Several infectious agents have been pinpointed as potential risk factors for lymphoma development. Members of the Chlamydia genus of bacteria, in particular, may play a role in tumour development through their involvement in a wide spectrum of human diseases that cause persistent infections. A well documented relationship already exists between the Chlamydia strain, C. trachomatis, and the development of cervical cancer. Similarly, the respiratory infectious Chlamydia bacteria, C. pneumoniae, has a known association with lung cancer.
New data showcased at ECCO stem from a study which set out to confirm the suggested association between the Chlamydia strain, Chlamydia psittaci, and development of ocular adnexal lymphoma (OAL). C. psittaci is the etiological agent of psittocosis, a human lung infection caused by exposure to infected birds and potentially also deriving from household pets such as cats which are known carriers of the bacteria.
Between 2003 and 2004, DNA was extracted from the 33 OAL cases identified at the Asian Medical Center in Seoul, Korea. DNA extraction was also undertaken for a further 21 cases of a comparable, yet non-cancerous condition, non-neoplastic ocular adnexal disease (NNOAD). The extracted DNA was analysed using a touchdown enzyme time-released polymerase chain reaction technique to isolate the presence of the three Chlamydia strains – C. psittaci, C. trachomatis and C. pneumoniae.
The results show that C. psittaci infection is highly correlated with OAL. C. psittaci was found in 78% of all OAL cases, yet observed in only 23% of cases of the non-cancerous disease NNOAD. Infection with C. trachomatis or C. pneumoniae was either non-existent or present at a very low rate in both OAL and NNOAD. Of the C. psittaci infections analysed, a total of six distinct bacterial sequences were identified.
Study author, Dr Changhoon You from the Asian Medical Centre, Seoul commented, "Certain subtypes of low grade lymphoma are thought to be caused by some antigenic stimuli, for example, Helicobacter pylori (H. pylori) induced gastric low grade MALT lymphoma, Hepatitis C (HCV) related marginal zone B-cell lymphoma, and C. psittaci - induced ocular adnexal lymphoma. Other types of low grade lymphoma may be related with some antigenic stimuli that have not been identified so far. In the future, eradication of the antigenic stimuli could be a common treatment method of low grade lymphoma, replacing current cytotoxic chemotherapy or radiation."
OAL belongs to a group of lymphomas known as mucosa-associated lymphoid tissue (MALT) lymphomas. Cellular changes that lead to the development of these lymphomas result from aberrant immune responses. Infectious agents such as C. psittaci can hence function as contributory factors in MALT lymphoma pathogenesis.
About Lymphomas
Lymphomas are malignant cell infiltrations of the lymphatic system. The lymph system includes the nodes located in the neck, armpit, and groin. These nodes are only part of the lymph system, as they are connected to each other and to the spleen, thymus, and parts of the tonsils, stomach, and small intestine by a network of vessels. The vessels carry a colourless, watery fluid called lymph, and contains lymphocytes. Once a malignancy begins in one part of the lymph system, it often spreads throughout the rest of the system before it is detected. Lymphoma symptoms include painless swelling of the lymph nodes, fever and fatigue. 1
There are 56,000 new cases of lymphomas diagnosed each year and 27,000 deaths annually. 2
About Chlamydia
Members of the Chlamydia genus of bacteria are responsible for a wide range of human diseases. Chlamydia trachomatis causes a number of sexually transmitted diseases including chlamydia, and Chlamydia pneumoniae causes acute respiratory tract infections. Both of these species have been shown to be associated with cervical cancer and lung cancer respectively.3
Infection with a third species, Chlamydia psittaci, results from exposure to infected birds and possibly other animals, and it can lead to a lung infection called psittacosis. Some studies suggest that infection with C. psittaci may also be associated with other conditions such as conjunctivitis.4
There are several similarities between the pathology of ocular adnexal lymphoma, a type of cancer that affects the tissue surrounding the eye, and that of gastric lymphoma, for which there is a well-established link with infection with the bacteria Helicobacter pylori. 5
1 www.lymphomaininfo.net
2 Boyle, P. Cancer incidence and mortality in Europe, 2004.
International Agency for Research on Cancer. 2004, p.483
3 Medline Plus (www.nlm.nih.gov)
4 www.vetgate.ac.uk
5 www.medicalnewstoday.com
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Abstract: 982
Leukemias and Lymphomas in adults and children
Ocular adnexal lymphoma is highly associated with Chlamydia psittaci
C. You1, M. Ryu2, J. Huh3, J. Park2, H. Ahn4, Y. Lee4, T. Kim2, H. Chang2, J. Lee2, Y. Kang2
1Asan Medical Center, Seoul, Korea
2Asan Medical Center, Internal Medicine, Seoul, Korea
3Asan Medical Center, Pathology, Seoul, Korea
4Asan Medical Center, Ophthalmology, Seoul, Korea
Background:
Ocular adnexal lymphomas (OAL) are mostly of low-grade MALT type. Recently, an association between C. psittaci and OAL was suggested (Ferreri AJM et al. J Natl Cancer Inst 2004;96:586). We conducted this study to confirm the relationship between C. psittaci and OAL.
Methods:
Between 1993 and 2004, a total of 33 OAL cases were identified in Asan Medical Center, Seoul, Korea. DNA was extracted from formalin-fixed, paraffin-embedded OAL tissues, and then touchdown enzyme time release-PCR was performed to identify three Chlamydia species (C. psittaci, C. tracomatis, and C. pneumoniae). DNA extraction and PCR for Chlamydia species were also performed in 21 cases with non-neoplastic ocular adnexal disease (NNOAD).
Results:
In all OAL cases, histologic type was low-grade MALT lymphoma. The median age was 42 yrs (range, 22 to 73 yrs). Male to female ratio was 1.1. C. psittaci was highly associated with OAL: C. psittaci was found in 78% of OAL cases, while it was observed only in 23% of NNOAD cases (P < 0.001). Direct DNA sequencing of C. psittaci was performed in 10 OAL cases with C. psittaci infection, and 6 different sequences of C. psittaci were identified. However, infection rates of C. trachomatis and C. pneumoniae were very low in both OAL and NNOAD: C. trachomatis was not observed in any cases, and C. pneumoniae was found in 9% of OAL cases and in 4.7% of NNOAD cases (P = 0.492).
Conclusion:
In this study, we observed high infection rate of C. psittaci in OAL cases. The results may suggest C. psittaci may play a role as a causative antigen to stimuli the development of OAL.