IL-10 Controls Early Microglial Phenotypes and Disease Onset in ALS Caused by Misfolded Superoxide Dismutase 1.

While reactive microgliosis is a hallmark of advanced stages of amyotrophic lateral sclerosis (ALS), the role of microglial cells in events initiating and/or precipitating disease onset is largely unknown. Here we provide novel in vivo evidence of a distinct adaptive shift in functional microglial phenotypes in preclinical stages of superoxide dismutase 1 (SOD1)-mutant-mediated disease. Using a mouse model for live imaging of microglial activation crossed with SOD1(G93A) and SOD1(G37R) mouse models, we discovered that the preonset phase of SOD1-mediated disease is characterized by development of distinct anti-inflammatory profile and attenuated innate immune/TLR2 responses to lipopolysaccharide (LPS) challenge. This microglial phenotype was associated with a 16-fold overexpression of anti-inflammatory cytokine IL-10 in baseline conditions followed by a 4.5-fold increase following LPS challenge. While infusion of IL-10R blocking antibody, initiated at day 60, caused a significant increase in markers of microglial activation and precipitated clinical onset of disease, a targeted overexpression of IL-10 in microglial cells, delivered via viral vectors expressed under CD11b promoter, significantly delayed disease onset and increased survival of SOD1(G93A) mice. We propose that the high IL-10 levels in resident microglia in early ALS represent a homeostatic and compensatory "adaptive immune escape" mechanism acting as a nonneuronal determinant of clinical onset of disease. Significance statement: We report here for the first time that changing the immune profile of brain microglia may significantly affect clinical onset and duration of disease in ALS models. We discovered that in presymptomatic disease microglial cells overexpress anti-inflammatory cytokine IL-10. Given that IL-10 is major homeostatic cytokine and its production becomes deregulated with aging, this may suggest that the capacity of microglia to adequately produce IL-10 may be compromised in ALS. We show that blocking IL-10 increased inflammation and precipitated clinical disease onset, whereas overexpression of IL-10 in microglia using a gene therapy approach significantly delayed disease onset and increased survival of ALS mice. Based on our results, we propose that targeted overexpression of IL-10 in microglia may have therapeutic potential in ALS.

Adeno-associated virus-mediated delivery of a recombinant single-chain antibody against misfolded superoxide dismutase for treatment of amyotrophic lateral sclerosis.

There is emerging evidence that the misfolding of superoxide dismutase 1 (SOD1) may represent a common pathogenic event in both familial and sporadic amyotrophic lateral sclerosis (ALS). To reduce the burden of misfolded SOD1 species in the nervous system, we have tested a novel therapeutic approach based on adeno-associated virus (AAV)-mediated tonic expression of a DNA construct encoding a secretable single-chain fragment variable (scFv) antibody composed of the variable heavy and light chain regions of a monoclonal antibody (D3H5) binding specifically to misfolded SOD1. A single intrathecal injection of the AAV encoding the single-chain antibody in SOD1(G93A) mice at 45 days of age resulted in sustained expression of single-chain antibodies in the spinal cord, and it delayed disease onset and extension of life span by up to 28%, in direct correlation with scFv titers in the spinal cord. The treatment caused attenuation of neuronal stress signals and reduction in levels of misfolded SOD1 in the spinal cord of SOD1(G93A) mice. From these results, we propose that an immunotherapy based on intrathecal inoculation of AAV encoding a secretable scFv against misfolded SOD1 should be considered as potential treatment for ALS, especially for individuals carrying SOD1 mutations.

Critically Ill Older Adults' Representation in Intervention Trials: A Systematic Review.

OBJECTIVES: Older adults may be under-represented in critical care research, and results may not apply to this specific population. Our primary objective was to evaluate the prevalence of inclusion of older adults across critical care trials focused on common ICU conditions or interventions. Our secondary objective was to evaluate whether older age was used as a stratification variable for randomization or outcome analysis. DESIGN SETTING AND SUBJECTS: We performed a systematic review of previously published systematic reviews of randomized controlled trials (RCTs) in critical care. We searched PubMed, Ovid, CENTRAL, and Cochrane from 2009 to 2022. Systematic reviews of any interventions across five topics: acute respiratory distress syndrome (ARDS), sepsis/shock, nutrition, sedation, and mobilization were eligible. MAIN RESULTS: We identified 216 systematic reviews and included a total of 253 RCTs and 113,090 patients. We extracted baseline characteristics and the reported proportion of older adults. We assessed whether any upper age limit was an exclusion criterion for trials, whether age was used for stratification during randomization or data analysis, and if age-specific subgroup analysis was present. The most prevalent topic was sepsis (78 trials, 31%), followed by nutrition (62 trials, 25%), ARDS (39 trials, 15%), mobilization (38 trials, 15%), and sedation (36 trials, 14%). Eighteen trials (7%) had exclusion criteria based on older age. Age distribution with information on older adults prevalence was given in six trials (2%). Age was considered in the analysis of ten trials (5%) using analytic methods to evaluate the outcome stratified by age. Conclusions: In this systematic review, the proportion of older critically ill patients is undetermined, and it is unclear how age is or is not an effect modifier or to what extent the results are valid for older adult groups. Reporting age is important to guide clinicians in personalizing care. These results highlight the importance of incorporating older critically ill patients in future trials to ensure the results are generalizable to this growing population.

Model system for live imaging of neuronal responses to injury and repair.

Although it has been well established that induction of growth-associated protein-43 (GAP-43) during development coincides with axonal outgrowth and early synapse formation, the existence of neuronal plasticity and neurite outgrowth in the adult central nervous system after injuries is more controversial. To visualize the processes of neuronal injury and repair in living animals, we generated reporter mice for bioluminescence and fluorescence imaging bearing the luc (luciferase) and gfp (green fluorescent protein) reporter genes under the control of the murine GAP-43 promoter. Reporter functionality was first observed during the development of transgenic embryos. Using in vivo bioluminescence and fluorescence imaging, we visualized induction of the GAP-43 signals from live embryos starting at E10.5, as well as neuronal responses to brain and peripheral nerve injuries (the signals peaked at 14 days postinjury). Moreover, three-dimensional analysis of the GAP-43 bioluminescent signal confirmed that it originated from brain structures affected by ischemic injury. The analysis of fluorescence signal at cellular level revealed colocalization between endogenous protein and the GAP-43-driven gfp transgene. Taken together, our results suggest that the GAP-43-luc/gfp reporter mouse represents a valid model system for real-time analysis of neurite outgrowth and the capacity of the adult nervous system to regenerate after injuries.

Live imaging of amyotrophic lateral sclerosis pathogenesis: disease onset is characterized by marked induction of GFAP in Schwann cells.

Amyotrophic lateral sclerosis (ALS) is a late-onset neurological disease characterized by progressive loss of motor neurons. At present, the pathological events precipitating disease onset and the exact pattern of disease progression are not fully understood. Recent studies suggest that glial cells, in particular activated astrocytes, can release factors that can directly kill motor neurons. To further investigate the involvement of glial cells (astrocytes and Schwann cells) in the pathogenesis of ALS, we generated ALS-(GFAP-luciferase/SOD(G93A)) reporter mouse in which upregulation of glial fibrillary acidic protein (GFAP) can be visualized from live animals throughout the different stages of disease. Our results suggest that the disease in mice is initiated simultaneously in the spinal cord and in the peripheral nerves and is characterized by several cycles of GFAP upregulation. Immunohistochemical analysis confirmed that the induction GFAP bioluminescence signals were associated with the significant increases in GFAP immunoreactivity. The first pathological GFAP signals occurring at 25-30 days were asymptomatic and detectable at the level of lumbar spinal cord projections and at the periphery. These early events were then followed by GFAP promoter inductions that were associated with the distinct clinical symptoms. As expected, the onset of paralysis (112 days) was associated with the gradual and marked GFAP upregulation in the spinal cord. Interestingly, however, the disease onset (90 days) was characterized by sharp and synchronized induction of GFAP in peripheral nerve Schwann cells suggesting that peripheral nerves pathology/denervation and associated Schwann cell stress may play an important role in the ALS pathogenesis.

Treatment with minocycline after disease onset alters astrocyte reactivity and increases microgliosis in SOD1 mutant mice.

Several reports have demonstrated that attenuation of microglial activation by minocycline, an antimicrobial drug with anti-inflammatory properties, delays disease progression in a mouse model of ALS. However, the negative results obtained in recent clinical trials raised some questions regarding the role of inflammatory response and glial cells as a therapeutic target in ALS. To investigate this controversy we took advantage of a mouse model for live imaging of neuroinflammatory responses in ALS (GFAP-luc/ SOD1(G93A) reporter mouse) and analyzed in real time the effects of minocycline treatment initiated at different stages of the disease. To our surprise, unlike neuroprotection that is conferred when minocycline is administered pre-symptomatically, treatment with minocycline initiated after the disease onset significantly altered glial responses and exaggerated neuroinflammation. Further analysis revealed that the late minocycline treatment was associated with significant induction of the end-stage GFAP-biophotonic signals, expression levels of connexin 43, a major protein of astrocytic gap junction and markers of microglial activation, such as Iba1 and CD68. The results of our study suggest that when administered at later stages of disease, once microglial cells are chronically reactive, minocycline may not have anti-inflammatory properties, and contrary to expectations, may alter astrocyte reactivity and increase microgliosis. Finally, our results further suggest the existence of close interactions/communication between activated microglia and astrocytes in late stage ALS.

Requirement for Map2k1 (Mek1) in extra-embryonic ectoderm during placentogenesis.

Map2k1(-/-) embryos die at mid-gestation from abnormal development and hypovascularization of the placenta. We now show that this phenotype is associated with a decreased labyrinth cell proliferation and an augmented cell apoptosis. Although the activation of MAP2K1 and MAP2K2 is widespread in the labyrinthine region, MAPK1 and MAPK3 activation is restricted to the cells lining the maternal sinuses, suggesting an important role for the ERK/MAPK cascade in these cells. In Map2k1(-/-) placenta, ERK/MAPK cascade activation is perturbed. Abnormal localization of the syncytiotrophoblasts is also observed in Map2k1(-/-) placenta, even though this cell lineage is specified at the correct time during placentogenesis. The placental phenotype can be rescued in tetraploid experiments. In addition, Map2k1-specific deletion in the embryo leads to normal embryo development and to the birth of viable Map2k1(-/-) mice. Altogether, these data enlighten the essential role of Map2k1 in extra-embryonic ectoderm during placentogenesis. In the embryo, the Map2k1 gene function appears dispensable.