Clinical standards for diagnosis, treatment and prevention of post-COVID-19 lung disease.

BACKGROUND: The aim of these clinical standards is to provide guidance on 'best practice' care for the diagnosis, treatment and prevention of post-COVID-19 lung disease.METHODS: A panel of international experts representing scientific societies, associations and groups active in post-COVID-19 lung disease was identified; 45 completed a Delphi process. A 5-point Likert scale indicated level of agreement with the draft standards. The final version was approved by consensus (with 100% agreement).RESULTS: Four clinical standards were agreed for patients with a previous history of COVID-19: Standard 1, Patients with sequelae not explained by an alternative diagnosis should be evaluated for possible post-COVID-19 lung disease; Standard 2, Patients with lung function impairment, reduced exercise tolerance, reduced quality of life (QoL) or other relevant signs or ongoing symptoms ≥4 weeks after the onset of first symptoms should be evaluated for treatment and pulmonary rehabilitation (PR); Standard 3, The PR programme should be based on feasibility, effectiveness and cost-effectiveness criteria, organised according to local health services and tailored to an individual patient's needs; and Standard 4, Each patient undergoing and completing PR should be evaluated to determine its effectiveness and have access to a counselling/health education session.CONCLUSION: This is the first consensus-based set of clinical standards for the diagnosis, treatment and prevention of post-COVID-19 lung disease. Our aim is to improve patient care and QoL by guiding clinicians, programme managers and public health officers in planning and implementing a PR programme to manage post-COVID-19 lung disease.

Correction to: Vilnius Declaration on chronic respiratory diseases: multisectoral care pathways embedding guided self-management, mHealth and air pollution in chronic respiratory diseases.

An amendment to this paper has been published and can be accessed via the original article.

Vilnius Declaration on chronic respiratory diseases: multisectoral care pathways embedding guided self-management, mHealth and air pollution in chronic respiratory diseases.

BACKGROUND: Over 1 billion people suffer from chronic respiratory diseases such as asthma, COPD, rhinitis and rhinosinusitis. They cause an enormous burden and are considered as major non-communicable diseases. Many patients are still uncontrolled and the cost of inaction is unacceptable. A meeting was held in Vilnius, Lithuania (March 23, 2018) under the patronage of the Ministry of Health and several scientific societies to propose multisectoral care pathways embedding guided self-management, mHealth and air pollution in selected chronic respiratory diseases (rhinitis, chronic rhinosinusitis, asthma and COPD). The meeting resulted in the Vilnius Declaration that was developed by the participants of the EU Summit on chronic respiratory diseases under the leadership of Euforea. CONCLUSION: The Vilnius Declaration represents an important step for the fight against air pollution in chronic respiratory diseases globally and has a clear strategic relevance with regard to the EU Health Strategy as it will bring added value to the existing public health knowledge.

Effectiveness of PCR and Immunofluorescence Techniques for Detecting Human Cytomegalovirus in Blood and Bronchoalveolar Lavage Fluid.

Current diagnostic methods allow a rapid and reliable detection of active human cytomegalovirus (hCMV) infection by identifying the presence of pp65 CMV antigen or CMV DNA in peripheral blood and affected organs. The goal of this study was to evaluate the effectiveness of CMV detection in blood and organ-specific biological material, such as bronchoalveolar lavage fluid (BALF), by comparing two standard diagnostic methods, immunofluorescence (IF) and the real-time polymerase chain reaction (PCR). We evaluated 25 patients with concomitant respiratory disease who were referred to our hospital for diagnosis due to suspected acute CMV infection. The presence of hCMV was concomitantly evaluated by IF and PCR in 16 peripheral blood samples. In two patients, we observed positive results for both IF and PCR, and in two other patients the results were discordant. Of 11 patients, CMV DNA was detected in six BALF samples, and in one blood plasma sample. Real-time PCR detected CMV DNA in 54.6 % of BALF samples and 12.0 % of blood samples, while indirect IF testing confirmed antigenemia in 12.5 % of blood samples. The results from our study suggest that the IF method is as effective as PCR for detecting an ongoing CMV infection in blood samples. However, real-time PCR was much more effective at detecting CMV DNA in BALF compared to blood samples. Our results suggest that the biological material being tested during CMV diagnosis should be derived directly from the virally infected organ(s).

Cryptogenic Organizing Pneumonia: IL-1ß, IL-6, IL-8, and TGF- ß1 Serum Concentrations and Response to Clarithromycin Treatment.

Cryptogenic organizing pneumonia (COP) is a distinct clinicopathological entity with unknown etiology. Inflammatory cytokines play a role in the development of the disease. The present study was performed to assess the correlation between concentrations of IL-1ß, IL-6, IL-8, and TGF-ß1 in the serum with response to clarithromycin (CAM) treatment in patients with COP. A total of 39 patients with COP were enrolled in to this study. An oral dose of 500 mg CAM was administered to all of the patients twice daily for 3 months. A complete response was noticed in 31 (80 %) of patients, and 8 (20 %) patients failed to respond to treatment. The concentration of cytokines were assessed by ELISAs before and after treatment. CAM treatment was associated with decreases in serum IL-6 (3.8 pg/mL [IQR 0.9-11.8] vs. 1.1 pg/mL [IQR 0.2-3.1]; p = 0.004), IL-8 (13.6 pg/mL [IQR 9.8-17.5] vs. 8.1 pg/mL [IQR 6.2-13.2]; p = 0.004), and TGF-ß1 (37.1 ng/mL [IQR 31.7-46.2] vs. 25.7 ng/mL [IQR 22-41.7];p = 0.0001), which was particularly notable in the responders. We conclude that IL-6, IL-8, and TGF-ß1 may play a role in the pathogenesis of COP, as their decreased concentrations were associated with a positive response to CAM treatment.

Frequency of Rare Alpha-1 Antitrypsin Variants in Polish Patients with Chronic Respiratory Disorders.

The SERPINA1 gene encoding the alpha-1 antitrypsin (A1AT) protein is highly polymorphic. It is known that, apart from the most prevalent PI*S and PI*Z A1AT deficiency variants, other so-called rare variants also predispose individuals to severe chronic respiratory disorders such as emphysema and chronic obstructive pulmonary disease. Our aim was to assess the frequencies of common and rare SERPINA1 mutations in a group of 1033 Polish patients referred for A1AT deficiency diagnostics due to chronic respiratory disorders in the period of January 2014-September 2015. All blood samples were analyzed according to the routine diagnostic protocol, including A1AT serum concentration assessment by nephelometry and immune isoelectric focusing, followed by PCR genotyping and direct sequencing when necessary. A total of 890 out of the 1033 samples (86 %) carried the normal PI*MM genotype, whereas, in 143 samples (14 %), at least one A1AT deficiency variant was detected. In 132 subjects, PI*S (2.1 %) and PI*Z (10.8 %) common deficiency alleles were identified, yielding frequencies of 0.011 and 0.062, respectively. Rare SERPINA1 variants were detected in nine patients: PI*F (c.739C>T) (n = 5) and PI*I (c.187C>T) (n = 4). Samples from the patients with an A1AT serum concentration below 120 mg/dl and presenting a PI*MM-like phenotypic pattern were retrospectively analyzed by direct sequencing for rare SERPINA1 mutations, revealing a PI*M2Obernburg (c.514G>T) mutation in one patient and a non-pathogenic mutation (c.922G>T) in another. We conclude that the deficiency PI*Z A1AT allele is considerably more common in patients with chronic respiratory disorders than in the general Polish population. The prevalence of the PI*F allele seems higher than in other European studies.

Cell-free DNA levels in plasma of patients with non-small-cell lung cancer and inflammatory lung disease.

BACKGROUND: The analysis of plasma cell-free DNA (cfDNA) is expected to provide useful biomarkers for early diagnosis of non-small-cell lung cancer (NSCLC). However, it remains unclear whether the intense release of cfDNA into the bloodstream of NSCLC patients results from malignancy or chronic inflammatory response. Consequently, the current diagnostic utility of plasma cfDNA quantification has not been thoroughly validated in subjects with chronic respiratory inflammation. Here we assess the effect of chronic respiratory inflammation on plasma cfDNA levels and evaluate the potential clinical value of this phenomenon as an early lung cancer diagnostic tool. METHODS: We measured plasma cfDNA concentrations in 50 resectable NSCLC patients, 101 patients with chronic respiratory inflammation (chronic obstructive pulmonary disease, sarcoidosis, or asthma) and 40 healthy volunteers using real-time PCR. RESULTS: We found significantly higher plasma cfDNA levels in NSCLC patients than in subjects with chronic respiratory inflammation and healthy individuals (P<0.0001). There were no significant differences in plasma cfDNA levels between patients with chronic respiratory inflammation and healthy volunteers. The cutoff point of >2.8 ng ml(-1) provided 90% sensitivity and 80.5% specificity in discriminating NSCLC from healthy individuals (area under the curve (AUC)=0.90). The receiver-operating characteristics curve distinguishing NSCLC patients from subjects with chronic respiratory inflammation indicated 56% sensitivity and 91% specificity at the >5.25-ng ml(-1) cutoff (AUC=0.76). CONCLUSIONS: We demonstrated that elevated plasma cfDNA levels in NSCLC resulted primarily from tumour development rather than inflammatory response, raising the potential clinical implications for lung cancer screening and early diagnosis. Further research is necessary to better characterise and identify factors and processes regulating cfDNA levels in the blood under normal and pathological conditions.

Rapid DNA extraction protocol for detection of alpha-1 antitrypsin deficiency from dried blood spots by real-time PCR.

The dried blood spot (DBS) specimens have been successfully employed for the large-scale diagnostics of α1-antitrypsin (AAT) deficiency as an easy to collect and transport alternative to plasma/serum. In the present study we propose a fast, efficient, and cost effective protocol of DNA extraction from dried blood spot (DBS) samples that provides sufficient quantity and quality of DNA and effectively eliminates any natural PCR inhibitors, allowing for successful AAT genotyping by real-time PCR and direct sequencing. DNA extracted from 84 DBS samples from chronic obstructive pulmonary disease patients was genotyped for AAT deficiency variants by real-time PCR. The results of DBS AAT genotyping were validated by serum IEF phenotyping and AAT concentration measurement. The proposed protocol allowed successful DNA extraction from all analyzed DBS samples. Both quantity and quality of DNA were sufficient for further real-time PCR and, if necessary, for genetic sequence analysis. A 100% concordance between AAT DBS genotypes and serum phenotypes in positive detection of two major deficiency S- and Z- alleles was achieved. Both assays, DBS AAT genotyping by real-time PCR and serum AAT phenotyping by IEF, positively identified PI*S and PI*Z allele in 8 out of the 84 (9.5%) and 16 out of 84 (19.0%) patients, respectively. In conclusion, the proposed protocol noticeably reduces the costs and the hand-on-time of DBS samples preparation providing genomic DNA of sufficient quantity and quality for further real-time PCR or genetic sequence analysis. Consequently, it is ideally suited for large-scale AAT deficiency screening programs and should be method of choice.

Angiogenic activity of sera from interstitial lung disease patients in relation to angiotensin-converting enzyme activity.

The role of angiogenesis in the pathogenesis of interstitial lung diseases (ILD) is unknown. Angiotensin-converting enzyme (ACE) is a marker of sarcoidosis activity and may modulate angiogenesis. The aim of this study was to examine the relationship between ACE activity in ILD patients' sera and their effect on microvessels formation in an in vivo model of leukocyte-induced angiogenesis. The study population consisted of 77 sarcoidosis patients, 22 idiopathic pulmonary fibrosis patients, 16 bird fanciers lung patients, eight silicosis patients and 14 healthy donors. Serum ACE activity was assayed by spectrophotometric method. As an angiogenic test, a leukocyte-induced angiogenesis assay in an animal model was used. Sera from interstitial lung disease patients significantly stimulated angiogenic activity of mononuclear cells compared with healthy donors (p < 0.001). The highest ACE serum activity was measured in sera from the silicosis patients, and lowest in sera from the sarcoidosis and IPF patients. A significantly lower serum ACE activity was detected in the bird fanciers lung patients. Serum angiogenic activity of ILD patients measured by angiogenesis index negatively correlated with ACE serum activity (r = ;-0.52; p < 0.01). This correlation was highest in the sarcoidosis group (r = -0.6; p < ). Sera from ILD patient constitute the source of factors modulating angiogenesis.

The effect of undecanones and their derivatives on tumor angiogenesis and VEGF content.

The in vivo effects of some derivatives of aliphatic ketones (2-undecanone, 3-undecanone, 4-undecanone and their derivatives) on L-1 sarcoma tumor angiogenesis and VEGF content were studied in Balb/c mice. Mice that inhaled 10% solution of 3-undecanone(3-on) or 1% solution of 2-undecanone propylene acetal (Acpr2) for 3 days after tumor cells implantation, presented lower neovascular response measured by tumor-induced cutaneous angiogenesis test (TIA) and lower tumor VEGF content in 5-days tumors, than non-inhaled controls. Other substances presented various effects on tumor VEGF concentration and angiogenesis. Histological examination of lesions collected from mice inhaled Acpr2, or non-inhaled controls, revealed small diffused areas of necrosis in the former group. In both groups, slight to moderate inflammatory infiltrations were seen at the tumor's margin. In Acpr2 group, there were less small blood vessels at tumor's margin than in the control group.

Neoadjuvant therapy affects tumor growth markers in early stage non-small-cell lung cancer.

INTRODUCTION: While adjuvant therapy of early-stage non-small-cell lung cancer (NSCLC) is widely accepted, literature data concerning neoadjuvant treatment provide contradictory results with both improved and unaffected survival rates. Also, data concerning potential effects of neo-adjuvant therapy on cellular level are scarce. OBJECTIVE: The aim of present study was to analyze the effect of chemotherapy followed by surgical resection on several key biological markers of tumor growth (TGF-beta, VEGF), apoptosis (sAPO-1/Fas/CD95) and invasiveness (TIMP-1) assessed in the sera of NSCLC early-stage patients (IB-IIIA). - MATERIAL AND METHODS: Measurements were performed by ELISA method in blood serum from 24 NSCLC patients (I-IIIA) collected prior therapy, one day before surgery and 3 days after. RESULTS: TGF-beta serum concentrations were significantly lower after both chemotherapy (P<0.05) and surgery (P<0.01) in comparison to the baseline. VEGF levels decreased following NEO therapy with subsequent significant up-regulation after surgery (P<0.001). Interestingly, post-surgery serum VEGF strongly correlated with TGF-beta concentration (r = 0.52, P = 0.014). No significant differences were observed for serum sAPO-1/CD95/FAS as well as TIMP-1 concentrations at any of three evaluated time-points. CONCLUSION: Neoadjuvant treatment of early-stage NSCLC affects mostly mechanisms responsible for tumor growth and vascularization. Its effect on cancer cells apoptotic activity needs further evaluation.

Real-time PCR quantification of plasma DNA in non-small cell lung cancer patients and healthy controls.

INTRODUCTION: Free-circulating DNA is present in minute amounts in plasma of healthy individuals, whereas increased levels are found in a number of malignant pathologies including non-small cell lung cancer (NSCLC). The objective of this research was the evaluation of the plasma DNA quantification capacity to distinguish between healthy subjects and non-small cell lung cancer (NSCLC) patients. MATERIAL AND METHODS: Plasma samples were collected prospectively from 16 healthy volunteers and 30 untreated NSCLC patients (I-IIIA). Subsequently, free-circulating DNA extraction and quantitative real-time PCR analysis were performed. RESULTS: The values of plasma DNA concentration ranged from 0.9 up to 7.0 ng/ml in healthy individuals and from 1.5 up to 50 ng/ml in NSCLC patients before treatment. Cancer group showed several-fold higher mean free-circulating DNA concentration than that present in healthy subjects (mean 12.00 vs. 2.65 ng/ml; P<0.001). A greater variability of plasma DNA concentrations was observed in NSCLC patients than in controls (SD 14.50 vs. 2.02, respectively). The area under the ROC curve was 0.87 (95% CI, 0.744 to 0.954, P<0.001). CONCLUSION: Non-small cell lung cancer is associated with elevated levels of cell-free DNA in plasma with respect to healthy controls. Real-time PCR method proved its utility in effective free-circulating DNA detection and quantification.

Induced sputum in patients with interstitial lung disease: a non-invasive surrogate for certain parameters in bronchoalveolar lavage fluid.

Induced sputum is a useful non-invasive method for the assessment of airway and parenchymal lung diseases. This study aimed to compare induced sputum and bronchoalveolar lavage fluid (BALF) cellular composition and T-lymphocyte subpopulations in patients with interstitial lung disease. We evaluated 33 patients: 15 with sarcoidosis, 11 with hypersensitivity pneumonitis, and 7 with idiopathic pulmonary fibrosis. The percentage of macrophages was significantly lower in induced sputum than in BALF in sarcoidosis (P=0.005), and the percentage of neutrophils was higher in induced sputum than in BALF in sarcoidosis (P=0.001) and hypersensitivity pneumonitis (P=0.006). A significant correlation was found between the BALF and induced sputum CD4+, CD8+ subsets and the CD4+/CD8+ ratio in both the whole patient group (r(s)=0.80, r(s)=0.88, r(s)=0.88, P<0.001, respectively) and in the 3 subgroups. A strong correlation of the T-lymphocyte subsets in induced sputum and BALF in patients with interstitial lung disease shows that induced sputum may be a non-invasive surrogate for certain parameters in BALF in these patients.

Evaluation of fluorescence-based methods for total vs. amplifiable DNA quantification in plasma of lung cancer patients.

In the last decade numerous reports demonstrated that free-circulating DNA in plasma/serum samples might be a promising biomarker in a number of pathologies, including cancer. Thus, choosing the reliable and efficient method of plasma DNA quantification would be an essential step prior to any clinical evaluation of cell-free DNA measurement in cancer patients. The aim of present study was to compare two highly-sensitive DNA quantification methods in regard to their applicability and effectiveness in monitoring the cell-free DNA level in the blood of patients with resectable non-small cell lung cancer. Plasma samples collected from 10 patients before any treatment, after neoadjuvant therapy and subsequent surgery, were used for DNA quantification by direct fluorescent PicoGreen staining and by real-time qPCR in SYBR Green and TaqMan probe approach using beta-actin gene as the amplifying target. The PicoGreen method demonstrated a high level of correlation with both the SYBR Green (r=0.87, P<0.0001) and TaqMan probe approach (r=0.94, P<0.0001). The total DNA content, determined by PicoGreen, proved to be several-fold higher than the amplifiable DNA amount measured by real-time qPCR. Consequently, intercalating fluorochromes, like PicoGreen, might serve as a rapid, accurate, and inexpensive alternative to real-time qPCR for routine dsDNA quantification and multicenter standardization.

Leptin measurement in urine is a reliable method of monitoring its secretion in patients with obstructive sleep apnea syndrome.

Leptin is believed to play a significant role in the pathogenesis of obstructive sleep apnea syndrome (OSAS) as well as progression of OSAS-related obesity. It is also known that other factors such as gender and diurnal variations in serum strongly affect the measurement results making repeated blood sampling necessary for leptin precise monitoring. Since renal metabolism and urine secretion are the main elimination mechanism for leptin, in this study we evaluated urine relevance for leptin secretion monitoring. Serum and urine (collected during the day and overnight) sampled from 169 OSAS patients and 41 controls were assayed by immunoenzymatic method specific for human leptin. Only 5 (17%) controls and 10 (5.8%) OSAS patients had undetectable urine leptin. We observed significant relationships between serum and urinary leptin in both day-time (r=0.656, P<0.001) and night-time (r=0.518, P<0.001) samples and between day and night-time urine leptin (r=0.811, P<0.001). Significance values did not alter when urinary leptin levels were expressed as the ratio to urinary creatinine. Gender-related differences in leptin concentrations were present both in serum (P<0.001) and overnight urine (P<0.01) in the OSAS group. However, mean night-time urine leptin was lower in the OSAS patients (P<0.05) and their subgroups stratified according to disease severity (P<0.01), while serum leptin levels were comparable in both groups. We conclude that assaying leptin in urine by immunoenzymatic method is a reliable and useful non-invasive alternative for its serum measurement. However, night-time urine leptin levels better reflect differences in its turnover due to gender and OSAS severity.

Theophylline inhibits free oxygen radicals production by human monocytes via phosphodiesterase inhibition.

Recent evidence suggests that theophylline, apart from bronchodilatation, derives its therapeutic activity in asthma from anti-inflammatory effects. Free oxygen radicals play important role in the perpetuation of inflammatory processes underlying bronchoconstriction and airway hyperresponsiveness in asthmatics. In our previous studies, we have analyzed the immunomodulatory effects of theophylline on human monocyte metabolic activity and showed that theophylline in doses of 5-20 microg/ml inhibited the process of zymosan-induced activation, decreasing total and maximum O2- production. The aim of present study was to analyze the mechanism of theophylline action on human monocytes. Therefore, the effects of papaverine--a phosphodiesterase inhibitor, LAS 31025--selective phosphodiesterase IV inhibitor, 8-phenyltheophylline--A1 and A2 adenosine receptors antagonist, and 8-cyclopenthyl-1, 3 dipropylxanthine--selective A1 receptor antagonist on O2- release were assessed. Adenosine receptor antagonist exerted no influence, while papaverine and LAS 31025 suppressed spontaneous, zymosan-induced total and maximum O2- production. The suppressant effect was concentration-dependent. We conclude that theophylline in therapeutic and subtherapeutic concentrations suppresses human monocyte metabolic activity via phosphodiesterase inhibition.

Vascular-endothelial growth factor (VEGF) in patients with peripheral ischemia.

Vascular endothelial growth factor (VEGF) is a key cytokine responsible for the spontaneous new blood vessel formation in the course of peripheral ischemia. It has repeatedly been observed in patients with critical leg ischemia that their clinical status does not reflect any effective local neovascularization processes as well as VEGF system up-regulation. Therefore, the aim of present study was to compare the proangiogenic status, assessed as the serum VEGF concentration, in patients with mild, moderate, and severe peripheral ischemia and to analyze to what extend it is influenced by the therapy applied. Serum VEGF level was evaluated by ELISA method in 31 patients with peripheral ischemia at different time points throughout the treatment. On Day 0 (before treatment), Day 2, and Day 7, VEGF concentration was significantly higher in subjects with critical leg ischemia (Group I) than in other groups (P<0.001). In Group I, VEGF decline was reported on Day 30 following radical surgery, while in a group of moderate disease treated by revascularization surgery a significant increase in serum VEGF concentration was observed (Day 7 and Day 30) (P=0.02). Serum cytokine level in the patients with mild ischemia (Group III) on pharmacotherapy was stable throughout the observation period. Interestingly, the increase in VEGF levels throughout the study period from Day 0 to Day 30 was significantly greater in unsuccessfully treated patients compared with subjects who positively responded to therapy or did not show any response at all. We conclude that mechanisms other than hypoxia might drive the observed up-regulation of VEGF production in peripheral ischemia.

Inflammatory markers in the exhaled breath condensate of patients with pulmonary sarcoidosis.

Pulmonary sarcoidosis may progress to fibrosis in some patients, so that close monitoring of its activity is essential for recommending clinical strategy. Examination of airway inflammatory markers in bronchoalveolar lavage (BAL) is one of the methods applied to assess the disease severity. Recently, the expired breath condensate (EBC) has become another source of cytokines and mediators. In sarcoidosis, except for NO and oxidative stress markers, no other mediators have yet been estimated in the exhaled air. In the present study we attempted to answer the question of whether airway inflammatory markers in pulmonary sarcoidosis patients might be assessable in EBC and to what extend these markers might reflect the disease activity in the lungs IL-6, TNF-alpha, PAI-1, and IGF-1 were measured by Elisa method in EBC and BALF samples from 9 patients with newly-diagnosed pulmonary sarcoidosis. TNF-alpha, IGF-1, and PAI-1 levels in EBC and BAL samples were comparable and closely positively correlated [TNF-alpha (r=0.79, P<0.001), IGF-1 (r=0.94, P<0.001), and PAI-1 (r=0.81, P<0.001)]. In contrast, IL-6 concentration in EBC was significantly lower compared with that in BALF, while the correlation between both materials was negative (r=-0.47, P<0.05). An important distinction in IL-6 performance, which might explain this inconsistency, is its tendency to form more complex molecular forms of a higher weight than that of other cytokines. Our study shows that EBC reflects cytokine production in the lung as effectively as BALF, providing that the characteristics of proteins evaluated allow their easy transfer into the exhaled air. Further studies are required before accepting EBC samples as an equivalent to BALF.

In vitro angiomodulatory activity of sera from type 2 diabetic patients with background retinopathy.

Diabetic retinopathy is the leading cause of adult vision loss and blindness. The most important contributors to the development of diabetic retinopathy are hyperglycemia and hypoxemia that lead to increased vasopermeability, endothelial cell proliferation, and pathological neovascularization. In our previous studies, close relationship between proangiogenic activity of sera from type 2 diabetes mellitus patients (DM2) with background retinopathy, assessed in the in vivo serum-induced mouse cutaneous test (SIA), and VEGF and IL-18 serum concentration were observed. Moreover, it was clearly shown that IGF-1 might play an important role in the negative regulation of neoangiogenesis induced by DM2 patients' sera by diminishing the VEGF stimulatory effect. To confirm the observed phenomenon we evaluated the effect of DM2 patients' sera on the in vitro proliferative activity of human endothelial cells, which is critical for the sprouting and generation of new blood capillaries. Endothelial proliferative activity was significantly higher in the presence of sera from DM2 patients than from healthy controls (P<0.001), as estimated by the MTT test. Moreover, the examined sera from DM2 patients were characterized by increased IL-18 (P<0.05), diminished IGF-1 (P<0.02), and unchanged VEGF levels compared with those in controls. In conclusion, the present study showed a strong stimulatory effect of DM2 patients' sera on the proliferation of endothelial cells, which, along with the findings of our previous studies, proves that the described phenomenon is universal and valid for both animal and human endothelium.