Welcome to KodaKoda's Weekly Immunology News, your go-to source for the latest discoveries in immunology and microbiology. I'm your host, and today we have a packed episode covering some truly fascinating new research published this week. From the gut to the brain, from tuberculosis to cancer, and even into the world of climate-driven disease outbreaks, there is a lot to cover. So let's dive right in.
We are starting in the gut, and this one is really exciting for anyone interested in how our intestines protect us from the microscopic world around us. Published on August 14th in Nature Immunology, a paper titled Peyer's patch M cells organize an epithelial niche that sustains group 3 innate lymphoid cells and IL-22 comes to us from Wang H J Cao and colleagues at The University of Queensland Frazer Institute in Woolloongabba, Queensland, Australia.
Now, Peyer's patches are small clusters of immune tissue in the lining of the small intestine, and they are packed with specialized cells that help the gut immune system do its job. One of those specialized cell types is called microfold cells, or M cells for short. We have known for a while that M cells help the immune system by grabbing antigens, which are basically foreign particles or molecules, from the gut contents and shuttling them across the intestinal lining to trigger adaptive immunity. But what this new paper shows is that M cells are doing a whole lot more than just that.
The researchers found that Peyer's patch M cells are organizing what they call an epithelial niche, essentially a carefully arranged physical and chemical environment within the dome epithelium, the part of the intestinal lining that sits right over the Peyer's patch. This niche acts as a kind of home base for group 3 innate lymphoid cells, which we call ILC3s. These are immune cells that are fast-acting defenders of mucosal surfaces, and they are major producers of a cytokine called IL-22, which is critical for maintaining the gut barrier. The M cells are essentially telling the ILC3s where to go, helping them settle in, multiply, and get to work making IL-22.
The team also found that a protein called SPI-B was required specifically in epithelial cells, not in blood-forming immune cells, to support intestinal immunoglobulin A responses and to build this niche. And when they did single-cell profiling of SPI-B-positive epithelial cells, they discovered something surprising: M cells are not a uniform population. They are highly heterogeneous, meaning they show different genetic activity depending on the tissue they are in and even what pathogen they have encountered.
Using elegant tools including subset-specific genetic manipulation and whole-mount imaging, they showed that the positioning of ILC3s within Peyer's patches depends on a molecule called CCR6, which acts as a kind of GPS signal telling cells where to go. And a signaling pair called RANK and RANKL was required to regulate ILC3 homeostasis, meaning how many of these cells are maintained in the tissue.
Altogether, this work reframes how we think about M cells. They are not just passive transporters of antigens. They are active organizers of innate immune responses, coordinating cell positioning, proliferation, and cytokine production to keep the mucosal barrier robust and healthy. A beautiful piece of biology.
Staying in the world of innate and adaptive immune coordination, let us move to the next paper, which deals with a topic that has become incredibly relevant in the post-pandemic world: how our immune systems respond to mutating viruses and whether vaccines are keeping up. This study is titled Potent type-specific de novo antibodies complement broadly reactive imprinted antibodies in immune responses to SARS-CoV-2 variants, published on August 14th in Nature Immunology. The first author is Timothy S Johnston from the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health in Bethesda, Maryland.
This paper tackles a phenomenon called original antigenic sin or immune imprinting. Here is the core idea: when you first encounter a virus or get vaccinated against it, your immune system builds a strong memory. Then when you encounter a related but slightly different version of that virus, your immune system tends to lean heavily on that old memory rather than building a fresh response tailored to the new variant. This is called immune imprinting, and it has been a major concern with both influenza and SARS-CoV-2.
But here is the question this team asked: what exactly is happening with the fresh, new responses that do get generated against new variants? Those are called de novo responses, meaning genuinely new immune responses, not just recalled memories. To find out, the researchers isolated and characterized hundreds of monoclonal antibodies from people who had been exposed to SARS-CoV-2 multiple times, starting with the ancestral strain and then encountering newer variants.
What they found was that the de novo antibodies, the genuinely new ones triggered by variant exposures, were quite distinct from the recalled ancestral antibodies. They used different V D J gene combinations, which are the genetic building blocks that shape antibody structure, and those combinations were closer to the germline sequence, meaning they were less mutated, suggesting they came from immune cells that had not been through much prior selection. And importantly, these de novo antibodies were particularly potent: they could neutralize even future variants and they targeted different parts of the receptor binding domain on the virus, compared to the cross-reactive recalled antibodies.
However, and this is a key finding, when people got the updated 2024 to 2025 booster vaccine, the immune response was still predominantly driven by those ancestral cross-reactive antibodies. The recalled memory still dominated. But the takeaway here is not that the new antibodies don't matter. It is that both types, the recalled broad responses and the new specific ones, work together in a complementary way. And updated boosters help amplify both. The researchers argue this underscores the importance of keeping vaccines updated to match circulating variants, even if the old memories do dominate the response.
Now let us move to a topic that affects over a million lives every year: tuberculosis. This next paper, published on August 14th in Cell Host and Microbe, is titled Strong sustained type I IFN signaling acts cell intrinsically to impair IFNgamma responses and cause tuberculosis susceptibility. The first author is Stefan A Fattinger from the Division of Immunology and Molecular Medicine at the University of California, Berkeley.
Mycobacterium tuberculosis, the bacterium that causes TB, kills more than one million people annually. And yet most people who are infected never get sick. So what separates those who succumb from those who do not? One major clue that researchers have been pursuing is the role of type I interferons, which are signaling proteins that the immune system uses to fight viruses but that seem to actually worsen TB outcomes. The big unanswered question has been: how exactly do type I interferons make things worse?
This paper provides a really clear and elegant answer. The team showed that when macrophages, the immune cells that engulf and try to destroy TB bacteria, experience high and sustained levels of type I interferon signaling, their ability to respond to IFNgamma becomes impaired. IFNgamma is a different type of interferon that is absolutely critical for controlling TB. Normally, IFNgamma would activate macrophages to kill the bacteria. But when type I IFN signaling is running too hot for too long, it specifically blunts the IFNgamma response in those same infected macrophages. And this happens in a cell-intrinsic way, meaning it is happening within each individual infected cell, not just through general immune suppression across the body.
The researchers also identified a recently described molecule called RESIST, which stands for regulated stimulator of interferon via stabilization of transcript, a positive regulator of type I IFN production. When they genetically eliminated RESIST, they specifically got rid of that high and sustained type I IFN response. And here is what is exciting: doing so fully restored IFNgamma signaling and actually rescued mice from tuberculosis susceptibility, without disrupting normal baseline type I IFN responses, which you need for other immune functions. This points toward RESIST as a very attractive potential therapeutic target.
Let us now move to the brain. The next paper is from Cell, published on August 14th, titled Brain perivascular macrophages regulate endothelial cell function via a cMAF-dependent transcriptional program in mouse and human. The first author is Simone Brioschi, affiliated with the Department of Pathology and Immunology at Washington University School of Medicine in Saint Louis and also the Center for Neuroimmunology and Glial Biology at the University of Texas Health Science Center in Houston.
Perivascular macrophages are immune cells that live right alongside the blood vessels of the brain. They are known to play important roles in brain health, but the molecular programs controlling what they do, and how they do it, have been poorly understood. Using single-cell multi-omics combined with functional experiments in living animals, the team identified a transcription factor called cMAF, which stands for cellular musculoaponeurotic fibrosarcoma oncogene, as the master regulator of brain perivascular macrophages.
When they deleted cMAF specifically in these cells, the macrophages lost their normal identity. And functionally, cMAF turned out to drive the expression of insulin-like growth factor 1, or IGF1, in perivascular macrophages, which then signals to endothelial cells, the cells lining the blood vessels. Without cMAF, the cerebral arteries showed transcriptional changes that affected vascular function. Interestingly, cMAF also emerged as the dominant transcription factor for human perivascular macrophages, suggesting this program is conserved between mice and people, which is always an important finding for translational relevance.
The paper also has compelling findings about Alzheimer's disease. In human AD brain tissue, perivascular macrophages upregulate cMAF and IGF1, apparently in an attempt to enhance communication with blood vessel cells and preserve vascular function. But in people who carry the APOE4 gene variant, a major genetic risk factor for Alzheimer's, this compensatory response is lost. The team also found an uncharacterized polymorphism in the cMAF gene that appears protective against Alzheimer's disease. This is a rich and multifaceted paper that opens up new directions for thinking about how brain-resident immune cells protect vascular and neuronal health.
Next up, we have a wonderful review published in Science Immunology on August 14th titled Regulation of inflammation by oxidized lipids, from Marco Di Gioia at the Division of Immunology and Division of Gastroenterology at Harvard Medical School and Boston Children's Hospital in Boston, Massachusetts.
This review brings together a field that might not always get the spotlight it deserves: the role of lipids in inflammation. Specifically, lipids that have been oxidized, meaning altered by oxygen-related chemistry. The authors walk us through how polyunsaturated fatty acids, cholesterol, and cholesterol intermediates can be enzymatically oxidized to produce signaling molecules that regulate tissue homeostasis and immunity. But they also discuss nonenzymatic oxidation, which happens spontaneously under conditions of oxidative stress, generating oxidized phospholipids called oxPLs.
These oxPLs accumulate during inflammation and have wide-ranging effects on cellular metabolism, immune cell functions, and even cell fate, meaning whether cells live, die, or change their identity. The review highlights what the authors call the double-edged nature of oxPLs: when they are produced transiently, they can trigger protective immune responses. But when they accumulate over time, they sustain inflammation and contribute to tissue damage. The review also discusses how oxPLs are involved in cell death programs, immune cell activation, and stromal cell functions, processes that are critically relevant to cancer biology. If you have ever wondered how lipid biology connects to your immune system, this review is a great entry point.
Moving along, we have another Science Immunology paper from August 14th titled Fusion of IgG antibodies to albumin inhibits transport across the placenta. The first author is Jeannette Nilsen from the Precision Immunotherapy Alliance at the University of Oslo in Norway.
This paper addresses a real clinical challenge. IgG antibodies are the backbone of many modern therapeutics for cancer, autoimmune diseases, and migraine. But they are actively transported across the placenta via a receptor called the neonatal Fc receptor, or FcRn, which means pregnant patients receiving these therapies can unintentionally expose their fetuses to the antibody. That is a significant problem.
The team tested a clever solution: fusing IgG antibodies to albumin, which is a major blood protein. FcRn binds both IgG and albumin, and one key role of FcRn is to give both of these molecules their long lifespans in the blood. But the researchers showed in mouse models and in an ex vivo human placental perfusion system that while albumin does bind FcRn, albumin itself is not transported to the fetus, neither in mice nor across human placental tissue. And when they fused IgG to albumin, that fusion drastically reduced transplacental transport in both models, while still maintaining the long plasma half-life that makes these drugs useful. They also tested antibody fragments fused to engineered albumin with enhanced FcRn binding and saw similarly minimal fetal exposure.
As a proof of concept, they used a mouse model of fetal and neonatal alloimmune thrombocytopenia, a condition where maternal antibodies attack fetal platelets. Fusing the therapeutic antibody to albumin reduced fetal antibody transfer and reduced thrombocytopenia in the offspring. This is a promising strategy for making biologics safer to use during pregnancy.
The third Science Immunology paper this week comes from a team at Institut Curie in Paris, and it is titled A dendritic cell autophagy-neutrophil axis limits intratumoral STING immunotherapy, published August 14th, first author Adriana Loverre.
The cGAS-STING pathway is a major innate immune sensing system that detects unusual DNA in the cell, triggering an immune response and making tumors more visible to the immune system. STING agonists, which are molecules that activate this pathway, have shown powerful effects in preclinical lab models. But in human clinical trials, they have repeatedly underperformed. This paper digs into why.
The team used viruslike particles to deliver the endogenous STING ligand cGAMP directly into tumors in mice. This approach preferentially activated STING in dendritic cells and led to priming of circulating tumor-specific T cells. Interestingly, they found that type I interferon signaling, which is what most people assume is the main effector of STING activation, was actually dispensable for tumor control in this system. Instead, dendritic cell autophagy, the process by which cells degrade and recycle their own components, was critically required for generating circulating antitumor CD8 T cells and for regulating baseline neutrophil levels in lymph nodes.
When cGAMP was delivered via the viruslike particles, it disrupted this regulation and caused an accumulation of neutrophils in the tumors and in the draining lymph nodes. And those neutrophils, rather than helping, were actually suppressing the antitumor response. Depleting neutrophils enhanced tumor control, with mechanisms involving neutrophil elastase and the immune checkpoint molecule programmed cell death 1 ligand 1. This is a really important finding for the field because it identifies defective dendritic cell autophagy and neutrophil-mediated immunosuppression as the key barriers to intratumoral STING immunotherapy, pointing toward new combination strategies that could be tested clinically.
Now let us shift gears to something at the intersection of ecology, climate science, and infectious disease. From Science Advances, published August 14th, a paper titled Drought dynamics explain once in a century yellow fever virus outbreak in Brazil with implications for climate change. The first author is Jamie M Caldwell from the High Meadows Environmental Institute at Princeton University.
This is a fascinating study about a yellow fever outbreak in Brazil that broke into an urban area for the first time in nearly a century, and it happened to coincide with an equally rare drought. We tend to associate mosquito-borne diseases with excess rainfall because wet conditions support mosquito breeding. But this team asked a really counterintuitive question: could drought also drive disease transmission?
Their hypothesis was that drought conditions pushed forest-dwelling mosquitoes and nonhuman primates toward the city in search of water. And those mosquitoes, trying to avoid drying out through a process called desiccation, were biting more frequently. Using a dynamical mathematical model of yellow fever virus transmission, they tested this and found that both of those behavioral changes, the animals moving toward the city and the mosquitoes biting more often, were necessary to explain the timing and scale of the outbreak. Without incorporating both behavioral shifts, the model could not reproduce what actually happened.
They also found that a combination of vector control, conservation measures, and vaccination all contributed to ending the outbreak, with vaccination having the strongest effect. Given that droughts are projected to become more frequent in this region of Brazil under climate change, the findings are a warning: climate-driven disease risk is not just about flooding and more mosquitoes. Drought can also create the conditions for explosive outbreaks, and sustained multifaceted interventions are going to be essential.
We have a few more papers to cover. From Science Advances, also on August 14th, there is a paper on a very clever diagnostic technology titled Ingestible probes for breath-based monitoring of drug-metabolizing activity from the microbiome, from Vishal A Manickam at the Wallace H Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University in Atlanta.
The gut microbiome contains enzymes that can alter how drugs behave in the body. One of the most important of these is called beta-glucuronidase, or GUS, which can cause drug toxicity by reactivating drug metabolites in the gut. Measuring GUS activity in a patient is not easy. These researchers developed an ingestible probe, essentially a pill you can swallow, that senses GUS activity and produces a breath signal as a readout. The probe travels through the gastrointestinal tract intact until it reaches the large intestine where the microbiome lives. There, GUS cleaves the probe and releases volatile reporters that are quickly exhaled. The breath signal can then be measured by mass spectrometry, giving a near real-time readout of GUS activity. In mouse studies, signals were detected in animals with GUS-expressing microbiomes but were absent in mice whose microbiomes had been depleted, confirming the specificity. Repeated dosing allowed the team to track dynamic changes in GUS activity over time. This is a noninvasive and elegant approach that could have real implications for personalizing drug therapy based on an individual's microbiome.
Also from Science Advances on August 14th, a paper titled Multimodal profiling of pro-inflammatory protease activity identifies caspase-1 as a target for lung cancer interception, from Cathy S Wang at the Department of Biological Engineering at Massachusetts Institute of Technology.
This paper connects inflammation to lung cancer in a really actionable way. There has already been clinical evidence that blocking interleukin-1 beta, a major inflammatory cytokine, can reduce lung cancer incidence. But how IL-1 beta gets activated in early tumors and what role it plays in the tumor microenvironment has not been fully clear. The team developed activity-based sensors and nanosensors to probe inflammation in a mouse model of inflammatory lung cancer. Their tools revealed elevated caspase-1 expression and activity in tumors. Caspase-1 is the enzyme that cleaves and activates IL-1 beta, and finding it highly active in early tumors was a key result. When they combined IL-1 beta blockade with caspase-1 inhibition in a preclinical trial, they saw significant reduction in lung cancer development, including complete prevention of tumor formation in nearly 20 percent of mice. This suggests caspase-1 is a translational target worth investigating further for cancer interception strategies.
We also have a fascinating structural biology and cell death paper from Science Advances on August 14th titled Mechanism and plasticity of primitive pyroptosis, from Zhi Su at Guangxi University in Nanning, China. The paper explores how pyroptosis, a proinflammatory form of cell death, works in primitive organisms. Pyroptosis is executed by gasdermin proteins, which punch holes called pores in cell membranes. The team characterized primitive gasdermin variants from a bacterium called Runella zeae and a fungus called Podospora anserina, solved high-resolution cryo-electron microscopy structures of the pores they form, and showed that despite forming very different pore sizes and arrangements, both can be activated by proteolytic cleavage. They also explored whether these primitive pores could be engineered to fight bacterial and fungal pathogens. The structures revealed provide a window into the evolutionary origins of cell death programs that are now central to human immunity.
From Science Advances, published August 14th, a paper looking at immune development in the skin titled Distinct postnatal trajectories of mouse dendritic epidermal T cells and Langerhans cells independent of microbiota, from David Obwegs at the University of Freiburg, Germany. Using immunophenotyping and single-cell transcriptomics, the team mapped how two key skin immune populations develop from late embryonic life through adulthood. They found that Langerhans cell maturation does not depend on the canonical gamma delta dendritic epidermal T cells and is also independent of microbial colonization, a result confirmed in germ-free mice. Comparative analysis with human skin revealed partially conserved programs, adding to our understanding of how the skin immune system is established.
From Science Advances on August 14th, a paper titled Nuclear RSK1 mediates interferon-gamma-induced proinflammatory activation in human primary macrophages and humanized mice, from Keishi Nihira at Brigham and Women's Hospital and Harvard Medical School in Boston. Using quantitative proteomics to monitor nuclear protein translocation in human macrophages stimulated with IFNgamma, the team identified RSK1, a ribosomal protein kinase, as a key nuclear mediator of macrophage activation. IFNgamma stimulation promotes RSK1 phosphorylation through JAK signaling, which in turn phosphorylates STAT1, a well-known inflammatory transcription factor. Silencing RSK1 blunted the secretion of proinflammatory chemokines in human macrophages, and RSK1-deficient human leukocytes showed altered IFNgamma responses in humanized mice. This positions RSK1 as a potential therapeutic target in inflammatory diseases.
From Cell Reports on August 14th, a paper titled Lung epithelial endothelin-1 drives iron dysregulation and skeletal injury after SARS-CoV-2 infection, from Junguo Ni at Hong Kong Polytechnic University and the Guizhou Provincial Center for Disease Control and Prevention. This paper uncovers a mechanism explaining post-COVID musculoskeletal problems, identifying a lung-joint axis driven by elevated endothelin-1 in alveolar type II cells following SARS-CoV-2 infection. Using single-cell RNA sequencing, histopathology, and animal models, the team showed that high ET-1 disrupts iron homeostasis, leading to iron accumulation that damages cartilage and growth plates. Silencing ET-1 in lung epithelial cells reduced iron overload, and the FDA-approved drug macitentan, an endothelin receptor antagonist, protected infected hamsters from joint damage. A clinically actionable finding for long-COVID complications.
Also from Cell Reports on August 14th, a paper titled TTN positive macrophages are enriched in the human choroid plexus in Alzheimer's disease, from Sagar Bhatta at Yale School of Medicine. The choroid plexus is a structure in the brain that produces cerebrospinal fluid and contributes to immune surveillance. Using single-nucleus RNA sequencing and spatial transcriptomics, the team built a high-resolution cellular atlas of the adult human choroid plexus and identified a novel macrophage subset expressing the giant protein TTN. In Alzheimer's disease, TTN positive macrophages expand and show increased senescence signatures, and the broader cellular landscape of the choroid plexus is extensively remodeled. This adds new detail to our understanding of neuroinflammation in Alzheimer's disease.
And finally from the Proceedings of the National Academy of Sciences, published August 18th, a paper titled Inflammatory kinase TBK1 suppresses homologous recombination DNA repair to sensitize tumors to chemotherapy, from Wei Zhou at the School of Life Science and Technology at Harbin Institute of Technology in China. This paper explores how TBK1, a kinase best known for its role in innate immune signaling, also impairs homologous recombination, a major DNA repair pathway in cancer cells. By suppressing this repair mechanism, TBK1 makes tumors more vulnerable to chemotherapy. Note that the abstract was truncated so we do not have the full details, but this is a compelling intersection of inflammatory signaling and cancer therapeutics.
Now, before we wrap up, I want to briefly mention a number of papers published this week that did not come with full abstracts but are worth noting.
In Nature Immunology on August 14th, a paper titled TIF1 gamma holds the line against regulatory T cell plasticity from Fotini Gounari at the Mayo Clinic Arizona explores how the transcription factor TIF1 gamma maintains the stability of regulatory T cells, which are essential for preventing autoimmunity.
Also in Nature Immunology on August 14th, a commentary titled Immune imprinting in a changing world from Daniel M Altmann at Imperial College London discusses how the phenomenon of immune imprinting shapes responses to emerging variants, a nice companion piece to the Johnston et al paper we covered earlier.
In Nature on August 14th, there is an author correction for a paper titled Cell intrinsic immunity spreads to bystander cells via the intercellular transfer of cGAMP, originally from Andrea Ablasser at the University of Bonn. And another author correction in Nature on August 13th for a paper on the structural mechanism of cGAS inhibition by the nucleosome, from Ganesh R Pathare at the Friedrich Miescher Institute for Biomedical Research in Basel.
Nature also published two news-style pieces this week. On August 13th, an article asking will the mRNA flu shot work better than a regular seasonal one, with science reporting by Dhruv Shenai. And on August 12th, a piece about the scientific case against splitting up the MMR vaccine, by Kaia Glickman, responding to recent political discussions in the United States.
In Nature Medicine on August 13th, a policy-oriented article titled Regulatory fragmentation as the hidden barrier to regional vaccine sovereignty, from Mnotho Ngcobo at the University of Louisville, examines how fragmented regulatory frameworks across regions undermine countries' ability to produce their own vaccines.
From Nature Communications on August 13th, an author correction to a hepatitis C vaccine design paper on native-like soluble E1E2 glycoprotein heterodimers on self-assembling protein nanoparticles, from Linling He at the Scripps Research Institute.
From the Proceedings of the National Academy of Sciences on August 18th, there is a correction for a paper by Chi et al on caspase-8 and inflammasome activation in acute glaucoma.
From Nature on August 11th, a research news article about HIV vaccines guiding rare immune cells to produce broadly neutralizing antibodies, from S Gnanakaran.
From Gastroenterology on August 11th, a paper titled A humanized celiac disease mouse model reflects histologic and immune effects of transglutaminase inhibition in patients, from Aline Pesi at the University Medical Center in Mainz, Germany. This one is particularly interesting for the field of autoimmune gut disease and therapeutic development.
And from Cell on August 11th, an article titled Reshaping Antibody Diversity from Feng Wang, as well as an author correction in Nature Immunology on August 10th to a paper titled Regulatory T cells function in established systemic inflammation and reverse fatal autoimmunity, originally from Wei Hu at the Howard Hughes Medical Institute.
And that brings us to the end of this week's episode of KodaKoda's Weekly Immunology News. It has been an incredible week for the field, with breakthroughs spanning mucosal immunity, vaccine biology, tuberculosis, neuroinflammation, cancer immunotherapy, and climate-driven infectious disease. Thank you so much for listening. If you found this episode helpful, please share it with a friend or colleague who loves science. We will be back next week with more discoveries fresh from the journals. Until then, stay curious and take care.