The septic granulomatosis (also Chronic granulomatosis ) is a very rare genetic disease of the immune system , in which the function of the NADPH oxidase and thus the sufficient production of various oxygen radicals is disturbed to immune defense. As a result, pathogens , especially pathogenic bacteria and fungi , can spread largely unhindered in the body of the person affected without constant drug treatment, which often leads to granulomas in various internal organs and in the skin area and consequently to early death.
In medical terminology, this disease is also known as CGD (from the English term chronic granulomatous disease ).
Approximately one in 200,000 newborns is born with this immune system disorder. About 150 patients are known in Germany. Around 1–5% percent of patients die each year, but most patients now reach adulthood.
The type of gene mutation is less important for the prognosis than the residual activity of the NADPH oxidase.
Pathogenesis and genetics
The cause of the disease are mutations in genes that encode proteins for parts of the protein complex cytochrome b (CYBB). There are several types of septic granulomatosis, depending on the mutations in genes.
The most common form (around 70 percent of all cases of septic granulomatosis) is X-linked - recessive inherited septic granulomatosis (X-CGD). This is caused by the mutation of the gp91-phox gene on the X chromosome, section p21.1 (Xp21.1). Due to inheritance, it only affects boys. The gp91-phox gene codes for the beta subunit (β-subunit) of the protein cytochrome b. Cytochrome b, in turn, is an indispensable component of the enzyme NADPH oxidase, which is responsible for killing bacteria and fungi in the white blood cells ( leukocytes , more precisely granulocytes ) through the production of superoxide radicals and other oxidants . Changes in the gp91-phox gene lead to changes in the protein structure of cytochrome b and these in turn lead to changes in the protein structure of NADPH oxidase with loss of function.
Since granulocytes with septic granulomatosis are unable to produce hydrogen peroxide themselves (defective NADPH oxidase), they use the hydrogen peroxide produced by bacteria and fungi and convert it into ROS . The defense against catalase- producing bacteria and fungi ( Staphylococcus , Serratia , E. coli , Aspergillus etc.) is severely hampered by the failure of superoxide radical production, as these neutralize their own hydrogen peroxide using catalase.
Granulocytes can take up catalase-producing bacteria and fungal cells unchanged by phagocytosis , but the subsequent killing is not necessary. The pathogens remain essentially undamaged in the granulocytes and are transported with them through the entire body. This can lead to the spread of the pathogen from one organ to the next. As a result, the generation of ROS and the formation of NETs are severely restricted.
Since the elimination of bacteria and fungi is not only based on the granulocytes, the defense has not completely collapsed, but only possible to a very limited extent. This leads to infections that are particularly difficult, such as inflammation of the lymph nodes ( lymphadenitis ), or to the spread of infectious agents throughout the organism, as in the case of infectious blood poisoning ( sepsis or septic spread). Typical of the disease process, for example, that inhaled spores of molds , which are eliminated in healthy humans within minutes by macrophages, germinate in the lungs, by growing the lung tissue and also damage nearby organs. There are known cases in which the spinal cord was damaged starting from the lungs and caused paraplegia .
Since cytochrome b consists of several subunits of proteins, changes in the genes coding for these proteins also lead to a reduced function or even failure of the NAPDH oxidase in the leukocytes and thus to the appearance of septic granulomatosis. In addition to the gp91-phox gene, changes in the genes p22-phox ( chromosome 16q24 ), p47-phox ( chromosome 7q11.23 ) and p67-phox ( chromosome 1q25 ) are also known. The changes in these genes are all rarer than the mutation of gp91-phox. In contrast to the gp91-phox gene mutation, the changes in these genes are not inherited in an X-linked recessive manner, but in an autosomal recessive manner. This means that, in contrast to the X-linked recessive inherited septic granulomatosis, both boys and girls are affected in these forms of septic granulomatosis.
Two other genes (rac1 and rac2) code for proteins that are also necessary for the function of NADPH oxidase. Mutations of the rac2 gene on chromosome 22q12.3 to 22q13.2 lead to the clinical picture of neutrophil immunodeficiency syndrome (NIDS), which is very similar to that of septic granulomatoses. This is also inherited in an autosomal recessive manner (boys and girls are affected) and is considerably rarer than the classic X-linked recessive inherited septic granulomatosis (X-CGD).
The proteins rac2, p47-phox (NCF1) and p67-phox (NCF2) are components of the granulocytic NADPH oxidase. The protein p22-phox is the α-subunit of cytochrome b.
|Overview of the different forms of septic granulomatosis (CGD)|
|CGD type||synonym||OMIM ID||gene||chromosome||Inheritance||Affected|
|X-linked recessive CGD||X-CGD, XR-CGD, p91-phox-CGD||306400||p91-phox
β subunit cytochrome b
|Xp21.1||X-linked recessive||only boys
|CGD cytochrome b positive type 1||AR-CGD type 1, NCF1 deficiency||233700||p47-phox
|7q11.23||autosomal recessive||Boys and girls|
|CGD cytochrome b positive type 2||AR-CGD type 2, NCF2 deficiency||233710||p67-phox
|1q25||autosomal recessive||Boys and girls|
|CGD cytochrome b negative||CYBA deficiency, AR-CGD CYBA-||233690||p22-phox
α-subunit cytochrome b
|16q24||autosomal recessive||Boys and girls|
|Neutrophilic immunodeficiency syndrome||NIDS, rac2 deficiency||608203||rac2||22q12.3-22q13.2||autosomal recessive||Boys and girls|
The diagnosis can be confirmed by measuring the oxygen change (O2 test) in the granulocytes (granulocyte function test) and by a genetic analysis.
Other forms of immunodeficiency must be distinguished from septic granulomatosis. These include diseases such as HIV ( AIDS ), congenital or acquired neutropenia , severe combined immunodeficiency , variable combined immunodeficiency (CVID) or congenital and / or acquired immunoglobulin deficiency .
The blood count - especially the number of leukocytes and granulocytes - are normal in septic granulomatosis.
The first symptoms of the disease show up in the earliest childhood in the form of the most severe bacterial diseases, inflammations and fungal infections, including on internal organs . Purulent inflammation of the lymph nodes , abscesses of the skin, liver and lungs often occur . In addition, pneumonia and inflammation of all bones ( osteomyelitis ) occur again and again . This inflammation and frequent granulomas can lead to constrictions in the digestive tract , so that many patients also suffer from swallowing difficulties and intestinal obstruction .
Because of the long-term treatment with antibiotics and antimycotics , resistances develop in many patients , so that the infections become more difficult to control with increasing age. The consequence of this is very frequent hospitalization.
Mortality is very high as a result of the various types of damage to vital internal organs. It also depends on exposure to mold spores (lower risk in the city than on a farm) and discipline in taking the medication.
The therapy is initially purely symptomatic through a daily, preventive administration of antibiotics and antimycotics . However, it is often necessary to administer additional medication intravenously . Patients often have to undergo repeated operations later to remove larger foci of infection or tissue growths ( granulomas ). Regular administration of gamma interferon may also be indicated. Therapy also means that patients should avoid all places and activities where they can expect higher concentrations of mold and bacteria. This includes, for example, the handling of potting soil and organic waste, but air conditioning systems and even whirlpools can be dangerous for you.
Blood stem cell transplant
If a suitable HLA-compatible donor can be found, stem cell transplantation is the most promising therapy today in the case of severe disease . The healing rates after allogeneic blood stem cell transplantation from HLA-identical siblings and voluntary third-party donors are now around 90%. Complications are rejection, graft versus host disease (GvHD) and inflammatory reactions in the area of inflamed or infected organs. Promising attempts are underway to reduce the toxicity of the chemotherapy (conditioning) required for stem cell transplantation so that patients can be transplanted more gently. The current survival rate after such chemotherapy with reduced toxicity conditioning RTC, which consists of fludarabine 180 mg / m², low-dose busulfan and in vivo T-cell depletion with antithymocyte globulin or alemtuzumab , is currently 96% (Zürcher EBMT WP Inborn Errors Study). Future studies will show whether this RTC method will be able to reduce the long-term effects of conditioning, such as infertility.
On April 2, 2006, the Georg-Speyer-Haus in Frankfurt am Main announced the treatment of two adults and one child who had suffered from septic granulomatosis in the end-stage. One of the two patients treated in Frankfurt died a few days after this success report from the consequences of blood poisoning. Whether there is a connection between the death of the man and gene therapy remained unclear.
In the Frankfurt study (lead: Dieter Hoelzer, implementation: Manuel Grez, Marion Gabriele Ott), hematopoietic stem cells ( CD34 + ) were first taken from the blood of the two patients, equipped in the laboratory with a functional copy of the patient's defective gene, and then again been infused into the blood of the patient. An inactivated mouse retrovirus was used as a gene ferry. In both patients the hoped-for permanent settlement of the genetically modified stem cells in their bodies, their multiplication and their differentiation into phagocytes ("scavenger cells") occurred .
The peculiarity of the Frankfurt procedure was to subject the patients to mild leukemia chemotherapy before the modified blood stem cells were transferred . The resulting reduction in blood stem cells later apparently facilitated the integration of the genetically modified blood stem cells into the patient's bone marrow . In 2006 Frankfurt am Main plans to start treating ten other seriously ill patients in the same way with gene therapy. By April 2006, the doctors had spent around one million euros in research funding for the preparation and implementation of the therapeutic attempt. The start of gene therapy was preceded by an approval process that lasted almost six years.
Within 50 days, the condition of the patients who had previously suffered from therapy-resistant bacterial and fungal infections improved significantly. About 150 days after the infusion, however, the number of genetically corrected cells increased again in both patients. Molecular biological control studies showed that these changes were due to an additional, unexpected activation of three genes by the viral gene ferry, which now stimulated cell growth. Therefore, no further patients were initially treated with this method, as the doctors could not safely rule out the risk of developing leukemia . According to the authors, the study was published in the journal Nature Medicine 16 months after the start of the first therapy attempt , as this observed effect had not had any negative consequences until then.
The two Frankfurt patients were 26 and 25 years old at the time of gene therapy. The 26-year-old man had the first diagnosis of septic granulomatosis at the age of 2½ years. He had survived several life-threatening bacterial infections and had suffered from liver abscesses since 1980, which had been therapy-resistant since 2003. Furthermore, in 2002 he had severe periosteum inflammation all over his body, which only subsided after months. The 25-year-old man was diagnosed with the disease when he was one year old. Since 2002 he suffered from therapy-resistant fungal infections of the lungs, and his wound healing was generally disturbed.
Both patients were allowed to leave the hospital one month after the stem cell transfer and had no more serious bacterial or fungal infections afterwards. 53 days after receiving the genetically modified blood stem cells, the liver abscess in the 26-year-old patient was no longer detectable by X-rays. At the time the study was published in April 2006, he no longer had to take any medication to protect against infection. In the 25-year-old patient, the fungal infection of the lungs almost subsided after 50 days, and later it disappeared completely. One year after his gene therapy (in April 2006) he was still taking small amounts of preventive antibiotics. In both patients, around 20 percent and 10 percent of the granulocytes, respectively, had the functional gene one month after gene therapy. As a result of the later, unexpected gene activation, their number later rose to 60 or 50 percent. According to the doctors, 5 percent of functioning cells would be enough to restore the immune system. Even more dramatic was the healing success of a five-year-old boy in Zurich , who was also treated with gene therapy in spring 2005 - due to an acute medical emergency - according to the specifications of the Frankfurt study by Prof. Reinhard Seger at the University Hospital Zurich . As a result of a therapy-resistant fungal infection of the lungs, the boy's lung had to be removed, but the fungal infection had broken through to the spinal canal and caused paraplegia. Just a few weeks after the gene therapy, the fungal infestation was completely eliminated, and to the surprise of the doctors, the neurological symptoms also gradually subsided: One year after the gene therapy, he was even able to stand on one leg for a while, or at least for a short time with his sister To play football.
On April 27, 2006 it became known that the man, who was 26 at the time of the operation, had died in Düsseldorf on April 10, about two years after the gene therapy . After he had been free from serious infections for months for the first time since childhood, his jaw had an initial inflammation in January 2006. Afterwards, his spleen had to be removed and an inflammation of the colon developed.
Two days before his death, this patient had a sudden rupture of the intestine, which resulted in severe infections in the abdomen and, as a result, septic shock and multiple organ failure . The doctors explained this course of the disease in a press release on May 23, 2006:
“Most of the genetically modified white blood cells have partially or completely lost their function. Unfortunately, the number of remaining functional, gene-corrected white blood cells was no longer sufficient to successfully combat the germs of an infection of this severity. "
It is currently unclear why the genetically modified cells were lost. The other two patients are still doing well, according to a press release from the doctors on April 28, 2006.
- The Chronic Granulomatous Disorder Society: Septic Granulomatosis Information Brochure.
- Description of the disease X-linked CGD. In: Online Mendelian Inheritance in Man . (English)
- Successful gene therapy against congenital blood disease. ( Memento from May 28, 2013 in the Internet Archive ) Swiss National Science Foundation, on: snf.ch, March 31, 2006
- DB Kuhns u. a .: Residual NADPH Oxidase and survival in chronic granulomatous disease . In: New England Journal of Medicine . 2010; 363, pp. 2600-2610.
- K. Akong-Moore, OA Chow, M. von Köckritz-Blickwede, V. Nizet: Influences of chloride and hypochlorite on neutrophil extracellular trap formation. In: PloS one. Volume 7, number 8, 2012, p. E42984, doi: 10.1371 / journal.pone.0042984 . PMID 22912772 . PMC 3418225 (free full text). .
- Q. Remijsen, T. Vandenberghe, E. Wirawan, B. Assel Bergh, E. Parthoens, R. De Rycke, p knobs, M. Delforge, J. Willems, P. Vandenabeele: neutrophil extracellular trap cell death requires Both autophagy and superoxide generation. In: Cell research. Volume 21, Number 2, February 2011, pp. 290-304, doi: 10.1038 / cr.2010.150 . PMID 21060338 . PMC 3193439 (free full text). .
- MG Ott u. a .: Correction of X-linked chronic granulomatous disease by gene therapy, augmented by insertional activation of MDS1-EVI1, PRDM16 or SETBP1. In: Nature medicine . advance online publication, April 2, 2006; doi: 10.1038 / nm1393
- see also: U. Wagemann: Gene therapy successful, patient dead? In: Gen-ethical information service. No. 176, 2006, pp. 32-35, full text