San Lucas Medical, LLC

JOURNAL OF CLINICAL DERMATOLOGY

REVIEW ARTICLE

Impact of Smoking on Collagen Metabolism: A Systematic Review Nadia A. Henriksen and Lars Tue Sørensen Affiliation: Department of Surgery, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark

A B S T R A C T

al,

LL C

Introduction: Smoking has a negative impact on postoperative wound and tissue healing, presumably due to impaired wound healing. A detrimental effect on collagen metabolism seems to be involved, but the exact pathophysiological mechanisms remain unknown. Material and Methods: A formal computer-assisted search of Pubmed was performed together with a cross-reference search of eligible papers. A total of 46 papers were systematically reviewed. Results: Smoking affects collagen synthesis and deposition of mature collagen in the wound and increases collagen degradation. Attenuated fibroblast migration and proliferation in addition to enhanced neutrophil collagenase (MMP-8) release from inflammatory cells appear to be involved. Depressed tissue oxygenation and low vitamin C levels by smoking most probably interfere with the molecular pathways of collagen metabolism. Smoking cessation restores MMP-8 levels but does not reverse collagen synthesis or deposition. Conclusion: The impact of smoking on collagen metabolism is complex attenuating synthesis and enhancing degradation. Abstinence from smoking for 3 months decreases the release of proteases but does not restore collagen metabolism. Further studies are needed to clarify if the detrimental effect of smoking is reversible at all.

dic

Keywords: Smoking, wound healing, collagen, vitamin C, collagenase, MMP, smoking abstinence Correspondence: Lars Tue Sørensen, Department of Surgery, Bispebjerg Hospital, DK-2400 Copenhagen NV, Denmark. Tel: 45 35 31 35 31; Fax: 45 35 31 39 11; email: [email protected]

Non-English papers were excluded. Papers addressing the pathogenesis for tissue-destructive disorders were excluded. A total of 46 papers were evaluated.

Me

INTRODUCTION

Smokers have more postoperative healing complications. Within the first 30 days after surgery the incidence of wound dehiscence, fascial ruptures, and anastomotic leaks is higher in smokers.1 Months to years after surgery, incisional hernia, recurrence of inguinal hernia, and lack of bone fusion in spinal surgery occur more frequent in smokers.1
3 In addition, degenerative diseases like premature skin wrinkling, pulmonary emphysema, parodontosis, and aorta aneurismal disease are all more prevalent in smokers,4
11 which indicate that smoking induces progressing tissue-destruction.12 The higher incidence of tissue-destructive disorders is probably related to smoking-induced alterations in the collagen metabolism. However, the pathophysiological mechanisms are not fully understood. The aim of this study was to systematically review the available literature on the effects of smoking on collagen metabolism in relation to wound healing.

COLLAGEN METABOLISM IN GENERAL

A formal computer-assisted search of the medical database Pubmed was performed using the mesh terms ‘‘smoking’’ combined with ‘‘collagen,’’ ‘‘collagenases,’’ ‘‘matrix metalloproteinases,’’ ‘‘wound healing,’’ and ‘‘skin.’’ A cross-reference search of eligible papers was done. We focused on papers with emphasis on collagen metabolism and wound healing.

There are more than 20 different kinds of collagen, however, type I and type III collagens are abundantly found in skin. Type III collagen is a weaker type of collagen, mostly synthesized during the early proliferative phase of wound healing, whereas type I collagen is stronger and deposited during the late proliferative phase and during remodeling.

Sa

nL uc

as

MATERIALS AND METHODS

The biosynthesis of collagen is well described in the biochemical literature. In short, proliferating fibroblasts produce a-chains of about 1000 amino acid residues, which are converted into procollagen. In an early crucial step with molecular oxygen as substrate and vitamin C as the essential cofactor, the amino acids proline and lysine are hydroxylated into hydroxyproline and hydroxylysine. These form interchain hydrogen bonds that stabilize the triple-stranded helix of procollagen. Hydroxyproline is rarely found in proteins other than collagen and, therefore, this amino acid is used as a specific biochemical marker for collagen. Extracellularly, the procollagens are converted into collagen fibers through strong covalent bonds between lysine and hydroxylysine residues, and the fibers are remodeled and orientated in an orderly pattern to support the tensile strength of the tissue.13

www.slm-dermatology.com

1

DERMA 2010; 000:(000). Month 2010

Journal of Clinical Dermatology

Damaged collagen fibers are being repaired in a continuous controlled process of proliferation and remodeling. The normal turnover of collagen is very slow and may persist for years before being degraded and replaced. Some matrix metalloproteinases (MMP) and serine proteases are characterized as collagenases, which specifically degrade collagen. The MMPs are tightly regulated by a tissue inhibitor of metalloproteinases (TIMP) and other protease inhibitors like a1-antitrypsin to limit extensive damage during degradation.14

proteinases and inhibitors and leading to a higher extracellular matrix turnover.

CONNECTIVE TISSUE CELL AFFECTION OF SMOKING On cellular levels, smoking seems to have a detrimental effect on the function of fibroblasts and macrophages indicating impaired wound healing potential. The monocyte, which is a precursor of the macrophage, has in smokers only half the chemotactic response as nonsmokers.22 In vitro studies of embryonic fibroblast cell cultures treated with a smoke solution are altered in the cytoskeleton resulting in inhibition of fibroblast migration, which is crucial for the wound healing process23,24. Furthermore, recent in vivo studies have disclosed significantly fewer wound macrophages and fibroblasts in smokers.25 Taken together, smokers not only have fewer wound macrophages and fibroblasts, but these cells also have a decreased chemotactic response.

TISSUE OXYGENATION IN SMOKERS

LL C

Smoking seems to affect several pathogenic pathways of collagen formation and degradation. First of all, smoking reduces tissue oxygenation. Oxygen is, by oxidative phosphorylation, necessary to produce ATP in the cell and thereby secure cellular functions and protein synthesis. In addition, oxygen is rate-limiting for collagen synthesis by hydroxylation of the amino acids lysine and proline, and for collagen crosslinking and collagen maturation.15,16

THE COLLAGEN LEVEL IN SMOKERS Only a few studies have measured the collagen level in smokers compared to nonsmokers. In a study from our group, smokers were found to accumulate less hydroxyproline in an ePTFE wound healing model than nonsmokers.26 In a later in vitro study, human skin fibroblasts were exposed to tobacco smoke extract and both the hydroxyproline concentration, type I, and type III procollagen levels were found to be significantly decreased.27 In vivo, Knuutinen et al found significantly less procollagen III levels in suction blister fluid and serum of smokers compared to nonsmokers. However, there was no significant difference in the procollagen I levels.28 Taken together, these studies suggest that the collagen biosynthesis is decreased in the skin of smokers.

as

Me

dic

al,

Experimental studies conducted in healthy smokers two decades ago found that smoking of one cigarette reduced subcutaneous oxygen tension for 45 minutes and in peripheral tissue blood flow up to 40%.17,18 These findings lead to the hypothesis that tissue oxygenation is permanently reduced in persons who smoke throughout the day.17 In addition, nicotine was suggested as causative for this mechanism based on the release of epinephrine in the central nervous system, and the fact that epinephrine in the peripheral tissue induces vasoconstriction.19 However, a recent study disclosed that nicotine infused intravenously increased peripheral blood flow and tissue oxygen levels, thus concluding that the vasoactive effect of smoking is not mediated by nicotine.20 The effect of smoking is likely to be induced by other mechanisms such as adrenomediated vasoconstriction, endovascular dysfunction, and baro-reflex alteration in the tissue.

Smoking appears to induce an increased collagen breakdown by MMPs. We have found that plasma MMP-8 and MMP-9 are correlated with the neutrophil blood count, which is significantly increased in smokers.29 We have demonstrated that the MMP-8 level is significantly increased in suction blister fluid of smokers compared to nonsmokers, which is in conjunction with the results of Knuutinen et al.28,30 However, no significant difference between the MMP8 level in plasma, serum, and saliva was found between smokers and nonsmokers.30, 31 Since the TIMP-1 protein level in suction blister fluid was significantly less in smokers.28 and no significant differences were found of the TIMP-1 level in serum,28 these findings show that enhanced collagen degradation most probably is a result of a proteaseantiprotease imbalance in smokers tissue and not systemically.

nL uc

Furthermore, carbon monoxide binds to hemoglobin with a 200 times higher affinity than that of oxygen, which reduces the oxygen fraction in the arterial blood and changes the oxygen dissociation curve attenuating release of oxygen from the hemoglobin molecule to the peripheral tissue. In addition, artherosclerosis and chronic obstructive lung disease are more prevalent in smokers and may decrease oxygen levels in the peripheral tissue.

TISSUE INFLAMMATION IN SMOKERS

Sa

In addition to reduced tissue oxygenation, smoking alters inflammatory cell function. The increased inflammatory response in smokers compared to nonsmokers is presumably caused by a higher oxidative stress induced by smoking.21 As a result, neutrophil function is altered with an increased cell count and enhanced chemotactic response but with a decreased bactericidal capacity.22 The activated neutrophils secrete potent tissue-destructive enzymes such as collagenases and elastase, thus shifting the balance between DERMA 2010; 000:(000). Month 2010

THE MMP LEVEL IN SMOKERS

Considering the fibroblast collagenase MMP-1 in relation to smoking, the MMP-1 mRNA level has been found to be significantly increased in skin biopsies of smokers.32 Besides, the MMP-1, MMP-1 mRNA, and MMP-3 mRNA levels are also 2

www.slm-dermatology.com

Impact of smoking on collagen metabolism

significantly increased in cultured fibroblasts treated with smoke extract, contrary to the TIMP-1 and TIMP-3 mRNA level.27,33 However, there is no significant difference in the MMP-1 protein level in suction blister fluid and the skin of smokers and nonsmokers.28,30

reported for how long the former smokers had been abstinent from smoking prior to surgery.

EFFECT OF SMOKING CESSATION PHARMACOTHERAPY ON COLLAGEN METABOLISM

The gelatinases MMP-2 and MMP-9 have been analyzed in skin, serum, and saliva of smokers and nonsmokers. Interestingly, MMP-9 was significantly lower in the skin and saliva of smokers, whereas both MMP-2 and MMP-9 were significantly higher in the serum of smokers.31

Nicotine replacement therapy is regarded as first-line therapy to overcome the symptoms of nicotine withdrawal.42 We have evaluated the effect of smoking cessation and the use of transdermal nicotine replacement therapy on postoperative complications. Interestingly, we have found no detrimental effects on wound healing using a transdermal nicotine patch.20,29,37 Actually, the use of transdermal nicotine patch by abstinent smokers increased the procollagen I level and disclosed a borderline significant increase of hydroxyproline, indicating a stimulatory effect of nicotine on wound healing.43

VITAMIN C

LL C

Vitamin C is an essential cofactor in the collagen synthesis. In the case of vitamin C deficiency, numerous large fibroblasts may be present, but proline and lysine are not being hydroxylated. This results in instable and immature procollagen molecules that are recognized as damaged and therefore destroyed before mature collagen fibers can be formed.34 Experimental studies of the effect of vitamin C deficiency on wound healing conducted in humans over 60 years ago, revealed impaired healing and disintegration of scars of experimental wounds after several months of dietary restrictions and subsequent normalization following vitamin C repletion.35

al,

Clonidine is an a-2 agonist with antihypertensive effects that can be used as second-line therapy to reduce nicotine withdrawal symptoms.44 When giving clonidine intravenously, it first causes vasoconstriction and then reduces the activity of noradrenergic neurons thereby reducing ischemia caused by systemic epinephrine and norepinephrine.45 The effect of clonidine on wound healing in abstinent smokers and in nonsmokers for that matter has not been tested in systematic studies and there are no indications that clonidine affects wound healing.

dic

Smokers have a high turnover of vitamin C resulting in a relative vitamin C deficiency. Accordingly, the systemic pool of vitamin C in smokers is reduced by a factor of two to three.36 In a recent study from our group, we found plasma procollagen I levels, being indicative of systemic collagen synthesis, were significantly correlated with vitamin C levels.29

Me

Apart from smoking cessation therapy, other agents such as vitamin C could have positive effects on the collagen metabolism. One study showed that in skin biopsies from postmenopausal women treated with L-ascorbic acid, the collagen type I and type III mRNA level increased significantly together with an increase in TIMP-1. Furthermore, in the biopsies of women with a low dietary intake of vitamin C, the collagen increase was higher.46 Since smokers have a reduced systemic pool of vitamin C, the topical vitamin C application might improve wound healing in these patients but further studies are needed.

EFFECT OF SMOKING CESSATION ON COLLAGEN METABOLISM

nL uc

as

Smoking cessation is recommended before elective surgery, since a part of the detrimental effects of smoking on wound healing is thought to be reversible. A study from our group has revealed that 4 weeks of smoking abstinence reduces the incidence of wound infections significantly. However, 12 weeks of smoking abstinence did not reduce the incidence of wound ruptures.37 We have also found that the neutrophil blood count and MMP-8 protein level in suction blister fluid decrease significantly after 4 weeks of smoking cessation toward the level of never smokers.29,30 Abstinence from smoking did not change collagen synthesis or deposition of mature collagen assessed by different wound healing models.12, 25

CONCLUSION

Sa

The impact of smoking on collagen metabolism and wound healing is complex and several mechanisms appear to be involved (Figure 1). To sum up, smoking leads to decreased tissue oxygenation and increased inflammatory response. The latter causes an increased neutrophil count correlating with a high collagenase level, which seems to be involved in tissuedestructive disorders. The collagen biosynthesis is decreased also, which might be related to the decreased tissue oxygenation and the decreased vitamin C level. Furthermore, there are fewer macrophages and fibroblasts in wounds of smokers, and these cells have a reduced chemotactic response. Smoking cessation improves inflammatory cell function and decreases oxidative stress. This mechanism may lead to diminished tissue degradation, but does not seem to enhance collagen synthesis or deposition.

The collagen metabolism in former smokers with years of abstinence has not been subject to specific studies. However, some cohort studies found that former smokers have a higher risk of postoperative wound complications than never smokers.38
41 These findings suggest that the detrimental effect of smoking on wound healing is prolonged despite smoking cessation. Unfortunately, none of these studies www.slm-dermatology.com

3

DERMA 2010; 000:(000). Month 2010

Journal of Clinical Dermatology

Tissue oxygenation

Tissue catabolism

Tissue inflammation

Fibroblasts Collagen

Collagen

biosynthesis

degradation

Macrophages

Proteolytic enzymes

Vitamin C

Neutrophil blood count

LL C

Figure 1. Smoking and collagen metabolism.

20. Sorensen LT, Jorgensen S, Petersen LJ, et al. Acute effects of nicotine and smoking on blood flow, tissue oxygen, and aerobe metabolism of the skin and subcutis. J Surg Res. 2009;May:224
230. 21. Lykkesfeldt J, Loft S, Nielsen JB, Poulsen HE. Ascorbic acid and dehydroascorbic acid as biomarkers of oxidative stress caused by smoking. Am J Clin Nutr. 1997;April:959
963. 22. Sorensen LT, Nielsen HB, Kharazmi A, Gottrup F. Effect of smoking and abstention on oxidative burst and reactivity of neutrophils and monocytes. Surgery. 2004;November:1047
1053. 23. Wong LS, Martins-Green M. Firsthand cigarette smoke alters fibroblast migration and survival: implications for impaired healing. Wound Repair Regen. 2004;July:471
484. 24. Wong LS, Green HM, Feugate JE, Yadav M, Nothnagel EA, Martins-Green M. Effects of ‘‘second-hand’’ smoke on structure and function of fibroblasts, cells that are critical for tissue repair and remodeling. BMC Cell Biol. 2004;April:13. 25. Sorensen LT, Toft B, Rygaard J, Ladelund S, Teisner B, Gottrup F. Smoking attenuates wound inflammation and proliferation while smoking cessation restores inflammation but not proliferation. Wound Repair Regen. 2010;February:186
192. 26. Jorgensen LN, Kallehave F, Christensen E, Siana JE, Gottrup F. Less collagen production in smokers. Surgery. 1998;123(4):450
455. 27. Yin L, Morita A, Tsuji T. Alterations of extracellular matrix induced by tobacco smoke extract. Arch Dermatol Res. 2000;June:188
194. 28. Knuutinen A, Kokkonen N, Risteli J, et al. Smoking affects collagen synthesis and extracellular matrix turnover in human skin. Br J Dermatol. 2002;April:588
594. 29. Sorensen LT, Toft BG, Rygaard J, et al. Effect of smoking, smoking cessation, and nicotine patch on wound dimension, vitamin C, and systemic markers of collagen metabolism. Surgery. 2010;March. 30. Sorensen LT, Zillmer R, Agren M, Ladelund S, Karlsmark T, Gottrup F. Effect of smoking, abstention, and nicotine patch on epidermal healing and collagenase in skin transudate. Wound Repair Regen. 2009;August:347
353. 31. Raitio A, Tuomas H, Kokkonen N, et al. Levels of matrix metalloproteinase-2, -9 and -8 in the skin, serum and saliva of smokers and nonsmokers. Arch Dermatol Res. 2005;December:242
248. 32. Lahmann C, Bergemann J, Harrison G, Young AR. Matrix metalloproteinase-1 and skin ageing in smokers. Lancet. 2001;April:935
936. 33. Yin L, Morita A, Tsuji T. Skin aging induced by ultraviolet exposure and tobacco smoking: evidence from epidemiological and molecular studies. Photodermatol Photoimmunol Photomed. 2001;August:178
183. 34. Bevelaqua FA, Hasselbacher P, Schumacher HR. Scurvy and hemarthrosis. JAMA. 1976;235(17):1874
1876. 35. Hirschmann JV, Raugi GJ. Adult scurvy. J Am Acad Dermatol. 1999;41(6):895
906. 36. Lykkesfeldt J, Christen S, Wallock LM, Chang HH, Jacob RA, Ames BN. Ascorbate is depleted by smoking and repleted by moderate supplementation: a study in male smokers and nonsmokers with matched dietary antioxidant intakes. Am J Clin Nutr. 2000;January:530
536. 37. Sorensen LT, Karlsmark T, Gottrup F. Abstinence from smoking reduces incisional wound infection: a randomized controlled trial. Ann Surg. 2003;June:1
5. 38. Bertelsen CA, Andreasen AH, Jorgensen T, Harling H. Anastomotic leakage after anterior resection for rectal cancer: risk factors. Colorectal Dis. 2010;12(1):37
43. 39. Nickelsen TN, Jorgensen T, Kronborg O. Lifestyle and 30-day complications to surgery for colorectal cancer. Acta Oncol. 2005;44(3):218
223. 40. Sadr AO, Lindstrom D, Adami J, Bellocco R, Linder S, Wladis A. Impact of body mass index and tobacco smoking on outcome after open appendicectomy. Br J Surg. 2008;95(6):751
757. 41. Sadr AO, Bellocco R, Eriksson K, Adami J. The impact of tobacco use and body mass index on the length of stay in hospital and the risk of postoperative complications among patients undergoing total hip replacement. J Bone Joint Surg Br. 2006;88(10):1316
1320. 42. Frishman WH. Smoking cessation pharmacotherapy. Ther Adv Cardiovasc Dis. 2009;3(4):287
308. 43. Sorensen LT, Jorgensen LN, Zillmer R, Vange J, Hemmingsen U, Gottrup F. Transdermal nicotine patch enhances type I collagen synthesis in abstinent smokers. Wound Repair Regen. 2006;June:247
251.

Disclosure The authors declare no conflict of interest.

REFERENCES

Sa

nL uc

as

Me

dic

al,

1. Sorensen LT, Hemmingsen U, Kallehave F, et al. Risk factors for tissue and wound complications in gastrointestinal surgery. Ann Surg. 2005;March:654
658. 2. Sorensen LT, Friis E, Jorgensen T, et al. Smoking is a risk factor for recurrence of groin hernia. World J Surg. 2002;March:397
400. 3. Andersen T, Christensen FB, Laursen M, Hoy K, Hansen ES, Bunger C. Smoking as a predictor of negative outcome in lumbar spinal fusion. Spine (Phila Pa 1976). 2001;26(23):2623
2628. 4. Thomsen SF, Sorensen LT. Smoking and skin disease. Skin Therapy Lett. 2010;June:4
7. 5. Sharafkhaneh A, Hanania NA, Kim V. Pathogenesis of emphysema: from the bench to the bedside. Proc Am Thorac Soc. 2008;5(4):475
477. 6. Ozcaka O, Bicakci N, Pussinen P, Sorsa T, Kose T, Buduneli N. Smoking and matrix metalloproteinases, neutrophil elastase and myeloperoxidase in chronic periodontitis. Oral Dis. 2010;July. 7. Murphy EA, Danna-Lopes D, Sarfati I, Rao SK, Cohen JR. Nicotinestimulated elastase activity release by neutrophils in patients with abdominal aortic aneurysms. Ann Vasc Surg. 1998;12(1):41
45. 8. Daniell HW. Smooth tobacco and wrinkled skin. N Eng J Med. 1969;January:53. 9. Daniell HW. Smoker’s wrinkles. A study in the epidemiology of ‘‘crow’s feet.’’ 1971;December:873
880. 10. Frances C. Smoker’s wrinkles: epidemiological and pathogenic considerations. Clin Dermatol. 1998;December:565
570. 11. Ernster VL, Grady D, Miike R, Black D, Selby J, Kerlikowske K. Facial wrinkling in men and women, by smoking status. Am J Public Health. 1995;January:78
82. 12. Sorensen LT. Effect of lifestyle, gender and age on collagen formation and degradation. Hernia. 2006;December:456
461. 13. Shoulders MD, Raines RT. Collagen structure and stability. Annu Rev Biochem. 2009;April:929
958. 14. Nagase H, Visse R, Murphy G. Structure and function of matrix metalloproteinases and TIMPs. Cardiovasc Res. 2006;January:562
573. 15. Rodriguez PG, Felix FN, Woodley DT, Shim EK. The role of oxygen in wound healing: a review of the literature. Dermatol Surg. 2008;June:1159
1169. 16. Hunt K, Hannah MK, West P. Contextualizing smoking: masculinity, femininity and class differences in smoking in men and women from three generations in the west of Scotland. Health Educ Res. 2004;May:239
249. 17. Jensen JA, Goodson WH, Hopf HW, Hunt TK. Cigarette smoking decreases tissue oxygen. Arch Surg. 1991;September:1131
1134. 18. Richardson D. Effects of tobacco smoke inhalation on capillary blood flow in human skin. Arch Environ Health. 1987;January:19
25. 19. Jensen JA, Jonsson K, Goodson WH III, Hunt TK, Roizen MF. Epinephrine lowers subcutaneous wound oxygen tension. Curr Surg. 1985;42(6):472
474.

DERMA 2010; 000:(000). Month 2010

4

www.slm-dermatology.com

Impact of smoking on collagen metabolism

Sa

nL uc

as

Me

dic

al,

LL C

44. Gourlay SG, Stead LF, Benowitz NL. Clonidine for smoking cessation. Cochrane Database Syst Rev. 2004;(3):CD000058. 45. Wallace AW. Clonidine and modification of perioperative outcome. Curr Opin Anaesthesiol. 2006;19(4):411
417. 46. Nusgens BV, Humbert P, Rougier A, et al. Topically applied vitamin C enhances the mRNA level of collagens I and III, their processing enzymes and tissue inhibitor of matrix metalloproteinase 1 in the human dermis. J Invest Dermatol. 2001;116(6):853
859.

www.slm-dermatology.com

5

DERMA 2010; 000:(000). Month 2010