Post-mating sexual cannibalism occurs as a regular element of mating behaviour in a number of spider species. Frequencies of cannibalism, however, are highly variable between and within species. In ...Argiope bruennichi, males apparently differ in their motivation to escape a female attack but causes for this variability are unknown. We observed that the probability of sexual cannibalism is positively correlated with male age, i.e. the number of days that passed between male maturation and copulation. The mating season in this species is short with 3-4 wk and males mostly mature days before the females, whose maturation phase is longer. Consequently, as the season progresses, the availability of virgin females increases, quickly reaches a peak and then rapidly declines. In addition, the age of still unmated males increases with the season and both of these factors can potentially affect the degree of sexual cannibalism. To separate these factors, males were collected in their penultimate stage and kept until mating either with or without contact to female pheromones. Thereby, we experimentally manipulated the male's perception of female presence. Within each treatment, we formed three male age groups: (1) 2-6 d, (2) 12-16 d and (3) 22-28 d. Our results demonstrate that the probability of cannibalism was independent of male age but was explained by the treatment of males: males exposed to virgin female pheromones were significantly more likely to be cannibalised than males that were kept without female pheromones. This suggests that males change their reproductive strategy according to perceived mating prospects.
Male genitalia are among the fastest evolving morphological characters, and at a general level sexual selection seems to be involved. But experimental determination of the functions of many ...remarkable genitalic elaborations is very rare. Here we present the first study to address experimentally the adaptive function of a male genital structure that is not involved in sperm transfer. Females of the orb-weaving spider Argiope bruennichi are sexually cannibalistic and polyandrous. The male increases his paternity by obstructing the female's insemination duct with a fragment of his complex genitalia (embolus tip). We manipulated males by detaching another species-specific structure, the median apophysis spur, and found that the spur promotes breakage of the embolus tip inside the female duct, but does not affect the probability and duration of copulation. These data are novel in that they suggest that a genitalic structure which does not transfer sperm nevertheless evolved in the context of sperm competition.
Experimental autoimmune encephalomyelitis (EAE) is a relevant animal model for the human demyelinating inflammatory disorder of the central nervous system (CNS), multiple sclerosis (MS). Induction of ...EAE by adoptive transfer allows studying the role of the donor T lymphocyte in disease pathogenesis. It has been challenging to reliably induce adoptive transfer EAE in C57BL/6 (H-2b) mice. The goal of this study was to develop a reproducible and high yield protocol for adoptive transfer EAE in C57BL/6 mice. A step-wise experimental approach permitted us to develop a protocol that resulted in a consistent relatively high disease incidence of ~70% in recipient mice. Donor mice were immunized with myelin oligodendrocyte glycoprotein (MOG)p35-55 in complete Freund's adjuvant (CFA) followed by pertussis toxin (PT). Only lymph node cells (LNC) isolated at day 12 post immunization, and restimulated in vitro for 72 hours with 10 μg/mL of MOGp35-55 and 0.5 ng/mL of interleukin-12 (IL-12) were able to transfer disease. The ability of LNC to transfer disease was associated with the presence of inflammatory infiltrates in the CNS at day 12. Interferon gamma (IFNγ) was produced at comparable levels in cell cultures prepared from mice at both day 6 and day 12 post immunization. By contrast, there was a trend towards a negative association between IL-17 and disease susceptibility in our EAE model. The amount of GM-CSF secreted was significantly increased in the culture supernatants from cells collected at day 12 post immunization versus those collected at day 6 post-immunization. Activated CD4+ T cells present in the day 12 LNC cultures maintained expression of the transcription factor T-bet, which has been shown to regulate the expression of the IL-23 receptor. Also, there was an increased prevalence of MOGp35-55-specific CD4+ T cells in day 12 LNC after in vitro re-stimulation. In summary, encephalitogenic LNC that adoptively transfer EAE in C57BL/6 mice were not characterized by a single biomarker in our study, but by a composite of inflammatory markers. Our data further suggest that GM-CSF expression by CD4+ T cells regulated by IL-23 contributes to their encephalitogenicity in our EAE model.
Multiple sclerosis (MS) is a heterogeneous disease with respect to lesion pathology, course of disease, and treatment response. Imaging modalities are needed that allow better definition of MS ...lesions in vivo. The aim of this study was to establish an MRI- and PET/CT-based imaging modality and to evaluate approved and promising PET tracers in experimental autoimmune encephalomyelitis (EAE), the animal model of MS.
MRI and PET/CT scans were obtained in Dark agouti rats with EAE and healthy control rats. The PET tracers 2-(18)F-fluoro-2-deoxy-d-glucose ((18)F-FDG), 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT), and O-(2-(18)F-fluoro-ethyl)-l-tyrosine ((18)F-FET) were used as surrogate markers of glucose utilization, proliferative activity, and amino acid transport and protein biosynthesis. Immediately after the PET/CT scan, animals were sacrificed for autoradiography, histologic work-up, or RNA expression analysis.
EAE lesions were predominantly located in the spinal cord. With MRI, we were able to detect inflammatory lesions in diseased rats, which correlated well with inflammatory infiltrates as determined by histology. Increased (18)F-FDG uptake was observed in spinal cord lesions in all diseased rats. Further investigation by volume-of-interest analysis demonstrated a correlation between the density of histologically proven cellular infiltrates and the (18)F-FDG signal intensity in PET (F(DF=3) = 5.9, P = 0.001) and autoradiography (F(DF=3) = 4.2, P = 0.008). With (18)F-FET and (18)F-FLT, no definite uptake could be observed on PET scans, whereas autoradiography showed slight radiotracer accumulation in some lesions.
Spinal cord inflammatory lesions in the EAE model can be noninvasively visualized in vivo using MRI and (18)F-FDG PET/CT. Localized (18)F-FDG uptake correlates better with a histologically proven abundance of inflammatory cells as a critical marker of disease activity than MRI. Neither (18)F-FET nor (18)F-FLT seems to be a suitable marker for the in vivo detection of inflammatory lesions.
X‐linked adrenoleukodystrophy (X‐ALD) is the most common leukodystrophy. Despite intensive research in recent years, it remains unclear, what drives the different clinical disease courses. Due to ...this missing pathophysiological link, therapy for the childhood cerebral disease course of X‐ALD (CCALD) remains symptomatic; the allogenic hematopoietic stem cell transplantation or hematopoietic stem‐cell gene therapy is an option for early disease stages. The inclusion of dried blood spot (DBS) C26:0‐lysophosphatidylcholine to newborn screening in an increasing number of countries is leading to an increasing number of X‐ALD patients diagnosed at risk for CCALD. Current follow‐up in asymptomatic boys with X‐ALD requires repetitive cerebral MRIs under sedation. A reliable and easily accessible biomarker that predicts CCALD would therefore be of great value. Here we report the application of targeted metabolomics by AbsoluteIDQ p180‐Kit from Biocrates to search for suitable biomarkers in X‐ALD. LysoPC a C20:3 and lysoPC a C20:4 were identified as metabolites that indicate neuroinflammation after induction of experimental autoimmune encephalitis in the serum of Abcd1tm1Kds mice. Analysis of serum from X‐ALD patients also revealed different concentrations of these lipids at different disease stages. Further studies in a larger cohort of X‐ALD patient sera are needed to prove the diagnostic value of these lipids for use as early biomarkers for neuroinflammation in CCALD patients.
X-linked adrenoleukodystrophy (X-ALD) is the most common leukodystrophy. Despite intensive research in recent years, it remains unclear, what drives the different clinical disease courses. Due to ...this missing pathophysiological link, therapy for the childhood cerebral disease course of X-ALD (CCALD) remains symptomatic; the allogenic hematopoietic stem cell transplantation or hematopoietic stem-cell gene therapy is an option for early disease stages. The inclusion of dried blood spot (DBS) C26:0-lysophosphatidylcholine to newborn screening in an increasing number of countries is leading to an increasing number of X-ALD patients diagnosed at risk for CCALD. Current follow-up in asymptomatic boys with X-ALD requires repetitive cerebral MRIs under sedation. A reliable and easily accessible biomarker that predicts CCALD would therefore be of great value. Here we report the application of targeted metabolomics by AbsoluteIDQ p180-Kit from Biocrates to search for suitable biomarkers in X-ALD. LysoPC a C20:3 and lysoPC a C20:4 were identified as metabolites that indicate neuroinflammation after induction of experimental autoimmune encephalitis in the serum of Abcd1
mice. Analysis of serum from X-ALD patients also revealed different concentrations of these lipids at different disease stages. Further studies in a larger cohort of X-ALD patient sera are needed to prove the diagnostic value of these lipids for use as early biomarkers for neuroinflammation in CCALD patients.
X‐linked adrenoleukodystrophy (X‐ALD) and metachromatic leukodystrophy (MLD) are two relatively common examples of hereditary demyelinating diseases caused by a dysfunction of peroxisomal or ...lysosomal lipid degradation. In both conditions, accumulation of nondegraded lipids leads to the destruction of cerebral white matter. Because of their high lipid content, oligodendrocytes are considered key to the pathophysiology of these leukodystrophies. However, the response to allogeneic stem cell transplantation points to the relevance of cells related to the hematopoietic lineage. In the present study, we aimed to better characterize the pathogenetic role of microglia in the above‐mentioned diseases. Applying recently established microglia markers to human autopsy cases of X‐ALD and MLD we were able to delineate distinct lesion stages in evolving demyelinating lesions. The immune‐phenotype of microglia was altered already early in lesion evolution, and microglia loss preceded full‐blown myelin degeneration both in X‐ALD and MLD. DNA fragmentation indicating phagocyte death was observed in areas showing microglia loss. The morphology and dynamics of phagocyte decay differed between the diseases and between lesion stages, hinting at distinct pathways of programmed cell death. In summary, the present study shows an early and severe damage to microglia in the pathogenesis of X‐ALD and MLD. This hints at a central pathophysiologic role of these cells in the diseases and provides evidence for an ongoing transfer of toxic substrates primarily enriched in myelinating cells to microglia.
Main Points
Immune‐phenotyping of microglia allows a more precise assessment of lesion evolution in leukodystrophies.
Microglia cell death is a seminal early feature in X‐ALD and MLD.
Cell death pathways differ according to the diseases and lesion stages.
Remyelination capacity decreases with age in adult mice, but data comparing remyelination capacity after toxic demyelination in developing mice versus adult mice are not available. We treated ...3-week-old and adult C57BL/6 mice with cuprizone for 1 to 5 weeks and studied demyelination/remyelination and cellular reactions in the corpus callosum and motor cortex by histology, immunohistochemistry, and electron microscopy. We compared results between the 2 treated groups and age-matched controls. In juvenile mice, significant demyelination was detectable in the corpus callosum on Week 2 and in the motor cortex on Week 5. Oligodendrocyte loss, microglial activation, and acute axonal damage peaked on Week 2. Increased numbers of oligodendrocyte precursor cells were evident on Week 1, and remyelination was detectable on Week 3. Juvenile mice showed more rapid demyelination than adult mice, which may be related to greater vulnerability of oligodendrocytes, lower myelin content, or dose-dependent cuprizone effects. Earlier activation of microglia and proliferation of oligodendrocyte precursor cells probably contributed to accelerated remyelination and less pronounced axonal damage. Our data indicate that oligodendroglial regeneration and remyelination are enhanced in the maturing rodent brain compared with the young-adult rodent brain.
Cortical demyelination is a widely recognized hallmark of multiple sclerosis (MS) and correlate of disease progression and cognitive decline. The pathomechanisms initiating and driving gray matter ...damage are only incompletely understood. Here, we determined the infiltrating leukocyte subpopulations in 26 cortical demyelinated lesions of biopsied MS patients and assessed their contribution to cortical lesion formation in a newly developed mouse model. We find that conformation-specific anti-myelin antibodies contribute to cortical demyelination even in the absence of the classical complement pathway. T cells and natural killer cells are relevant for intracortical type 2 but dispensable for subpial type 3 lesions, whereas CCR2
+
monocytes are required for both. Depleting CCR2
+
monocytes in marmoset monkeys with experimental autoimmune encephalomyelitis using a novel humanized CCR2 targeting antibody translates into significantly less cortical demyelination and disease severity. We conclude that biologics depleting CCR2
+
monocytes might be attractive candidates for preventing cortical lesion formation and ameliorating disease progression in MS.
Multiple sclerosis (MS) is a chronic disease of the CNS that is characterized by inflammation, demyelination and axonal injury. Although the etiology of MS is still unknown, many findings point ...toward a central role for the immune system in the pathogenesis of the disease. This hypothesis is strongly supported by the beneficial effects of immunomodulatory and immunosuppressive therapy on disease activity. Over the past few years, substantial progress has been made in deciphering the immune response in MS. Although animal models have advanced our knowledge of basic mechanisms of immune responses in the CNS, recent studies have also highlighted the differences between MS and its animal equivalent, experimental autoimmune encephalomyelitis. New immunotherapeutic agents have been developed and evaluated in clinical trials. Here, we review current knowledge of the immunopathogenesis of MS and corresponding animal models of disease, and discuss new immunointerventional treatment strategies based on changing pathogenetic concepts.
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