Chromosomal breakage in systemic sclerosis and related disorders

Aneugenic and clastogenic alterations in the DBA/IJ mouse model of rheumatoid arthritis treated with rituximab, an anti-CD20 antibody

Rheumatoid arthritis (RA), an autoimmune disorder in which the immune system attacks healthy cells, is associated with elevated risk of lymphoma. Rituximab, a treatment for non-Hodgkin's lymphoma, has been approved as a treatment for RA. We studied the effects of rituximab on chromosomal stability in collagen-induced arthritis DBA/1J animal models. Micronucleus levels were increased in the mouse models, mainly due to chromosome loss, as detected by fluorescence in situ hybridization; rituximab-treated arthritic mice had significantly less micronucleus formation. Serum 8-hydroxydeoxyguanosine, a DNA oxidative stress marker, was increased in the mice models but reduced following rituximab administration.

Centromere defects, chromosome instability, and cGAS-STING activation in systemic sclerosis

Centromere defects in Systemic Sclerosis (SSc) have remained unexplored despite the fact that many centromere proteins were discovered in patients with SSc. Here we report that lesion skin fibroblasts from SSc patients show marked alterations in centromeric DNA. SSc fibroblasts also show DNA damage, abnormal chromosome segregation, aneuploidy (only in diffuse cutaneous (dcSSc)) and micronuclei (in all types of SSc), some of which lose centromere identity while retaining centromere DNA sequences. Strikingly, we find cytoplasmic "leaking" of centromere proteins in limited cutaneous SSc (lcSSc) fibroblasts. Cytoplasmic centromere proteins co-localize with antigen presenting MHC Class II molecules, which correlate precisely with the presence of anti-centromere antibodies. CENPA expression and micronuclei formation correlate highly with activation of the cGAS-STING/IFN-β pathway as well as markers of reactive oxygen species (ROS) and fibrosis, ultimately suggesting a link between centromere alterations, chromosome instability, SSc autoimmunity, and fibrosis.

Molecular Basis of Accelerated Aging with Immune Dysfunction-Mediated Inflammation (Inflamm-Aging) in Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is a chronic connective tissue disorder characterized by immune dysregulation, chronic inflammation, vascular endothelial cell dysfunction, and progressive tissue fibrosis of the skin and internal organs. Moreover, increased cancer incidence and accelerated aging are also found. The increased cancer incidence is believed to be a result of chromosome instability. Accelerated cellular senescence has been confirmed by the shortening of telomere length due to increased DNA breakage, abnormal DNA repair response, and telomerase deficiency mediated by enhanced oxidative/nitrative stresses. The immune dysfunctions of SSc patients are manifested by excessive production of proinflammatory cytokines IL-1, IL-6, IL-17, IFN-α, and TNF-α, which can elicit potent tissue inflammation followed by tissue fibrosis. Furthermore, a number of autoantibodies including anti-topoisomerase 1 (anti-TOPO-1), anti-centromere (ACA or anti-CENP-B), anti-RNA polymerase enzyme (anti-RNAP III), anti-ribonuclear proteins (anti-U1, U2, and U11/U12 RNP), anti-nucleolar antigens (anti-Th/T0, anti-NOR90, anti-Ku, anti-RuvBL1/2, and anti-PM/Scl), and anti-telomere-associated proteins were also found. Based on these data, inflamm-aging caused by immune dysfunction-mediated inflammation exists in patients with SSc. Hence, increased cellular senescence is elicited by the interactions among excessive oxidative stress, pro-inflammatory cytokines, and autoantibodies. In the present review, we will discuss in detail the molecular basis of chromosome instability, increased oxidative stress, and functional adaptation by deranged immunome, which are related to inflamm-aging in patients with SSc.

Genomic and genetic studies of systemic sclerosis: A systematic review

Systemic sclerosis is an autoimmune rheumatic disease characterised by fibrosis, vasculopathy and inflammation. The exact aetiology of SSc remains unknown but evidences show that various genetic factors may be involved. This review aimed to assess HLA alleles/non-HLA polymorphisms, microsatellites and chromosomal abnormalities that have thus far been associated with SSc. PubMed, Embase and Scopus databases were searched up to July 29, 2015 using a combination of search-terms. Articles retrieved were evaluated based on set exclusion and inclusion criteria. A total of 150 publications passed the filters. HLA and non-HLA studies showed that particular alleles in the HLA-DRB1, HLA-DQB1, HLA-DQA1, HLA-DPB1 genes and variants in STAT4, IRF5 and CD247 are frequently associated with SSc. Non-HLA genes analysis was performed using the PANTHER and STRING₁₀ databases. PANTHER classification revealed that inflammation mediated by chemokine and cytokine, interleukin and integrin signalling pathways are among the common extracted pathways associated with SSc. STRING₁₀ analysis showed that NFKB1, CSF3R, STAT4, IFNG, PRL and ILs are the main "hubs" of interaction network of the non-HLA genes associated with SSc. This study gathers data of valid genetic factors associated with SSc and discusses the possible interactions of implicated molecules.

Mosaic chromosomal aberrations in synovial fibroblasts of patients with rheumatoid arthritis, osteoarthritis, and other inflammatory joint diseases

Chromosomal aberrations were comparatively assessed in nuclei extracted from synovial tissue, primary-culture (P-0) synovial cells, and early-passage synovial fibroblasts (SFB; 98% enrichment; P-1, P-4 [passage 1, passage 4]) from patients with rheumatoid arthritis (RA; n = 21), osteoarthritis (OA; n = 24), and other rheumatic diseases. Peripheral blood lymphocytes (PBL) and skin fibroblasts (FB) (P-1, P-4) from the same patients, as well as SFB from normal joints and patients with joint trauma (JT) (n = 4), were used as controls. Analyses proceeded by standard GTG-banding and interphase centromere fluorescence in situ hybridization. Structural chromosomal aberrations were observed in SFB (P-1 or P-4) from 4 of 21 RA patients (19%), with involvement of chromosome 1 [e.g. del(1)(q12)] in 3 of 4 cases. In 10 of the 21 RA cases (48%), polysomy 7 was observed in P-1 SFB. In addition, aneusomies of chromosomes 4, 6, 8, 9, 12, 18, and Y were present. The percentage of polysomies was increased in P-4. Similar chromosomal aberrations were detected in SFB of OA and spondylarthropathy patients. No aberrations were detected in i) PBL or skin FB from the same patients (except for one OA patient with a karyotype 45,X[10]/46,XX[17] in PBL and variable polysomies in long-term culture skin FB); or ii) synovial tissue and/or P-1 SFB of normal joints or of patients with joint trauma. In conclusion, qualitatively comparable chromosomal aberrations were observed in synovial tissue and early-passage SFB of patients with RA, OA, and other inflammatory joint diseases. Thus, although of possible functional relevance for the pathologic role of SFB in RA, these alterations probably reflect a common response to chronic inflammatory stress in rheumatic diseases.

Increased susceptibility to oxidation of low-density lipoproteins isolated from patients with systemic sclerosis

OBJECTIVE

To examine the resistance to oxidation of low-density lipoproteins (LDL) from patients with systemic sclerosis (SSc) and primary Raynaud's phenomenon (RP) compared with healthy controls.

METHODS

Plasma LDL were isolated from patients with diffuse cutaneous and limited cutaneous SSc (dcSSc and lcSSc, respectively), patients with primary RP, and healthy control subjects. The lipoproteins were assessed for their resistance to oxidation in the presence of cupric ions, using spectrophotometric assays.

RESULTS

LDL from patients with dcSSc and lcSSc were more susceptible to oxidation than were those from healthy control subjects or patients with RP.

CONCLUSION

Our findings suggest that free radicals may play a role in the pathology of SSc.

Chromosome instability in bladder carcinoma patients

The relationship between the presence of a high frequency of chromosome aberrations and a predisposition to cancer has been well established in the so-called chromosome instability syndromes. Chromosome instability is also present in a variety of patients affected by cancer, and sometimes in their healthy relatives. We present a cytogenetic study carried out in lymphocytes from 13 untreated bladder carcinoma patients (only four of them had a history of occupational exposure to mutagens). Percentages of aberrant metaphases were significantly higher in cancer patients than in controls. Of the total number of chromosome aberrations in cancer patients, 67.16% corresponded to major structural chromosome abnormalities, while 25.37% were gaps or breaks. Numerical abnormalities represented 7.46% of the total. The bands more frequently involved in chromosome rearrangements were 5q31 and 1q32. Our results tentatively indicate that a significant proportion of patients with bladder carcinoma may have an underlying inherent chromosome instability. An age effect cannot be excluded, but we did not find significant differences between patients over 50 years of age and patients under 50 years of age.

Genetic control of avian scleroderma

The inheritance of avian scleroderma, a fibrotic autoimmune disease of chickens resembling human scleroderma, was investigated. Comb inflammations and lesions were used to determine the state of disease of 4-week-old chickens. All line 200 males and 60% of female line 200 chicks showed abnormalities. Crosses (F1) between line 200 and eight partially inbred lines of chickens maintained at the University of California at Davis were all normal. Backcrosses of F1 cocks to line 200 hens showed a higher incidence of scleroderma in males than in females for all lines. The incidence of affected birds varied between backcrosses from a low of 42% for backcross line 217 males derived from a New Hampshire line, to 88% for males of backcross line 213 derived from a partially inbred Leghorn line, demonstrating the presence of genes modifying the penetrance of presumed major genes causing the disease. Backcross genotypes segregating for haplotypes of the major histocompatibility complex (MHC) derived from inbred lines showed consistently lower penetrance of scleroderma than homozygotes carrying the line 200 haplotype. Thus B3Bs (lines 211 and 215), B14Bs (line 217), and B15Bs (lines 212, 213, 216, and 218) all had fewer affected individuals than BsBs homozygotes from the same families.

Clastogenic inosine nucleotide as components of the chromosome breakage factor in scleroderma patients

In the present study, we attempted to identify the chemical nature of the clastogenic factor (CF) from patients with progressive systemic sclerosis (scleroderma). Computerized mass spectrometry of clastogenic fractions obtained by HPLC of plasma ultrafiltrates detected molecular peaks compatible with inosine triphosphate and inosine diphosphate (ITP and IDP). The concomitant detection of IDP, together with ITP, and the absence of these peaks in nonclastogenic fractions and corresponding control fractions are arguments in favor of a biological relevance of these observations. The most important confirmation came from the clastogenic effect of commercial ITP and IDP added to the culture medium of the test cultures. The induction of chromatid type damage by these substances in lymphocytes exposed in the G0 phase of their cell cycle and the prevention of this damage by superoxide dismutase are analogous to the observations with CF.

Increased numbers of spontaneous micronuclei in blood lymphocytes and cultures fibroblasts of individuals with familial cutaneous malignant melanoma

In vitro detection of micronuclei was used to determine spontaneous chromosomal instability in cultured fibroblasts of 28 healthy normal controls, 28 individuals with nonfamilial cutaneous malignant melanoma (CMM) and 14 people with familial occurrence of CMM. Lymphocytes from 40 healthy controls, 40 CMM patients and 6 individuals with familial CMM were also compared for spontaneous expression of micronuclei in vitro. In the familial cases micronucleus frequency was found to be higher, both in cultured fibroblasts (P less than 0.005) and in lymphocytes (P less than 0.001) as compared to normal controls. There was no significant difference between nonfamilial cases and normal controls. We conclude that chromosomal instability may contribute to a genetic risk for development of cutaneous malignant melanoma.

Familial clustering of scleroderma spectrum disease

This is the second case report of familial scleroderma (systemic sclerosis) in South Carolina. The family includes two cases of scleroderma meeting American Rheumatism Association criteria, one of systemic sclerosis sine scleroderma, and two other cases of undifferentiated connective tissue disease with features of scleroderma spectrum disorders; there are also two cases of Raynaud's phenomenon (one associated with rheumatoid arthritis), for a total of seven affected relatives. Evidence of scleroderma spectrum disorders was sought in six siblings of the two co-index cases and in 23 of the 35 offspring. Laboratory studies included antinuclear antibody determinations and typing for the following genetic markers: HLA (A, B, C, DR), complotypes, Gm and Km allotypes, and alpha-1 antitrypsin phenotypes. No common genetic markers restricted to affected members of this family were found, and no environmental exposures were detected that could explain this familial clustering of cases. This report should, however, add to the slowly accumulating information on the genetic characteristics of families at unusually high risk for scleroderma spectrum disorders. Positive antinuclear antibody tests at a titer of 1/40 or higher were present in 57 percent of the first-degree relatives of the affected cases.

Chromosome abnormalities in peripheral blood lymphocytes from untreated Hodgkin's patients. A possible evidence for chromosome instability

We describe the presence of a high frequency of spontaneous chromosome aberrations in lymphocytes from six untreated patients with Hodgkin's disease. The characteristics of the chromosome abnormalities observed suggest the existence of a certain degree of chromosome instability in these cases, that could be a predisposing factor for the development of malignancies.

Genetic predisposition to cancer with special reference to mutagen sensitivity

From studies on cancer genetics, available information suggests the following tentative conclusions: 1. Cancer starts with a genetic change (or changes) from a normal somatic cell, but the changes (mutational events) must be specific in a target tissue cell. In a number of cases, genetic changes can be detected at the chromosome level. 2. Hereditary cancers usually have one genetic lesion already existing prezygotically; therefore only one additional mutational event is required in the homologous gene to complete the process of neoplastic transformation. In nonhereditary neoplasms, both mutations must occur postzygotically. 3. Individuals with high spontaneous mutation rates (monitored by chromosome breakage rates) are more liable to acquire specific genetic lesions than those with low mutation rates; therefore they are at higher risk to develop neoplasms. 4. Individuals with genetic defects in response to damage induced by mutagens (carcinogens) are more liable to accumulate genetic lesions than those who are more resistant; therefore, they are more liable to develop cancers. Mutagen sensitivity or resistance is probably genetic expression of DNA repair capabilities. 5. An effective assay method for sensitivity or resistance to mutagens can be developed to analyze the human population to identify the at-risk fraction.

Spontaneous chromosomal aberrations in patients with precancerous and cancerous lesions of the cervix uteri

Chromosomal aberrations were studied in metaphases from peripheral blood cultures of 52 women with cancer of the cervix uteri, 89 cases of various grades of cervical precancerous lesions, and 47 age-matched normal (control) women. The frequency of metaphases with chromosome and chromatid aberrations was 17.24% in cancer patients, 10.41% in those with precancerous lesions, and 6.39% in control women. There was a significant (p less than 0.001) increase in the frequency of chromosome aberrations in patients with cervical precancerous and cancerous lesions, compared with controls. After the exclusion of the treated cases, cancer patients also revealed a highly significant (p less than 0.001) increase in the frequency of chromosome aberrations, compared with controls. The results of the present study indicate the existence of chromosomal instability in the majority of cervical cancer patients and in some cases of precancerous lesions. The increased frequency of spontaneous chromosome aberrations in patients with precancerous lesions may be of importance for the understanding of their biological behavior.

The immunopathology of progressive systemic sclerosis (PSS)

Progressive systemic (sclerosis) is one of the most enigmatic of the rheumatic diseases. It is a connective tissue disorder of unknown etiology characterized by fibrosis in skin and internal organs. Although similar lesions are found with increased prevalence in workers exposed to coal, gold, silica, and polyvinyl chloride, most patients have had no known predisposing factors. Select reports of a familial occurrence of PSS have been observed but a definitive genetic basis is lacking and no clear associations with the major histocompatability complex have been demonstrated. Moreover, although a variety of immunologic abnormalities in patients with PSS have been reported, they are generally diffuse and non-diagnostic. Such abnormalities include defects in cell mediated immunity, increases in sera immunoglobulins, antinuclear antibodies, and cryoglobulins. In contrast to these non-specific findings, there appears to be significant evidence of a relationship between cell mediated immunity to collagen and appearance of scleroderma. For example, peripheral blood lymphocytes in patients with scleroderma undergo lymphocyte transformation when cultured with specific collagen preparations. The pathology of skin and internal organs in PSS generally reflects both collagen deposition and small vessel occlusion. All organ systems may be involved but mortality significantly increases with involvement of heart, kidney, or lung. Unfortunately, at present a reliable experimental model of PSS has not been found although similar immunopathology can be induced in homologous disease of rats and in chronic graft vs host disease of humans.

Chromosome breakage and sister chromatid exchange frequencies in scleroderma

Peripheral lymphocytes from 3 scleroderma patients with systemic disease and from 3 normal controls were examined for frequencies of chromosomal aberration and sister chromatid exchange (SCE). Significant increases in the levels of chromosomal anomaly and SCE were found for all 3 patients. These results are discussed in terms of the diagnostic potential of SCE in scleroderma and the possible etiologic role of cytogenetic instability in this disease.

Characterization of a spontaneous disease of white leghorn chickens resembling progressive systemic sclerosis (scleroderma)

University of California, Davis (UCD) line 200 White Leghorn Chickens spontaneously develop a syndrome that has many analogous features to human progressive systemic sclerosis. This syndrome is characterized by progressive involution of comb, dermal fibrosis, and distal polyarthritis. These three features occur within 6 wk after hatching, and are accompanied by a 40% mortality as a result of vaso-occlusive disease, with development of secondary infection of peripheral gangrenous lesions. Birds that survive greater than 2 mo after hatching progressively develop fibrosis of the esophagous and mononuclear infiltration of heart and kidney, with prominent occlusion of small and medium sized blood vessels. In addition, line 200 chickens develop rheumatoid factors, antinuclear antibodies, and antibodies to collagen, but do not have antibodies to thymocytes, DNA, or extractable nuclear antigens. Moreover, antinuclear antibodies when studied using HEp-2 cells as substrate demonstrate predominantly a speckled pattern. This syndrome of line 200 chickens is not detectable in F1 crosses to several UCD inbred lines. F1 X parental line BC1 backcrosses have an approximately 50% incidence of disease, suggesting that this syndrome is inherited as autosomal recessive. However, only 4% of F2 generation birds show abnormal symptoms, suggesting the presence of modifying genes. There is no appearance of IgG deposition, as determined by immunofluorescence, in either skin, blood vessels, esophagus, or heart. However, approximately 20% of chickens have a glomerulonephritis; this feature appears to be a terminal event and does not appear clinically significant. Although this syndrome of line 200 chickens has several features that are in sharp distinction to human scleroderma, the presence of common immunologic and pathologic denominators suggest that this spontaneous disease may be an appropriate model to develop a better understanding of autoimmune connective tissue diseases.

Mechanism of photosensitivity in systemic lupus erythematosus patients

Patients who have systemic lupus erythematosus have increased numbers of chromosome breaks and rearrangements correlated with a low molecular weight chromosome-damaging agent that is released from their lymphocytes into the serum. This clastogenic factor also produces chromosome breaks and sister chromatid exchanges in healthy persons' lymphocytes when they are incubated in the presence of lupus patients' serum or lymphocytes or purified factor. The lymphocytes from lupus patients are sensitive to near-UV (360- to 400-nm light. This sensitivity seems to be related to the presence of the clastogenic factor in these cells; lymphocytes of healthy persons exposed to the factor also become sensitive to light of the same wavelengths. A significant increase in nonviable cells (trypan blue exclusion test) was observed after 5 min of irradiation with 360- and 380-nm light in the presence of the factor. The number of chromosome aberrations observed after stimulation of the irradiated lymphocytes with phytohemagglutinin was also maximal after irradiation at 380 nm in presence of the factor. The combined action of near-UV light plus clastogenic factor was inhibited by superoxide dismutase if the enzyme were present during irradiation, suggesting that activation involves photoproduction of superoxide ions. Irradiation of the purified factor and immediate addition of it to lymphocytes gave the same results whereas preirradiation of cells or of medium was without effect. The presence of this photoactivated agent explains why patients who have lupus erythematosus show an aggravated condition after exposure to sunlight and the appearance of typical skin lesions.

The influence of culture medium composition on the incidence of chromosomal breakage

In patients with chromosomal instability and healthy subjects, significant differences were observed in the chromosomal breakage incidence in simultaneous lymphocyte cultures set up with TC medium 199, Eagle's Minimum Essential Medium, or RPMI, or RPMI 1629. The importance of the choice of culture medium for mutagenicity testing and studies of so-called spontaneous breakage is shown. Cultures incubated with TC Medium 199 showed the highest chromosomal breakage incidence.

Chromosomal breakage in Crohn's disease: anticlastogenic effect of D-penicillamine and L-cysteine

The incidence of chromosome breakage was found to be elevated in 42 patients with Crohn's disease. This phenomenon was much more striking in cultures set up with TCM 199 than in cultures set up with RPMI 1629 rich in L-cysteine. The drug D-penicillamine, a close analog of L-cysteine, gave an apparent therapeutic response in several patients and reduced the chromosome breakage frequency in the lymphocytes of these patients in vitro and in vivo.

Acute myelofibrosis in progressive systemic sclerosis. Report of a case developing during long term chlorambucil therapy and discussion of pathogenetic factors

A case of acute myelofibrosis occurring in the course of long-term chlorambucil therapy for cardiac manifestations of progressive systemic sclerosis (PSS) is reported. Although hematologic malignancies have been known to develop consequent to long-term use of alkylating agents, and bone marrow suppression is well known, acute myelofibrosis has not, to our knowledge, been reported as a complication of this therapy, nor has any specific myeloproliferative syndrome been described consequent to such therapy in a patient with PSS. As abnormal fibroblastic proliferation is central to both PSS and myelofibrosis, it may be speculated that the patient with scleroderma may be predisposed to this particular expression of hematologic dyscrasia. The roles of fibroblastic proliferation, and immunologic and vascular factors in these two illnesses are currently poorly understood.