Nikolaos Siafakas

Dr. Nikolaos Siafakas

orcid

Research Focus & Metrics

Academic Career Length

25Years (2002-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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20 May 2012 in BMC Pulmonary Medicine
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ITIoanna G Tsiligianni
Ioanna G Tsiligianni
TMThys van der Molen
Thys van der Molen
DMDespoina Moraitaki
Despoina Moraitaki
ILIlaine Lopez
Ilaine Lopez
JKJanwillem Kocks
Janwillem Kocks
NTNikolaos E Tzanakis
Nikolaos E Tzanakis
Health status provides valuable information, complementary to spirometry and improvement of health status has become an important treatment goal in COPD management. We compared the usefulness and validity of the COPD Assessment Test (CAT) and the Clinical COPD Questionnaire (CCQ), two simple questionnaires, in comparison with the St. George Respiratory Questionnaire (SGRQ).

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Fotini BoufidouFotini Boufidou
Fotini Boufidou
SMSnežana Medić
Snežana Medić
VLVicky Lampropoulou
Vicky Lampropoulou
NSNikolaos Siafakas
Nikolaos Siafakas
Athanasios TsakrisAthanasios Tsakris
Athanasios Tsakris
Cleo AnastassopoulouCleo Anastassopoulou
Cleo Anastassopoulou
We are reviewing the current state of knowledge on the virological and immunological correlates of long COVID, focusing on recent evidence for the possible association between the increasing number of SARS-CoV-2 reinfections and the parallel pandemic of long COVID. The severity of reinfections largely depends on the severity of the initial episode; in turn, this is determined both by a combination of genetic factors, particularly related to the innate immune response, and by the pathogenicity of the specific variant, especially its ability to infect and induce syncytia formation at the lower respiratory tract. The cumulative risk of long COVID as well as of various cardiac, pulmonary, or neurological complications increases proportionally to the number of SARS-CoV-2 infections, primarily in the elderly. Therefore, the number of long COVID cases is expected to remain high in the future. Reinfections apparently increase the likelihood of long COVID, but less so if they are mild or asymptomatic as in children and adolescents. Strategies to prevent SARS-CoV-2 reinfections are urgently needed, primarily among older adults who have a higher burden of comorbidities. Follow-up studies using an established case definition and precise diagnostic criteria of long COVID in people with or without reinfection may further elucidate the contribution of SARS-CoV-2 reinfections to the long COVID burden. Although accumulating evidence supports vaccination, both before and after the SARS-CoV-2 infection, as a preventive strategy to reduce the risk of long COVID, more robust comparative observational studies, including randomized trials, are needed to provide conclusive evidence of the effectiveness of vaccination in preventing or mitigating long COVID in all age groups. Thankfully, answers not only on the prevention, but also on treatment options and rates of recovery from long COVID are gradually starting to emerge.

1 November 2016 in Respiratory Investigation
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Journal Article
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Alexandru CorlateanuAlexandru Corlateanu
Alexandru Corlateanu
SCSerghei Covantsev
Serghei Covantsev
Alexander MathioudakisAlexander Mathioudakis
Alexander Mathioudakis
VBVictor Botnaru
Victor Botnaru
NSNikolaos Siafakas
Nikolaos Siafakas

1 August 2002 in Respiratory Medicine
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Journal Article
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NSNikolaos Siafakas
Nikolaos Siafakas
ETE.G. Tzortzaki
E.G. Tzortzaki

1 April 2006 in International Journal of Chronic Obstructive Pulmonary Disease
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MPMaria Plataki
Maria Plataki
ETEleni Tzortzaki
Eleni Tzortzaki
PRPaula Rytila
Paula Rytila
MDMakris Demosthenes
Makris Demosthenes
AKAnastassios Koutsopoulos
Anastassios Koutsopoulos
NSNikolaos Siafakas
Nikolaos Siafakas
COPD is a leading cause of morbidity and mortality, characterized by a chronic abnormal inflammatory response to noxious agents. Apoptosis is a physiologic process, critical to cellular homeostasis, in which cell death follows a programmed sequence of events. Apoptosis has been recognized to play an important role in clinical and experimental models of lung diseases. Abnormal apoptotic events in smokers’ and in emphysematous lungs have been shown in epithelial and endothelial lung cells, neutrophils, lymphocytes, and myocytes. Many factors associated with COPD, including cigarette smoke, have the potential to cause apoptosis of alveolar epithelial cells, the main sites of vascular endothelial growth factor (VEGF) production. The decreased expression of VEGF, a known survival factor for endothelial cells, and its receptor, results in lung septal endothelial cell death, leading perhaps to the emphysema observed in COPD. In smokers who develop COPD there is an activation of adaptive immunity, with an infiltration of CD4+ and, especially, CD8 + cells. CD8 + cells are cytotoxic to epithelial cells through the release of granzymes and perforin, which can further induce apoptosis of alveolar cells. Moreover, any reduction in neutrophil apoptosis or dysregulation of macrophage uptake of apoptotic neutrophils could lead to chronic inflammation and tissue injury. Increased rates of T-cell apoptosis may lead to a defective immune response to infective organisms, contributing to the high frequency of infections seen in COPD. Increased apoptosis of skeletal muscle could be responsible for the skeletal muscle atrophy, the main cause of unexplained weight loss in patients with COPD. This paper is a review of the current knowledge on the apoptotic pathways involved in COPD pathogenesis and their interaction with other known contributing factors.

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ENEirini Neofytou
Eirini Neofytou
ETEleni Tzortzaki
Eleni Tzortzaki
ACArgiro Chatziantoniou
Argiro Chatziantoniou
NSNikolaos Siafakas
Nikolaos Siafakas
According to the American Thorasic Society (ATS)/European Respiratory Society (ERS) Statement, chronic obstructive pulmonary disease (COPD) is defined as a preventable and treatable disease with a strong genetic component, characterized by airflow limitation that is not fully reversible, but is usually progressive and associated with an enhanced inflammatory response of the lung to noxious particles or gases. The main features of COPD are chronic inflammation of the airways and progressive destruction of lung parenchyma and alveolar structure. The pathogenesis of COPD is complex due to the interactions of several mechanisms, such as inflammation, proteolytic/antiproteolytic imbalance, oxidative stress, DNA damage, apoptosis, enhanced senescence of the structural cells and defective repair processes. This review focuses on the effects of oxidative DNA damage and the consequent immune responses in COPD. In susceptible individuals, cigarette smoke injures the airway epithelium generating the release of endogenous intracellular molecules or danger-associated molecular patterns from stressed or dying cells. These signals are captured by antigen presenting cells and are transferred to the lymphoid tissue, generating an adaptive immune response and enhancing chronic inflammation.