliferation of rat CCR7-effector memory T cells without affecting naive and central memory subsets and inhibit the delayed-type hypersensitivity (DTH) response caused by skin-homing effector memory T cells in rats. Further, they suppress IFNγ production by human T lymphocytes. ShK-related peptides in parasitic worms may contribute to the potential beneficial effects of probiotic parasitic worm therapy in human autoimmune diseases. - Chhabra, S., Chang, S. C., Nguyen, H. M., Huq, R., Tanner, M. R., Londono, L. M., Estrada, R., Dhawan, V., Chauhan, S., Upadhyay, S. K., Gindin, M., Hotez, P. J., Valenzuela, J. G., Mohanty, B., Swarbrick, J. D., Wulff, H., Iadonato, S. P., Gutman, G. A., Beeton, C., Pennington, M. W., Norton, R. S., Chandy, K. G. Kv1.3 channelblocking immunomodulatory peptides from parasitic worms: implications for autoimmune diseases.

Spinal cord injury (SCI) results in devastating changes to almost all aspects of a patient's life. In addition to a permanent loss of sensory and motor function, males also will frequently exhibit a profound loss of fertility through poorly understood mechanisms. We demonstrate that SCI causes measureable pathology in the testis both acutely (24 h) and chronically up to 1.5 years post-injury, leading to loss in sperm motility and viability. SCI has been shown in humans and rats to induce leukocytospermia, with the presence of inflammatory cytokines, anti-sperm antibodies, and reactive oxygen species found within the ejaculate. Using messenger RNA and metabolomic assessments, we describe molecular and cellular changes that occur within the testis of adult rats over an acute to chronic time period. From 24 h, 72 h, 28 days, and 90 days post-SCI, the testis reveal a distinct time course of pathological events. The testis show an acute drop in normal sexual organ processes, including testosterone production, and establishment of a pro-inflammatory environment. This is followed by a subacute initiation of an innate immune response and loss of cell cycle regulation, possibly due to apoptosis within the seminiferous tubules. At 1.5 years post-SCI, there is a chronic low level immune response as evidenced by an elevation in T cells. These data suggest that SCI elicits a wide range of pathological processes within the testes, the actions of which are not restricted to the acute phase of injury but rather extend chronically, potentially through the lifetime of the subject. The multiplicity of these pathological events suggest a single therapeutic intervention is unlikely to be successful.

Autoimmune diseases mediated by a type of white blood cell—T lymphocytes—are currently treated using mainly broad-spectrum immunosuppressants that can lead to adverse side effects. Antioxidants represent an alternative approach for therapy of autoimmune disorders; however, dietary antioxidants are insufficient to play this role. Antioxidant carbon nanoparticles scavenge reactive oxygen species (ROS) with higher efficacy than dietary and endogenous antioxidants. Furthermore, the affinity of carbon nanoparticles for specific cell types represents an emerging tactic for cell-targeted therapy. Here, we report that nontoxic poly(ethylene glycol)-functionalized hydrophilic carbon clusters (PEG-HCCs), known scavengers of the ROS superoxide (O2•−) and hydroxyl radical, are preferentially internalized by T lymphocytes over other splenic immune cells. We use this selectivity to inhibit T cell activation without affecting major functions of macrophages, antigen-presenting cells that are crucial for T cell activation. We also demonstrate the in vivo effectiveness of PEG-HCCs in reducing T lymphocyte-mediated inflammation in delayed-type hypersensitivity and in experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. Our results suggest the preferential targeting of PEG-HCCs to T lymphocytes as a novel approach for T lymphocyte immunomodulation in autoimmune diseases without affecting other immune cells.

Fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA-FLS) contribute to joint inflammation and damage characteristic of the disease. RA-FLS express KCa1.1 (BK, Slo1, MaxiK, KCNMA1) as their major plasma membrane potassium channel. Blocking KCa1.1 reduces the invasive phenotype of RA-FLS and attenuates disease severity in animal models of RA. This channel has therefore emerged as a promising therapeutic target in RA. However, the pore-forming α subunit of KCa1.1 is widely distributed in the body, and blocking it induces severe side effects, thus limiting its value as a therapeutic target. On the other hand, KCa1.1 channels can also contain different accessory subunits with restricted tissue distribution that regulate channel kinetics and pharmacology. Identification of the regulatory subunits of KCa1.1 expressed by RA-FLS may therefore provide the opportunity for generating a selective target for RA treatment.Highly invasive RA-FLS were isolated from patients with RA, and FLS from patients with osteoarthritis (OA) were used as minimally invasive controls. The β subunit expression by FLS was assessed by quantitative reverse transcription polymerase chain reactions, Western blotting, and patch-clamp electrophysiology combined with pharmacological agents. FLS were sorted by flow cytometry on the basis of their CD44 expression level for comparison of their invasiveness and with their expression of KCa1.1 α and β subunits. β1 and β3 subunit expression was reduced with small interfering RNA (siRNA) to assess their specific role in KCa1.1α expression and function and in FLS invasiveness.We identified functional β1 and β3b regulatory subunits in RA-FLS. KCa1.1 β3b subunits were expressed by 70 % of the cells and were associated with highly invasive CD44(high) RA-FLS, whereas minimally invasive CD44(low) RA-FLS and OA-FLS expressed either β1 subunit. Furthermore, we found that silencing the β3 but not the β1 subunit with siRNA reduced KCa1.1 channel density at the plasma membrane of RA-FLS and inhibited RA-FLS invasiveness.Our findings suggest the KCa1.1 channel composed of α and β3b subunits as an attractive target for the therapy of RA.

Allergic asthma is a chronic inflammatory disease of the airways. Of the different lower airway-infiltrating immune cells that participate in asthma, T lymphocytes that produce Th2 cytokines play important roles in pathogenesis. These T cells are mainly fully differentiated CCR7(-) effector memory T (TEM) cells. Targeting TEM cells without affecting CCR7(+) naïve and central memory (TCM) cells has the potential of treating TEM-mediated diseases, such as asthma, without inducing generalized immunosuppression. The voltage-gated KV1.3 potassium channel is a target for preferential inhibition of TEM cells. Here, we investigated the effects of ShK-186, a selective KV1.3 channel blocker, for the treatment of asthma. A significant proportion of T lymphocytes in the lower airways of subjects with asthma expressed high levels of KV1.3 channels. ShK-186 inhibited the allergen-induced activation of peripheral blood T cells from those subjects. Immunization of F344 rats against ovalbumin followed by intranasal challenges with ovalbumin induced airway hyper-reactivity, which was reduced by the administration of ShK-186. ShK-186 also reduced total immune infiltrates in the bronchoalveolar lavage and number of infiltrating lymphocytes, eosinophils, and neutrophils assessed by differential counts. Rats with the ovalbumin-induced model of asthma had elevated levels of the Th2 cytokines IL-4, IL-5, and IL-13 measured by ELISA in their bronchoalveolar lavage fluids. ShK-186 administration reduced levels of IL-4 and IL-5 and induced an increase in the production of IL-10. Finally, ShK-186 inhibited the proliferation of lung-infiltrating ovalbumin-specific T cells. Our results suggest that KV1.3 channels represent effective targets for the treatment of allergic asthma.

HsTX1 toxin, from the scorpion Heterometrus spinnifer, is a 34-residue, C-terminally amidated peptide cross-linked by four disulfide bridges. Here we describe new HsTX1 analogues with an Ala, Phe, Val or Abu substitution at position 14. Complexes of HsTX1 with the voltage-gated potassium channels Kv1.3 and Kv1.1 were created using docking and molecular dynamics simulations, then umbrella sampling simulations were performed to construct the potential of mean force (PMF) of the ligand and calculate the corresponding binding free energy for the most stable configuration. The PMF method predicted that the R14A mutation in HsTX1 would yield a > 2 kcal/mol gain for the Kv1.3/Kv1.1 selectivity free energy relative to the wild-type peptide. Functional assays confirmed the predicted selectivity gain for HsTX1[R14A] and HsTX1[R14Abu], with an affinity for Kv1.3 in the low picomolar range and a selectivity of more than 2,000-fold for Kv1.3 over Kv1.1. This remarkable potency and selectivity for Kv1.3, which is significantly up-regulated in activated effector memory cells in humans, suggest that these analogues represent valuable leads in the development of therapeutics for autoimmune diseases.

Myoblasts are mononucleated precursors of myofibers; they persist in mature skeletal muscles for growth and regeneration post injury. During myotonic dystrophy type 1 (DM1), a complex autosomal-dominant neuromuscular disease, the differentiation of skeletal myoblasts into functional myotubes is impaired, resulting in muscle wasting and weakness. The mechanisms leading to this altered differentiation are not fully understood. Here, we demonstrate that the calcium- and voltage-dependent potassium channel, KCa1.1 (BK, Slo1, KCNMA1), regulates myoblast proliferation, migration, and fusion. We also show a loss of plasma membrane expression of the pore-forming α subunit of KCa1.1 in DM1 myoblasts. Inhibiting the function of KCa1.1 in healthy myoblasts induced an increase in cytosolic calcium levels and altered nuclear factor kappa B (NFκB) levels without affecting cell survival. In these normal cells, KCa1.1 block resulted in enhanced proliferation and decreased matrix metalloproteinase secretion, migration, and myotube fusion, phenotypes all observed in DM1 myoblasts and associated with disease pathogenesis. In contrast, introducing functional KCa1.1 α-subunits into DM1 myoblasts normalized their proliferation and rescued expression of the late myogenic marker Mef2. Our results identify KCa1.1 channels as crucial regulators of skeletal myogenesis and suggest these channels as novel therapeutic targets in DM1.

Rheumatoid arthritis (RA) is a chronic autoimmune disease that mainly affects synovial joints, resulting in cartilage and bone degradation. Current therapies for RA typically focus on suppressing the immune response, although resident joint cells known as fibroblast-like synoviocytes (FLS) are responsible for many of the pathogenic features of RA. In normal joints, FLS line the capsule and function to maintain the extracellular matrix and to lubricate the joint. However, FLS in RA (RA-FLS) develop an invasive phenotype tightly correlated with joint damage and release proteases and pro-angiogenic and pro-inflammatory growth factors. Due to their pathogenic nature, understanding how to regulate RA-FLS activity could provide the basis for novel therapeutics for RA that would bypass the need for immunosuppressants.We have found that the KCa1.1 channels are involved in many of the pathogenic features of RA-FLS. KCa1.1 is up-regulated in RA-FLS and localizes on the leading edge of the plasma membrane. Blocking KCa1.1 ex vivo inhibits cellular migration and invasion, along with the production of VEGF, IL-8, and MMP-2. This inhibition in cellular motility agrees with our finding that blocking KCa1.1 inhibits the formation of lamellipodia and interferes with integrin regulation in RA-FLS. These changes in phenotype are likely due to a calcium transient that forms as a result of KCa1.1 block, as invasiveness of KCa1.1-blocked RA-FLS is rescued upon blocking CaV channels on the cell membrane. We have also found that blocking KCa1.1 with the small molecule paxilline significantly decreases clinical signs in two complementary rat models of RA.Our results point to KCa1.1 channels as a promising new target for RA therapy and open the possibility for treatments that would not induce immunosuppression.

Voltage-gated K+ channels (Kv) are responsible for myoblasts proliferation and differentiation by triggering changes in membrane potential and cell volume. Since individuals with myotonic dystrophy type 1 (DM1) display reduced myogenesis led by prolonged myoblasts proliferation and delayed myotubes fusion, we investigated the roles of K+ channels in primary human myoblasts obtained from DM1 patients and healthy volunteers. DM1 is an autosomal dominant neuromuscular disorder affecting 1 in 8000 people worldwide. It is the most common adult-onset muscular dystrophy and currently has no treatment. DM1 is characterized by muscle wasting and multi-system disorders.We have identified a switch in functional potassium channel expression from KCa1.1 to Kv1 channels when comparing myoblasts from healthy individuals to myoblasts from patients with DM1. We showed increase in Kv1.2 and Kv1.5 channels, and decrease in KCa1.1 channels in DM1 myoblasts at mRNA level by RT-PCR, at protein level by immunofluorescence, and at channel activity by patch-clamp technique. We hypothesized that this switch in K+ channels plays a role in the reduced myogenesis observed in patients with DM1, and that selective inhibition of Kv1 channels rescues the pathological features of DM1 in skeletal muscle.We show that pharmacological inhibition of Kv1 channels in DM1 myoblasts normalized proliferation, rescued matrix metalloproteinase-2 (MMP-2, a protease necessary for myotube fusion) production, and partially rescued myotube fusion shown as increase in fusion index. On the contrary, selective inhibition of KCa1.1 in normal myoblasts lowered MMP-2 production, impaired wound healing repair, and decreased myotubes formation. Therefore we conclude that loss of KCa1.1 and up-regulation of Kv1 channels in DM1 impairs early stage of myogenesis and can be partially rescued by modulating such K+ channels.

Background Fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA-FLS) contribute to joint inflammation and damage characteristic of the disease. RA-FLS express KCa1.1 (BK, Slo1, MaxiK, KCNMA1) as their major plasma membrane potassium channel. Blocking KCa1.1 reduces the invasive phenotype of RA-FLS and attenuates disease severity in animal models of RA. This channel has therefore emerged as a promising therapeutic target in RA. However, the pore-forming α subunit of KCa1.1 is widely distributed in the body, and blocking it induces severe side effects, thus limiting its value as a therapeutic target. On the other hand, KCa1.1 channels can also contain different accessory subunits with restricted tissue distribution that regulate channel kinetics and pharmacology. Identification of the regulatory subunits of KCa1.1 expressed by RA-FLS may therefore provide the opportunity for generating a selective target for RA treatment. Methods Highly invasive RA-FLS were isolated from patients with RA, and FLS from patients with osteoarthritis (OA) were used as minimally invasive controls. The β subunit expression by FLS was assessed by quantitative reverse transcription polymerase chain reactions, Western blotting, and patch-clamp electrophysiology combined with pharmacological agents. FLS were sorted by flow cytometry on the basis of their CD44 expression level for comparison of their invasiveness and with their expression of KCa1.1 α and β subunits. β1 and β3 subunit expression was reduced with small interfering RNA (siRNA) to assess their specific role in KCa1.1α expression and function and in FLS invasiveness. Results We identified functional β1 and β3b regulatory subunits in RA-FLS. KCa1.1 β3b subunits were expressed by 70 % of the cells and were associated with highly invasive CD44high RA-FLS, whereas minimally invasive CD44low RA-FLS and OA-FLS expressed either β1 subunit. Furthermore, we found that silencing the β3 but not the β1 subunit with siRNA reduced KCa1.1 channel density at the plasma membrane of RA-FLS and inhibited RA-FLS invasiveness. Conclusions Our findings suggest the KCa1.1 channel composed of α and β3b subunits as an attractive target for the therapy of RA.

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease attacking principally freely-moveable joints and affecting approximately 1.3 million in the US. Recently, joint-resident fibroblast-like synoviocytes in RA (RA-FLS) have been implicated in disease pathogenesis. We have shown that KCa1.1 is the predominant potassium channel expressed by RA-FLS and by FLS from the pristane-induced arthritis (PIA) rat model of RA. Blocking KCa1.1 with paxilline or iberiotoxin or reducing its expression with siRNA inhibited the production of pro-inflammatory cytokines, chemokines, and proteases, and the invasiveness of both RA- and PIA-FLS. In contrast, the over-expression of KCa1.1 increased the invasiveness of PIA-FLS and induced the invasiveness of healthy rat FLS. These data demonstrate a crucial role of KCa1.1 in regulating the aggressive behavior of FLS during RA.We induced two models of RA in rats, moderate PIA and severe complete Freund's adjuvant collagen-induced arthritis. Treatment with the small molecule KCa1.1 blocker paxilline, starting after onset of clinical signs, significantly reduced disease severity in both models. However, paxilline can cross the blood-brain barrier and block all variants of KCa1.1 throughout the body, thereby inducing side effects that preclude its use as a therapeutic for human use without significant modification. A strategy to target KCa1.1 on RA-FLS without side effects in other tissues involves the identification of the β and γ regulatory subunits of KCa1.1 in RA-FLS through qPCR, western blotting, and patch-clamp electrophysiology. This has the potential for the development of blockers that selectively target KCa1.1 on RA-FLS and do not enter the central nervous system.

Parasites have coexisted with their human hosts for thousands of years and are known mainly for their harmful disease-causing role in humans. However, probiotic worm therapy is beneficial in human autoimmune diseases, suggesting the existence of immunomodulators in parasitic worms. By screening a cDNA library and searching genome databases we identified a family of peptides in parasitic worms that share sequence similarity and evolutionary relatedness to potassium channel-blocking peptides secreted by venomous sea anemones. AcK1, a 51-residue secreted peptide of the hookworm Ancylostoma caninum, and BmK1, the C-terminal domain of a 413-residue zinc metalloprotease from the filarial worm Brugia malayi, share structural similarity to ShK and BgK peptides from sea anemones. These peptides block cloned and native human T-cell Kv1.3 channels at nanomolar to low micromolar concentrations. BmK2, an analog of BmK1, blocks Kv1.3 with an IC50 of 2 nM and exhibits >4000-fold selectivity for Kv1.3 over Kv1.1, Kv1.2, Kv1.6, Kv3.2, KCa3.1, K2P3.1. These peptides suppress proliferation of effector memory T cells that use Kv1.3 channels to regulate membrane potential, without affecting other T cell subsets that are not dependent on Kv1.3. They inhibit cytokine production and suppress the in vivo delayed type hypersensitivity response. Our results provide a mechanistic basis for pro-biotic worm therapy in human autoimmune disease, and suggest that these or related peptides and proteins could supplant the need for worm therapy.