Tissue inhibitors of metalloproteinases are proteolytic targets of matrix metalloproteinase 9

Extracellular proteolysis and turnover are core processes of tissue homeostasis. The predominant matrix-degrading enzymes are members of the Matrix Metalloproteinase (MMP) family. MMPs extensively degrade core matrix components in addition to processing a range of other factors in the extracellular, plasma membrane, and intracellular compartments. The proteolytic activity of MMPs is modulated by the Tissue Inhibitors of Metalloproteinases (TIMPs), a family of four multi-functional matrisome proteins with extensively characterized MMP inhibitory functions. Thus, a well-regulated balance between MMP activity and TIMP levels has been described as critical for healthy tissue homeostasis, and this balance can be chronically disturbed in pathological processes. The relationship between MMPs and TIMPs is complex and lacks the constraints of a typical enzyme-inhibitor relationship due to secondary interactions between various MMPs (specifically gelatinases) and TIMP family members. We illustrate a new complexity in this system by describing how MMP9 can cleave members of the TIMP family when in molar excess. Proteolytic processing of TIMPs can generate functionally altered peptides with potentially novel attributes. We demonstrate here that all TIMPs are cleaved at their C-terminal tails by a molar excess of MMP9. This processing removes the N-glycosylation site for TIMP3 and prevents the TIMP2 interaction with latent proMMP2, a prerequisite for cell surface MMP14-mediated activation of proMMP2. TIMP2/4 are further cleaved producing ∼14 kDa N-terminal proteins linked to a smaller C-terminal domain through residual disulfide bridges. These cleaved TIMP2/4 complexes show perturbed MMP inhibitory activity, illustrating that MMP9 may bear a particularly prominent influence upon the TIMP:MMP balance in tissues.

Abstract 2354: Regulation of TIMPs through MMP dependent cleavage in breast cancer

Tissue Inhibitors of Matrix Metalloproteinases (TIMPs) are a broadly expressed family of matrisome proteins that are the primary regulators of matrix metalloproteinases (MMPs). In addition to their originally described function, TIMPs display a broad range of MMP independent biological functions associated with proliferation, apoptosis, migration, and differentiation. MMPs are zinc containing endopeptidases that play an essential role in maintaining the extracellular matrix (ECM) through proteolytic turnover; a balancing act maintained (in part) by the local MMP:TIMP ratio. Disturbances in the balance between MMPs and TIMPs is associated with various disease states, including cancer, heart disease, arthritis, and cognitive dysfunction. While TIMPs are classically characterized as regulators of MMP proteolytic activity, we describe a novel mode of MMP-dependent regulation of TIMP function. We show that active MMP9 (aMMP9) in molar excess can cleave TIMP proteins within their C-terminal domains. As a result of this cleavage, the MMP-dependent and MMP-independent functions of the TIMP proteins are predicted to be altered. MMP9 has been found to contribute to the pathogenesis of many cancer types including breast cancer. Additionally, MMP9 is described as a breast cancer biomarker, with high levels of MMP9 being associated with a worse prognosis. Previous research from our lab has shown recombinant TIMP2 may represent a novel biological therapeutic in triple negative breast cancer models. Utilizing murine models of breast cancer, we describe the prevalence of TIMP cleavage in 4T1 breast tumors as well as the functional outcomes of TIMP cleavage within this model system. Studying the outcomes of TIMP regulation by MMPs may allow researchers to target this model system more effectively in translational studies of breast cancer.

Citation Format: Sasha Coates-Park, Sadeechya Gurung, Josh Rich, William Stetler-Stevenson, David Peeney. Regulation of TIMPs through MMP dependent cleavage in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2354.

Individual and poly-substance use and condomless sex among HIV-uninfected adults reporting heterosexual sex in a multi-site cohort

BACKGROUND

We analyzed the association between substance use (SU) and condomless sex (CS) among HIV-negative adults reporting heterosexual sex in the Seek, Test, Treat, and Retain (STTR) consortium. We describe the impact of SU as well as person/partner and context-related factors on CS, identifying combinations of factors that indicate the highest likelihood of CS.

METHODS

We analyzed data from four US-based STTR studies to examine the effect of SU on CS using two SU exposures: 1) recent SU (within 3 months) and 2) SU before/during sex. Behavioral data were collected via 1:1 or self-administered computerized interviews. Adjusted individual-study, multivariable relative risk regression was used to examine the relationship between CS and SU. We also examined interactions with type of sex and partner HIV status. Pooled effect estimates were calculated using traditional fixed-effects meta-analysis. We analyzed data for recent SU (n = 6781; 82% men, median age = 33 years) and SU before/during sex (n = 2915; 69% men, median age = 40 years).

RESULTS

For both exposure classifications, any SU other than cannabis increased the likelihood of CS relative to non-SU (8-16%, p-values< 0.001). In the recent SU group, however, polysubstance use did not increase the likelihood of CS compared to single-substance use. Cannabis use did not increase the likelihood of CS, regardless of frequency of use. Type of sex was associated with CS; those reporting vaginal and anal sex had a higher likelihood of CS compared to vaginal sex only for both exposure classifications (18-21%, p < 0.001). Recent SU increased likelihood of CS among those reporting vaginal sex only (9-10%, p < 0.001); results were similar for those reporting vaginal and anal sex (5-8%, p < 0.01). SU before/during sex increased the likelihood of CS among those reporting vaginal sex only (20%; p < 0.001) and among those reporting vaginal and anal sex (7%; p = 0.002). Single- and poly-SU before/during sex increased the likelihood of CS for those with exclusively HIV-negative partners (7-8%, p ≤ 0.02), and for those reporting HIV-negative and HIV-status unknown partners (9-13%, p ≤ 0.03).

CONCLUSION

Except for cannabis, any SU increased the likelihood of CS. CS was associated with having perceived HIV-negative partners and with having had both anal/vaginal sex.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

The academic-practice gap: Strategies for an enduring problem

The academic-practice gap in nursing is well documented. Academe is criticized for producing nurses insufficiently prepared to fully participate in patient care. Practice settings are criticized for having unrealistic expectations of new graduates. This article is based on a review of the literature and an exploration of contemporary practices used to bridge academic and practice partnerships. Differences in outcome expectations for new graduates between academe and practice are outlined and consequences of the gap for new graduates, patients, and employers are discussed. Five specific strategies to address the gap are discussed, with the primary realm and responsibility for two falling to education, one to practice, and two to both. Strategies discussed include increased use of simulated learning in nursing education; disruptive innovations in education that promote learner-centered active learning; extended orientation/Transition to Practice Programs for new graduates; dedicated education units; and academic service partnerships. Current literature suggests the viewpoints of academic and practice leaders continue to appear divergent. Closing the gap will require a dedicated and coordinated response from both academe and clinical practice.

One-pot synthesis of nanochain particles for targeting brain tumors

To synthesize multi-component nanochains, we developed a simple 'one-pot' synthesis, which exhibited high yield and consistency. The nanochains particles consist of parent nanospheres chemically linked into a higher-order, chain-like assembly. The one-pot synthesis is based on the addition of two types of parent nanospheres in terms of their surface chemical functionality (e.g., decorated with PEG-NH₂ or PEG-COOH). By reacting the two types of parent nanospheres at a specific ratio (∼2 : 1) for a short period of time (∼30 min) under rigorous stirring, nanochains were formed. For example, we show the synthesis of iron oxide nanochains with lengths of about 125 nm consisting of 3-5 constituting nanospheres. The chain-like shaped nanoparticle possessed a unique ability to target and rapidly deposit on the endothelium of glioma sites via vascular targeting. To target and image invasive brain tumors, we used iron oxide nanochains with the targeting ligand being the fibronectin-targeting peptide CREKA. Overexpression of fibronectin is strongly associated with the perivascular regions of glioblastoma multiforme and plays a critical role in migrating and invasive glioma cells. In mice with invasive glioma tumors, 3.7% of the injected CREKA-targeted nanochains was found in gliomas within 1 h. Notably, the intratumoral deposition of the nanochain was ∼2.6-fold higher than its spherical variant. Using MR imaging, the precise targeting of nanochains to gliomas provided images with the exact topology of the disease including their margin of infiltrating edges and distant invasive sites.

Suicidal ideation reported by adults with Type 1 or Type 2 diabetes: results from Diabetes MILES-Australia

AIMS

To examine the prevalence and correlates of suicidal ideation (SI) in a community-based sample of adults with Type 1 or Type 2 diabetes.

METHODS

Participants were 3338 adults aged 18-70 years with Type 1 diabetes (n = 1376) or Type 2 diabetes (non-insulin: n = 1238; insulin: n = 724) from a national survey administered to a random sample registered with the National Diabetes Services Scheme. Depression and SI were assessed using the Patient Health Questionnaire, and diabetes-specific distress with the Problem Areas In Diabetes scale. Separate logistic regression analyses by diabetes type/treatment were used to determine relative contribution to SI.

RESULTS

Overall, we observed a SI rate of 14% in our sample. Participants with Type 2 diabetes using insulin reported more frequent depressive symptoms, and were more likely to report recent SI (19%) compared with those with either Type 1 diabetes or Type 2 diabetes not using insulin (14 and 12%, respectively). After controlling for depression, there was little difference in the prevalence of SI between diabetes types/treatments, but higher diabetes-specific distress significantly increased the odds of SI.

CONCLUSIONS

As SI is a significant risk factor for a suicide attempt, the findings have implications for healthcare professionals, pointing to the importance of adequate screening and action plans for appropriate follow-up of those reporting depression. Our findings are also indicative of the psychological toll of diabetes more generally, and the need to integrate physical and mental healthcare for people with diabetes.

In Vivo Behavior of Poly(∈-Caprolactone-co-DL-Lactide)/Bioactive Glass Composites in Rat Subcutaneous Tissue

In this study, tissue reactions and possible toxicological responses of two different bioactive and degradable composite materials consisting of poly( ∈-caprolactone-co-DL-lactide) and bioactive glass (S53P4) granules were evaluated. The chosen materials were implanted subcutaneously in the back of rats for six months. The glass granules retained their bioactivity within the polymer matrices. A fibrous capsule formed around all tested materials and around the materials containing bioactive glass the fibrous capsules appeared to be thicker. Tissue growth into these materials was observed during the healing period while no growth was noticed into the plain polymer matrices. No adverse reactions were seen with any of the evaluated materials.