Adipocytokines in obstructive sleep apnea: A systematic review and meta-analysis

BACKGROUND AND AIM

Adipocytokines play an important role in obstructive sleep apnea (OSA) by mediating inflammatory responses. Previous studies have reported that OSA is related to a change in the serum levels of adipocytokines; however, the results are still controversial. This meta-analysis aimed to assess the relationship between OSA and circulating level of adipocytokines in adults and children.

METHODS

A comprehensive search was conducted in databases of Medline/PubMed and Scopus for pertinent articles published since their inception to July 2022. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to assess the strength of the relationship between the concentrations of adipocytokines with OSA.

RESULTS

In the overall analysis, contrary to IL-10, which showed a significant reduction, IL-1β, IL-4, IL-8, IL-17, and IFN- gamma showed higher levels in OSA patients in comparison with control groups (p <0.05). For adults, IL-1β, IL-8, IL-17, IL-18, vaspin, visfatin, and chemerin were linked to a greater serum levels in patients with OSA, while, IL-5 and IL-10 were detected significantly lower in adults with OSA in comparison with healthy adults (p <0.05). In children with OSA, the serum levels of IL-4, IL-8, IL-12, IL-17, IL-23, and IFN-gamma were significantly higher than healthy children (p <0.05).

CONCLUSION

The levels of inflammatory markers were found to be higher in OSA patients compared with control individuals, suggesting that adipocytokines may contribute to the pathology of OSA.

The dysbiosis gut microbiota induces the alternation of metabolism and imbalance of Th17/Treg in OSA patients

The aim of this research was to test the hypothesis that changes in the intestinal microbiota lead to the alternation of histidine metabolism and Th17/Treg cell imbalance in obstructive sleep apnea (OSA) patients. In total, 46 subjects were enrolled in the study, with 32 subjects in the OSA group and 14 in the healthy group, according to polysomnography examinations. Basic clinical characteristics were collected for this analysis. Feces were collected from OSA patients to detect the gut microbiota using 16S rRNA sequencing. Peripheral blood was obtained to detect the Th17/Treg cell ratio by flow cytometry. The present research demonstrated that at the phylum level, OSA patients have a disproportionate Firmicutes/Bacteroidetes ratio with increased Firmicutes and decreased Bacteroidetes in the gut microbiota compared to the healthy population. A Metastats analysis also indicated that the family Rikenellaceae was prevalent in the control group but not the OSA group. In addition, the abundance of Clostridium_XlVa was reduced and the abundance of Alistipes was elevated in healthy subjects at the genus level. Furthermore, a Phylogenetic Investigation of Communities by Reconstruction of Unobserved States analysis identified the alternation of metabolic pathways in OSA patients. The current study also identified an imbalance of Th17/Treg cells in OSA patients, with OSA patients having an elevated number of Treg cells compared to the control group. We determined that the abundance of Rikenellaceae and Alistipes increased and Clostridium_XlVa decreased in patients with OSA, which may have caused an imbalance in the proportion of Th17/Treg cells.

Redistribution of Monocyte Subsets in Obstructive Sleep Apnea Syndrome Patients Leads to an Imbalanced PD-1/PD-L1 Cross-Talk with CD4/CD8 T Cells

Obstructive sleep apnea syndrome (OSAS) represents a substantial disease of recurrent sleep fragmentation, leading to intermittent hypoxia and subsequent diseases such as cardiovascular, metabolic, or cognitive dysfunctions. In addition, OSAS is considered as low-grade systemic inflammation, which is associated with a higher incidence of cancer, severity of infections, and an overall immune dysregulation. This research project aims to comprehensively investigate the interplay of wholesome sleep and the immune functions of circulating monocytes and T cells in OSAS patients, which are known to be affected by oxidative stress. We studied the distribution of the CD14/CD16 characterized monocyte subsets in peripheral blood as well as their PD-L1 expression and complex formation with T cells. Furthermore, a detailed analysis of T cell subsets with regard to their PD-1 and PD-L1 expression was performed. Data revealed a decrease of classical monocytes accompanied by an increase of both CD16⁺ monocyte subsets in OSAS patients that was positively correlated with the body mass index. OSAS patients revealed an increased PD-1 and PD-L1 expression in T cells and monocytes, respectively, which was linked to the severity of monocyte subset alterations. The complex formation of monocytes and T cells was also elevated in OSAS patients, which indicates a deregulated PD-1/PD-L1 cross-talk between these cells. Our data show for the first time, to our knowledge, massive alterations of peripheral monocyte subsets in response to OSAS and its accompanying phenomena.

Maternal history of recurrent pregnancy loss increases the risk for long-term pediatric respiratory morbidity of the offspring

BACKGROUND

While the etiology in many cases of recurrent pregnancy loss (RPL) is unclear, recent evidence suggests possible immunological dysfunction, which is also implicated in the pathophysiology of many pediatric respiratory diseases.

OBJECTIVE

We sought to investigate whether maternal history of RPL is associated with long-term respiratory morbidity of the offspring.

STUDY DESIGN

A population based cohort analysis was performed comparing the risk of long-term respiratory morbidity (up to the age of 18 years) of children born to mothers with and without a history of RPL (defined as two or more losses). Respiratory morbidity included hospitalizations involving a predefined set of ICD-9 codes, as recorded in the hospital medical records. Deliveries occurred between the years 1991 and 2014 in a tertiary medical center. A Kaplan-Meier survival curve was constructed to compare cumulative respiratory morbidity, and a Cox proportional hazards model was used to control for confounders.

RESULTS

During the study period, 242 187 newborns met the inclusion criteria; 5% (n = 12 182) of which were offspring to mothers with a history of RPL. Respiratory morbidity was significantly more common in the exposed group (6.0% vs 4.8%, P < .001). Specifically, offspring to mothers with a history of RPL had higher rates of obstructive sleep apnea and asthma (P < .05). The Kaplan-Meier survival curve exhibited a higher cumulative incidence of total respiratory morbidity in offspring of mothers with a history of RPL (Log rank P < .001). In the Cox regression, maternal history of RPL was independently associated with increased pediatric respiratory morbidity of the offspring with an adjusted hazard ratio of 1.24 (95 % confidence interval [95%CI], 1.15-1.34, P < .001).

CONCLUSION

Maternal history of RPL is associated with a higher risk of future pediatric respiratory morbidity of the offspring; possibly explained by a common immunological etiology.

Inflammatory Factors: Nonobese Pediatric Obstructive Sleep Apnea and Adenotonsillectomy

Background: Inflammation is often considered relating to pediatric obstructive sleep apnea (OSA). We conducted a study investigating cytokines, including Il-17 and Il-23, in children with OSA before and after adenotonsillectomy (T&A), compared with controls. Methods: Children with OSA between age 4 and 12 receiving T&A were prospectively followed. Evaluation before and reevaluation six months after the treatment were done, including polysomnography (PSG), blood tests, and questionnaires. Blood samples were obtained to determine the values of high-sensitivity-C-reactive-protein (HS-CRP); tumor-necrosis-factor-alpha (TNF-α); and interleukin (IL)-1, 6, 10, 12, 17, and 23. We compared the results with an age-matched control group. Results: We included 55 OSA children and 32 controls. Children with OSA presented significant improvement after T&A in complaints, signs, apnea hypopnea index (AHI) (p < 0.001), mean oxygen desaturation index (p < 0.001), and mean oxygen saturation (p = 0.010). Upon entering this study, children with OSA had significantly higher cytokine levels than the controls and significant changes in HS-CRP (p = 0.013), TNF-α (p = 0.057), IL-1β (p = 0.022), IL-10 (p = 0.035), and IL-17 (p = 0.010) after T&A. Children with improved but persistently abnormal AHI did not have all cytokine levels normalized, particularly IL-23 and HS-CRP. Conclusion: Sleep-disordered breathing can persist after T&A and can continue to have a negative inflammatory effect. HS-CRP and IL-23 may serve as blood markers for the persistence of sleep-disordered breathing after T&A.

Less than 7 hours of sleep per night is associated with transitioning to systemic lupus erythematosus

Background The role of sleep in the etiology of systemic lupus erythematosus (SLE) has not been well studied. We examined whether sleep duration was associated with subsequent transitioning to SLE in individuals at risk for SLE. Methods Four hundred and thirty-six relatives of SLE patients who did not have SLE themselves at baseline were evaluated again an average of 6.3 (± 3.9) years later. Fifty-six individuals transitioned to SLE (≥ 4 cumulative American College of Rheumatology (ACR) criteria). Sleep duration, medication use and medical history were assessed by questionnaire; ACR criteria were confirmed by medical record review. Vitamin D was measured by ELISA. Generalized estimating equations, accounting for correlation within families, assessed associations between baseline sleep and the outcome of transitioning to SLE. Results Reporting sleeping less than 7 hours per night at baseline was more common in those who subsequently transitioned than those who did not transition to SLE (55% versus 32%, p = 0.0005; OR: 2.8, 95% CI 1.6-4.9). Those who transitioned to SLE were more likely to sleep less than 7 hours per night than those who did not transition to SLE adjusting for age, sex and race (OR: 2.8, 95% CI 1.6-5.1). This association remained after individual adjustment for conditions and early symptoms that could affect sleep, including prednisone use, vitamin D deficiency and number of ACR criteria (OR: 2.0, 95% CI 1.1-4.2). Conclusion Lack of sleep may be associated with transitioning to SLE, independent of early clinical manifestations of SLE that may influence sleep duration. Further evaluation of sleeping patterns and biomarkers in at-risk individuals is warranted.

Auditory behavior and auditory temporal resolution in children with sleep-disordered breathing

OBJECTIVE

Intermittent hypoxia caused by obstructive sleep apnea syndrome (OSAS) may lead to damage in brain areas associated to auditory processing. The aim of this study was to compare children with OSAS or primary snoring (PS) to children without sleep-disordered breathing with regard to their performance on the Gaps-in-Noise (GIN) test and the Scale of Auditory Behaviors (SAB) questionnaire.

METHODS

Thirty-seven children (6-12 years old) were submitted to sleep anamnesis and in-lab night-long polysomnography. Three groups were organized according to clinical criteria: OSAS group (13 children), PS group (13 children), and control group (11 children). They were submitted to the GIN test and parents answered SAB questionnaire. The Kruskal-Wallis statistical test was used to compare the groups; p < 0.05 was considered statistically significant.

RESULTS

The OSAS group performed significantly worse than PS (p = 0.011) and Control (p = 0.029) groups on gap detection percentage, while PS and Control groups showed no significant differences. The three groups showed similar gap detection thresholds. Regarding SAB questionnaire, PS group had significantly worse scores when compared to Control (p = 0.011), but not to OSAS (p = 0.101) groups. No statistical difference between OSAS and Control groups were found.

CONCLUSION

Children with OSAS showed worse performance on GIN test in comparison to children with PS and children without sleep-disordered breathing. PS negatively affected auditory behavior in children. These findings suggest that sleep-disordered breathing may lead to auditory behavior impairment.

Vitamin D deficiency and interleukin-17 relationship in severe obstructive sleep apnea-hypopnea syndrome

PURPOSE

We aimed to assess Vitamin D (VD) abnormalities in patients with severe obstructive sleep apnea-hypopnea syndrome (OSAHS), to study its association with clinical and polygraphic data, and to correlate VD levels with interleukin-17 (IL-17).

METHODS

Ninety-two patients with severe OSAHS were consecutively enrolled between September 2014 and February 2016 and compared to age-, sex-, and body mass index (BMI)-matched controls. Anthropometric parameters and medical history were collected. The serum levels of VD and IL-17 were determined by radioimmunoassay and enzyme-linked immunosorbent assay, respectively.

RESULTS

Ninety-two severe OSAHS patients and thirty controls were enrolled in the study. All OSAHS patients had VD deficiency. The mean level of VD was at 7.9 ng/ml among OSAHS group versus 16.8 ng/ml among control group. IL-17A levels were elevated (20.3 pg/ml) in OSAHS group compared to healthy group (10.05 pg/ml). VD levels were negatively correlated with nocturia severity (r = -0.26; P = 0.01) and positively correlated with mean O₂ saturation (r = 0.59; P = 0.02) and lowest O₂ saturation (r = 0.3; P = 0.03). IL-17 levels were positively correlated with nocturia severity (r = 0.24; P = 0.03) and negatively correlated with mean O₂ saturation (r = -0.42; P = 0.03). A significant negative association was observed between IL-7 and VD levels (r = -0.64, P = 0.2 10^-4). The magnitude of this correlation was higher for important nocturia, lower MSaO₂, or higher BMI.

CONCLUSIONS

VD deficiency in patients with severe OSAHS is common with a negative association between IL-17 and VD serum levels. Hypoxia could play an important role in this association. Further studies are needed to clarify this relationship.

Inflammatory cytokines in pediatric obstructive sleep apnea

Pediatric obstructive sleep apnea (OSA) is associated with chronic systemic inflammation and with cognitive impairments. This study aimed to investigate the status of proinflammatory cytokines, particularly interleukin 17 (IL-17) and interleukin 23 (IL-23) and cognition in pediatric OSA.Controls and OSA children participated in the study. Exclusion criteria were adenotonsillectomy, heart, neurological and severe psychiatric diseases, craniofacial syndromes, and obesity. Polysomnogram was followed by serum testing for inflammatory markers and neurocognitive tests such as continuous performance task (CPT) and Wisconsin card sorting test, questionnaires, analyses of plasma high-sensitivity C-reactive protein (HS-CRP), tumor necrosis factor alpha (TNF-α), interleukin 1 (IL-1), interleukin 6 (IL-6), IL-17, and IL-23.Seventy-nine, 4 to 12-year-old subjects in 2 groups ended the study: 47 nonobese OSA children (mean age = 7.84 ± 0.56 years, body mass index [BMI] = 16.95 ± 0.47 kg/m, BMI z-score = 0.15 ± 0.21, and mean apnea-hypopnea index [AHI] = 9.13 ± 1.67 events/h) and 32 healthy control children (mean age = 7.02 ± 0.65 years, with BMI = 16.55 ± 0.58 kg/m, BMI z-score = -0.12 ± 0.27, and mean AHI = 0.41 ± 0.07 event/h) were enrolled. Serum cytokine analyses showed significantly higher levels of HS-CRP, IL-17, and IL-23 in OSA children (P = 0.002, P = 0.024, and P = 0.047). Regression test showed significant influence of HS-CRP, TNF-α, IL-6, IL-17, and specifically IL-23, with the continuous performance test and Wisconsin card sorting test.OSA children have abnormal levels of IL-17, an interleukin related to T helper 17 cells, a T helper cell involved in development of autoimmunity and inflammation. This high expression level may contribute to the complications of pediatric OSA; we also found a significant influence of inflammatory cytokines, particularly IL-23, on abnormal neurocognitive testing.

P2X7 Receptor Antagonism Attenuates the Intermittent Hypoxia-induced Spatial Deficits in a Murine Model of Sleep Apnea Via Inhibiting Neuroinflammation and Oxidative Stress

Background:

The mechanism of the neural injury caused by chronic intermittent hypoxia (CIH) that characterizes obstructive sleep apnea syndrome (OSAS) is not clearly known. The purpose of this study was to investigate whether P2X7 receptor (P2X7R) is responsible for the CIH-induced neural injury and the possible pathway it involves.

Methods:

Eight-week-old male C57BL/6 mice were used. For each exposure time point, eight mice divided in room air (RA) and IH group were assigned to the study of P2X7R expression. Whereas in the 21 days-Brilliant Blue G (BBG, a selective P2X7R antagonist) study, 48 mice were randomly divided into CIH group, BBG-treated CIH group, RA group and BBG-treated RA group. The hippocampus P2X7R expression was determined by Western blotting and real-time polymerase chain reaction (PCR). The spatial learning was analyzed by Morris water maze. The nuclear factor kappa B (NFκB) and NADPH oxidase 2 (NOX2) expressions were analyzed by Western blotting. The expressions of tumor necrosis factor α, interleukin 1β (IL-β), IL-18, and IL-6 were measured by real-time PCR. The malondialdehyde and superoxide dismutase levels were detected by colorimetric method. Cell damage was evaluated by Hematoxylin and Eosin staining and Terminal Transferase dUTP Nick-end Labeling method.

Results:

The P2X7R mRNA was elevated and sustained after 3-day IH exposure and the P2X7R protein was elevated and sustained after 7-day IH exposure. In the BBG study, the CIH mice showed severer neuronal cell damage and poorer performance in the behavior test. The increased NFκB and NOX2 expressions along with the inflammation injury and oxidative stress were also observed in the CIH group. BBG alleviated CIH-induced neural injury and consequent functional deficits.

Conclusions:

The P2X7R antagonism attenuates the CIH-induced neuroinflammation, oxidative stress, and spatial deficits, demonstrating that the P2X7R is an important therapeutic target in the cognition deficits accompanied OSAS.

Th17/Treg balance in children with obstructive sleep apnea syndrome and the relationship with allergic rhinitis

OBJECTIVE

This study aims to explore the role of the Th17 to Treg cell ratio in children with OSA and its relationship with allergic rhinitis.

METHODS

The study included 127 children diagnosed with OSA by polysomnography (PSG) testing and 29 children without OSA. The 127 children with OSA were divided into the following groups: OSA with moderate adenoidal hypertrophy (n=47), OSA with severe adenoidal hypertrophy (n=49), and OSA complicated by allergic rhinitis (AR) (n=31). The adenoids of the 29 children without OSA were mildly hypertrophic. We measured the number of Th17 and Treg cells, the levels of related serum cytokines in cellular secretions, and the expression of key transcription factors in both the peripheral blood and adenoid tissue. The Th17/Treg ratio was calculated and analyzed between groups. The numbers of Th17 and Treg cells were measured by flow cytometry; the secreted IL-17, IL-10, and TGF-β were measured by ELISA; and the expression levels of RORγt and Foxp3 were measured by RT-PCR.

RESULTS

Compared with the control group, OSA children exhibited a significant increase in the number of peripheral Th17 cells, Th17-related cytokine secretion (IL-17), and RORγt mRNA levels, whereas they exhibited a decrease in the number of Treg cells, Treg-related cytokine secretions (IL-10, TGF-β) and Foxp3 mRNA levels. The Th17/Treg ratio was higher (p<0.05) in the OSA groups than in the control group. The Th17/Treg ratio was correlated with the size of the adenoids. We also found that the Th17/Treg balance in OSA patients was complicated by allergic rhinitis; the increase was significantly larger in the AR group (p<0.05, p=0.021) than in OSA groups without AR. These results were observed in both the peripheral blood and local adenoid tissue.

CONCLUSION

The Th17/Treg imbalance may increase the risk of developing OSA, and AR may promote the development of the disease. These results provide an alternative explanation for OSA pathogenesis that warrants additional research and presents new directions for the prevention and treatment of OSA in children.

A Bone Anabolic Effect of RANKL in a Murine Model of Osteoporosis Mediated Through FoxP3+ CD8 T Cells

TNF-α and IL-17 secreted by proinflammatory T cells (T(EFF)) promote bone erosion by activating osteoclasts. We previously demonstrated that in addition to bone resorption, osteoclasts act as antigen-presenting cells to induce FoxP3 in CD8 T cells (Tc(REG)). The osteoclast-induced regulatory CD8 T cells limit bone resorption in ovariectomized mice (a murine model of postmenopausal osteoporosis). Here we show that although low-dose receptor activator of NF-κB ligand (RANKL) maximally induces Tc(REG) via Notch signaling pathway to limit bone resorption, high-dose RANKL promotes bone resorption. In vitro, both TNF-α and IL-17, cytokines that are abundant in ovariectomized animals, suppress Tc(REG) induction by osteoclasts by repressing Notch ligand expression in osteoclasts, but this effect can be counteracted by addition of RANKL. Ovariectomized mice treated with low-dose RANKL induced Tc(REG) that suppressed bone resorption, decreased T(EFF) levels, and increased bone formation. High-dose RANKL had the expected osteolytic effect. Low-dose RANKL administration in ovariectomized mice lacking CD8 T cells was also osteolytic, confirming that Tc(REG) mediate this bone anabolic effect. Our results show that although RANKL directly stimulates osteoclasts to resorb bone, it also controls the osteoclasts' ability to induce regulatory T cells, engaging an important negative feedback loop. In addition to the conceivable clinical relevance to treatment of osteoporosis, these observations have potential relevance to induction of tolerance and autoimmune diseases.

Relationship of redundant Th17 cells and IL-17A, but not IL-17 F, with the severity of obstructive sleep apnoea/hypopnoea syndrome (OSAHS)

Background

The pathogenesis of obstructive sleep apnoea/hypopnoea syndrome (OSAHS), a highly prevalent disease, is not completely understood. The purpose of this study was to investigate the contributions of Th17 cells and the Th17-associated cytokines IL-17A and IL-17 F to OSAHS.

Methods

46 male patients with a clinical suspicion of OSAHS were enrolled and divided into four groups based on their polysomnography results: controls and mild, moderate, and severe OSAHS. The serum levels of IL-17A and IL-17 F were determined by enzyme linked immunosorbent assay (ELISA), pulmonary arterial pressure (PAP) was determined by echocardiography, and Th17 cell frequencies in peripheral blood were measured by flow cytometry.

Results

Serum IL-17A levels in the severe group were elevated (median value: control group 0.89 pg/ml, mild OSAHS 1.02 pg/ml, moderate OSAHS 1.18 pg/ml, and severe OSAHS 1.62 pg/ml; p < 0.05) and positively correlated with AHI (r = 0.52, p < 0.05) but negatively related to the mean O₂ saturation and lowest O₂ saturation (r = −0.349, p < 0.05; and r = −0.336, p < 0.05, respectively). Although the frequencies of Th17 cells in the OSAHS groups were higher than that in the control group, these differences were not significant (p = 0.275). Pulmonary arterial hypertension was not present in our patients as the median PAP of the normal control and the mild, moderate, and severe OSAHS groups were 26, 27.5, 24.5, and 25.5 mmHg, respectively (p = 0.676).

Conclusion

IL-17A may be involved in the pathogenesis of OSAHS and may represent a target for therapeutic intervention.