Primary Motility  Disorders of the  Esophagus
 The Esophageal
 Mucosa
 The
 Esophagogastric  Junction
 Barrett's
 Esophagus

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OESO©2015
 
Volume: The Esophagogastric Junction
Chapter: Esophageal columnar metaplasia (Barrett s esophagus)
 

Is ablation of the esophageal columnar tissue more likely to induce restoration of squamous epithelium than just acid suppression?

M.M. Berenson (Salt Lake City)

Glandular epithelium that lines the distal esophagus is thought to develop as a consequence of metaplastic re-epithelialization of injured or denuded stratified squamous esophageal mucosa. The glandular epithelium may evolve gradually or rapidly [1]. Bremner et al. [2] found that regeneration of denuded esophageal mucosa in dogs occurred with squamous epithelium unless reflux of gastroduodenal contents was present in which case glandular tissue developed. They suggested the tissue extended from the gastric mucosa. Presumably, noxious components of the refluxate prevented normal squamous tissue regeneration. Gillen et al. [3] also found that columnar tissue regenerated in place of denuded stratified squamous esophageal tissue of dogs that refluxed gastric contents, but extension of gastric mucosa into the esophagus was precluded by separating the denuded area of the esophagus from the stomach by a strip of squamous tissue. They suggested the glandular epithelium originated from cells that lined the ducts of the esophageal cardiac glands. Using this canine model, it was subsequently shown that glandular tissue could re-epithelialize denuded areas of squamous epithelium in an anacid environment. Only the presence of islands of squamous tissue mixed into the glandular epithelium differentiated dogs with an anacid environment from dogs with free acid reflux [4]. These observations suggest that esophageal columnar epithelium may develop in the absence of acid reflux. The source of the islands of tissue could be the proximal superficial squamous cells that line the ducts of the esophageal cardiac glands [4], persistent microscopic foci of normally-differentiated squamous epithelium within the glandular tissue, or primordial stem cells.

Metaplastic tissue has the potential to revert to normal [5]. Both medical [6, 7] and surgical [8-10] therapy to reduce gastric acid secretion, and gastroesophageal reflux have been reported to induce regression of Barrett's epithelium. However, the reports have been infrequent [11-13] and controversial [14]. More commonly, macroscopic and microscopic islands of squamous epithelium have been detected in Barrett's epithelium after antireflux surgery [10] and long-term acid suppression [11, 12]. Squamous tissue has been observed to grow over glandular epithelium [15].

We hypothesized that squamous epithelium could be restored to areas of columnar mucosa if the established columnar tissue was ablated and the presence of noxious agents was reduced during the time the esophageal epithelium healed [16]. Argon laser was used to ablate glandular tissue in locations that varied from "islands," totally surrounded by squamous tissue to "patches," totally surrounded by glandular tissue. Gastric acid secretion was suppressed with 40 mg omeprazole daily during the period of re-epithelialization. Normal appearing squamous tissue was partially or totally restored in 38 of 40 treatment locations. No change occurred in Barrett's epithelium that was not treated. Destruction of esophageal glandular tissue using thermal devices [17-21] or photodynamic treatments [22, 23] have subsequently been reported to facilitate squamous tissue re-epithelialization. But, this experience is not without exception [24]. In all cases, antireflux surgery and/or medical treatment to reduce acid secretion and gastroesophageal reflux have been applied during the regenerative period. No study in humans has systematically evaluated the role of acid or other components of the gastroesophageal refluxate on the regenerative process. There are three reasons for which it is generally concluded that anacidity favors normal esophageal tissue regeneration:

1) gastroesophageal acid reflux is the principal pathogenetic factor in Barrett's esophagus,

2) an acid environment promoted glandular tissue formation in animal studies,

3) successful restoration of squamous epithelium has been reported in an anacid but not an acid environment [25].

Although the precise mechanisms responsible for restoration of squamous tissue after ablation of the metaplastic glandular tissue are not known, an explanation can be proposed based upon studies of wound healing of the skin, an organ with keratinized stratified squamous epithelium [26-29]. Wound healing is a complex process that has been separated into three overlapping phases: inflammation, tissue formation, and tissue remodeling. These phases are distinguishable by specific soluble and insoluble mediators and cellular elements integral to inflammation, cell migration, angiogenesis, matrix synthesis, collagen deposition and re-epithelialization. Regulation of the interplay of growth factors, cytokines, matrix molecules, and epithelial-mesenchymal cell interactions that orchestrate the healing phenomenon, however, remains unclear.

Injury that disrupts the continuity of the stratified squamous epithelium induces signals to repair the rent and reestablish epithelial integrity. In the esophagus, normal squamous tissue re-epithelialization may be perturbed by agents that directly affect pluripotent stem cells or progenitor cells. Squamous tissue re-epithelialization may also be perturbed indirectly by altering growth factors, cytokines, and other elements that regulate the reparative process. As mentioned, animal experiments indicate that the presence of acid in the environment of injured esophageal mucosa impedes normal squamous tissue re-epithelialization. Acid may directly affect epithelial cell proliferation and differentiation, but it is more likely that the process is disturbed by the persistence of inflammation induced by the acid. Inflammation is known to impair healing and induce histopathologic features of dysplasia. Inflammation is probably responsible for the morphologic characteristics described at the squamocolumnar junction in Barrett's epithelium [30]. The diverse array of morphological and functional phenotypes present in the glandular tissue favor derivation from a primordial stem cell. Presumably, acid and inflammation promote the development of metaplastic esophageal columnar tissue which is able to close the breech in the epithelium and restore tissue continuity.

Stem cells in the proliferative compartment of the glandular tissue are regulated and constrained by needs of the epithelium-renewal of surface cells and repair of tissue injuries including acid-induced ulcerations that may disrupt the mucosa. There are no data to support the notion that an anacid environment induces the stem cells in the glandular mucosa to revert to a squamous pathway of differentiation. Restoration of squamous epithelium in Barrett's esophagus can be facilitated by eradication of the abnormal glandular mucosa. It appears that the wound produced by ablation of the glandular tissue can be re-epithelialized in a normal fashion if reflux and its attendant injury and inflammation are reduced or eliminated. The restored squamous epithelium could be derived from any of the potential progenitor sources within the esophagus. Clearly, there is a need to clarify the fundamental processes regulating esophageal mucosal repair.

References

1. Cameron AJ, Lomboy CT. Barrett's esophagus: age, prevalence, and extent of columnar epithelium. Gastroenterology 1992;103:1241-1245.

2. Bremner CG, Lynch JP, Ellis FH Jr. Barrett's esophagus: congenital or acquired? An experimental study on esophageal mucosal regeneration in the dog. Surgery 1970;68:209-216.

3. Gillen P, Keeling P, Byrne PJ, West AB, Hennessy TPJ. Experimental columnar metaplastic in canine esophagus. Br J Surg 1988;75:113-115.

4. Li H, Walsh TN, O'Dowd G, Gillen P, Byrne PJ, Hennesy TP. Mechanisms of columnar metaplasia and squamous regeneration in experimental Barrett's esophagus. Surgery 1996;115:176-181.

5. Pope CE II. Regression of Barrett's epithelium. In: Spechler SJ, Goyal RK, eds. Barrett's esophagus. Pathophysiology, diagnosis, and treatment. New York: Elsevier, 1985 223-229.

6. Patel GK, Clift SA, Schaefer RA, Read RC, Texter EC Jr. Resolution of severe dysplastic (Ca in situ) changes with regression of columnar epithelium in Barrett's esophagus on medical treatment. 1982;82:1147.

7. Deviere J, Buset M, Dumonceau JM, Rickaert F, Cremer M. Regression of Barrett's epithelium with omeprazole. N Engl J Med 198;320:1497-1498.

8. Brand D, Ylvisaker J, Gelfand M, Pope C. Regression of columnar esophageal (Barrett's) epithelium after antireflux surgery. N Engl J Med 1980;302:844-848.

9. Williamson WA, Ellis FH, Gibb SP. Effect of antireflux operation in Barrett's mucosa. Ann Thor Surg 1990;49:537-542.

10. Sagar PM, Ackroyd R, Hosie KB, Patterson, JE, Stoddard CJ, Kingsnorth AN. Regression and progression of Barrett's oesophagus after antireflux surgery. Br J Surg 1995;82:806-810.

11. Gore S, Healey CJ, Sutton R, Eyre-Brook IA, Gear MW, Sheperd NA, Wilkinson SP. Regression of columnar lined (Barrett's) oseophagus with continuous omeprazole therapy. Aliment Pharmacol Ther 1993;7:623-638.

12. Sampliner RE. Effect of up to 3 years or high-dose lansoprazole on Barrett's esophagus. Am J Gastroenterol 1994;89:1844-1848.

13. Neumann CS, Igbal TH, Cooper BT. Long-term continuous omeprazole treatment of patients with Barrett's oesophagus. Aliment Pharmacol Ther 1995;9:451-454.

14. Sampliner RE. Anti-reflux surgery and Barrett's esophagus regression: wheel of fortune or to tell the truth? Am J Gastroenterol 1991;86:645-646.

15. Sampliner RE, Steinbronn K, Garewal HS, Riddell RH. Squamous mucosa overlying columnar epithelium in Barrett's esophagus in the absence of antireflux surgery. Am J Gastroenterol 1988;83:510-512.

16. Berenson MM, Johnson TD, Markowitz NR, Buchi KN, Samowitz WS. Restoration of squamous mucosa after ablation of Barrett's esophageal epithelium. Gastroenterology 1993;104:1686.

17. Sampliner RE, Hixon, LJ, Fennerty B, Garewal HS. Regression of Barrett's esophagus by laser ablation in an anacid environment. Dig Dis Sci 1993;38:365-368.

18. Sampliner RE, Fennerty MB, Garewal HS. Controlled trial of reversal of Barrett's esophagus with acid suppression and multipolar electrocoagulation. Gastroenterology 1995;108:A208.

19. Aronchick CA, Lipshutz WH, Wright SH, Dufrayne FJ. Bicap cautery converts Barrett's esophagus to sqamous mucosa. Am J Gastroenterol 1995;90:1554.

20. Ertan A, Zimmerman M, Younes M. Esophageal adenocarcinoma associated with Barrett's esophagus: Long-term managment with laser ablation. Am J Gastroenterol 1995;90:2201-2203.

21. Salo JA, Nemlander A, Färkkilä M, Kivilato R, Kivilaakso E. Treatment of Barrett's metaplasia by antireflux surgery and endoscopic laser ablation: Clinical experience in 10 patients. Gastroenterology 1995;108:A1245.

22. Overholt BF, Panjehpour M. Photodynamic therapy for Barrett's esophagus: clinical update. Am J Gastroenterol 1996;91;1719-1723.

23. Laukka MA, Wang KK. Initial results using low-dose photodynamic therapy in the treatment of Barrett's esophagus. Gastrointest Endosc 1995;42:59-63.

24. Luman W, Palmer KR. Nd:YAG laser: ineffective therapy for Barrett's esophagus. Gut 1995;37(suppl 2):A4.

25. Brandt LJ, Blansky RL, Kauvar DR. Repeat laser therapy of recurrent Barrett's epithelium: Success with anacidity. Gastrointest Endosc 1995;41:267.

26. Clark RAF. Basics of cutaneous wound repair. J Dermatol Surg Oncol 1993;19:693-706.

27. Pierce GF, Mustoe TA. Pharmacologic enhancement of wound healing. Annu Rev Med 1995;46:467-481.

28. Wu L, Pierce GF, Galiano RD, Mustoe TA. Keritinocyte growth factor induces granulation tissue in ischemic dermal wounds: Importance of epithelial-mesenchymal cell interactions. Arch Surg 1996;131:660-666.

29. Rogers JJ, Young HE, Adkinson LR, Lucas PA, Black AC. Differentiation factors induce expression of muscle, fat, cartilage, and bone in a clone of mouse pluripotent mesenchymal stem cells. Am Surgeon 1995;3:231-236.

30. Sawhney RA, Shields AM, Allen CA, Boch JA, Trier JS, Antonioli DA. Morphological characterization of the squamo columnar junction of the esophagus in patients with and without Barrett's epithelium. Dig Dis Sci 1996;41:1088-1098.

 

 


Publication date: May 1998 OESO©2015