Nicotine accelerates diabetes-induced retinal changes

Role of Systemic Factors in Improving the Prognosis of Diabetic Retinal Disease and Predicting Response to Diabetic Retinopathy Treatment

Topic

To review clinical evidence on systemic factors that might be relevant to update diabetic retinal disease (DRD) staging systems, including prediction of DRD onset, progression, and response to treatment.

Clinical relevance

Systemic factors may improve new staging systems for DRD to better assess risk of disease worsening and predict response to therapy.

Methods

The Systemic Health Working Group of the Mary Tyler Moore Vision Initiative reviewed systemic factors individually and in multivariate models for prediction of DRD onset or progression (i.e., prognosis) or response to treatments (prediction).

Results

There was consistent evidence for associations of longer diabetes duration, higher glycosylated hemoglobin (HbA1c), and male sex with DRD onset and progression. There is strong trial evidence for the effect of reducing HbA1c and reducing DRD progression. There is strong evidence that higher blood pressure (BP) is a risk factor for DRD incidence and for progression. Pregnancy has been consistently reported to be associated with worsening of DRD but recent studies reflecting modern care standards are lacking. In studies examining multivariate prognostic models of DRD onset, HbA1c and diabetes duration were consistently retained as significant predictors of DRD onset. There was evidence of associations of BP and sex with DRD onset. In multivariate prognostic models examining DRD progression, retinal measures were consistently found to be a significant predictor of DRD with little evidence of any useful marginal increment in prognostic information with the inclusion of systemic risk factor data apart from retinal image data in multivariate models. For predicting the impact of treatment, although there are small studies that quantify prognostic information based on imaging data alone or systemic factors alone, there are currently no large studies that quantify marginal prognostic information within a multivariate model, including both imaging and systemic factors.

Conclusion

With standard imaging techniques and ways of processing images rapidly evolving, an international network of centers is needed to routinely capture systemic health factors simultaneously to retinal images so that gains in prediction increment may be precisely quantified to determine the usefulness of various health factors in the prognosis of DRD and prediction of response to treatment.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Influence of quitting smoking on diabetes-related complications: A scoping review with a systematic search strategy

INTRODUCTION

Smoking in people with diabetes markedly elevates their risk of developing complications and increases the likelihood of cardiovascular mortality. This review is the first to specifically provide evidence-based analysis about the influence of quitting smoking on diabetes-related complications in people with type 2 diabetes.

METHOD

The present review was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews. All human clinical studies assessing the effects of stopping smoking cessation on diabetes-related complications were included. PubMed and Embase were screened until January 2024. References of primary studies and principal peer-reviewed scientific journals in the field were manually screened.

RESULTS

We identified a total of 1023 studies. Only 26 met the criteria for eligibility. In general quitting smoking is associated with decreased risks of myocardial infarction and ischemic stroke. Regarding microvascular complications, the strongest evidence for the beneficial effects of smoking cessation is observed in diabetic nephropathy. However, the relationship between smoking cessation and retinopathy, neuropathy, diabetic foot complications and diabetic-related erectile dysfunction, is poorly investigated.

CONCLUSION

Quitting smoking offers significant advantages in managing diabetes-related complications, significantly lowering the risks of myocardial infarction, ischemic stroke, and diabetic nephropathy. This underscores the importance of cessation. Providing evidence-based information on the benefits of stopping smoking for people with type 2 diabetes who smoke, can bolster smoking cessation efforts in the context of diabetes management.

The influence of smoking on retinal ganglion cell-inner plexiform layer complex in male diabetes

PURPOSE

This study aims to evaluate the influence of smoking on ganglion cell-inner plexiform layer complex (GC-IPL) thickness and central macular thickness (CMT) measured by spectral domain optical coherence tomography (OCT) in male diabetes.

METHODS

90 smoking and 90 never-smoking male subjects were included in this study. They were divided into six groups based on the diagnostic criteria for diabetes and the Early Treatment Diabetic Retinopathy Study (ETDRS) classification: smoking healthy subjects (SH, n = 20), non-smoking healthy subjects (NSH, n = 20), smoking diabetic patients without diabetic retinopathy (SNDR, n = 40), non-smoking diabetic patients without diabetic retinopathy (NSNDR, n = 40), smoking diabetic patients with diabetic retinopathy (SDR, n = 30), and non-smoking diabetic patients with diabetic retinopathy (NSDR, n = 30). After a full ophthalmologic examination, GC-IPL thickness and central macular thickness (CMT) were measured by OCT. Statistical analysis was performed to compare GC-IPL thickness and CMT between groups. Multiple linear regression equations were constructed to explore the potential risk factors of mean GC-IPL thickness.

RESULTS

There were no significant differences in GC-IPL thickness and CMT between SH and NSH (all p > 0.05). Mean, superonasal, superior, superotemporal, inferonasal, inferior GC-IPL (p＜0.001, p＜0.001, p＜0.001, p = 0.003, p = 0.001, and p = 0.005, respectively) were thinner in the SNDR than NSNDR except for inferotemporal GC-IPL thickness and CMT (p = 0.066, p = 0.605, respectively). Mean, superonasal, superior, and inferonasal GC-IPL were thinner in the SDR than NSDR (p = 0.019, p = 0.045, p = 0.037, and p = 0.049, respectively). Multiple regression analysis demonstrated that age (β [SE], -0.141 [0.060]; p = 0.020) and smoking (β [SE], -4.470 [1.015]; p＜0.001) were the most important determinants for mean GC-IPL thickness.

CONCLUSION

Smoking is associated with reduced retinal GC-IPL thickness in male diabetes. Smoking behavior and age are important determinants of mean GC-IPL thickness.

Smoking and diabetes interplay: A comprehensive review and joint statement

Evidence shows that smoking increases the risk of pre-diabetes and diabetes in the general population. Among persons with diabetes, smoking has been found to increase the risk of all-cause mortality and aggravate chronic diabetic complications and glycemic control. The current paper, which is a joint position statement by the French-Speaking Society on Tobacco (Société Francophone de Tabacologie) and the French-Speaking Society of Diabetes (Société Francophone du Diabète), summarizes the data available on the association between smoking and diabetes and on the impact of smoking and smoking cessation among individuals with type 1, type 2, and gestational diabetes mellitus. It also provides evidence-based information about the pharmacological and behavioral strategies for smoking cessation in these patients.

Effects of Smoking on Outcomes of Anti-Vascular Endothelial Growth Factor Therapy in Patients with Diabetic Macular Edema: A Retrospective Case-Control Study

PURPOSE

To determine the effect of smoking on the response to anti-vascular endothelial growth factor (anti-VEGF) therapy treatment in patients with diabetic macular edema (DME).

METHODS

This is a retrospective case - control study that included 60 eyes with DME. Smoking habits were obtained from hospital records and patient recall. Patients were divided into two groups: the ever-smoker group and the never-smoker group. All patients received Intravitreal ranibizumab with three loading doses followed by PRN protocol and all were followed up for at least 1 year. Outcome measures were best-corrected visual acuity (BCVA), central retinal thickness (CRT) at the fovea, and number of visits.

RESULTS

Smoking was not associated with worse posttreatment visual acuity and was not found to influence the change in ocular coherence tomography measurement of central macular thickness and the change in BCVA (posttreatment minus pretreatment). There were no statistically significant differences in the duration of treatment or number of visits between two groups of patients the ever-smoker group and the never-smoker group (P > 0.05).

CONCLUSION

In this study, smoking status did not influence the treatment outcome of anti-VEGFs; however, smoking should be encouraged due to its well-known other systemic unwanted effects.

Evaluation of subclinical alterations in retinal layers and microvascular structures with OCT and OCTA in healthy young short-term smokers

PURPOSE

To detect the changes that can be determined with optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) in young and short-term smokers.

METHOD

In this cross-sectional, observational, and comparative study, 45 "healthy" smokers and 45 healthy non-smoker control participants were included. Those with a smoking history between 1 year to 5 years and an average of 10-30 cigarettes per day were included in the study. OCT and OCTA measurements were made at least 60 min after smoking and at least 8 h after caffeine-containing beverages in order to end the effect of nicotine on systemic and retinal blood flow in the smoking group.

RESULTS

The mean smoking period was 2.2 ± 0.13 years. Mean macular thickness(MMT), retinal nerve fiber layer(RNFL), and choroidal thickness(Cht) were significantly lower in the smoker group, while ganglion cell-inner plexiform layer(GC-IPL) thickness was higher. Vessel density(VD) values were similar between groups, while perfusion density(PD) values were significantly higher in the smoker group. There were significant correlations between MMT and outer VD, outer PD, foveal avascular zone(FAZ) perimeter and circularity index. FAZ area and central VD and PD were inversely correlated. Also, FAZ circularity index and subfoveal, nasal, and temporal ChTs were positively correlated.

CONCLUSION

Despite the short-term smoking, ischemic effects were observed in retinochoroidal and vascular structures.

Immuno-histological detection of resistant columnar units and vulnerable networks in the rat retina after asphyxia-induced transient cardiac arrest

BACKGROUND

Stroke-related loss of vision is one of the residual impairments, restricting the quality of life. However, studies of the ocular manifestations of asphyxia cardiac arrest/resuscitation (ACA/R) have reported very heterogeneous results.

OBJECTIVE

We aimed to evaluate the ACA/R-induced degeneration pattern of the different retinal cell populations in rats using different immuno-histological stainings.

METHODS

The staining pattern of toluidine blue and the ganglion cell markers β-III-tubulin and NeuN; the calcium-binding protein parvalbumin, indicating ganglion, amacrine, and horizontal cells; calretinin D28k, indicating ganglion and amacrine cells; calbindin, indicating horizontal cells; Chx 10, indicating cone bipolar cells; PKCα, indicating ON-type rod bipolar cells; arrestin, indicating cones; and rhodopsin, a marker of rods, as well as the glial cell markers GFAP (indicating astroglia and Müller cells) and IBA1 (indicating microglia), were evaluated after survival times of 7 and 21 days in an ACA/R rat model. Moreover, quantitative morphological analysis of the optic nerve was performed. The ACA/R specimens were compared with those from sham-operated and completely naïve rats.

RESULTS

ACA/R-induced effects were: (i) a significant reduction of retinal thickness after long-term survival; (ii) ganglion cell degeneration, including their fiber network in the inner plexiform layer; (iii) degeneration of amacrine and cone bipolar cells; (iv) degeneration of cone photoreceptors; (v) enhanced resistance to ACA/R by rod photoreceptors, ON-type rod bipolar and horizontal cells, possibly caused by the strong upregulation of the calcium-binding proteins calretinin, parvalbumin, and calbindin, counteracting the detrimental calcium overload; (vi) significant activation of Müller cells as further element of retinal anti-stress self-defense mechanisms; and (vii) morphological alterations of the optic nerve in form of deformed fibers.

CONCLUSIONS

Regardless of the many defects, the surviving neuronal structures seemed to be able to maintain retinal functionality, which can be additionally improved by regenerative processes true to the "use it or lose it" dogma.

Spatial analysis of metformin use compared with nicotine and caffeine consumption through wastewater-based epidemiology in China

Monitoring the consumption of pharmaceuticals and licit drugs is important for assessing the needs of public health owing to the impact on individuals as well as society. The present work applied wastewater-based epidemiology to profile the spatial patterns of metformin, nicotine, and caffeine use and their correlations. Influent wastewater samples were collected from 27 wastewater treatment plants in 22 typical Chinese cities that covered all geographic regions of the country. The consumption of metformin ranged from 0.02 g/d/1000 inh to 8.92 g/d/1000 inh, whereas caffeine and nicotine consumption ranged from 4.33 g/d/1000 inh to 394 g/d/1000 inh and 0.17 g/d/1000 inh to 1.88 g/d/1000 inh, respectively. There were significant regional differences in the consumption of caffeine, with the highest consumption in East China and the lowest consumption in Northeast China. The consumption and concentration of caffeine were related to the gross domestic product and per capita disposable income of urban residents, respectively. There was a correlation between the concentrations of caffeine and cotinine (a nicotine metabolite), thereby indicating that individuals that use one of these substances are likely to use the other substance. A significant relationship was found between the concentration of metformin and cotinine, thereby implying that the use of tobacco may be correlated with type 2 diabetes. Co-analysis of these substances in wastewater may provide a more accurate picture of substance use situations within different communities and provide more information on human health, human behavior, and the economy. This report describes the newest study related to the consumption of metformin among the general population in China.

Tobacco smoking is an independent factor associated with retinal damage in systemic lupus erythematosus: a cross-sectional and retrospective study

To analyze the influence of tobacco smoking on systemic lupus erythematosus (SLE) clinical features and damage. Cross-sectional and retrospective, case-control study comparing SLE patients with and without tobacco exposure. Cumulative clinical data and comorbidities were collected, and severity (Katz index) and damage (SLICC/ACR damage index) (SDI) indices were calculated. Pack-years (PY) was used to estimate lifetime tobacco exposure. A logistic regression was carried out to explore the impact of tobacco use on retinal damage. 216 patients were included. The mean age was 49 years (± 12.7), 93% were females, and median disease duration was 17 years [interquartile range (IQR):9-25]. Fifty-three percent of patients were smokers at some point. The median PY was 13 (IQR: 6-20.5). Only 54.8% of active smokers recalled having been informed of the negative effects of smoking, versus 83.3% of never smokers (< 0.001). In a bivariant analysis, an association between tobacco use at any time and discoid lupus [OR: 3.5(95%CI 1.5-8.9); p = 0.002] photosensitivity [OR: 2.06(95%CI 1.16-3.7); p = 0.01] and peripheral arteriopathy (p = 0.007) was found. Considering SDI item by item, a significant association with retinal damage, adjusted for age [OR: 1.03(95%CI 1-1.07); p = 0.04], was found. Using PYs, an association was found with discoid lupus (p = 0.01), photosensitivity (p = 0.03) and peripheral arteriopathy (p = 0.01), global SDI > 0 (p = 0.002) and retinal damage (p = 0.02). In a multivariate analysis exploring factors associated with retinal damage, any previous smoking history and SDI remained associated with retinal damage. Tobacco smoking is associated with cutaneous manifestations and damage and is an independent predictor of retinal damage in SLE patients.

Retinal vascular tortuosity in schizophrenia and bipolar disorder

The micro-vasculature of retina and brain share common morphological, physiological, and pathological properties. Retina being easily accessible, retinal vascular examination provides an indirect assessment of cerebral vasculature. Considering the high prevalence of vascular morbidity in SCZ and BD a few studies have examined retinal vascular caliber and have reported increased retinal venular caliber in schizophrenia (SCZ). Retinal vascular tortuosity could serve as a better structural measure than caliber as it is static and less susceptible to pulse period variations. However, to date, no study has examined retinal vascular tortuosity in SCZ and bipolar disorder (BD). Hence, we examined retinal vascular tortuosity in comparison with healthy volunteers (HV). We included 255 subjects (78 HV, 79 SCZ, and 86 BD) in the age range of 18 to 50 years. Trained personnel acquired images using a non-mydriatic fundus camera. To measure the average retinal arteriolar tortuosity index (RATI) and retinal venular tortuosity index (RVTI), we used a previously validated, semi-automatic algorithm. The results showed significant differences across the three groups in RATI but not in RVTI; both BD and SCZ had significantly increased RATI compared to HV. There was also a significant difference between SCZ and BD, with BD having higher RATI. If shown to be of predictive utility in future longitudinal studies, it has the potential to identify patients at risk of development of adverse vascular events. As retinal vascular imaging is non-invasive and inexpensive, it could serve as a proxy marker and window to cerebral vasculature.

Biological effects of nicotine exposure: A narrative review of the scientific literature

The emergence of new tobacco heating products and electronic nicotine delivery systems (ENDS) is changing the way humans are exposed to nicotine. The purpose of this narrative review is to provide a broad overview of published scientific literature with respect to the effects of nicotine on three key health-related areas: 1) cardiovascular risk, 2) carcinogenesis and 3) reproductive outcomes. These areas are known to be particularly vulnerable to the effects of cigarette smoke, and in addition, nicotine has been hypothesized to play a role in disease pathogenesis. Acute toxicity will also be discussed. The literature to February 2019 suggests that there is no increased cardiovascular risk of nicotine exposure in consumers who have no underlying cardiovascular pathology. There is scientific consensus that nicotine is not a direct or complete carcinogen, however, it remains to be established whether it plays some role in human cancer propagation and metastasis. These cancer progression pathways have been proposed in models in vitro and in transgenic rodent lines in vivo but have not been demonstrated in cases of human cancer. Further studies are needed to determine whether nicotine is linked to decreased fertility in humans. The results from animal studies indicate that nicotine has the potential to act across many mechanisms during fetal development. More studies are needed to address questions regarding nicotine exposure in humans, and this may lead to additional guidance concerning new ENDS entering the market.

Cardiovascular, carcinogenic and reproductive effects of nicotine exposure: A narrative review of the scientific literature

The emergence of new tobacco heating products and electronic nicotine delivery systems (ENDS) is changing the way humans are exposed to nicotine. The purpose of this narrative review is to provide a broad overview of published scientific literature with respect to the effects of nicotine on three key health-related areas: 1) cardiovascular risk, 2) carcinogenesis and 3) reproductive outcomes. These areas are known to be particularly vulnerable to the effects of cigarette smoke, and in addition, nicotine has been hypothesized to play a role in disease pathogenesis. Acute toxicity will also be discussed. The literature to February 2019 suggests that there is no increased cardiovascular risk of nicotine exposure in consumers who have no underlying cardiovascular pathology. There is scientific consensus that nicotine is not a direct or complete carcinogen, however, it remains to be established whether it plays some role in human cancer propagation and metastasis. These cancer progression pathways have been proposed in models in vitro and in transgenic rodent lines in vivo but have not been demonstrated in cases of human cancer. Further studies are needed to determine whether nicotine is linked to decreased fertility in humans. The results from animal studies indicate that nicotine has the potential to act across many mechanisms during fetal development. More studies are needed to address questions regarding nicotine exposure in humans, and this may lead to additional guidance concerning new ENDS entering the market.

The Preventive Effect of Oxytocin on Retinopathy in Streptozotocin-Induced Diabetic Rats

Objectives:

The aim of this study was to investigate the impact of intravitreal and intraperitoneal use of oxytocin (OT) on retinopathy in streptozotocin-induced diabetic rats.

Materials and Methods:

Twenty-four 6-8-week-old adult male and female Sprague Dawley rats were used in the study. Diabetes was induced in the rats with a single injection of intraperitoneal streptozotocin. Diabetes was verified after 48 hours by measuring blood glucose levels of 260 mg/dl (14.4 mmol/L) or higher in diabetic rats. The rats were divided into 4 groups and treated as follows: intravitreal physiological saline group (0.01 mL saline weekly), intravitreal OT group (10 μU/μL OT weekly), intraperitoneal physiological saline group (1 mL daily), and intraperitoneal OT group (100 IU/kg OT daily). Hamilton syringes fitted with 27-gauge needles were used for intraperitoneal injections while 31-gauge needles were used for intravitreal injection. After 4 weeks of treatment the rats were euthanized to evaluate outer nuclear layer (ONL) thickness, vascular endothelial growth factor (VEGF) immunoexpression, and plasma VEGF levels from blood samples obtained by cardiac puncture.

Results:

Morphometric analysis of retinal cross-sections showed that intravitreal and intraperitoneal OT significantly increased ONL thickness compared to physiological saline-treated groups. Also, OT treatment significantly decreased VEGF protein expression compared with the physiological saline groups. Plasma VEGF level was significantly higher in the physiological saline treatment group compared to the OT treatment group.

Conclusion:

OT reduces diabetic retinopathy progression, particularly when administered intravitreally. To our knowledge, this is the first attempt to investigate the impact of OT on diabetic retinopathy and may provide a new area for further research.

Retinal explant culture: A platform to investigate human neuro-retina

The retina is the tissue responsible for light detection, in which retinal neurons convert light energy into electrical signals to be transported towards the visual cortex. Damage of retinal neurons leads to neuronal cell death and retinal pathologies, compromising visual acuity and eventually leading to irreversible blindness. Models of retinal neurodegeneration include 2D systems like cell lines, disassociated cultures and co-cultures, and 3D models like organoids, organotypic retinal cultures and animal models. Of these, ex vivo human retinal cultures are arguably the most suitable models for translational research as they retain complex inter-cellular interactions of the retina and precisely mimic in-situ responses. In this review, we summarize the distinguishing features of the human retina which are important to preserve in experimental culture, the historical development of human retinal culture systems, the factors affecting ex vivo human retinal culture and the applications and challenges associated with current methods of human retinal explant culture.

"Dangerous duo": Chronic nicotine exposure intensifies diabetes mellitus-related deterioration in bone microstructure - An experimental study in rats

AIMS

Bony complications of diabetes mellitus (DM) are still insufficiently understood. Our aims were to analyze the individual and combined effects of chronic hyperglycemia and nicotine exposure on the femoral trabecular and cortical microarchitecture on a rat experimental model.

MAIN METHODS

The micro-computed tomography based bone microstructural evaluation was performed on male Wistar rats divided into four groups: control (n = 7), experimentally-induced DM (n = 8), chronically exposed to nicotine (n = 9) and the DM group exposed chronically to nicotine (n = 9).

KEY FINDINGS

Chronic hyperglycemia caused mild trabecular deterioration; yet, the combination of hyperglycemia and nicotine exposure showed more deleterious effects on the trabecular bone. Namely, the DM + nicotine group had significantly lower bone volume fraction, fewer and more rod-like shaped trabeculae, along with higher trabecular separation and lower connectivity than the control group (p < 0.05). Nicotine alone did not show any significant deterioration compared to the control group. DM and DM + nicotine groups had lower cortical porosity than control and nicotine groups (p < 0.05). Cortical thickness did not show any significant intergroup differences, whereas bone perimeter and the mean polar moment of inertia were reduced in DM + nicotine group.

SIGNIFICANCE

Mild effects of chronic hyperglycemia on bone structure were accentuated by the chronic nicotine exposure, although nicotine alone did not cause any significant bone changes. That suggests a synergistic effect of hyperglycemia and nicotine on bone deterioration and increased propensity to fracture. Indeed, better understanding of risk factors driving bone structural deterioration is a precondition to limit the complications associated with DM.

Nicotine and autoimmunity: The lotus' flower in tobacco

Nicotine, the major component of cigarettes, has demonstrated conflicting impact on the immune system: some authors suggest that increases pro-inflammatory cytokines and provokes cellular apoptosis of neutrophils, releasing intracellular components that act as auto-antigens; others claimed that nicotine has a protective and anti-inflammatory effects, especially by binding to α7 subunit of nicotinic acetylcholine receptors. The cholinergic pathway contributes to an anti-inflammatory environment characterized by increasing T regulatory cells response, down-regulating of pro-inflammatory cytokines and a pro-inflammatory cells apoptosis. The effects of nicotine were studied in different autoimmune disease, as multiple sclerosis, type 1 diabetes, rheumatoid arthritis, sarcoidosis, Behçet's disease and inflammatory bowel diseases. The major problems about nicotine are the addiction and the adverse effects of related to each commercialized formulation. We sought in this review to summarize the knowledge accumulated to date concerning the relationship between nicotine and autoimmunity.

Nicotine promotes blood retinal barrier damage in a model of human diabetic macular edema

More than 1 billion world's population actively smokes tobacco containing the bioactive component nicotine (NT). The biological role of this molecule is mediated through the activation of nicotinic cholinergic receptors, widely distributed in various human tissues including retinal pigmented epithelium. The long-term assumption of NT contributes to several diseases development such as diabetic retinopathy. The major complication of this pathology is the diabetic macular edema (DME), characterized by macular area thinning and blood-retinal barrier (BRB) breakdown. Retinal hyperglycemic/hypoxic microenvironment represents one of the main factors favoring DME progression by eliciting the hypoxia-inducible factors (HIFs) expression. The latter induce new vessels formation by stimulating cellular secretion of vascular endothelial growth factor (VEGF). The etiology of DME is multifactorial, but little is known about the risk factors linked to cigarette smoking, in particular to nicotine's contribution. In the present study, we have investigated the NT role in a model, in vitro, of DME, by evaluating its effect on outer BRB permeability and HIFs/VEGF expression following exposure to hyperglycemic/hypoxic insult. Our results have demonstrated that this compound alters outer BRB integrity exposed to high glucose and low oxygen pressure microenvironment by upregulating HIF-1α/HIF-2α, VEGF expression and ERK1/2 phosphorylation. These data have suggested that NT may play a negative role in active smokers affected by DME.

Effects of nicotine on corneal wound healing following acute alkali burn

Epidemiological studies have indicated that smoking is a pivotal risk factor for the progression of several chronic diseases. Nicotine, the addictive component of cigarettes, has powerful pathophysiological properties in the body. Although the effects of cigarette smoking on corneal re-epithelialization have been studied, the effects of nicotine on corneal wound healing-related neovascularization and fibrosis have not been fully demonstrated. The aim of this study was to evaluate the effects of chronic administration of nicotine on corneal wound healing following acute insult induced by an alkali burn. BALB/C female mice randomly received either vehicle (2% saccharin) or nicotine (100 or 200 μg/ml in 2% saccharin) in drinking water ad libitum. After 1 week, animals were re-randomized and the experimental group was subjected to a corneal alkali burn, and then nicotine was administered until day 14 after the alkali burn. A corneal alkali burn model was generated by placing a piece of 2 mm-diameter filter paper soaked in 1N NaOH on the right eye. Histopathological analysis and the expression level of the pro-angiogenic genes vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP9) revealed that chronic nicotine administration enhanced alkali burn-induced corneal neovascularization. Furthermore, the mRNA expression of the pro-fibrogenic factors α-smooth muscle actin (αSMA), transforming growth factor-β (TGF-β), and collagen α1 (Col1) was enhanced in the high-concentration nicotine-treated group compared with the vehicle group after corneal injury. Immunohistochemical analysis also showed that the αSMA-positive area was increased in chronic nicotine-treated mice after corneal alkali burn. An in vitro assay found that expression of the α3, α7, and β1 nicotinic acetylcholine receptor (nAChR) subunits was significantly increased by chemical injury in human corneal fibroblast cells. Moreover, alkali-induced fibrogenic gene expression and proliferation of fibroblast cells were further increased by treatment with nicotine and cotinine. The proliferation of such cells induced by treatment of nicotine and cotinine was reduced by inhibition of the PI3K and PKC pathways using specific inhibitors. In conclusion, chronic administration of nicotine accelerated the angiogenic and fibrogenic healing processes in alkali-burned corneal tissue.

Lower urinary cotinine level is associated with a trend toward more myopic refractive errors in Korean adolescents

PurposeTo investigate the association between urinary cotinine levels as an objective biological marker for exposure to nicotine and refractive status.Patients and methodsThis cross-sectional study analyzed data from the Korea National Health and Nutrition Examination Survey between 2008 and 2011. A total of 1139 Korean adolescents aged 12-18 years were enrolled. Urinary cotinine concentrations and other potential risk factors for myopia were examined. Correlation analyses and multivariate regression analysis were performed to investigate the association between urinary cotinine level and refractive error.ResultsSpherical equivalent correlated significantly with urinary cotinine concentration (r=0.104, P=0.011). Lower urinary cotinine level was associated with a trend toward more myopic refractive errors (P for trend=0.003). After adjusting for age, sex, area of residence, physical activity, serum 25-hydroxyvitamin D level, parental income level, and receipt of basic livelihood security, subjects with a low urinary cotinine level had a significantly increased risk of myopia <-0.5 D (odds ratio (OR) 1.95, 95% confidence interval (CI) 1.18-3.21), <-3.0 D (OR 2.03, 95% CI 1.29-3.2), and <-6.0 D (OR 2.2, 95% CI, 1.15-4.23) when compared with subjects with a high urinary cotinine level. As urinary cotinine level decreased, the risks of myopia <-0.5 D, <-3.0 D, and <-6.0 D increased significantly (P for trend <0.05).ConclusionA trend toward less myopic refractive error was observed among Korean adolescents with higher urinary cotinine levels. This result provides the epidemiologic evidence implying nicotine as a potential modulator related with refractive development. Further studies with full consideration for myopia-associated risk factors are required to yield clear answers on the direct effect of smoking to the refractive status.

Diabetic retinopathy - ocular complications of diabetes mellitus

In industrialized nations diabetic retinopathy is the most frequent microvascular complication of diabetes mellitus and the most common cause of blindness in the working-age population. In the next 15 years, the number of patients suffering from diabetes mellitus is expected to increase significantly. By the year 2030, about 440 million people in the age-group 20-79 years are estimated to be suffering from diabetes mellitus worldwide (prevalence 7.7%), while in 2010 there were 285 million people with diabetes mellitus (prevalence 6.4%). This accounts for an increase in patients with diabetes in industrialized nations by 20% and in developing countries by 69% until the year 2030. Due to the expected rise in diabetic patients, the need for ophthalmic care of patients (i.e., exams and treatments) will also increase and represents a challenge for eye-care providers. Development of optimized screening programs, which respect available resources of the ophthalmic infrastructure, will become even more important. Main reasons for loss of vision in patients with diabetes mellitus are diabetic macular edema and proliferative diabetic retinopathy. Incidence or progression of these potentially blinding complications can be greatly reduced by adequate control of blood glucose and blood pressure levels. Additionally, regular ophthalmic exams are mandatory for detecting ocular complications and initiating treatments such as laser photocoagulation in case of clinical significant diabetic macular edema or early proliferative diabetic retinopathy. In this way, the risk of blindness can considerably be reduced. In advanced stages of diabetic retinopathy, pars-plana vitrectomy is performed to treat vitreous hemorrhage and tractional retinal detachment. In recent years, the advent of intravitreal medication has improved therapeutic options for patients with advanced diabetic macular edema.