EFFECT OF M2 MACROPHAGE-DERIVED SOLUBLE FACTORS ON DIFFERENTIATION OF SH-SY5Y CELLS

Macrophages play a key role in triggering and regulation of neuroregeneration. The characteristic feature of macrophages is pronounced plasticity, which manifests itself in the ability of macrophages to change their functional phenotype depending on the micromilieu. Apoptotic cell clearance (efferocytosis) is an important inducer of a macrophage polarization to M2 phenotype under pathological settings. Previously, we have developed an original protocol for the generation of M2-like macrophages, polarized by efferocytosis under serum-deprived conditions (M2 (LS), Low Serum). The present study was aimed to assess a neuroregenerative potential of M2 (LS) macrophages. We studied their effect on the differentiation of SH-SY5Y cells in comparison with retinoic acid (RA). As the morphological criteria of differentiation we have assessed the relative content of differentiated cells, i.e., cells with a neurite length exceeding the cell body length, and the average neurite length on days 3, 7, and 13. The ratio of neuron-like (N-type) and epithelial-like (S-type) cells in cultures was also assessed. SH-SY5Y cells were characterized by a low level of spontaneous differentiation, both under standard conditions (10% FBS) and serum deprivation (1% FBS). Upon RA treatment, SH-SY5Y cells stopped proliferating and underwent neuronal differentiation. Cultivation of SH-SY5Y cells in the presence of M2 (LS) conditioned medium also led to a significant increase in the relative content of differentiated cells, the average length of neurite-like processes, as well as a change in the balance of S- and N-type cells towards a pronounced predominance of the latter. The morphological features of differentiation were significantly less pronounced at early stage (day 3) of differentiation as compared with the RA-induced changes and reached the level of positive control only at later stages (day 13) (p < 0.05). In contrast to retinoic acid, M2 (LS) conditioned medium induced neuronal differentiation of SH-SY5Y cells without suppressing their proliferative activity. The data obtained may indicate a high neuroregenerative potential of M2 macrophages in vitro, which is realized through soluble factors and manifests itself in promoting SH-SY5Y differentiation

Effect of soluble factors of macrophages polarized by efferocytosis on neuronal density in the frontal cortex and hippocampus of mice in a model of stress-induced depression

Recently, there has been a steady increase in depressive disorders, which occupy an important place in the structure of the causes of disability. In the pathogenesis of depression, an important role is played by neuroinflammation, which is associated with impaired adult neurogenesis. Notably, neuroinflammation is partially reversible, and the leading role in the initiation and regulation of neuroregeneration is given to macrophages. Opposite states of macrophage activation are classically activated M1 and alternatively activated M2 macrophages, characterized, respectively, by pro- and anti-inflammatory activity. A balance shift towards M2 macrophages has been considered as a new therapeutic strategy of psycho-neurological disorders. One of the inducers of the M2 phenotype is the efferocytosis. We have previously developed an original protocol for the generation of human macrophages under conditions of deficiency of growth / serum factors, in which M2 phenotype is formed through efferocytosis. Macrophages (M2(LS), LS – Low Serum) obtained according to this protocol express M2-associated markers, and are characterized by high production of growth and pro- angiogenic factors (IGF-1, VEGF, BDNF, EGF, FGF-basic, etc.), which can suppress inflammation and stimulate neuroregeneration / neuroplasticity. In the model of stress-induced depression, the antidepressant effect of soluble factors of M2(LS) macrophages was shown, accompanied by a decrease in the level of pro- inflammatory cytokines in certain brain structures. However, the effect of M2(LS) factors on neurogenesis remained unexplored. In the present work, which is a continuation of the aforementioned study, we analyzed the effect of intranasal administration of M2(LS) soluble factors on neuronal density in different brain areas – the frontal cortex and hippocampus – of depression-like mice. The results obtained showed that neuronal density in the frontal cortex, CA1 and CA3 zones of the hippocampus, was significantly higher in mice with intranasal administration of M2(LS) conditioned medium than in depression-like mice, and reached the level of neuronal density in intact animals. These results may indicate the neuroregenerative activity of M2(LS) macrophages in the model of stress-induced depression, which is mediated through soluble factors and manifests itself in an increase in the density of neurons in the brain

Therapeutic effect of soluble factors of M2 phenotype macrophages in children with language impairments

The aim of the present study was to assess safety and clinical efficacy of inhalation immunotherapy based on intranasal administration of bioactive factors produced by the M2 phenotype macrophages in children with language impairments, as well as to study the effect of inhalation immunotherapy on the cytokine profile in the patients' blood serum. The study was carried out according to the NCT04689282 protocol (www.ClinicalTrials.gov) and included 14 children (9 boys / 5 girls), aged 3 to 8 years, with language impairments associated with perinatal or postnatal CNS lesions of various origin. The children recruited into the study were assessed by a neurologist and speech therapist before the therapy, at the end of the course (1 month), and 6 months later. Serum samples for cytokine analysis were obtained before and 1 month after therapy. The course of intranasal inhalations by the conditioned M2 media (2 ml one time per day for 28-30 days) was safe and well tolerated. None of the 14 treated children had significant adverse reactions and severe undesirable events. Intranasal immunotherapy led to a decrease in the severity of language problems, which manifested by improved speech understanding by 45%; the sensorimotor level of speech, by 51%; word formation skills, by 72%, as well as a twofold increase in general and fine motor skills. In children with signs of autism spectrum disorders, along with a language improvement, a decrease in the severity of autistic symptoms was registered, as evidenced by statistically significant decrease in the CARS score from 42.5 to 38.5 after 1 month, and to 33 points after 6 months (p < 0.05). The clinical effect was revealed rather soon, i.e., within a month after the first procedure, being maintained or intensified during a follow-up for 6 months. At the same time, two-thirds of the children showed a clear clinical improvement, with insignificant effect in the rest of patients. Comparative analysis of the serum cytokine levels in these subgroups showed that children with a pronounced positive response to inhaled immunotherapy differed in the following parameters: (1) initially higher level of VEGF and IGF-1, and (2) decrease the level of TNFα in response to intranasal immunotherapy. In summary, we first tested a fundamentally new approach based on the use of soluble factors from M2-type macrophages and intranasal route of their administration in order to treat the children with severe language impairments, demonstrating safety and obtained preliminary data on effectiveness of such approach