The rockefeller university

Patients with systemic lupus erythematosus (SLE) are photosensitive, developing skin inflammation with even ambient ultraviolet radiation (UVR), and this cutaneous photosensitivity can be associated with UVR-induced flares of systemic disease, which can involve increased autoantibodies and further end-organ injury. Mechanistic insight into the link between the skin responses and autoimmunity is limited. Signals from skin are transmitted directly to the immune system via lymphatic vessels, and here we show evidence for potentiation of UVR-induced lymphatic flow dysfunction in SLE patients and murine models. Improving lymphatic flow by manual lymphatic drainage (MLD) or with a transgenic model with increased lymphatic vessels reduces both cutaneous inflammation and lymph node B and T cell responses, and long-term MLD reduces splenomegaly and titers of a number of autoantibodies. Mechanistically, improved flow restrains B cell responses in part by stimulating a lymph node fibroblastic reticular cell-monocyte axis. Our results point to lymphatic modulation of lymph node stromal function as a link between photosensitive skin responses and autoimmunity and as a therapeutic target in lupus, provide insight into mechanisms by which the skin state regulates draining lymph node function, and suggest the possibility of MLD as an accessible and cost-effective adjunct to add to ongoing medical therapies for lupus and related diseases.

Female sociosexual behaviors, essential for survival and reproduction, are modulated by ovarian hormones and triggered in the context of appropriate social cues. Here, we identify primary estrous-sensitive Cacna1h-expressing medial prefrontal cortex (mPFCCacna1h+) neurons that integrate hormonal states with recognition of potential mates to orchestrate these complex cognitive behaviors. Bidirectional manipulation of mPFCCacna1h+ neurons shifts opposite-sex-directed social behaviors between estrus and diestrus females via anterior hypothalamic outputs. In males, these neurons serve opposite functions compared with estrus females. Miniscope imaging reveals mixed representation of self-estrous states and social target sex in distinct mPFCCacna1h+ subpopulations, with biased encoding of opposite-sex cues in estrus females and males. Mechanistically, ovarian-hormone-induced Cacna1h upregulation enhances T-type rebound excitation after oxytocin inhibition, driving estrus-specific activity changes and the sexually dimorphic function of mPFCCacna1h+ neurons. These findings uncover a prefrontal circuit that integrates internal hormonal states and target-sex information to exert sexually bivalent top-down control over adaptive social behaviors.

The rate-limiting isozyme of de novo guanosine biosynthesis, IMPDH2, was identified as an essential gene in Merkel cell carcinoma (MCC) but the consequences of its functional disruption were unclear. Inhibition of IMPDH2 led to reduced MCC cell viability, independent of functional p53 or Merkel cell polyomavirus status, but dependent on depletion of guanylate nucleotides. In contrast to other cancer models, inhibition of IMPDH2 in MCC led to rapid ablation of nascent DNA synthesis and the onset of replication stress without a significant effect on total or ribosomal RNA biosynthesis. Combining IMPDH inhibitors with ataxia telangiectasia mutated and Rad3-related (ATR) inhibitors significantly increased levels of replication stress in vitro and reduced tumor growth in vivo. These findings support replication stress as the dominant consequence of IMPDH2 inhibition in MCC and, when combined with ATR inhibition, indicate a potential therapeutic strategy.

JGP study (Han et al. https://doi.org/10.1085/jgp.202413729) reveals that glycerol storage increases the titin-based stiffness of muscle fibers, suggesting that this commonly used method should be avoided by researchers interested in the passive properties of muscle.

Background: Recent single-cell studies indicated that IL-17-producing T cells (T17) have diverse subsets expressing IL-17A, IL-17F, or a combination in human psoriasis skin. However, it is unknown how T17 subsets are differently regulated by IL-23 versus IL-17A blockade. Objective: We sought to investigate how systemic monoclonal antibody injections blocking IL-23 versus IL-17A differently modify immune cell transcriptomes in human psoriasis skin. Methods: We analyzed a total of 93 human skin single-cell libraries, including 42 psoriasis pretreatment lesional skin, 25 psoriasis pretreatment nonlesional skin, 12 psoriasis posttreatment after IL-23 inhibition, 4 psoriasis posttreatment after IL-17A inhibition, and 10 control skin samples. ClinicalTrials.gov NCT04630652. Results: Of the six T17 subsets identified, an IL17A+IFNG+ subset and an IL17F+IL102 subset expressed the IL-23 receptor along with other inflammatory cytokines, and IL-23 inhibition downregulated these potentially pathogenic T17 subsets. In contrast, T17 cells expressing both IL-17A and IL-17F did not express the IL-23 receptor, and the percentage of this potentially nonpathogenic T17 subset increased after IL-23 inhibition. In addition, the expression of the IL-17-negative regulation genes, such as TNFAIP3, increased in myeloid cells more after IL-23 inhibition than after IL-17A inhibition. Conclusions: This study suggests multiple immune mechanisms of how IL-23 inhibition can modify the complex inflammatory environment present in psoriatic skin, highlighting the roles of specific T17 subsets in psoriasis development and background skin protection. (J Allergy Clin Immunol 2025;155:1898-912.)

The lack of T cells in tumors is a major hurdle to successful immune checkpoint therapy (ICT). Therefore, ther-apeutic strategies promoting T cell recruitment into tumors are warranted to improve the treatment efficacy. Here, we report that Fc-optimized anti-cytotoxic T lymphocyte antigen 4 (CTLA-4) antibodies are potent re-modelers of tumor vasculature that increase tumor-associated high endothelial venules (TA-HEVs), special-ized blood vessels supporting lymphocyte entry into tumors. Mechanistically, this effect is dependent on the Fc domain of anti-CTLA-4 antibodies and CD4+ T cells and involves interferon gamma (IFNy). Unexpectedly, we find that the human anti-CTLA-4 antibody ipilimumab fails to increase TA-HEVs in a humanized mouse model. However, increasing its Fc effector function rescues the modulation of TA-HEVs, promotes CD4+ and CD8+ T cell infiltration into tumors, and sensitizes recalcitrant tumors to programmed cell death protein 1 (PD-1) blockade. Our findings suggest that Fc-optimized anti-CTLA-4 antibodies could be used to repro-gram tumor vasculature in poorly immunogenic cold tumors and improve the efficacy of ICT.

PurposeIn the receptor organs of the inner ear, hair cells detect mechanical stimuli such as sounds and accelerations by deflection of their hair bundles. Myosin regulatory light chain (RLC) and non-muscle myosin II (NM2) are expressed at the apical surfaces of hair cells, and NM2 and the phosphorylation of RLC by myosin light chain kinase (MLCK) have earlier been shown to regulate the shapes of hair cells' apical surfaces in rodents. The aim of our study was to elucidate the function of myosin molecules on hair cell physiology.MethodsWe investigated the expression of NM2 and RLC in the bullfrog's saccule by immunostaining. Using NM2 and MLCK inhibitors, we measured the stiffness, spontaneous oscillation, and resting open probability of frog hair bundles. Six to ten saccules from pleural animals were used in each experiment. In addition, we recorded auditory brainstem responses in ten mice after transtympanic injection of an MLCK inhibitor.ResultsWe confirmed the expression of NM2A/B and MYL9 on the apical surfaces of hair cells and of NM2A and MYL12A in hair bundles. We found that NM2 and MLCK inhibitors reduce the stiffness of hair bundles from the bullfrog's saccule. Moreover, MLCK inhibition inhibits the spontaneous oscillation of hair bundles and increases the resting open probability of transduction channels. In addition, MLCK inhibition elevates hearing thresholds in mice.ConclusionWe conclude that NM2 and the phosphorylation of RLC modulate the physiological function of hair cells and thereby help to set the normal operating conditions of hair bundles.

Type III CRISPR-Cas systems defend against viral infection in prokaryotes by using an RNA-guided complex that recognizes foreign transcripts and synthesizes cyclic oligoadenylate (cOA) messengers to activate CRISPR-associated Rossmann-fold (CARF) immune effectors. In this study, we investigated a protein containing a CARF domain-fused Toll/interleukin-1 receptor (TIR) domain, Cat1. We found that Cat1 provides immunity by cleaving and depleting oxidized nicotinamide adenine dinucleotide (NAD+) molecules from the infected host, inducing a growth arrest that prevents viral propagation. Cat1 forms dimers that stack upon each other to generate long filaments that are maintained by bound cOA ligands, with stacked TIR domains forming the NAD+ cleavage catalytic sites. Furthermore, Cat1 filaments assemble into distinct trigonal and pentagonal networks that enhance NAD+ degradation. Cat1 presents an unprecedented chemistry and higher-order protein assembly for the CRISPR-Cas response.