The anti-inflammatory effects of aerobic exercise training in patients with type 2 diabetes: A systematic review and meta-analysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a low-grade, chronic inflammatory disease, associated with increased cardiovascular risk. The purpose of this systematic review/ meta-analysis was to evaluate the effects of aerobic exercise training (AET) on inflammatory markers in T2DM patients.

METHODS

The literature search was conducted utilizing PubMed, Web of Science, Embase, and the Cochrane Library from their inception up to April 2022. We screened only for randomized controlled trials (RCTs) investigating the effects of AET on C-reactive protein (CRP) and adipokines: adiponectin, resistin, interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-a), along with changes in anthropometric indices and glycemic control in adult T2DM patients. Pooled post-exercise weighted mean differences (WMDs) with 95% Confidence Intervals (CIs) were calculated for all outcomes of interest between exercise-treated patients and controls.

RESULTS

Twenty-six RCTs involving 1239 T2DM patients were retrieved from the databases for meta-analysis. The cumulative results showed that post-AET inflammatory markers were lower in exercise-treated patients compared to controls regarding CRP (mg/L): WMD: -0.91; 95%CIs: -1.43, -0.40; p < 0.001 resistin (mg/ml): (WMD: -2.08; 95%CIs: -3.32, -0.84; p < 0.001); TNF-a (pg/ml): (WMD: -2.70; 95%CIs: -4.26, -1.14; p < 0.001), and IL-6 (pg/ml): (WMD: -1.05; 95%CIs: -1.68, -0.43; p < 0.001). Those effects were accompanied by significant amelioration of fasting glucose (mg/dl) (WMD: -13.02; 95%CIs: -25.39, -0.66; p = 0.04), HbA1c (%) (WMD: -0.51; 95%CIs: -0.73, -0.28, p < 0.001), and fat mass (%) (WMD: -3.14; 95%CI: -4.71, -1.58; p < 0.001). Our meta-analysis demonstrated less-consistent results for adiponectin (μg/ml), (WMD: 1.00; 95%CI: -0.12, 2.12; p = 0.08) and body-mass index (kg/m²) (WMD: -1.34; 95%CI: -2.76, 0.08; p = 0.06) tending to differ between AET and control group.

CONCLUSIONS

AET can significantly reduce the inflammatory burden in T2DM patients. by ameliorating the circulating levels of CRP, resistin, TNF-a and IL-6, even without accompanied significant weight-loss. The clinical impact of those anti-inflammatory effects of AET needs to be determined.

A Comprehensive Review of the Cardiovascular Protective Properties of Silibinin/Silymarin: A New Kid on the Block

Silibinin/silymarin has been used in herbal medicine for thousands of years and it is well-known for its hepato-protective properties. The present comprehensive literature review aimed to critically summarize the pharmacological properties of silymarin extract and its main ingredient silibinin in relation to classical cardiovascular risk factors (e.g., diabetes mellitus, etc.). We also assessed their potential protective and/or therapeutic application in cardiovascular diseases (CVDs), based on experimental and clinical studies. Pre-clinical studies including in vitro tests or animal models have predominantly implicated the following effects of silymarin and its constituents: (1) antioxidant, (2) hypolipidemic, (3) hypoglycemic, (4) anti-hypertensive and (5) cardioprotective. On the other hand, a direct amelioration of atherosclerosis and endothelial dysfunction after silymarin administration seems weak based on scarce data. In clinical trials, the most important findings are improved (1) glycemic and (2) lipid profiles in patients with type 2 diabetes mellitus and/or hyperlipidemia, while (3) the anti-hypertensive effects of silibinin/silymarin seem very modest. Finally, the changes in clinical endpoints are not robust enough to draw a firm conclusion. There are significant limitations in clinical trial design, including the great variety in doses and cohorts, the underlying conditions, the small sample sizes, the short duration and the absence of pharmacokinetic/pharmacodynamic tests prior to study commitment. More data from well-designed and high-quality pre-clinical and clinical studies are required to firmly establish the clinical efficacy of silibinin/silymarin and its possible therapeutic application in cardiovascular diseases.

The Positional Logic of Sensory-Motor Reflex Circuit Assembly

Throughout his scientific career, Tom Jessell pioneered the spinal cord as a model system to study the molecular programs of neural specification, axon guidance, and connection specificity. His contributions to these fields and more broadly to that of developmental neuroscience will continue to inspire and define many generations of researchers. It is challenging to capture all of Tom's findings in one essay, and therefore, here we wish to briefly highlight his contributions to the problem of connection specificity, with a focus on the spinal sensory-motor reflex circuit. In particular, emphasis will be placed on discoveries from his laboratory that revealed a significant role of positional strategies in establishing selective sensory-motor connections. This work introduced novel principles of neuronal connectivity that may apply to how precise circuit wiring occurs throughout the nervous system.

Positional Strategies for Connection Specificity and Synaptic Organization in Spinal Sensory-Motor Circuits

Proprioceptive sensory axons in the spinal cord form selective connections with motor neuron partners, but the strategies that confer such selectivity remain uncertain. We show that muscle-specific sensory axons project to motor neurons along topographically organized angular trajectories and that motor pools exhibit diverse dendritic arbors. On the basis of spatial constraints on axo-dendritic interactions, we propose positional strategies that can account for sensory-motor connectivity and synaptic organization. These strategies rely on two patterning principles. First, the degree of axo-dendritic overlap reduces the number of potential post-synaptic partners. Second, a close correlation between the small angle of axo-dendritic approach and the formation of synaptic clusters imposes specificity of connections when sensory axons intersect multiple motor pools with overlapping dendritic arbors. Our study identifies positional strategies with prominent roles in the organization of spinal sensory-motor circuits.

Gene regulatory logic for reading the Sonic Hedgehog signaling gradient in the vertebrate neural tube

Secreted signals, known as morphogens, provide the positional information that organizes gene expression and cellular differentiation in many developing tissues. In the vertebrate neural tube, Sonic Hedgehog (Shh) acts as a morphogen to control the pattern of neuronal subtype specification. Using an in vivo reporter of Shh signaling, mouse genetics, and systems modeling, we show that a spatially and temporally changing gradient of Shh signaling is interpreted by the regulatory logic of a downstream transcriptional network. The design of the network, which links three transcription factors to Shh signaling, is responsible for differential spatial and temporal gene expression. In addition, the network renders cells insensitive to fluctuations in signaling and confers hysteresis--memory of the signal. Our findings reveal that morphogen interpretation is an emergent property of the architecture of a transcriptional network that provides robustness and reliability to tissue patterning.

Foxj1 regulates floor plate cilia architecture and modifies the response of cells to sonic hedgehog signalling

Sonic hedgehog signalling is essential for the embryonic development of many tissues including the central nervous system, where it controls the pattern of cellular differentiation. A genome-wide screen of neural progenitor cells to evaluate the Shh signalling-regulated transcriptome identified the forkhead transcription factor Foxj1. In both chick and mouse Foxj1 is expressed in the ventral midline of the neural tube in cells that make up the floor plate. Consistent with the role of Foxj1 in the formation of long motile cilia, floor plate cells produce cilia that are longer than the primary cilia found elsewhere in the neural tube, and forced expression of Foxj1 in neuroepithelial cells is sufficient to increase cilia length. In addition, the expression of Foxj1 in the neural tube and in an Shh-responsive cell line attenuates intracellular signalling by decreasing the activity of Gli proteins, the transcriptional mediators of Shh signalling. We show that this function of Foxj1 depends on cilia. Nevertheless, floor plate identity and ciliogenesis are unaffected in mouse embryos lacking Foxj1 and we provide evidence that additional transcription factors expressed in the floor plate share overlapping functions with Foxj1. Together, these findings identify a novel mechanism that modifies the cellular response to Shh signalling and reveal morphological and functional features of the amniote floor plate that distinguish these cells from the rest of the neuroepithelium.

Distinct Sonic Hedgehog signaling dynamics specify floor plate and ventral neuronal progenitors in the vertebrate neural tube

The secreted ligand Sonic Hedgehog (Shh) organizes the pattern of cellular differentiation in the ventral neural tube. For the five neuronal subtypes, increasing levels and durations of Shh signaling direct progenitors to progressively more ventral identities. Here we demonstrate that this mode of action is not applicable to the generation of the most ventral cell type, the nonneuronal floor plate (FP). In chick and mouse embryos, FP specification involves a biphasic response to Shh signaling that controls the dynamic expression of key transcription factors. During gastrulation and early somitogenesis, FP induction depends on high levels of Shh signaling. Subsequently, however, prospective FP cells become refractory to Shh signaling, and this is a prerequisite for the elaboration of their identity. This prompts a revision to the model of graded Shh signaling in the neural tube, and provides insight into how the dynamics of morphogen signaling are deployed to extend the patterning capacity of a single ligand. In addition, we provide evidence supporting a common scheme for FP specification by Shh signaling that reconciles mechanisms of FP development in teleosts and amniotes.

Dynamic assignment and maintenance of positional identity in the ventral neural tube by the morphogen sonic hedgehog

Morphogens are secreted signalling molecules that act in a graded manner to control the pattern of cellular differentiation in developing tissues. An example is Sonic hedgehog (Shh), which acts in several developing vertebrate tissues, including the central nervous system, to provide positional information during embryonic patterning. Here we address how Shh signalling assigns the positional identities of distinct neuronal subtype progenitors throughout the ventral neural tube. Assays of intracellular signal transduction and gene expression indicate that the duration as well as level of signalling is critical for morphogen interpretation. Progenitors of the ventral neuronal subtypes are established sequentially, with progressively more ventral identities requiring correspondingly higher levels and longer periods of Shh signalling. Moreover, cells remain sensitive to changes in Shh signalling for an extended time, reverting to antecedent identities if signalling levels fall below a threshold. Thus, the duration of signalling is important not only for the assignment but also for the refinement and maintenance of positional identity. Together the data suggest a dynamic model for ventral neural tube patterning in which positional information corresponds to the time integral of Shh signalling. This suggests an alternative to conventional models of morphogen action that rely solely on the level of signalling.

Foxa1 and Foxa2 function both upstream of and cooperatively with Lmx1a and Lmx1b in a feedforward loop promoting mesodiencephalic dopaminergic neuron development

Mesodiencephalic dopaminergic neurons control voluntary movement and reward based behaviours. Their dysfunction can lead to neurological disorders, including Parkinson's disease. These neurons are thought to arise from progenitors in the floor plate of the caudal diencephalon and midbrain. Members of the Foxa family of forkhead/winged helix transcription factor, Foxa1 and Foxa2, have previously been shown to regulate neuronal specification and differentiation of mesodiencephalic progenitors. However, Foxa1 and Foxa2 are also expressed earlier during regional specification of the rostral brain. In this paper, we have examined the early function of Foxa1 and Foxa2 using conditional mutant mice. Our studies show that Foxa1 and Foxa2 positively regulate Lmx1a and Lmx1b expression and inhibit Nkx2.2 expression in mesodiencephalic dopaminergic progenitors. Subsequently, Foxa1 and Foxa2 function cooperatively with Lmx1a and Lmx1b to regulate differentiation of mesodiencephalic dopaminergic neurons. Chromatin immunoprecipitation experiments indicate that Nkx2.2 and TH genes are likely direct targets of Foxa1 and Foxa2 in mesodiencephalic dopaminergic cells in vivo. Foxa1 and Foxa2 also inhibit GABAergic neuron differentiation by repressing the Helt gene in the ventral midbrain. Our data therefore provide new insights into the specification and differentiation of mesodiencephalic dopaminergic neurons and identifies Foxa1 and Foxa2 as essential regulators in these processes.

Histopathological lesions in lead intoxicated dogs

The ultra-structural lesions of lead poisoning and the deposition of lead in liver, kidney, peritoneum, cerebellum and retina of dogs were studied. Specimens were obtained from 5 3-4 mo-old crossbreed dogs each injected i.p. with a total dose of 120 mg lead acetate, divided in 10 equal doses of 12 mg, administered every other day. Two dogs were controls. Histopathological examination revealed degeneration of the epithelial cells of the urinary tubules, the endothelial cells of the renal capillaries and the hepatocytes. Characteristic lead inclusion bodies were observed intracytoplasmically and intranuclearly in mesothelial and giant cells of the peritoneum. Lead needle-like inclusions were intracytoplasmically in the interstitial connective tissue cells of the kidney, and substantial quantities of lead were in collagen fibers of the interstitial kidney tissue.