PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Integrin alpha2”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources

Specific residues within the alpha 2 integrin subunit cytoplasmic domain regulate migration and cell cycle progression via distinct MAPK pathways.

The alpha(2) integrin subunit cytoplasmic domain is necessary for epidermal growth factor (EGF)-stimulated chemotactic migration and insulin-dependent entry into S-phase of mammary epithelial cells adherent to type I collagen. Truncation mutants revealed that the seven amino acids, KYEKMTK, in addition to the GFFKR motif were sufficient for these functions. Mutation of tyrosine 1134 to alanine inhibited the ability of the cells to phosphorylate p38 MAPK and to migrate in response to EGF but had only a modest effect on the ability of the cells to induce sustained phosphorylation of the ERK MAPK, to up-regulate cyclin E and cdk2 expression, and to enter S-phase when adherent to type I collagen. Conversely, mutation of the lysine 1136 inhibited the ability of the cells to increase cyclin E and cdk2 expression, to maintain long term phosphorylation of the ERK MAPK, and to enter S-phase but had no effect on the ability of the cells to phosphorylate the p38 MAPK or to migrate on type I collagen in response to EGF. Methionine 1137 was essential for both migration and entry into S-phase. Thus, distinctly different structural elements of the alpha(2) integrin cytoplasmic domain are required to engage the signaling pathways leading to cell migration or cell cycle progression.

Amino Acid Sequence↗

Structural analysis of the alpha(2) integrin I domain/procollagenase-1 (matrix metalloproteinase-1) interaction.

Previous studies have established that ligation of keratinocyte alpha(2)beta(1) integrin by type I collagen induces expression of matrix metalloproteinase-1 (MMP-1) and that MMP-1 activity is required for the alpha(2)beta(1) integrin-dependent migration of primary keratinocytes across collagenous matrices. We now present evidence that MMP-1 binds the alpha(2)beta(1) integrin via the I domain of the alpha(2) integrin subunit. Using an enzyme-linked immunosorbent assay with purified human MMP-1 and recombinant alpha(2) integrin I domain, we showed that the alpha(2) integrin I domain specifically bound in a divalent cation-dependent manner to both the pro and active forms of MMP-1, but not to MMP-3 or MMP-13. Although both the I domain and MMP-1 bind divalent cations, MMP-1 bound, in a divalent cation-dependent manner, to alpha(2) integrin I domains containing metal ion-dependent adhesion sites motif mutations that prevent divalent cation binding to the I domain, demonstrating that the metal ion dependence is a function of MMP-1. Using a series of MMP-1-MMP-3 and MMP-1-MMP-13 chimeras, we determined that both the linker domain and the hemopexin-like domain of MMP-1 were required for optimal binding to the I domain. The alpha(2) integrin/MMP-1 interaction described here extends an emerging paradigm in matrix biology involving anchoring of proteinases to the cell surface to regulate their biological activities.

Antigens, CD↗

Structural and functional analysis of integrin alpha2I domain interaction with echovirus 1.

Integrins are cell surface receptors for several microbial pathogens including echovirus 1 (EV1), a picornavirus. Cryo-electron microscopy revealed that the functional domain (alpha(2)I) of human alpha(2)beta(1) integrin binds to a surface depression on the EV1 capsid. This three-dimensional structure of EV1 bound to alpha(2)I domain provides the first structural details of an integrin interacting with a picornavirus. The model indicates that alpha(2)beta(1) integrin cannot simultaneously bind both EV1 and the physiological ligand collagen. Compared with collagen binding to the alpha(2)I domain, the virus binds with a 10-fold higher affinity but in vitro uncoating of EV1 was not observed as a result of attachment of alpha(2)I. A molecular model, constructed on the basis of the EV1-integrin complex, shows that multiple alpha(2)beta(1) heterodimers can bind at adjacent sites around the virus 5-fold symmetry axes without steric hindrance. In agreement with this, virus attachment to alpha(2)beta(1) integrin on the cell surface was found to result in integrin clustering, which can give rise to signaling and facilitate the initiation of the viral entry process that takes place via caveolae-mediated endocytosis.

Capsid↗

Ets-dependent regulation of target gene expression during megakaryopoiesis.

Megakaryopoiesis is the process by which hematopoietic stem cells in the bone marrow differentiate into mature megakaryocytes. The expression of megakaryocytic genes during megakaryopoiesis is controlled by specific transcription factors. Fli-1 and GATA-1 transcription factors are required for development of megakaryocytes and promoter analysis has defined in vitro functional binding sites for these factors in several megakaryocytic genes, including GPIIb, GPIX, and C-MPL. Herein, we utilize chromatin immunoprecipitation to examine the presence of Ets-1, Fli-1, and GATA-1 on these promoters in vivo. Fli-1 and Ets-1 occupy the promoters of GPIIb, GPIX, and C-MPL genes in both Meg-01 and CMK11-5 cells. Whereas GPIIb is expressed in both Meg-01 and CMK11-5 cells, GPIX and C-MPL are only expressed in the more differentiated CMK11-5 cells. Thus, in vivo occupancy by an Ets factor is not sufficient to promote transcription of some megakaryocytic genes. GATA-1 and Fli-1 are both expressed in CMK11-5 cells and co-occupy the GPIX and C-MPL promoters. Transcription of all three megakaryocytic genes is correlated with the presence of acetylated histone H3 and phosphorylated RNA polymerase II on their promoters. We also show that exogenous expression of GATA-1 in Meg-01 cells leads to the expression of endogenous c-mpl and gpIX mRNA. Whereas GPIIb, GPIX, and C-MPL are direct target genes for Fli-1, both Fli-1 and GATA-1 are required for formation of an active transcriptional complex on the C-MPL and GPIX promoters in vivo. In contrast, GPIIb expression appears to be independent of GATA-1 in Meg-01 cells.

Base Sequence↗

The fibril-associated collagen IX provides a novel mechanism for cell adhesion to cartilaginous matrix.

Collagen IX is the prototype fibril-associated collagen with interruptions in triple helix. In human cartilage it covers collagen fibrils, but its putative cellular receptors have been unknown. The reverse transcription-PCR analysis of human fetal tissues suggested that based on their distribution all four collagen receptor integrins, namely alpha1beta1, alpha2beta1, alpha10beta1, and alpha11beta1, are possible receptors for collagen IX. Furthermore primary chondrocytes and chondrosarcoma cells express the four integrins simultaneously. Chondrosarcoma cells, as well as Chinese hamster ovary cells transfected to express alpha1beta1, alpha2beta1, or alpha10beta1 integrin as their only collagen receptor, showed fast attachment and spreading on human recombinant collagen IX indicating that it is an effective cell adhesion protein. To further study the recognition of collagen IX we produced recombinant alphaI domains in Escherichia coli. For each of the four alphaI domains, collagen IX was among the best collagenous ligands, making collagen IX exceptional compared with all other collagen subtypes tested so far. Rotary shadowing electron microscopy images of both alpha1I- and alpha2I-collagen IX complexes unveiled only one binding site located in the COL3 domain close to the kink between it and the COL2 domain. The recognition of collagen IX by alpha2I was considered to represent a novel mechanism for two reasons. First, collagen IX has no GFOGER motif, and the identified binding region lacks any similar sequences. Second, the alpha2I domain mutations D219R and H258V, which both decreased binding to collagen I and GFOGER, had very different effects on its binding to collagen IX. D219R had no effect, and H258V prevented type IX binding. Thus, our results indicate that collagen IX has unique cell adhesion properties when compared with other collagens, and it provides a novel mechanism for cell adhesion to cartilaginous matrix.

Amino Acid Sequence↗

Platelet interactions with liposomes carrying recombinant platelet membrane glycoproteins or fibrinogen: approach to platelet substitutes.

Liposomes carrying both recombinant platelet membrane glycoproteins GPIa/IIa (rGPIa/IIa) and GPIb alpha (rGPIb alpha) (rGPIa/IIa-Ib alpha-liposomes), or fibrinogen (Fbg-liposomes) were prepared. Their interactions with platelets on a collagen surface under flow conditions were evaluated using a recirculating flow chamber, mounted on an epifluorescence microscope, which allows for real-time visualization of fluorescence-labeled liposomes or platelets interacting with the surface. Adhesion of platelets to the collagen surface increased with increasing the shear rate from 600 to 2400 s(-1). Also, the percentages of surface coverage of rGPIa/IIa-Ib alpha-liposomes or Fbg-liposomes increased with increasing platelet adhesion. These phenomena were attenuated by a peptide containing arginine-glycine-aspartic acid (RGD-peptide), or prostaglandin E1 (PGE), but not by a peptide containing arginine-glycine-glutamic acid (RGE-peptide). In a homogeneous solution, rGPIa/IIa-Ib alpha-liposomes and Fbg-liposomes enhanced platelet aggregation in a dose-dependent manner, as evaluated using an aggregometer. These findings suggest that rGPIa/IIa-Ib alpha-liposomes and Fbg-liposomes form aggregates at the site of injury in blood vessels, resulting in stationary adhesion together with activated platelets.

Antigens, CD↗

PDGF induction of alpha 2 integrin gene expression is mediated by protein kinase C-zeta.

Platelet-derived growth factor (PDGF) stimulates fibroblasts to move over collagen and contract three-dimensional collagen gels, processes important in wound repair and fibrocontractive diseases. These processes depend on alpha 2 beta 1 integrin ligation of collagen and PDGF induces the expression of this integrin. Several lines of evidence presented here suggest that PKC-zeta plays a role in alpha 2 integrin gene expression. The induction was blocked by chemical inhibitors for protein tyrosine kinases (PTK), genistein, and protein kinase C (PKC), chelerythrine, and bisindolylmaleimide GF 109203X. Cells depleted of phorbol 12-myristate 13-acetate (PMA)-inducible PKCs by chronic treatment with PMA still demonstrated an alpha 2 response to PDGF indicating that a non-PMA-sensitive PKC isoform was required. PDGF induced kinase activity in PKC-zeta immunoprecipitates. Antisense oligonucleotides complementary to 5' end of PKC-zeta mRNA sequences blocked the PDGF-induced increase of alpha 2 mRNA levels up to 70%, indicating PKC-zeta, a non-PMA-sensitive PKC isoform, is a component of the PDGF stimulatory pathway for alpha 2 mRNA synthesis. A 961-base pair (bp) upstream region of alpha 2 gene/CAT construct transfected into human dermal fibroblasts was positively regulated by PDGF as judged by CAT enzymatic levels. Both PTK and PKC inhibitors blocked PDGF-stimulation of the alpha 2 promoter fragment/CAT construct, indicating that the phosphorylation requirement occurred at alpha 2 promoter-directed transcription level. Therefore, we propose that PDGF-stimulatory pathway of alpha 2 integrin gene expression involves multiple cellular protein kinases, one of which is PKC-zeta.

Adult↗

Plasma Proteomic Profiling Reveals ITGA2B as A Key Regulator of Heart Health in High-altitude Settlers.

Myocardial injury is a common disease in the plateau, especially in the lowlanders who have migrated to the plateau, in which the pathogenesis is not well understood. Here, we established a cohort of lowlanders comprising individuals from both low-altitude and high-altitude areas and conducted plasma proteomic profiling. Proteomic data showed that there was a significant shift in energy metabolism and inflammatory response in individuals with myocardial abnormalities at high altitude. Notably, integrin alpha-Ⅱb (ITGA2B) emerged as a potential key player in this context. Functional studies demonstrated that ITGA2B upregulated the transcription and secretion of interleukin-6 (IL-6) through the integrin-linked kinase (ILK)/nuclear factor-κB (NF-κB) signaling axis under hypoxic conditions. Moreover, ITGA2B disrupted mitochondrial structure and function, increased glycolytic capacity, and aggravated energy reprogramming from oxidative phosphorylation to glycolysis. Leveraging the therapeutic potential of traditional Chinese medicine in cardiac diseases, we discovered that tanshinone ⅡA (TanⅡA) effectively alleviated the myocardial injury caused by the abnormally elevated expression of ITGA2B and hypobaric hypoxia exposure in mice, thus providing a novel candidate therapeutic strategy for the prevention and treatment of high-altitude myocardial injury.

Animals↗

The cytolytic activity of natural killer cells is not involved in the restriction of Mycobacterium avium growth.

Severe combined immunodeficiency (SCID) mice were used to analyze the role of NK cells in resistance to Mycobacterium avium. The neutralization of IFN-gamma in these animals led to an exacerbation of the infection associated with a reduction in macrophage activation, suggesting a role for NK cells in innate immunity to mycobacteria. In contrast, administration of anti-asialo-GM(1) polyclonal serum or mAb specific for Thy1.2 did not affect mycobacterial growth or macrophage activation despite causing the almost complete abrogation of the natural cytolysis of a tumor cell target. Treatment with anti-asialo-GM(1)-specific serum depleted only two-thirds of the Thy1.2+ spleen cells, and anti-Thy1.2 treatment allowed for the persistence of a small number of cells still exhibiting an NK cell marker recognized by mAb DX5 and able to express IFN-gamma as analyzed by flow cytometry. In vivo treatment of B6.SCID mice with anti-NK1.1 mAb again failed to affect resistance to infection and allowed for the persistence of 2-8% of IFN-gamma-producing cells, many of them still expressing the DX5 marker. In vitro depletion studies showed that removal of IFN-gamma-expressing cells required the combined action of anti-Thy1.2, anti-Ly49C and DX5 antibodies in the presence of complement. Our data show that resistance to M. avium mediated by NK cells is independent of their cytolytic activity, and that there is a marked phenotypic and functional heterogeneity of the NK cell lineage in vivo during infection.

Animals↗

Spontaneous luteinization of antral marmoset follicles in vitro.

Large non-luteinized follicles of the marmoset monkey were cultured for up to 96 h in the presence of substances that are known to induce luteinization, i.e. LH, transforming growth factor (TGF)-beta and cyclic AMP. The state of the basal lamina, and the expression of connexin-43, alpha(2) integrin subunit and TGF-beta receptor type II (TbetaR-II) were chosen as parameters to judge the progress of luteinization. Antral follicles, cultured for 1 h, were not luteinized, as shown by an intact basal lamina, strong immunoreactivity of connexin-43 in granulosa cells, and no expression of TbetaR-II in the theca layer. After 12 h, most follicles showed a dissolution of the basal lamina, a faint reactivity of connexin-43, high expression of TbetaR-II in theca- and outer granulosa cells and high expression of alpha(2) integrin subunit in granulosa cells bordering at the basement membrane; all of which indicate luteinization. After 96 h of culture, luteal structures (e.g. corpora lutea accessoria) had developed. This was true for both non-stimulated and stimulated follicles. Our results strongly suggest that antral follicles luteinize spontaneously. The decisive determinant appears to be the follicular stage.

Animals↗

Regulation of tight junction proteins and bladder epithelial paracellular permeability by an antiproliferative factor from patients with interstitial cystitis.

PURPOSE: Previous reports have suggested that the bladder epithelial barrier may be compromised in interstitial cystitis (IC). Antiproliferative factor (APF) is a small glycoprotein made specifically by bladder epithelial cells in patients with IC that induces changes in expression of certain epithelial cell proteins and profoundly inhibits cell growth. Therefore, we confirmed the increased permeability and decreased tight junction formation of bladder epithelial cell monolayers grown from biopsies in patients with IC compared to cells from normal controls. We then determined the effect of APF on the permeability of normal bladder epithelial cell monolayers and the expression of tight junction proteins. MATERIALS AND METHODS: Permeability was determined by measuring the C-mannitol and H-inulin flux between cells in confluent monolayers on Transwell culture plates (Corning, Corning, New York). Tight junction formation was assessed by immunofluorescence microscopy and the expression of specific proteins was determined by Western blot. RESULTS: APF treatment caused significant increases in the paracellular permeability of normal bladder epithelial cell monolayers and the attenuation of tight junctions compared to mock APF, similar to changes seen in IC cells. APF treatment also decreased expression of the tight junction proteins zonula occludens-1 and occludin. CONCLUSIONS: Because of its apparent effects on bladder epithelial cell tight junctions and paracellular permeability in vitro, APF may contribute to the leakiness of the bladder epithelial barrier seen in IC.

Adolescent↗

807 C/T Polymorphism of the glycoprotein Ia gene and pharmacogenetic modulation of platelet response to dual antiplatelet treatment.

Glycoprotein (GP) Ia/IIa is a major platelet-collagen receptor playing a key role in thrombosis following collagen exposure. The 807 C/T polymorphism of the GP Ia gene (ITGA2) has been associated with platelet GP Ia/IIa receptor expression, having T-allele carriers, increased receptor density and thrombotic risk. The aim of the study was to assess the role of the 807 C/T polymorphism on modulating platelet function in patients undergoing coronary stenting receiving a 300 mg clopidogrel loading dose. Platelet aggregation was assessed in 44 patients by light transmittance aggregometry following adenosine diphosphate and collagen stimuli at baseline, and 10 min, 4 h and 24 h after clopidogrel front loading. The T allele was found in 73% of patients. Clopidogrel reduced adenosine diphosphate-induced platelet aggregation (P < 0.01), which was similar in carriers and non-carriers of the T allele throughout the study (P = 0.73). Clopidogrel reduced collagen-induced platelet aggregation only in non-carriers of the T allele (P = 0.03), which resulted in an increase in T allele carriers during the overall study (P = 0.04). In conclusion, the T allele of the GP Ia gene modulates platelet aggregation and clopidogrel antiplatelet effects, suggesting an enhanced reactivity to fibrillar collagens (exposed during coronary stenting) in T allele carriers and might contribute to an increased thrombotic risk in these patients.

Adenosine Diphosphate↗

Impact of disparity of minor histocompatibility antigens HA-1, CD31, and CD49b in hematopoietic stem cell transplantation of patients with chronic myeloid leukemia with sibling and unrelated donors.

Despite human leukocyte antigen (HLA) identity between donor and recipient, several patients develop acute graft-versus-host disease (aGVHD) after hematopoetic stem cell transplantation (HSCT) because of minor histocompatibility antigen (mHag) incompatibilities. The impact of multiple mHag disparities on the clinical outcome after HSCT still remains to be determined. We studied the genomic polymorphisms of HA-1, CD31, and CD49b and correlated mHag distribution with the occurrence of aGVHD after HSCT from HLA-matched sibling and unrelated donors. All 163 patients examined in our single-center study underwent HSCT for chronic myeloid leukemia in the first chronic phase. HA-1 and CD31 disparities are associated with increased aGVHD incidence in a subgroup of patients who test HLA-B44 supertype positive in univariate analysis. However, in a multivariate analysis, only increased patient age was confirmed as an independent aGVHD risk factor. Our findings indicate that the impact of mHag disparity on aGVHD development in HSCT from HLA-matched sibling and unrelated donors seems to be subordinated to classic aGVHD risk factors.

Adult↗

Natural killer cell activation after infection with lactate dehydrogenase-elevating virus.

Early after infection, lactate dehydrogenase-elevating virus (LDV) alters the immune system by polyclonally activating B lymphocytes, which leads to IgG2a-restricted hypergammaglobulinaemia, and by suppressing the secretion of Th2 cytokines. Considering that these alterations may involve cells of the innate immune system and cytokines such as interferon-gamma (IFN-gamma), we analysed the effect of LDV on natural killer (NK) cells. Within a few days of infection, a strong and transient NK cell activation, characterized by enhanced IFN-gamma message expression and cytolysis, was observed. LDV triggered a large increase in serum IFN-gamma levels. Because NK cells and IFN-gamma may participate in the defence against virus infection, we analysed their possible role in the control of LDV titres with a new agglutination assay. Our results indicate that neither the activation of NK cells nor the IFN-gamma secretion affect the early and rapid virus replication that follows LDV inoculation.

Animals↗

Platelet autoantibodies are common in hepatitis C infection, irrespective of the presence of thrombocytopenia.

OBJECTIVE: To investigate the generation of platelet antibodies in hepatitis C virus (HCV)-infected individuals and their relation to the development to thrombocytopenia with the aim of using their detection as a diagnostic aid of immune thrombocytopenia in these patients. MATERIALS AND METHODS: We tested by the monoclonal antibody-specific immobilization of platelet antigen assay (MAIPA) for the presence of platelet antibodies against specific glycoprotein (GP) targets (GPIIb/IIIa, GPIb/IX, GPIa/IIa, GPIIIb, GPV, and FcRgammaIIa) in 48 HCV-infected individuals of various stages of disease and compared the results with those from 35 patients with alcoholic liver cirrhosis. RESULTS: Thirty-two HCV-infected individuals (66%) had detectable platelet antibodies. The most common target was GPIIb/IIIa, but all other GP were also targets. Results were not different from patients with alcoholic liver cirrhosis. There was no correlation between antibodies and platelet counts, or the stage of disease, or the viral genotype, or a discernible influence of treatment with alpha-interferon. CONCLUSION: While platelet autoantibodies are common in individuals with HCV infection, their detection does not assist in the diagnosis of immune thrombocytopenia.

Adult↗

Induction of patching and its reversal on surface-activated human platelets.

Fibrinogen coupled to colloidal gold (Fgn/Au) has been used to follow GPIIb-IIIa receptors on surface-activated platelets and to evaluate the effects of the anti-actin agent, cytochalasin B (CB), on the movement of receptor-ligand complexes. Fgn/Au binds diffusely to spread platelets, but is translocated rapidly from the peripheral margin to cell centres and to channels of the open canalicular system (OCS). CB added after spreading and incubation with Fgn/Au reverses the centripetal movement of receptor-ligand complexes. Fgn/Au particles move back toward the margins of spread cells and form patches. The patches of receptor-ligand complexes overlie segments of the OCS filled with Fgn/Au. Washing out the CB reverses the process and receptor-ligand complexes are again translocated toward platelet centres.

Blood Platelets↗

Biosynthesis of FVIII in megakaryocytic cells: improved production and biochemical characterization.

Haemophilia A is an attractive target for gene therapy. We designed a haemophilia A gene therapy strategy involving the genetic modification of haematopoietic stem cells to achieve tissue-specific expression of a factor VIII (FVIII) transgene in the megakaryocytic lineage. Platelets would then serve as vehicles to store the expressed FVIII and deliver the coagulation factor at the site of vascular injury. A local correction of the haemostasis defect could, therefore, be expected following platelet activation and secretion. In this study, we demonstrated that a model of haematopoietic cell lines (Dami cells) could produce a correctly processed FVIII. FVIII transgenes were placed under the control of the human platelet glycoprotein IIb (GPIIb) promoter and used for stable transfection of the Dami megakaryocytic cell line. The highest FVIII production was obtained when the FVIII transgene contained a factor IX intron 1 gene sequence inserted in the FVIII intron 1 and 13 sites. Reverse transcription polymerase chain reaction demonstrated that the splicing of these introns was complete. Recombinant FVIII (rFVIII) produced in Dami cells was a biologically active molecule (specific activity: 5664 IU/mg) that was correctly glycosylated and sulphated. This recombinant FVIII protein exhibited biochemical characteristics after deglycosylation or thrombin activation that were comparable to a commercially available B-domainless rFVIII. These results demonstrate the advantages of a modified FVIII transgene and represent the first biochemical characterization of megakaryocyte-produced FVIII.

Bioreactors↗

Porphyromonas gingivalis-induced platelet aggregation in plasma depends on Hgp44 adhesin but not Rgp proteinase.

Evidence from recent epidemiological studies suggests a link between periodontal infections and increased risk of atherosclerosis and related cardiovascular and cerebrovascular events in human subjects. One of the major pathogens of periodontitis, Porphyromonas gingivalis, has the ability to aggregate human platelets in platelet-rich plasma (PRP). Mechanism of P. gingivalis-induced platelet aggregation in PRP was investigated. Proteinase inhibitors toward Arg-gingipain (Rgp) and Lys-gingipain (Kgp) did not suppress P. gingivalis-induced platelet aggregation in PRP, whereas the Rgp inhibitor markedly inhibited P. gingivalis-induced platelet aggregation using washed platelets. Mutant analysis revealed that P. gingivalis-induced platelet aggregation in PRP depended on Rgp-, Kgp- and haemagglutinin A (HagA)-encoding genes that intragenically coded for adhesins such as Hgp44. Hgp44 adhesin on the bacterial cell surface, which was processed by Rgp and Kgp proteinases, was essential for P. gingivalis-induced platelet aggregation in PRP. P. gingivalis cell-reactive IgG in plasma, and FcgammaRIIa receptor and to a lesser extent GPIbalpha receptor on platelets were found to be a prerequisite for P. gingivalis-induced platelet aggregation in PRP. These results reveal a novel mechanism of platelet aggregation by P. gingivalis.

Adhesins, Bacterial↗