Wenner-Gren Foundations

Abstract All animals age. However, aging is a heterogeneous process and individual organisms age differently. Moreover, within the same organism, cells or organs do not age at the same time or speed. For instance, although neurodegeneration is a key trait of aging, neurological symptoms normally manifest long after multiple indicators of aging in peripheral tissues. The genetic determinants of aging remain poorly understood. Mutations in leucine-rich repeat kinase 2 (LRRK2) are major genetic risk factors for Parkinson’s disease (PD). By analyzing PD patients and mice with LRRK2 gain of function mutation (LRRK2 GoF ), we demonstrate that PD is an accelerated aging disease characterized by systemic low-grade STING-dependent inflammation (inflammaging) that first manifests in the periphery then disrupts the blood brain barrier and progresses to the brain resulting in neurodegeneration. Mechanistically, we demonstrate that a primary consequence of aging or Lrrk2 GoF is endolysosomal decline. This results in the cytosolic build-up of extraneous self-DNA and subsequent shedding of DNA-containing extracellular vesicles thereby triggering the cGAS- STING pathway cell-intrinsically and intercellularly in distant host cells. This study unveils the cGAS-STING pathway and LRRK2 GoF as key determinants and potential targets for preventive or therapeutic strategies against accelerated aging, inflammaging and neurodegeneration.

Toxoplasma gondii chronically infects the central nervous system (CNS), but the mechanisms enabling its traversal of the blood-brain barrier (BBB) remain unclear. Here, we investigated BBB penetration using brain endothelial spheroids and cerebral tissue-derived organoids that recapitulate three-dimensional barrier features. We show that T. gondii tachyzoites efficiently colonize spheroids, without detectable barrier disruption or obligatory parasite replication. Following direct transmigration, tachyzoites invaded and replicated within deeper cell layers. Type I strains (RH, CPS) exhibited higher colonization efficiency than type II strains (PRU, ME49), independent of replication. In contrast, when spheroids were exposed to T. gondii-infected dendritic cells (DCs), both strain types were transported similarly into deep cellular layers. Infected DCs adopted an amoeboid-like migratory phenotype that facilitated parasite transport and subsequent dissemination after egress. Colonization was attenuated by ICAM-1 blockade or heparin treatment, while the parasite effector GRA15, despite modulating DC-endothelial adhesion, did not significantly impact intratissue migration. In contrast, deletion of the effector TgWIP markedly reduced the number of infected DCs entering the spheroids. Similar colonization dynamics were observed in murine cerebral organoids. Collectively, these findings highlight spheroid and organoid models as robust systems for uncovering the cellular and molecular mechanisms underlying T. gondii BBB traversal and CNS colonization.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00018-025-06035-7.

Many bacteria have complex pleomorphic lifecycles -a feature particularly widespread across the class Alphaproteobacteria of the phylum Pseudomonadota. While research on bacteria with pleomorphic lifecycles has for many years focused on the dimorphic bacterium Caulobacter crescentus, more recent studies on less established alphaproteobacterial model bacteria have uncovered diverse variations of bacterial pleomorphism. Here, we provide an overview of the diversity and evolution of the complex lifecycles among dimorphic Alphaproteobacteriaand highlight the presence of analogous lifecycles in unrelated bacteria across the bacterial domain. We discuss the commonalities and differences between dimorphic species, as well as the selective pressures that might have sculpted their lifecycles. Furthermore, we exemplify how the cellular appendages common among dimorphic Alphaproteobacteria, referred to as prosthecae, are not inherently linked to dimorphism. Finally, we highlight how the large diversity of dimorphic Alphaproteobacteria can be used to shed light onto the evolution of bacterial cell biology.

Trypanosoma cruzi is the etiological agent of Chagas' disease, a neglected tropical disease affecting six to eight million people worldwide. The infection has a chronic progression, with cardiac, digestive, or neurological pathologies typically manifesting 10 or more years after the initial infection. However, during the first weeks of infection, the parasite colonizes nearly all tissues and organs of the mammalian host. The circulating trypomastigote stage is responsible for this systemic dissemination. After extravasation, trypomastigotes migrate through the interstitial matrix of target tissues to locate and invade nucleated cells. Although the mechanisms underlying this process are not yet fully elucidated, parasite migration and motility in a three-dimensional environment play crucial roles.This chapter discusses the technical aspects of monitoring trypomastigote motility using 3D collagen-I matrices and time-lapse microscopy. It begins with a straightforward method for isolating collagen-I (Col-I) from rat tail tendons. Next, a protocol is provided to assess the correct co-polymerization of Col-I and trypomastigotes into a three-dimensional structure using confocal reflection microscopy. Finally, we describe the monitoring and analysis of trypomastigote motility patterns through time-lapse microscopy. This protocol enables the real-time observation of live trypomastigotes, facilitating the study of their dynamics within a three-dimensional extracellular environment that closely mimics in vivo conditions. Additionally, the model allows the analysis of trypomastigote trajectories, movement types, and speed. Our protocol provides a valuable platform for investigating T. cruzi trypomastigote motility, offering insights into their dissemination strategies and potential interactions with host tissues.

Type 2 diabetes (T2D) represents a growing global health challenge, with its prevalence and associated metabolic complications rising sharply over the past two decades. Although the pathogenesis of T2D is complex and influenced by lifestyle and (micro)environmental factors, genetic constituents have been considered major predisposing factors. Recent literature shows significant individual variations in both the progression of T2D and the efficacy of antidiabetic drugs. These individual variations are expected to emanate from the inherent genetic make-up and potential epigenetic modifications by environmental factors. It has been proposed that altered metabolism (including cellular bioenergetic mechanisms) provides protection from T2D. Moreover, several researchers have proposed that proteins regulating cellular bioenergetics, for example, involved in adaptive thermogenesis, represent good targets to counter T2D. Therefore, we thoroughly searched the literature on genetic variability associated with T2D in this review. We could only find genes involved in (1) insulin secretion (INS, PDX1, ABCC8, KCNJ11, KCNQ1, CDKAL1, IGFBP2) and (2) cellular bioenergetics in insulin-responsive tissues (INSR, IRS, AKT, SLC2A4, TBC1D4, PPP1R3A, LEP, LEPR, ADIPOQ, TCF7L2, PPAR-γ, SLC30A8). Specific attention is given to diverse ethnic populations, in particular Indian subgroups where these genetic factors may display clearer association to T2D. By emphasizing genetic predispositions, this review highlights the lack of studies on the genetic association of cellular bioenergetics proteins in T2D pathogenesis. It also underscores the potential for early detection, personalized management, and the development of targeted therapies for individuals with T2D across different genetic profiles.

BackgroundNeisseria meningitidis asymptomatically colonizes the nasopharyngeal mucosa, but occasionally, the bacteria disseminate to cause sepsis and meningitis. In the epithelial cell layer, the pathogen co-colonizes with other resident inhabitants, such as Lactobacillus species that are part of the nasopharyngeal-oral microbiota. In this study, we investigated the interaction between lactobacilli and meningococci.ResultsWe demonstrated that Lactobacillus crispatus strain MV24 can co-aggregate with meningococci, whereas all other Lactobacillus strains tested did not co-aggregate. The binding ability of L. crispatus was not strain- or serogroup-specific but was dependent on the ability of meningococci to form microcolonies. The finding that N. meningitidis lacking pili did not co-aggregate with L. crispatus, but that hyperpiliated N. meningitidis exhibited strong co-aggregation, led us to examine the interaction between purified meningococcal pili and lactobacilli. Our results showed that L. crispatus MV24 can bind to purified meningococcal Class I and II pili, explaining the aggregative clusters observed under the microscope. Co-aggregation with L. crispatus disrupted microcolony formation, and increased the killing of meningococci by LL-37, hBD2 and cephalexin. Further, co-aggregation had the added effect of impeding motility.ConclusionN. meningitidis pili bind to L. crispatus, which interferes with the meningococcal microcolonies and increases sensitivity to antimicrobial agents. Taken together, our findings suggest that L. crispatus MV24 may have a beneficial effect on the host through co-aggregating with meningococci.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12866-025-04201-2.

Determination of the capacity for adaptive nonshivering thermogenesis is of importance in a broad range of metabolic studies, including investigations of the effects of cold acclimation, preparation for and arousal from hibernation, diet-induced thermogenesis, and metabolic balance. Adaptive nonshivering thermogenesis is understood as being mediated through the activity of uncoupling-protein-1 (UCP1). Norepinephrine and the β3-adrenergic agonist CL-316,423 have long been used to assess the capacity for nonshivering thermogenesis in intact mammals. Here we examine whether in mice (Mus musculus Linnaeus, 1758) the acclimation-induced thermogenic effect of the β3-adrenergic agent CL-316,243 underestimates true adrenergically (norepinephrine-)induced capacity for nonshivering thermogenesis, whether anesthesia partly masks true thermogenic capacity, and to what degree adrenergic responses are proportional to and dependent upon the presence of UCP1. All conditions yielded significant differences between cold- and thermoneutral-acclimated mice and between wildtype and UCP1-KO mice. The cold-acclimation-recruited thermogenesis elicited by CL-316,243 was not statistically significantly lower than that elicited by norepinephrine, and the level of cold acclimation-recruited adrenergically induced thermogenesis was not statistically significantly affected by anesthesia. The absence of UCP1 practically eliminated cold acclimation-recruited adrenergically induced thermogenesis. Cold acclimation-recruited adrenergically-induced thermogenesis is positively associated with UCP1 amount. Qualitatively and quantitatively comparable results are thus obtained irrespective of which adrenergic activator is used.

Microbial translocation across the blood-brain barrier (BBB) is a prerequisite for colonization of the central nervous system. The obligate intracellular parasite Toxoplasma gondii chronically infects the brain parenchyma of humans and animals, in a remarkably stealthy fashion. We investigated the mechanisms of BBB traversal by T. gondii (genotypes I, II, III) and T. gondii-infected leukocytes, using intracarotid arterial delivery into the cerebral circulation of mice. Unexpectedly, parasitized dendritic cells (DCs) and other peripheral blood mononuclear cells were found to persistently sequester within cortical capillaries. Post-replicative egress of T. gondii from sequestered DCs was followed by rapid parasite localization within cortical neurons. Infection-induced microvascular inflammation dramatically elevated the sequestration of parasitized DCs, while treatments targeting the ICAM-1/CD18 leukocyte adhesion axis with blocking antibodies strongly reverted sequestration. The parasite effectors TgWIP and GRA15, known to promote leukocyte hypermigration and inflammatory activation, further increased both the capillary sequestration of infected DCs and cerebral parasite loads in a strain-dependent manner. These findings reveal that the sequestration of parasitized leukocytes in cortical capillaries, with subsequent BBB traversal following parasite egress, provides a mechanism for T. gondii’s rapid access to cortical neurons during primary infection.