Journal of Experimental Medicine最新文献

Embryonic hematopoietic cells develop in the fetal liver (FL), surrounded by diverse non-hematopoietic stromal cells. However, the spatial organization and cytokine production patterns of the stroma during FL development remain poorly understood. Here, we characterized and mapped the hematopoietic and stromal cell populations at early (E12.5-14.5) FL stages, revealing that while hepatoblasts were the primary source of hematopoietic growth factors, other stromal cells-including mesenchymal, mesothelial, and endothelial cells-also contributed to this signaling network. Using a dedicated image analysis pipeline, we quantified cell distances to tissue structures and defined neighbor relationships, uncovering that different hematopoietic progenitors exhibit distinct preferences for neighboring stromal cells and show developmental changes in spatial distribution. Notably, our data suggest that the sub-mesothelium region plays a prominent role in early fetal hematopoiesis. This approach offers a valuable tool for studying complex cellular interactions in biological systems, providing new insights into hematopoietic niche organization during development.

IKKα, encoded by CHUK, is crucial in the non-canonical NF-κB pathway and part of the IKK complex activating the canonical pathway alongside IKKβ. The absence of IKKα causes fetal encasement syndrome in humans, fatal in utero, while an impaired IKKα-NIK interaction was reported in a single patient and causes combined immunodeficiency. Here, we describe compound heterozygous variants in the kinase domain of IKKα in a female patient with hypogammaglobulinemia, recurrent lung infections, and Hay-Wells syndrome-like features. We showed that both variants were loss-of-function. Non-canonical NF-κB activation was profoundly diminished in stromal and immune cells while the canonical pathway was unexpectedly partially impaired. Reintroducing wt CHUK restored non-canonical NF-κB activation. The patient had neutralizing autoantibodies against type I IFN, akin to non-canonical NF-κB pathway deficiencies. Thus, this is the first case of biallelic CHUK mutations disrupting IKKα kinase function, broadening non-canonical NF-κB defect understanding, and suggesting IKKα's role in canonical NF-κB target gene expression in humans.

Professor Cindy Ma heads the Human Immune Disorders Laboratory at the Garvan Institute of Medical Research. She is a member of the Garvan Faculty, holds a conjoint appointment with UNSW Sydney (School of Clinical Medicine, Faculty of Medicine and Health), and is an NHMRC of Australia Investigator Grant Fellow (L1). Her research interests lie in the study of human diseases of the immune system such as primary immunodeficiencies due to inborn errors of immunity (IEI), resulting from disease-causing monogenic germline variants. Another area of research her laboratory is perusing is the pathways that cause severe allergies and atopic diseases such as atopic dermatitis and food anaphylaxis.

T helper 17 (Th17) cells are effector cells that mediate inflammatory responses to bacterial and fungal pathogens. While the cytokine signaling inputs required to generate Th17s are established, less is known about intracellular pathways that drive Th17 differentiation. Our previously published phosphoproteomic screen identifies that PIKFYVE, a lipid kinase that generates the phosphatidylinositol PtdIns(3,5)P2, is activated during Th17 differentiation. Herein, we discovered that PIKFYVE regulates kinase and transcription factor networks to promote Th17 differentiation. As a specific example, PtdIns(3,5)P2 directly stimulates mTORC1 kinase activity to promote cell division and differentiation pathways. Furthermore, PIKFYVE promotes STAT3 phosphorylation, which is required for Th17 differentiation. Chemical inhibition or CD4-specific deletion of PIKFYVE reduces Th17 differentiation and autoimmune pathology in the experimental autoimmune encephalomyelitis murine model of multiple sclerosis. Our findings identify molecular mechanisms by which PIKFYVE promotes Th17 differentiation and suggest that PIKFYVE is a potential therapeutic target in Th17-driven autoimmune diseases.

Dysfunctional lymphatic drainage from the central nervous system (CNS) has been linked to neuroinflammatory and neurodegenerative disorders, but our understanding of the lymphatic contribution to CNS fluid autoregulation remains limited. Here, we studied forces that drive the outflow of the cerebrospinal fluid (CSF) into the deep and superficial cervical lymph nodes (dcLN and scLN) and tested how the blockade of lymphatic networks affects CNS fluid homeostasis. Outflow to the dcLN occurred spontaneously in the absence of lymphatic pumping and was coupled to intracranial pressure (ICP), whereas scLN drainage was driven by pumping. Impaired dcLN drainage led to elevated CSF outflow resistance and delayed CSF-to-blood efflux despite the recruitment of the nasal-to-scLN pathway. Fluid regulation was better compensated after scLN obstruction. The dcLN pathway exhibited steady, consistent drainage across conditions, while the nasal-to-scLN pathway was dynamically activated to mitigate perturbances. These findings highlight the complex physiology of CSF homeostasis and lay the groundwork for future studies aimed at assessing and modulating CNS lymphatic function.

Invariant natural killer T (iNKT) cells are unconventional T cells recognizing lipid antigens in a CD1d-restricted manner. Among these lipid antigens, α-galactosylceramide (α-GalCer), which was originally identified in marine sponges, is the most potent antigen. Although the presence of α-anomeric hexosylceramide and microbiota-derived branched α-GalCer is reported, antigenic α-GalCer has not been identified in mammals. Here, we developed a high-resolution separation and detection system, supercritical fluid chromatography tandem mass spectrometry (SFC/MS/MS), that can discriminate hexosylceramide diastereomers (α-GalCer, α-GlcCer, β-GalCer, or β-GlcCer). The B16 melanoma tumor cell line does not activate iNKT cells; however, ectopic expression of CD1d was sufficient to activate iNKT cells without adding antigens. B16 melanoma was unlikely to generate iNKT cell antigens; instead, antigen activity was detected in cell culture serum. Activity-based purification and SFC/MS/MS identified dihydrosphingosine-based saturated α-GalCer as an antigenic component in serum, bile, and lymphoid tissues. These results show the first evidence for the presence of potent antigenic α-GalCer in mammals.

Despite the established use of immune checkpoint inhibitors (ICIs) to treat non-small cell lung cancer (NSCLC), only a subset of patients benefit from treatment and ∼50% of patients whose tumors respond eventually develop acquired resistance (AR). To identify novel drivers of AR, we generated murine Msh2 knock-out (KO) lung tumors that initially responded but eventually developed AR to anti-PD-1, alone or in combination with anti-CTLA-4. Resistant tumors harbored decreased infiltrating T cells and reduced cancer cell-intrinsic MHC-I and MHC-II levels, yet remained responsive to IFNγ. Resistant tumors contained extensive regions of hypoxia, and a hypoxia signature derived from single-cell transcriptional profiling of resistant cancer cells was associated with decreased progression-free survival in a cohort of NSCLC patients treated with anti-PD-1/PD-L1 therapy. Targeting hypoxic tumor regions using a hypoxia-activated pro-drug delayed AR to ICIs in murine Msh2 KO tumors. Thus, this work provides a rationale for targeting tumor metabolic features, such as hypoxia, in combination with immune checkpoint inhibition.

Group 3 innate lymphoid cells (ILC3s) are important for maintaining gut homeostasis. Upon stimulation, ILC3s can rapidly produce cytokines to protect against infections and colitis. However, the regulation of ILC3 quick response is still unclear. Here, we find that eIF6 aggregates with Nsun2 and cytokine mRNA in ILC3s at steady state, which inhibits the methyltransferase activity of Nsun2 and the nuclear export of cytokine mRNA, resulting in the nuclear reservation of cytokine mRNA. Upon stimulation, phosphorylated p38α phosphorylates eIF6, which in turn releases Nsun2 activity, and promotes the nuclear export of cytokine mRNA and rapid cytokine production. Genetic disruption of p38α, Nsun2, or eIF6 in ILC3s influences the mRNA nuclear export and protein expression of the protective cytokines, thus leading to increased susceptibility to colitis. Together, our data identify a crucial role of the p38α-eIF6-Nsun2 axis in regulating rapid ILC3 immune response at the posttranscriptional level, which is critical for gut homeostasis maintenance and protection against gut inflammation.

Tumor-associated neutrophils (TANs) are heterogeneous; thus, their roles in tumor development could vary depending on the cancer type. Here, we showed that TANs affect metabolic dysfunction-associated steatohepatitis hepatocellular carcinoma (MASH-related HCC) more than viral-associated HCC. We attributed this difference to the predominance of SiglecFhi TANs in MASH-related HCC tumors. Linoleic acid and GM-CSF, which are commonly elevated in the MASH-related HCC microenvironment, fostered the development of this c-Myc-driven TAN subset. Through TGFβ secretion, SiglecFhi TANs promoted HCC stemness, proliferation, and migration. Importantly, SiglecFhi TANs supported immune evasion by directly suppressing the antigen presentation machinery of tumor cells. SiglecFhi TAN removal increased the immunogenicity of a MASH-related HCC model and sensitized it to immunotherapy. Likewise, a high SiglecFhi TAN signature was associated with poor prognosis and immunotherapy resistance in HCC patients. Overall, our study highlights the importance of understanding TAN heterogeneity in cancer to improve therapeutic development.

The importance of calcium (Ca2+) as a second messenger in T cell signaling is exemplified by genetic deficiencies of STIM1 and ORAI1, which abolish store-operated Ca2+ entry (SOCE) resulting in combined immunodeficiency (CID). We report five unrelated patients with de novo missense variants in ITPR3, encoding a subunit of the inositol 1,4,5-trisphosphate receptor (IP3R), which forms a Ca2+ channel in the endoplasmic reticulum (ER) membrane responsible for the release of ER Ca2+ required to trigger SOCE, and for Ca2+ transfer to other organelles. The patients presented with CID, abnormal T cell Ca2+ homeostasis, incompletely penetrant ectodermal dysplasia, and multisystem disease. Their predominant T cell immunodeficiency is characterized by significant T cell lymphopenia, defects in late stages of thymic T cell development, and impaired function of peripheral T cells, including inadequate NF-κB- and NFAT-mediated, proliferative, and metabolic responses to activation. Pathogenicity is not due to haploinsufficiency, rather ITPR3 protein variants interfere with IP3R channel function leading to depletion of ER Ca2+ stores and blunted SOCE in T cells.