Cellular Manifestations Research Articles

Intermolecular Failure of L-type Ca2+ Channel and Ryanodine Receptor Signaling in Hypertrophy

Pressure overload–induced hypertrophy is a key step leading to heart failure. The Ca2+-induced Ca2+ release (CICR) process that governs cardiac contractility is defective in hypertrophy/heart failure, but the molecular mechanisms remain elusive. To examine the intermolecular aspects of CICR during hypertrophy, we utilized loose-patch confocal imaging to visualize the signaling between a single L-type Ca2+ channel (LCC) and ryanodine receptors (RyRs) in aortic stenosis rat models of compensated (CHT) and decompensated (DHT) hypertrophy. We found that the LCC-RyR intermolecular coupling showed a 49% prolongation in coupling latency, a 47% decrease in chance of hit, and a 72% increase in chance of miss in DHT, demonstrating a state of “intermolecular failure.” Unexpectedly, these modifications also occurred robustly in CHT due at least partially to decreased expression of junctophilin, indicating that intermolecular failure occurs prior to cellular manifestations. As a result, cell-wide Ca2+ release, visualized as “Ca2+ spikes,” became desynchronized, which contrasted sharply with unaltered spike integrals and whole-cell Ca2+ transients in CHT. These data suggested that, within a certain limit, termed the “stability margin,” mild intermolecular failure does not damage the cellular integrity of excitation-contraction coupling. Only when the modification steps beyond the stability margin does global failure occur. The discovery of “hidden” intermolecular failure in CHT has important clinical implications.

IKr and IKs remodeling differentially affects QT interval prolongation and dynamic adaptation to heart rate acceleration in bradycardic rabbits

Bradycardic ventricular electrical remodeling predisposes to lethal tachyarrhythmias. We investigated the early temporal sequence and reversibility of electrical remodeling in a rabbit complete heart block model subjected to bradycardic ventricular pacing for either 2 or 8 days, with a third group of animals undergoing 8 days of bradycardic pacing followed by 8 days of physiological-rate pacing. At specified time points after complete heart block induction and pacing initiation, steady-state QT interval measurements and variability as well as dynamic QT interval adaptation to abrupt heart rate acceleration were assessed in the absence and presence of isoproterenol. Rapidly (I(Kr)) and slowly (I(Ks)) activating delayed rectifier repolarizing K(+) tail current densities were evaluated using whole cell patch clamp in isolated right ventricular myocytes. Steady-state QT interval prolongation at both 2 and 8 days was associated with moderate I(Kr) reduction. I(Ks) downregulation was apparent by day 2 but more profound at day 8. Dynamic QT interval adaptation was impaired under baseline conditions at day 8 but only during isoproterenol administration at day 2. Both in vivo and cellular manifestations of remodeling reverted toward control values after 8 days of physiological-rate pacing. In conclusion, in this bradycardic model, I(Ks) downregulation 1) proceeds more gradually but more extensively than that of I(Kr) and 2) is most prominently associated with impaired dynamic QT interval adaptation to heart rate acceleration. Isoproterenol blunts the dynamic QT interval response in animals with partially downregulated I(Ks), consistent with stress-related phenomena in known I(Ks)-impaired states. Relative early sparing of I(Ks) could explain the delay in the onset of lethal tachyarrhythmia predisposition in bradycardic electrical remodeling. Reversibility of remodeling supports the potential utility of preventive pacing intervention soon after bradycardia onset.

Radioadaptive response and genomic instability: a phenotypic dichotomy of genome–environment interaction

There emerged an upsurge of concern on the diverse cellular response to radiation which was new to the existing paradigm of radiobiology. They include adaptive response, genomic instability, bystander effect, pseudocytokine effect and apoptosis. Their molecular mechanism and health consequences are largely unknown. However, accumulated data indicate that they are all cellular manifestations of programmed adaptive mechanism intrinsic to the organisms for the existence of life either by epistatic response to minimize the negative impact (adaptive response) or by remodeling their genome (genomic instability). The cells have efficient damage sensing and signaling mechanisms for dose-dependent blanching cooperated by protein kinase C (PKC), p38 mitogen-activated protein kinase (p38MAPK) and phospholipase C (PLC) with p53 protein as a downstream effector. The signals are transferred to the bystander cells for orchestrated response. For the adaptive response to have an effect in vivo, two hits must be present within a limited time in a cell or a mass of bystander cells. This determines a minimum effective dose rate, below which remodeling of genome in tissue by apoptotic removal of cells with potentially genotoxic damage may be the prevailing mechanism for modulating radiation effect. Dose refractoriness of chromosome aberrations of stem cell origin in human low dose-rate exposures is consistent with this model.

Adverse drug reactions, transcription factors and transcriptomics

It is currently believed that most idiosyncratic adverse drug reactions arise because of enzymatic modification of the parent drug structure to produce reactive chemical intermediates. However, there is very little direct evidence that can link the formation of a reactive metabolite with a particular idiosyncratic adverse drug reaction. Further study is required to understand the relationship between metabolic bioactivation, induction of oxidative stress and the particular pathways underlying the biological response. In particular, an understanding of the early processes in cellular signalling and defensive manifestations after oxidative insult may help determine the final outcome, i.e. recovery or toxicity. A stress response is initiated when the reductive capacity of a cell, or specialised compartment within a cell, becomes compromised. This could be via depletion of the first line of cellular defences such as glutathione or ascorbate, or by oxidation of critical sulphydryl groups on the surface of redox-sensitive proteins. Once detected, the cell activates the expression of genes involved in antioxidant response. This `switching-on' of gene expression is performed by transcription factors that encode for specific groups of genes that contain the particular transcriptional response element within the promoter region of the gene. Through the profiling of transcription factors and the subsequent genetic regulation, after oxidative insult or exposure to reactive chemical species, we will gain an insight into the underlying biological pathways. Using this information we can identify areas for potential therapeutic modulation as well as obtaining more detailed and predictive toxicity fingerprints for informative decision-making during the drug development process.

The mitochondrial-lysosomal axis theory of aging: accumulation of damaged mitochondria as a result of imperfect autophagocytosis.

Cellular manifestations of aging are most pronounced in postmitotic cells, such as neurons and cardiac myocytes. Alterations of these cells, which are responsible for essential functions of brain and heart, are particularly important contributors to the overall aging process. Mitochondria and lysosomes of postmitotic cells suffer the most remarkable age-related alterations of all cellular organelles. Many mitochondria undergo enlargement and structural disorganization, while lysosomes, which are normally responsible for mitochondrial turnover, gradually accumulate an undegradable, polymeric, autofluorescent material called lipofuscin, or age pigment. We believe that these changes occur not only due to continuous oxidative stress (causing oxidation of mitochondrial constituents and autophagocytosed material), but also because of the inherent inability of cells to completely remove oxidatively damaged structures (biological 'garbage'). A possible factor limiting the effectiveness of mitochondial turnover is the enlargement of mitochondria which may reflect their impaired fission. Non-autophagocytosed mitochondria undergo further oxidative damage, resulting in decreasing energy production and increasing generation of reactive oxygen species. Damaged, enlarged and functionally disabled mitochondria gradually displace normal ones, which cannot replicate indefinitely because of limited cell volume. Although lipofuscin-loaded lysosomes continue to receive newly synthesized lysosomal enzymes, the pigment is undegradable. Therefore, advanced lipofuscin accumulation may greatly diminish lysosomal degradative capacity by preventing lysosomal enzymes from targeting to functional autophagosomes, further limiting mitochondrial recycling. This interrelated mitochondrial and lysosomal damage irreversibly leads to functional decay and death of postmitotic cells.

Cellular manifestations of human papillomavirus infection in laryngeal tissues

Cellular manifestations of human papillomavirus infection in laryngeal tissues

Cellular manifestations of human papillomavirus infection in laryngeal tissues.

Although epidemiologic studies have suggested human papillomavirus (HPV) to be an etiological agent in laryngeal carcinogenesis, little is known on the cellular manifestations of HPV infection in these tumors. In this study, we investigated the frequency of HPV infection in various neoplastic and non-neoplastic laryngeal tissue and its association with expression of the proliferating cell nuclear antigen (PCNA) and the tumor suppressor protein p53. Tissues were analyzed by polymerase chain reaction (PCR) for the presence of HPV and by immunocytochemistry for the expression of p53 and PCNA. None of the six normal laryngeal tissues showed the presence of HPV. Thirteen out of the 16 papillomas were positive for HPV, while 15 out of the 44 invasive cancers were HPV positive. PCNA expression increased as the lesion progressed through increasing histological abnormality (r = 0.64400, P = 0.00000). The correlation between the type of laryngeal neoplasm and p53 accumulation was significant (r = 0.54839, P = 0.00000). Significant correlation was also evident between presence of HPV and p53 accumulation (r = 0.34259, P = 0.00424) and PCNA expression (r = 0.036024, P = 0.00266) indicating that HPV positive tumors showed significant p53 accumulation and increased proliferation. There was also correlation between p53 and PCNA expression (r = 0.67475, P = 0.00000) indicating that in all tumors with p53 accumulation, there was a corresponding increase in PCNA expression. The results suggests that changes in p53 and PCNA expression may be associated with HPV infection, and could play a role in laryngeal carcinogenesis.

Role of cyclin kinase inhibitor p21 in systemic autoimmunity.

The cyclin kinase inhibitor protein p21 affects multiple processes relevant to the immune system, including cell cycle progression, replicative senescence, hemopoietic stem cell quiescence, and apoptosis. Therefore, malfunction of this protein may be a contributor to the pathogenesis of systemic autoimmunity. Here, we report that mixed background p21-deficient 129/Sv x C57BL/6 mice showed increased in vitro and in vivo T cell cycling and activation, moderate hypergammaglobulinemia and, at low penetrance, anti-chromatin autoantibodies. Homeostatic anti-self MHC/peptide ligand-induced proliferation of p21-deficient T cells was also enhanced. However, lymphoid organ enlargement was very mild, presumably due to increased apoptosis of the rapidly dividing cells. Moreover, the older p21-deficient mice had kidney pathology representing a similar, but slightly more advanced, state than that seen in the control mice. The timing and severity of the above serologic, cellular, and histologic manifestations in p21-deficient mice were unaffected by gender. Thus, p21 deficiency significantly enhances T cell activation and homeostatic proliferation, and can induce mild autoimmune manifestations at a low incidence without gender bias, but does not in itself generate the full spectrum of lupus-like disease.

Cellular aspects of SDHD mutations in head and neck paragangliomas

Introduction. Mutations in the SDHD gene, a nuclear gene encoding for a mitochondrial protein involved in oxidative phosphorylation, are responsible for the majority of hereditary head and neck paragangliomas. The aim was characterization of cellular manifestations of SDHD mutations in paragangliomas. Methods. Tumours of patients with and without inherited mutations were examined using electron microscopy, enzyme histochemistry and immunohistochemistry. Results. Ultrastructurally, large numbers of mitochondria with disturbed morphology were detected. In almost all cases, the SDH enzyme activity was virtually absent. The expression of two catalytic proteins in the SDH complex displayed two general patterns: the flavo protein was strongly upregulated, whereas the iron protein was reduced in the tumour cells. However, in some cases deviations from these patterns in enzyme activity and protein expression were observed. Conclusion. Cellular aspects of SDHD mutations are composed of increased numbers of mitochondria with disturbed morphology, reduced SDH enzyme activity and aberrant expression of catalytic components of the SDH complex. In some cases, deviations from these patterns are observed. Analysis of histopathological changes will lead to further understanding of the biology of paragangliomas and contribute to clinical treatment strategies in the future.

Eccentric exercise-induced injuries to contractile and cytoskeletal muscle fibre components.

Exercise involving lengthening of an activated muscle can cause injury. Recent reports documented the mechanics of exercise-induced muscle injury as well as physiological and cellular events and manifestations of injury. Loss of the cytoskeletal protein desmin and loss of cellular integrity as evidenced by sarcolemmal damage occur early during heavy eccentric exercise. These studies indicate that the earliest events in muscle injury are mechanical in nature, while later events indicate that it may be more appropriate to conclude that intense exercise initiates a muscle remodeling process. We conclude that muscle injury after eccentric exercise is differently severe in muscles with different architecture, is fibre type-specific, primarily because of fibre strain in the acute phase, and is exacerbated by inflammation after the initial injury.

Development and Characterization of A Recombinant Truncated Type VII Collagen “Minigene”: IMPLICATION FOR GENE THERAPY OF DYSTROPHIC EPIDERMOLYSIS BULLOSA

Dystrophic epidermolysis bullosa (DEB) is an inherited mechano-bullous disorder of skin caused by mutations in the type VII collagen gene. The lack of therapy for DEB provides an impetus to develop gene therapy strategies. However, the full-length 9-kilobase type VII collagen cDNA exceeds the cloning capacity of current viral delivery vectors. In this study, we produced a recombinant type VII minicollagen containing the intact noncollagenous domains, NC1 and NC2, and part of the central collagenous domain using stably transfected human 293 cell clones and purified large quantities of the recombinant minicollagen VII from culture media. Minicollagen VII was secreted as correctly-folded, disulfide-bonded, helical trimers resistant to protease degradation. Purified minicollagen VII bound to fibronectin, laminin-5, type I collagen, and type IV collagen. Furthermore, retroviral-mediated transduction of the minigene construct into DEB keratinocytes (in which type VII collagen was absent) resulted in persistent synthesis and secretion of a 230-kDa recombinant minicollagen VII. In comparison with parent DEB keratinocytes, the gene-corrected DEB keratinocytes demonstrated enhanced cell-substratum adhesion, increased proliferative potential, and reduced cell motility, features that reversed the DEB phenotype toward normal. We conclude that the use of the minicollagen VII may provide a strategy to correct the cellular manifestations of gene defects in DEB.

HIV-I-associated central nervous system dysfunction

Despite more than 15 years of extensive investigative efforts, a complete understanding of the neurological consequences of HIV-1 CNS infection remains elusive. Although the resources of numerous investigators have been focused on studies of HIV-1-associated CNS disease, the complex nature of the disease processes that underlie the clinical, pathological, and cellular manifestations of HIV-1 CNS infection have required a larger volume of studies than was initially envisioned. Several major areas remain as the focus of current research efforts. One of the more pressing issues facing researchers and clinicians alike is the search for correlates to the development of HIV-1-associated CNS neuropathology and the onset of HIVD. Although numerous parameters have been studied, none have been shown to be absolute predictors or markers of HIV-1-related CNS dysfunction. The identification of solid correlates of HIVD is an important goal that would permit clinical identification of individuals at risk for developing potentially crippling, life-threatening CNS abnormalities and would facilitate early treatment of nascent neurological problems. A more complete comprehension of the cellular foundations of CNS dysfunction and HIVD is also a fundamental part of strategies designed to treat or prevent HIV-1-associated CNS disease. Future investigations will strive to expand the body of knowledge concerning the complex interactions between infected and uninfected neuroglial cells and the roles of numerous cytokines, chemokines, and other soluble agents that are deregulated during HIV-1 CNS infection. In particular, a thorough understanding of the mechanisms of neurotoxicity may facilitate the development of new therapies that alleviate or eliminate the clinical consequences of CNS infection. Finally, investigators will continue to study HIVD within the context of single and combination drug therapies used in the treatment of HIV-1 infection and AIDS. As newer and more effective systemic treatments for HIV-1 infection and AIDS are introduced, the effects of these treatments on the onset, incidence, and severity of HIVD will also require intensive study. The impact of drug therapies on the ability of the CNS to act as an HIV-1 reservoir will also need to be addressed. Introduction of each new drug or drug combination will necessitate studies of drug penetration into the CNS and efficacy against the development of CNS abnormalities. Furthermore, as more effective treatments prolong the lifespan of individuals infected with HIV-1, the impact of extended survival on the occurrence and severity of HIVD will also require further investigations. The quest for answers to these and other questions will be complicated by the diversity of experimental systems used to study different aspects of HIV-1 CNS infection and HIVD. Each system has its own unique strengths and weaknesses. Clinical observations provide a continuous spectrum of symptomatic findings but reveal little about the underlying mechanisms of disease. In vivo imaging techniques, such as CT and MRI, also provide a continuum of observations, but the images are limited in their resolution. Neuropathological examinations of postmortem HIV-1-infected brains offer gross, cellular, and molecular views (including phenotypic and genotypic analyses of CNS viral isolates) of the diseased brain, but only provide a snapshot of the end-stage neurologic dysfunction. Studies that rely on animal surrogates for HIV-1, including SIV, simian-HIV (SHIV), feline immunodeficiency virus (FIV), visna virus, and HIV-1 SCID-hu models, permit experimental protocols that cannot be carried out in humans, but are limited by the fidelity with which each virus and animal model emulates the conditions and events observed in the human host. Finally, in vitro techniques, which include the use of primary cells and cell lines, adult or fetal human cell cultures, and BBB barrier model systems, are also convenient means by which aspe

BLADDER TREATMENT: Immunotherapy and Chemotherapy

The urinary bladder is affected by numerous treatments, including surgery, chemotherapy radiotherapy, photodynamic and laser therapy, and immunotherapy. The literature on therapy for bladder cancer is abundant but tends to offer little information concerning the tissue and cellular manifestations related to treatment. A variety of changes in urothelial cells may be seen on urinary cytology or biopsy. Therapy-associated cytologic abnormalities remain the most common cause of false-positive reports in urothelial cytology. Most pathologic changes are characterized by an exuberant inflammatory reaction, blood vessel abnormalities, and degenerative/regenerative urothelial atypia; none of these findings are diagnostic of the outcome of a specific therapy.

Cellular manifestations of human papillomavirus infection in the oral mucosa.

Human papillomavirus infection has been suggested to play a role in the development of epithelial carcinomas, particularly those of the uterine cervix. Less information is available on the role of the virus in oral lesions. It has been proposed that the viral oncoproteins specifically complex with the products of cellular tumor suppressor gene, namely E6 with p53 and E7 with retinoblastoma gene product. Inactivation or mutation in p53 gene is also known to result in loss of control over the cell cycle and increases in tumor proliferation rates. The present study examines the role of HPV infection in relation to p53 and the extent of the tumor proliferative compartment reflected by cyclin D1 and Ki-67 expression during various phases of tumor progression in the oral epithelium. Nonisotopic in situ hybridization (NISH) was performed to detect HPV 6/11 and 16/18. Expression of p53, cyclin D1, Ki-67, and the HPV 16/18 E6 protein were detected by immunocytochemistry. There was significant correlation between the extent of histological abnormality and HPV infection. A correlation (r = 0.250, P = 0.0089) was evident between the presence of HPV 16 and occurrence of invasive cancer. Expression of the tumor suppressor p53 protein also showed significant positive correlation with histology (r = 0.475, P = 0.00004). The tumor proliferative fraction also increased with the extent of histological abnormality (r = 0.387, P = 0.0003 for cyclin D1 and r = 0.463, P = 0.0001 for Ki 67). Accumulation of p53 and increase in tumor proliferation also correlated to the presence of HPV infection (r = 0.511, P = 0.00003 for p53; r = 0.478, P = 0.00002 for cyclin D1 and r = 0.521, P = 0.00004 for Ki-67). The present study thus demonstrates the importance of HPV infection in oral tissue. Expression of the high-risk HPV 16/18 E6 protein also appears to be a critical event along with aberrant p53 expression. These results are of significance to the molecular epidemiology of oral cancer and may also be used to supplement and elaborate the diagnosis of oral lesions.

Immune responses to inflammation and trauma: a physical training model

Physical activity and training have some potential as tools for examining immune responses to inflammation and trauma. Contributors to the present symposium review various aspects of the inflammatory process, including issues of lymphocyte recirculation and endotoxemia. They examine also the extent and nature of the immune disturbances induced by acute and chronic exercise and consider parallels between such responses and cellular manifestations of clinical sepsis. Factors modulating immune responses during physical activity include changes in the circulating levels of various cytokines, alterations in nutritional status, an altered expression of adhesion molecules, and the possible intervention of reactive species. Factors that can exacerbate exercise-induced changes include exposure to adverse environments, particularly hot conditions, and disturbances of the normal sleep-wakefulness cycle. Current research in exercise immunology finds clinical application in attempts to regulate aging, acute viral infections, and neoplasia.Key words: cold exposure, environmental stress, heat exposure, high altitudes, immunosuppression.

Immune responses to inflammation and trauma: a physical training model.

Physical activity and training have some potential as tools for examining immune responses to inflammation and trauma. Contributors to the present symposium review various aspects of the inflammatory process, including issues of lymphocyte recirculation and endotoxemia. They examine also the extent and nature of the immune disturbances induced by acute and chronic exercise and consider parallels between such responses and cellular manifestations of clinical sepsis. Factors modulating immune responses during physical activity include changes in the circulating levels of various cytokines, alterations in nutritional status, an altered expression of adhesion molecules, and the possible intervention of reactive species. Factors that can exacerbate exercise-induced changes include exposure to adverse environments, particularly hot conditions, and disturbances of the normal sleep-wakefulness cycle. Current research in exercise immunology finds clinical application in attempts to regulate aging, acute viral infections, and neoplasia.

Diagnostic cytology of the uterine cervix: a major contribution and classic reference in gynecologic cytopathology.

Diagnostic cytology of the uterine cervix: a major contribution and classic reference in gynecologic cytopathology.

Ultra-low doses of naltrexone or etorphine increase morphine's antinociceptive potency and attenuate tolerance/dependence in mice

In previous studies we showed that low (pM) concentrations of naloxone (NLX), naltrexone (NTX) or etorphine selectively antagonize excitatory, but not inhibitory, opioid receptor-mediated functions in nociceptive types of sensory neurons in culture. Cotreatment of these neurons with pM NTX or etorphine not only results in marked enhancement of the inhibitory potency of acutely applied nM morphine [or other bimodally-acting (inhibitory/excitatory) opioid agonists], but also prevents development of cellular manifestations of tolerance and dependence during chronic exposure to μM morphine. These in vitro studies were confirmed in vivo by demonstrating that acute cotreatment of mice with morphine plus a remarkably low dose of NTX (ca. 10 ng/kg) does, in fact, enhance the antinociceptive potency of morphine, as measured by hot-water tail-flick assays. Furthermore, chronic cotreatment of mice with morphine plus low doses of NTX markedly attenuates development of naloxone-precipitated withdrawal-jumping in physical dependence assays. The present study provides systematic dose-response analyses indicating that NTX elicited optimal enhancement of morphine's antinociceptive potency in mice when co-administered (i.p.) at about 100 ng/kg together with morphine (3 mg/kg). Doses of NTX as low as 1 ng/kg or as high as 1 μg/kg were still effective, but to a lesser degree. Oral administration of NTX in the drinking water of mice was equally effective as i.p. injections in enhancing the antinociceptive potency of acute morphine injections and even more effective in attenuating development of tolerance and NLX-precipitated withdrawal-jumping during chronic cotreatment. Cotreatment with a subanalgesic dose of etorphine (10 ng/kg) was equally effective as NTX in enhancing morphine's antinociceptive potency and attenuating withdrawal-jumping after chronic exposure. These studies provide a rationale for the clinical use of ultra-low-dose NTX or etorphine so as to increase the antinociceptive potency while attenuating the tolerance/dependence liability of morphine or other conventional bimodally-acting opioid analgesics.

Na + -H + Exchange and Essential Hypertension

Enhanced activity of the ubiquitous (housekeeping) isoform of the Na+-H+ exchanger (NHE-1) is expressed in circulating cells from a subset of patients with essential hypertension (reviewed in Reference 11 ). This results from differences in pathways regulating exchanger function, since no mutations have been shown in the NHE-1 gene in patients with essential hypertension.2 3 A 1993 report by Rosskopf et al4 demonstrated that this phenotype persisted in immortalized lymphoblasts generated with Epstein-Barr virus from the lymphocytes of patients with essential hypertension. The lymphoblasts from hypertensive patients also showed an increased proliferation rate compared with those from normotensive subjects. Since these cells can be easily obtained from patients and maintained indefinitely in tissue culture, the findings of Rosskopf et al signaled the arrival of a new approach to studying the cellular manifestations of essential hypertension. In this issue of Hypertension , Ng and colleagues5 confirm the original findings of Rosskopf et al and provide important clues as to the molecular basis for the elevated NHE-1 activity in essential hypertension. These investigators show that the enhanced exchange activity is caused by an increased turnover of the exchanger itself and that this is associated with an increased phosphorylation of the NHE-1 protein. An additional finding reported by Ng et al is that the increased NHE-1 activity is also expressed in immortalized lymphoblasts from subjects who are normotensive but have a family history of essential hypertension. There are several technical differences in the study of Ng et al5 and the previous study. Rosskopf et al4 selected hypertensive and control subjects primarily on …

Immunological characterization of (tight skin/NZB)F1 hybrid mice with connective tissue and autoimmune features resembling human systemic sclerosis.

A new murine model of Systemic Sclerosis (SSc) has been developed by breeding the Tsk+/+pa tight skin mouse (TSK) and the autoimmune disease-prone NZB strain to produce an F1 hybrid displaying the connective tissue abnormalities of the TSK parent and the autoimmune abnormalities of the NZB parent. The interscapular skin thickness in the (TSK/NZB)F1 was significantly greater than in the (+pa/NZB)F1 litter mates. Protein biosynthesis in skin punch biopsies was over 3.5 times higher in the (TSK/NZB)F1 mice than in controls. Hydroxyproline analyses confirmed that the increase in protein synthesis was primarily in collagen. These (TSK/NZB)F1 mice were tested for a number of cellular and humoral autoimmune manifestations. Autoantibodies, including antinuclear antibodies (ANA) and anti-DNA, were present in their sera, and the proliferative response to autologous lymphocyte stimulation (AMLR) was decreased as is commonly observed in murine and human autoimmune disorders. These results indicate that the (TSK/NZB)F1 mice display connective tissue and immunologic abnormalities resembling those present in human SSc and, therefore, these mice may be a valuable model for the study of the disease.