Placenta-Expanded Stromal Cell Therapy in a Rodent Model of Simulated Weightlessness

Long duration spaceflight poses potential health risks to astronauts during flight and re-adaptation after return to Earth. There is an emerging need for NASA to provide successful and reliable therapeutics for long duration missions when capability for medical intervention will be limited. Clinically relevant, human placenta-derived therapeutic stromal cells (PLX-PAD) are a promising therapeutic alternative. We found that treatment of adult female mice with PLX-PAD near the onset of simulated weightlessness by hindlimb unloading (HU, 30 d) was well-tolerated and partially mitigated decrements caused by HU. Specifically, PLX-PAD treatment rescued HU-induced thymic atrophy, and mitigated HU-induced changes in percentages of circulating neutrophils, but did not rescue changes in the percentages of lymphocytes, monocytes, natural killer (NK) cells, T-cells and splenic atrophy. Further, PLX-PAD partially mitigated HU effects on the expression of select cytokines in the hippocampus. In contrast, PLX-PAD failed to protect bone and muscle from HU-induced effects, suggesting that the mechanisms which regulate the structure of these mechanosensitive tissues in response to disuse are discrete from those that regulate the immune- and central nervous system (CNS). These findings support the therapeutic potential of placenta-derived stromal cells for select physiological deficits during simulated spaceflight. Multiple countermeasures are likely needed for comprehensive protection from the deleterious effects of prolonged spaceflight.

Abstract TMP29: Mesenchymal Stromal Cell Administration Attenuates Post-Stroke Susceptibility to Spontaneous Infection Through Prevention of Caspase-1-Dependent Splenic Marginal Zone B Cell Death

Spontaneous infection is one of most common complications of acute ischemic stroke (AIS) and leads to increased mortality and morbidity in stroke patients. However, current interventions fail to improve clinical outcomes in these patients. Since stroke-induced immunodeficiency is thought to contribute to the risk of infections, we suppose mesenchymal stromal cells (MSCs) therapy, based on its potent immunomodulatory capacities, could be a potential solution to this problem. Here, we show MSCs administration successfully ameliorates post-stroke infections and reduces the mortality in mouse middle cerebral artery occlusion (MCAO) model of AIS. Additionally, the intravenously infused MSCs preferentially migrate to the spleen and mainly distribute around the marginal zone (MZ). These grafted MSCs rescue stroke-induced splenic atrophy, especially the marginal zone B (MZB) cells loss, a subset of innate-like lymphocytes localized in MZ. Using the CD19-deficient mice model lacking MZB cells, we found that MSCs transplantation could not reduce post-stroke infections or mortality in CD19 -/- mice, reconfirming MZB cells are indispensable for the immunoprotective effects of MSCs. In terms of mechanism, we demonstrate that MSCs attenuate caspase-1-dependent MZB cells death partially through direct mitochondrial transfer and subsequent inhibition of NLRP3 activation. Taken together, this study suggests MSCs administration alleviates post-stroke immunodepression and spontaneous infections via MZB cells protection.

Suppression of the Peripheral Immune System Limits the Central Immune Response Following Cuprizone-Feeding: Relevance to Modelling Multiple Sclerosis

Cuprizone (CPZ) preferentially affects oligodendrocytes (OLG), resulting in demyelination. To investigate whether central oligodendrocytosis and gliosis triggered an adaptive immune response, the impact of combining a standard (0.2%) or low (0.1%) dose of ingested CPZ with disruption of the blood brain barrier (BBB), using pertussis toxin (PT), was assessed in mice. 0.2% CPZ(±PT) for 5 weeks produced oligodendrocytosis, demyelination and gliosis plus marked splenic atrophy (37%) and reduced levels of CD4 (44%) and CD8 (61%). Conversely, 0.1% CPZ(±PT) produced a similar oligodendrocytosis, demyelination and gliosis but a smaller reduction in splenic CD4 (11%) and CD8 (14%) levels and no splenic atrophy. Long-term feeding of 0.1% CPZ(±PT) for 12 weeks produced similar reductions in CD4 (27%) and CD8 (43%), as well as splenic atrophy (33%), as seen with 0.2% CPZ(±PT) for 5 weeks. Collectively, these results suggest that 0.1% CPZ for 5 weeks may be a more promising model to study the ‘inside-out’ theory of Multiple Sclerosis (MS). However, neither CD4 nor CD8 were detected in the brain in CPZ±PT groups, indicating that CPZ-mediated suppression of peripheral immune organs is a major impediment to studying the ‘inside-out’ role of the adaptive immune system in this model over long time periods. Notably, CPZ(±PT)-feeding induced changes in the brain proteome related to the suppression of immune function, cellular metabolism, synaptic function and cellular structure/organization, indicating that demyelinating conditions, such as MS, can be initiated in the absence of adaptive immune system involvement.

Level-Specific Differences in Systemic Expression of Pro- and Anti-Inflammatory Cytokines and Chemokines after Spinal Cord Injury

While over half of all spinal cord injuries (SCIs) occur in the cervical region, the majority of preclinical studies have focused on models of thoracic injury. However, these two levels are anatomically distinct—with the cervical region possessing a greater vascular supply, grey-white matter ratio and sympathetic outflow relative to the thoracic region. As such, there exists a significant knowledge gap in the secondary pathology at these levels following SCI. In this study, we characterized the systemic plasma markers of inflammation over time (1, 3, 7, 14, 56 days post-SCI) after moderate-severe, clip-compression cervical and thoracic SCI in a rat model. Using high-throughput ELISA panels, we observed a clear level-specific difference in plasma levels of VEGF, leptin, IP10, IL18, GCSF, and fractalkine. Overall, cervical SCI had reduced expression of both pro- and anti-inflammatory proteins relative to thoracic SCI, likely due to sympathetic dysregulation associated with higher level SCIs. However, contrary to the literature, we did not observe level-dependent splenic atrophy with our incomplete SCI model. This is the first study to compare the systemic plasma-level changes following cervical and thoracic SCI using level-matched and time-matched controls. The results of this study provide the first evidence in support of level-targeted intervention and also challenge the phenomenon of high SCI-induced splenic atrophy in incomplete SCI models.

Level-specific differences in systemic expression of pro- and anti-inflammatory cytokines and chemokines after spinal cord injury

While over half of all spinal cord injuries (SCIs) occur in the cervical region, the majority of preclinical studies have focused on models of thoracic injury. However, these two levels are anatomically distinct—with the cervical region possessing a greater vascular supply, grey-white matter ratio and sympathetic outflow relative to the thoracic region. As such, there exists a significant knowledge gap in the secondary pathology at these levels following SCI. In this study, we characterized the systemic plasma markers of inflammation over time (1, 3, 7, 14, 56 days post-SCI) after moderate-severe, clip-compression cervical and thoracic SCI in the rat. Using high-throughput ELISA panels, we observed a clear level-specific difference in plasma levels of VEGF, leptin, IP10, IL18, GCSF, and fractalkine. Overall, cervical SCI had reduced expressions of both pro- and anti-inflammatory proteins relative to thoracic SCI, likely due to sympathetic dysregulation associated with higher level SCIs. However, contrary to the literature, we did not observe level-dependent splenic atrophy with our incomplete SCI model. This is the first study to compare the systemic plasma-level changes following cervical and thoracic SCI using level-matched and time-matched controls. The results of this study provide the first evidence in support of level-targeted intervention and also challenge the phenomenon of high SCI-induced splenic atrophy in incomplete SCI models.

Small Bowel Imaging in Celiac Disease

Background: Modern small bowel imaging techniques allow detailed depiction of small-intestinal abnormalities. The role of these techniques in the investigation of celiac disease is increasing, especially in patients with suspected complicated celiac disease. Key Messages: In general, there is no need for radiological small bowel imaging in uncomplicated celiac disease. It is however important that clinicians and radiologists are aware of certain specific radiological findings that may suggest celiac disease, especially since celiac disease is often not considered in adult patients, and small bowel radiology may be performed before specific tests for celiac disease. Radiological abnormalities can be observed with both conventional small bowel radiology studies, like small bowel follow-through or double-contrast small bowel enteroclysis, and newer modalities, like computed tomography or magnetic resonance enterography or enteroclysis. These signs include a decreased number of jejunal folds, an increased number of ileal folds, small bowel dilatation, wall thickening and intussusception. Extraintestinal abnormalities include mesenteric lymphadenopathy, vascular changes and splenic atrophy. Abnormalities congruent with refractory celiac disease type II include a severe decrease in jejunal folds, infiltration of the mesenteric fat and thickening of the small bowel wall. Additionally, a severely decreased splenic volume may indicate complicated celiac disease. Malignant complications of celiac disease, such as enteropathy-associated T-cell lymphoma and small-intestinal adenocarcinoma, can be reliably investigated with cross-sectional enteroclysis techniques. Conclusions: Small bowel imaging and especially cross-sectional enteroclysis techniques are important extensions to the diagnostic workup of clinicians involved in the care of patients with celiac disease, especially those with suspected complicated disease.